Jim Lovelock, of the Gaia hypothesis (the idea of earthly life as a self-regulating organism, maintaining conditions, especially climate conditions, favorable to itself) thinks our civilization has had it. By 2100 perhaps 1 billion people will be left. I tend to agree with him but would put things a little later—200 million people by 2200. This is not necessarily a bad thing, except for those poor souls who must live through the demographic catastrophe. (We could of course engineer our own demographic collapse by limiting woman to one child. Population would fall to 1.6 billion by 2100 and the carbon problem would solve itself. How to do such a thing is a puzzler.)
Lovelock thinks we must start pulling carbon out of the atmosphere immediately to keep climate from flipping into a new, unfriendly regime. He may be right: for the last 650,000 years, the carbon dioxide content of the atmosphere has fluctuated between 180 and 300 parts per million. For the last 8000 years of most favorable climate that has seen the flowering of human agricultural civilizations, the carbon dioxide content of the atmosphere has fluctuated between 250 and 290 parts per million. It is now over 380 parts per million and growing by 1-2 parts per million every year.
Lovelock thinks the only reasonable way to sequester sufficient carbon from the atmosphere to stabilize the climate is to bury it. He thinks schemes like burying the carbon dioxide from burning coal are too expensive, too dangerous, too late and too little (and perhaps too nuts). Burying organic carbon has been proposed before: to cut forests and bury the trees in long ditches below the depth of decomposition, thus locking up their carbon. The forest regrows, storing more carbon in its trees, which are cut and buried again. The idea is also somewhat nuts but a variation on it is less nuts. Most of the carbon plants fix through photosynthesis is returned to the atmosphere, from where plants recycle it once again, every year. This amount of carbon dwarfs what we emit and a considerable amount of it is fixed by crop plants. We could take such carbon—corn stalks; grain straw; food waste; waste wood, such as old pallets, or demolition waste—and turn it, through a low oxygen combustion, into charcoal, and then, instead of burying the charcoal, spread it on the fields that grew it. Charcoal was used 1000 years ago by native farmers in the Amazon Basin to improve their soils, which otherwise would grow crops for only a year or two after being cleared. Most of the nutrients in tropical forest soils are stored in the vegetation: when that is removed and the ash from burning the trees leached away, few nutrients are left. When charcoal is added with ash (producing charcoal makes some ash and puts some carbon dioxide into the atmosphere), the charcoal provides a place for nutrients to attach, prevents leaching and encourages the growth of bacteria that increase the soil’s biomass. So-called Amazonian “black earths” contain charcoal, plant wastes, human urine and manure, fish guts and bones, broken pots. The fields were huge compost heaps. Present day peasant farmers in the Amazon seek out old black earths to farm, since their soils are much more fertile than the surrounding ones. Charcoal remains stable for 50,000 years. So the carbon remains locked up from the atmosphere for that time.
This method gives farmers a way of fertilizing their fields and storing a measured amount of carbon, for which they could be compensated. Natural grasslands store carbon more or less permanently in their soils (as long as the sod isn’t broken, perhaps half a ton to a ton an acre a year) but this gives grain farmers a way to do it too. How long one could keep adding carbon is unclear but black earths in the Amazon range from a foot to eight feet deep. Will we do it? I doubt it. It’s too sensible, too easy and too nuts.
Well I’m off for two weeks. No more posts for a while. Gotta keep up my carbon footprint, lower my winter heating bills. Suppose airline passengers paid $50 a ton for farmers to store carbon as charcoal, then they could fly guilt free.
Saturday, January 31, 2009
The Price of Gas and Car Mileage
What to do about the price of gas? Certainly $4 gas made people think about their cars’ mileage. Prius sales boomed and then collapsed when gas went down to $2. Gas will go back up when the world economy recovers. The only way to keep fuel prices (per mile) low is to manufacture much more efficient cars. We could create a demand for such cars by maintaining gas at $4 per gallon with a tax, rebated in a progressive way, with perhaps some siphoned off to support carbon reducing schemes (public transportation, buying up old inefficient cars, subsidizing the purchase of very efficient cars). In the short run, this would still be terrible for a large part of the American population, who would have to pay for the gas long before receiving their rebate checks.
It would be simpler to put a tax of 10 cents a gallon on gas, rising yearly by 10 cents a gallon for 25 years. Instituted now, such a tax would hardly be noticeable. After 25 years gas would cost at least $4-$5 a gallon, probably—if the world economy recovers—more like $10. But by then, with luck, cars will be getting 100-150 miles per gallon, so, depending on the price of the cars, driving would be cheaper (or at least not more expensive) than now. Monies from the tax would go to support carbon reducing schemes, such as those listed above, perhaps including the subsidizing of solar panels, perhaps the development of very efficient cars.
While developing cars that get 100-200 miles to the gallon is not technically difficult, it is politically difficult to get there. Europeans pay over $5 a gallon for gas, have excellent public transportation systems and still drive everywhere in cars that are more efficient than ours but not that much more efficient. Almost all freight in Europe moves by truck rather than rail. Together with the gas tax, we would have to have rising fuel efficiency goals. A low but steadily increasing gas tax would focus our eyes on the goal.
During the last 30 years the country has lost a sense of community—that we are all in this together. I always felt that most strongly when I lived in New York City. But we are all in this together, not only as members of separate countries, but as inhabitants of the planet, and we will all share in earth’s pleasures and vicissitudes.
It would be simpler to put a tax of 10 cents a gallon on gas, rising yearly by 10 cents a gallon for 25 years. Instituted now, such a tax would hardly be noticeable. After 25 years gas would cost at least $4-$5 a gallon, probably—if the world economy recovers—more like $10. But by then, with luck, cars will be getting 100-150 miles per gallon, so, depending on the price of the cars, driving would be cheaper (or at least not more expensive) than now. Monies from the tax would go to support carbon reducing schemes, such as those listed above, perhaps including the subsidizing of solar panels, perhaps the development of very efficient cars.
While developing cars that get 100-200 miles to the gallon is not technically difficult, it is politically difficult to get there. Europeans pay over $5 a gallon for gas, have excellent public transportation systems and still drive everywhere in cars that are more efficient than ours but not that much more efficient. Almost all freight in Europe moves by truck rather than rail. Together with the gas tax, we would have to have rising fuel efficiency goals. A low but steadily increasing gas tax would focus our eyes on the goal.
During the last 30 years the country has lost a sense of community—that we are all in this together. I always felt that most strongly when I lived in New York City. But we are all in this together, not only as members of separate countries, but as inhabitants of the planet, and we will all share in earth’s pleasures and vicissitudes.
Thursday, January 29, 2009
Commentary 1/29/09
I erased Chapter 1 while correcting it (according to John Batki's keen observations), so now the chapters are out of order. I posted chapters 3 and 4 because I won't be able to blog much until the middle of February.
Keep reading!
Keep reading!
The Natural History of the Present, Chapter 4
Chapter 4: A Little History of the Edible Landscape in North America
Where did the modern system of resource exploitation come from? Before the world was marketable, it was edible, and humans, like all plants and animals, were part of that world.
About 13,000 years ago, amidst the retreat of the glaciers that had covered much of northern North America, signs of human occupation appear. In some places, signs appear much earlier: in southern Chile perhaps 30,000 years ago, somewhat less in a cave in western Pennsylvania (the age of the Pennsylvania remains is still disputed). Some writers claim the diversity of North American Indian languages would have taken 50,000 years to evolve. In the present-day United States undisputed signs of people appear as fluted stone points embedded in the bones of the so-called Pleistocene megafauna, the larger (greater than a 100 pounds) grazers and browsers and their predators (also large) that inhabited that slightly earlier earth, 400 to 600 human generations removed from us. So-called Folsom points were found with the bones of ice-age bison in Folsom, New Mexico, and with those of woolly mammoths and mastodons in the Ohio Valley and in New York State. The eastern landscapes would have been just south of the glacier’s edge. During the next few thousand years most of these large animals would become extinct. (Some writers claim the extinctions occurred much faster, over a period of 300 years, from 13,200 to 12,900 years ago.) In North America the Pleistocene megafauna included species of hairy elephant like the herb-eating mammoth (animals of the tundra) and the forest-browsing mastadon, a fierce carnivorous bear (which some claim kept many people from crossing the Bering Plains), 4 genera of giant ground sloth, a large wolf, a tiger, several kinds of horse and donkey, a camel, a moose-elk, a tapir, a cheetah, 2 types of llama, a yak, a giant beaver, 3 kinds of ox. All these animals disappeared. Most of them were larger than those that succeeded them.
In the eastern half of North America, the area south of the glacial front was an open tundra of grasses and sedges, with scattered clumps of balsam poplar and black spruce. This belt was 50 to 100 miles wide. Modern deciduous trees like oak, hickory, beech and birch grew near the glacier in favorable locations (within 100 miles in the Northeast, 15 miles in south central Illinois), along with white-tailed deer. The tundra was more productive than the modern tundra because of its more southerly location and thus its warmer summers. The grassland extended south along the Appalachians to Georgia. Here, lower elevations supported an open and parklike boreal forest, with deciduous trees in south-facing coves. In Georgia this forest merged into a closed oak and hickory forest like that of the Middle West today. West of the Mississippi, the Plains and Southwest were wetter. Much of the Plains was a humid forest; the water in the Ogallala aquifer was still accumulating. Sea levels were 300 feet lower and grazing and browsing land extended some ways out onto the continental shelves, though less far off the coasts of North America than off those of Europe, whose shallow continental shelves were extensive. What would become cod banks in the Gulf of Maine were forested islands. The climate that favored the steppe was created by the mile-high ice, which held a constant high pressure system over it. This kept the climate cool and dry. As the glacier had advanced, trees had retreated south, finally reaching their so-called southern refugia. Trees move a few hundred to a thousand feet a year, depending on how they are dispersed (gravity, wind, the guts of seed-eating birds, the beaks of blue jays, the mouths of squirrels). Oaks in Europe returned north at 500 meters a year, in North America perhaps two-thirds of that, or 200 miles a millennium. (While jays will carry an acorn several kilometers in a trip, it takes several decades for that tree to bear acorns.) The seeds of North American wild ginger are dispersed by ants up to 35 meters a year, so ginger could theoretically move north only 10 to 11 kilometers (6 miles) in 16,000 years; but ginger probably moved north 450 kilometers (250 miles) in that time. Many herbs and trees seem to have moved faster than observation would support, an indication that uncommon occurrences (such as seed transport by floods, windstorms or tornadoes) become relatively common ones over a long period of time. Fish also retreated south along favorable drainages and disappeared from rivers and lakes under the ice. The north-south alignment of the Mississippi is one reason that river is so rich in fish species. But oak, hickory and white-tailed deer were found within a hundred miles of the glacial wall in New England; and oak, elm and ash (the last two nutrient-demanding species that require good soils) amidst clumps of black spruce within 15 miles of the glacier in south-central Illinois. Such trees would re-occupy the landscape when the climate ameliorated.
In North America, as the ice began to retreat, and incontrovertible signs of people appear, the Pleistocene megafauna began to disappear. Its disappearance was worldwide, except in Africa, where modern people and large animals evolved together. The extinctions took much longer in northern Eurasia, where people had also lived with the animals for a long time. Were the extinctions caused by people or the changing climate? People may have been new to the Americas but people had been hunting mammoths in central Europe and Russia for tens of thousands of years. In Australia and South America large mammal species also disappeared when humans arrived. In Australia this happened 50,000 years ago and corresponded with a long-term drying of the climate and also with the modification of the habitat by fire. Fire set by humans changed large portions of Australia’s semi-arid zone from a mosaic of trees, shrubs and grasslands to fire-adapted scrub. With the grassland also disappeared a large flightless bird and the marsupial lions and carnivorous kangaroos that preyed on it and a 7 meter long lizard. One of the more ingenious theories to explain the extinction of the Pleistocene megafauna in North America puts animal behavior, climate change and human predation together. As the glaciers retreat and the climate grows wetter (and more favorable to trees), the large grazers help maintain the grass, through the fertilizing effects of their dung and the constant re-creation of new grass shoots, whose high transpiration rates dry and oxygenate the soil. Mastodons, like modern elephants, fed on trees, breaking off branches and stripping bark. They kept forests open. Mammoths and mastodons recycle nutrients quickly, eating 250 to 300 pounds of vegetation a day, much of it of poor quality (that is, woody: only large animals with large fermenting stomachs can eat such poor quality vegetation). Thus they maintain the habitat. Continual hunting pressure reduces the number of large grazers somewhat. A relatively small kill rate may accomplish this since the large animals mature slowly and have widely spaced young. While in Asia, these animals had evolved with increasingly skilled human hunters, in North America game animals had lived without people for tens or hundreds of thousands of years and had little fear of them, and so, despite their size, may have been easy to hunt. As grazing pressure falls, parts of the grassland begin to be replaced by forbs and shrubs, then with willow, aspen, birch, black spruce. With a climate less and less favorable to grassland, and continuing predation on the large animals, such changes accelerate. At the same time a rapidly rising ocean eliminates more of the grazers’ habitat. So this scenario turns into a downward spiral for the grassland and its inhabitants. For the most part, the large animals were replaced by smaller modern grazers and browsers, all adapted to predation by man: the modern bison, elk, big-horn sheep. Many of these animals came with people across the Bering Strait. Because of the extinctions, some niches are still open. The Southwest could support more browsers on its thorny scrub. The fruits of some species of large-fruited trees in the American tropics are eaten nowadays only by a few species of large-beaked birds. Once they were eaten by elephants and their relatives (or several other genera of megafaunal fruiteaters), the seeds that survived passage through the animal’s gut getting a good start in a pile of dung. (This trick was used by a biologist to re-establish dry tropical forest in Central America; he fed the tree fruits to horses, who shed the seeds in their dung; the seeds sprouted in the manure.)
While the demise of large, tame animals under human hunting has happened in many places (California Indians eliminated large sea mammals from their coasts, New Zealand Polynesians the moas, the Australians their large mammals), matters may have been complicated in North America by a comet that struck 12,900 years ago. The explosion caused immense wildfires, and would have reduced or eliminated both the peoples of the Clovis culture and the large mammals on which those peoples depended. This would explain why Clovis points disappear abruptly from the fossil record about the time the comet struck, while stone points of a different make (reflecting another wave of immigration) appear some time later. The comet may also have triggered the massive release of glacial meltwater from the center of the continent to the North Atlantic that slowed the Gulf Stream, causing 1500 years of Younger Dryas cooling in Europe (12,800 to 11,500 years ago).
Deglaciation took 8000 years. It was a time of flood stories, biblical or Abenaki. The melting ice raised sea levels about 360 feet. During some periods the sea rose as much as 10 feet in 70 years; depending on the slope of the coastline, this could mean the sea moved inland hundreds of yards during a man’s lifetime. But there were more catastrophic events. One reading of the geological data indicates that approximately 7600 years ago, the rising waters of the Mediterranean broke through a natural dam in the Bosporus and flowed into the basin of the Black Sea. At that time the lands around the Black Sea were occupied by Neolithic farmers. The rising flood waters moved over the grainfields and villages of the lakeside plains at a quarter mile a day. The refilling of the Sea happened in a year or two. An alternative theory claims that the rise in the Sea was much slower and was caused by glacial meltwater draining into it from the north; and that the Black Sea then broke through the dam and flowed into the Mediterranean. At any rate a flood, and almost within sight of Ararat. Rising sea levels invaded Hudson’s Bay and floated the remains of the Laurentide ice sheet about 12,800 years ago. Icebergs sailed out through Hudson and Davis Straits and drifted 1900 miles across the Atlantic toward the coast of France, dropping behind them over the ocean floor the rocks and mud of the Bay that had been frozen to their bottoms, thus letting us read of their passage. The melting of the ice sheet changed the air circulation pattern over North America, and let a more modern climate develop. The glacial grassland of eastern North America became an open woodland of boreal conifers, with paper birch, balsam poplar, alder and willow; and then a forest of northern hardwoods, such as sugar and red maple, quaking aspen, and yellow birch, together with hemlock, red and white pine, and red spruce. The more nutrient-demanding species such as white ash, elm, and basswood arrived last. Some species, like red oak, continue to move north and upslope. Meanwhile the boreal conifers continued their move north, overshooting the modern treeline by 175 miles during the Hypsithermal, 9000 years ago, when the climate was warmer and drier than today. A fully modern climate was dependent on the return of the Gulf Stream, which was shut off by massive meltwater drainage into the North Atlantic during the final collapse of the North American ice sheet.
With the return of the Gulf Stream came the establishment of a modern air circulation pattern over North America. East of the Rocky Mountains the climate is controlled by three air streams: warm, moist air from the Gulf of Mexico; cold, dry air from the Canadian Arctic; and moderate maritime air from the Pacific. Precipitation in the East for most of the year depends largely on the converging streams from Canada and the Gulf, one cold and dry, one warm and moist, meeting along the axis of the jet stream. Summer precipitation is often convective: moisture rising from the sun-warmed landscape and transpired by trees and grasses condenses into clouds as it rises into the cooler upper atmosphere. Condensation occurs about marine salt particles and methyl sulfate nuclei produced by marine algae, as well as about other natural and industrial aerosols, and falls as rain. (Condensation droplets that form around sulfur dioxide particles from the burning of fossil fuels are usually too small to fall as raindrops and remain as clouds.) The Pacific air loses its moisture over the mountain chains of the western United States (the Sierra Nevada, the Rocky Mountains): thus the broad arrow of modern grassland that pushes east from the rain shadow of the Rockies over the plains of the Dakotas and the prairies of Illinois and Ohio into western Pennsylvania, and along the shores of the Great Lakes into New York State. With a modern climate, a modern forest developed in the eastern United States between 6000 and 8000 years ago. None of this is static; more warmth loving trees (oaks, hemlock, hickory, chestnut) kept moving north and upslope; and red spruce, a slightly more boreal species than its companions in the northern forest, and a signature tree of the higher elevations of the Appalachians during Euro-American settlement, only became abundant there 2000 years ago.
People had inhabited this landscape for at least 11,000 years. They had hunted the large animals and watched the glaciers retreat. They had begun to influence forests long before the trees came into equilibrium with their soils. Were these prairies, newly created, with their buffalo and elk, entirely natural? Some argue that by helping to eliminate the Pleistocene megafauna, human hunters also helped create the modern grazers, partly through hunting pressure, partly by opening the ecosystem to animals that migrated with the people from Eurasia. Hunting pressure by humans tends to favor early-maturing, smaller animals: the modern bison, as compared to the larger earlier species, whose bones are found at the bottoms of the boneyards beneath buffalo jumps. The grasslands of North America were once thought to be a creation of climate and topography alone; of atmospheric circulation patterns, a mountain rain shadow. Now it seems more likely that in parts of the landscape climate and topography only set the scene. Much of the Plains are too dry and windy for trees, and the wet prairies of Illinois were too wet for too long in the spring and then too dry in the late summer and fall; these wet prairies were inhabitated paradoxically by drought-resistant plants. But grazing (by buffalo, elk, bighorn sheep, prairie dogs) and browsing and grazing (by antelope and by jackrabbits in the drier short-grass and sagebrush steppes) as well as burning (by lightning strikes and Native Americans) maintained and extended the reach of the prairie. In part, both the landscape and the large grazers that inhabited it were man-made. Former prairies in Illinois or Minnesota that are not burned today are invaded by trees. Burning was a major tool of landscape modification by gathering and hunting peoples. Modern studies indicate that burning every 2 to 5 years maximizes prairie productivity. The Kentucky barrens (called barrens by the Americans because they were treeless) consisted of 6000 square miles of buffalo and elk pasture kept open by grazing and browsing by the animals and by burning by their Native American hunters. Some eastern prairie landscapes still existed at the time of European contact, when most of the natives who maintained them were already dead of European diseases. LaSalle saw buffalo grazing along the south shores of the Great Lakes. These would have been the Pennsylvania buffalo, larger and blacker than the Plains buffalo. There were still an estimated 12,000 of these animals in Pennsylvania in the 1700s. (Since the modern buffalo crossed the Mississippi in their movement east only 1000 years ago, these animals may have been there only a few hundred years.) Buffalo, New York, was named for a buffalo trail that went along Lake Erie. Such trails, following the easiest route between two points, may have been quite old; perhaps migrating mammoths laid out the original paths. At any rate, during a period of damper climate, burning would have held back the forests in places where they would have otherwise invaded. Thus the “oak openings” of Ohio and western Pennsylvania; the buffalo along the southern shores of the Great Lakes; the elk in Michigan and New York State; the populations of buffalo along parts of the Atlantic coastal plain. The oak scrub and blueberry barrens used by prairie chickens in New England and New York State were also maintained by fire, and may have been (like the vegetation on mountaintops) relics from glacial times, kept open by humans for their plants and animals. All these animal pastures, which had existed for thousands of years, many since the melting of the glaciers, would be cleared of wild animals in no time by the Euro-Americans, who had no intention of pasturing communally-owned wild animals. They were capitalists and agriculturists, with visions of a privately-owned landscape of barns, fields, woodlots, iron plantations, gristmills, cattle.
Edible landscapes provide food, shelter, clothes, tools and fuel in a renewable way, and in amounts that support a more or less constant human population. While the human population increased steadily up to the time of the adoption of agriculture 10,000 to 11,000 years ago, most of this increase is thought to have been because of the occupation of new habitats. For most of human time (perhaps 160,000 years), the landscape was renewable and edible; edibility was its function. A buffalo hunter sitting on the edge of the Plains in Wyoming a thousand years ago would have been aware of animal traps as far as he could see. A trap might consist of a log enclosure at the foot of a low bank. The animals would be driven over the bank into the pen; the injured, frantic animals caught inside were then speared, shot with arrows, battered with stone mauls, slashed with hatchets. Converging lines of piles of stones (the stones for the piles and the logs for the trap had to be gathered and carried by hand, perhaps for miles, from wherever they might be found) extended back from the brink of the bank for a thousand yards or more, forming a chute up which the animals would be driven. People would jump out from behind the stones waving hides to drive the beasts on. The problem for hunters on foot was getting the animals into the chute. Buffalo have poor vision but are curious and approachable upwind; one might decoy them by pretending to be buffalo, or wolves. In the early spring the grass near a chute might be burned: this would provide new grass to lure the animals. A tall enough bank or cliff wouldn’t need a pen since the animals would be sufficiently hurt in the fall so as not be able to escape. Some sites are quite old; some cliff drives have bones from the larger, Pleistocene bison that preceded the modern “dwarf” bison of the Plains. Hunting in this way was a group endeavor. Once dead, the animals had to be tended to immediately or their flesh would spoil. The meat from four adult bison (about 1600 pounds) would yield about 160 pounds of dried meat (depending on how dry one got it, the amount could be double that), which would keep for several months, and feed a family of six for two months on a ration of half a pound a person a day. (Fresh meat was consumed at six to eight pounds per person per day.) Most of the animal was used. The Plains Indians were buffalo gourmands: delicacies included the stomach contents (a sort of salad), unborn fetuses, the milk from nursing cows, bone marrow, nose gristle. Hunters in a hurry took only the hump and tongue. A green soup was made from drowned and rotten buffalo. What was left at a kill site, which would vary with the number of animals killed and the number of people and the state of their food supply, turned into bait for scavenging bears, wolves, golden eagles, coyotes, skunks, badgers, and bobcats, all of which fed and were ambushed at kill sites. The buffalo returned to the prairie not only through their dung and remains but through the dung and bodies of their predators. Cliff drives were undoubtedly wasteful, when more animals were killed than the people could use.
Animal traps varied with location and prey. The Pit River, the longest tributary of the Sacramento River of northern California, was named for the abundance of pit traps for deer (steep-sided holes in the ground, lightly covered with brush) in its valley. In historic times mountain sheep were trapped in pens in Rocky Mountain pastures by the Shoshone. The drives exploited the animals’ tendency to run down from a look-out area and then up again; and from there off a bank and into the pen. Nursing herds, which formed more tractable groups, were usually driven. Animals in the pen were killed with clubs, which have been found in caves. Eight thousand years before this, when the climate on the Plains was wetter, and some anthropologists think the hunters came by sailing canoe from Pacific islands rather than by foot across the Bering Strait, mountain sheep were netted with nets of juniper bark cordage. Nets 50 to 60 meters long and 1.5 to 2 meters high have been found folded in mountain caves. In the Great Basin, pronghorn antelope, which can be restrained by a visual fence, were lured into brushwood enclosures and driven round and round until exhausted, then clubbed to death. Their numbers in the Great Basin may have been kept artificially low by this method. On the North American taiga, frozen lakes were used to set up traps for caribou. The chute for the drive was made from small evergreens set out on the ice, the trap constructed in the forest on shore. Samuel Hearne reports trap enclosures reached a mile around and the chute would reach out for a mile or more. Openings in the trap’s brush fence were fitted with snares. Animals that weren’t snared were shot with bows and arrows or speared. If possible, in all these cases, no trapped animals were spared, as people thought that escaped animals would warn the others. Modern peoples of the eastern woodland, such as the Huron, drove white-tailed deer into similar pens, on land.
People who depended mostly on hunting and gathering moved often. Some of the plains hunters of the time before the horse moved every second or third day. Because of the lack of water, only the edges of the plains, along the rivers and creeks, were habitable. (But seasonal pools, seeps, and wallows were more abundant in the pre-settlement plains, letting individual hunters travel further.) The technology of drying meat was one of the things that made the lives of hunters on foot possible, as were dogs, used for transport. Whether such cultures had any effect on the numbers of game animals is uncertain. Before the plains hunters began trading with the Americans, their effect on the buffalo was probably negligible. Antelope may have been suppressed in the Great Basin, but probably not in California (where the Central Valley had a herd of a million or more animals). In the East some writers think the population of white-tailed deer was kept artificially low. The Iroquois take of deer has been estimated at 11,000 animals, while the annual deer kill in New York State by automobiles is now about 60,000 animals, and the herd numbers over a million; the kill by hunters is around 200,000. The farmed, logged-over and developed habitat of the State is now much more suitable for deer, which like most game animals prefer early successional (some would say partly destroyed) landscapes. (White-tailed deer are one of the few large mammals in North America more numerous now than at European contact.) But villages could keep the populations of game animals near them low.
Most hunters and gatherers get the bulk of their calories from gathering and the buffalo hunters also gathered wild plants: young stems and leaves of Balsamorrhiza and Chenopodium; bitter-root roots; sego lily bulbs; wild onions; fruits of chokecherry, buffalo berry, gooseberry. Such wild fruits, bitter-sweet and rich in vitamin C, would be beaten up with fat and dried meat into pemmican, a calorie-rich, easily transportable winter food. In the Great Basin, seeds of yucca, Indian ricegrass, wild rye, limber pine, saltbush, and Chenopodium were collected, the small-seeded grasses beaten off the stem into baskets, the pine cones with their large seeds collected before the seeds had fallen and let open in baskets or on mats in the sun or around the fire; some cones, like those of the sugar pine, were set alight so they would open and shed their seeds. Sometimes rodents collected the food: the Pawnee and Winnebago stole caches of ground beans from meadow voles, the Northwest Indians robbed caches of aquatic arrowheads from muskrat nests, the Seri and Yaqui robbed caches of mesquite pods from pack rats. In the Great Basin, Mormon crickets, an abundant, large insect, were driven into shallow trenches, grass was set over the top of the trench and lit, the roasted insects then collected and stored. A woman could collect several bushels in a day, the caloric equivalent of a year’s supply of pizza. Harvesting can increase the abundance of some plants. Grizzly bears create lily gardens above timberline by digging and eating the lily bulbs in the fall. Digging loosens the sod in which the lilies grow. Some of the sod is left exposed and rots, releasing nutrients to the ground. The lilies reproduce by bulb scales on the sides of the bulb, which fall off when they are handled, thus starting new lily plants; the bears also leave many bulbs (especially smaller ones) in the ground. The result is a thicker growth of lilies in the dug-over ground (a lily garden), more forage for animals like mountain goats (which eat the blooms), more spectacular scenery for the hiker, a greater resource for the bears. Bitter-root and sego lily (as well as roots like camas and groundnut in other regions) probably responded this way for the Native Americans, as ramps (wild onions) are said to increase yearly when gathered by modern commercial collectors. The point of course is not to take all the bulbs. Australian aborigines replanted the tops of the wild yams they dug, so the plants would regrow. In general, harvesting seeds and wild fruits tends to spread the plants around. Some plants however require other techniques: California Indians burned stands of wild rice grass in the fall to increase the yield. Burning volatilizes some nutrients but cycles others through the system more rapidly, increasing yields. With some species of perennial plants, lightly harvesting young stems for food, as the Californians did with their native clovers, increases the size of the underground parts, which then produce more stems. Using the landscape by gathering thus subtly changed it, often for the better, from the point of view of the gatherers.
Other landscapes demanded other forms of accommodation. In the boreal woodland south and east of Hudson’s Bay, a more difficult landscape fed the Cree. The Cree ate mammals and fish, greens, berries. One of their prey animals, the varying hare, has a strong population cycle with a 7 year period. Such cycles are typical of many northern animals. In this case, the rise and fall of the hare was followed, at a slight remove, by that of the lynx that ate them. The lynx is a furbearer, so records of lynx skins sold to traders provide a record of varying hare populations. The Cree would eat more hare when they were available, taking hunting pressure off the moose, their other major meat resource and the big game animal of the snowy regions south of the caribou range, and north of the deer. Beaver were a reliable winter food, if not over-exploited. A hunter knew where to find them, how to trap them. It was said a winter camp smelled of balsam boughs and boiling beaver. The animal’s fur was an added benefit. Anadromous fish like Atlantic salmon, blue-back herring and sea-run trout inhabited the rivers of the St. Lawrence drainage up to Niagara Falls and north around the coast through much of Labrador (when, far enough north, trout and salmon are replaced by Arctic char). Other fishes lived in the drainages of the large inland lakes. Fish were relatively easy to capture in spring and fall, when they made their spawning runs. They could also be caught through the ice in winter. Waterfowl and shorebirds were seasonally abundant. Some bands depended largely on muskrat, which were extremely abundant, and also somewhat cyclical, in large river deltas. The small lakes scattered inland from Hudson’s Bay held large lake trout. They could not be fished every year. Growth of the fish was too slow, so the lakes had to be fished in rotation. Game management was handled by the tribes through the assignment of individual hunting territories. (Individual territories probably replaced those of small hunting bands, a change associated with trapping for fur.) Further north, caribou were taken where their migration paths took them across rivers or through lakes, where the animals could be ambushed and shot with bows and arrows as they approached a river crossing, or speared from canoes while swimming a lake. Berries were often abundant. Blueberry barrens were burned, which increased their yield tenfold, making more food available for people, for foxes and bears, for the chicken-like birds of the barrens (grouse, ptarmigan, prairie chickens). Fires often got away and regrowth of the forest could take a long time. The Cree of northern Alberta set landscape-manipulating fires to produce a mosaic of mature and early successional landscapes attractive to game: berries to lure birds and bears; herbs and grasses for rabbits and mice, and thus martens and foxes. The Cree might renew cattail marshes for muskrats or aspen stands for beaver with fire. Fires in the boreal forest could be destructive. Life under the gray winter sky of Quebec or Maine was perhaps not so hard as one supposes: one old Cree lady told an anthropologist that her rabbit-skin winter clothes were so warm that as a girl she sometimes slept outside in the snow.
Perhaps this was an exaggeration. In the late 1700s Samuel Hearne records finding a young Western Dog-rib woman living alone on the taiga. (Hearn, an employee of the Hudson’s Bay Company, made several exploratory walks of a thousand miles or more north and west from the Company’s trading settlement on Hudson’s Bay.) She had been captured by a war party of Athapascans and adopted into that tribe. The Athapascans had killed her infant child when she was captured. She had not forgiven them this and had escaped. Her tribe lived far to the west and she didn’t know where she was, so once free of her captors she set up camp on the taiga, certain that sooner or later some of her people would come her way. She lived by snaring ptarmigan, hare and ground squirrels, along with a few beaver and porcupines. She had made fire from two stones and had sewn a new set of rabbit-skin clothes. She also had fashioned a hundred fathoms of line from the inner bark of willow for a fishing net, which she was planning to use when the fish began to run that fall. She lived alone for seven months. What is impressive about the woman is that she could survive so easily and so well; and she apparently didn’t mind being alone. The landscape was her home in a way it could not be for the Europeans; their own natural landscape was not home for them in this way. For Europeans of that time, human life took place on a divine earth, remade by men in god’s image: the cultivated, domesticated landscape of Europe, a landscape whose history went back several thousand pre-Christian years. The natural post-glacial landscape of Europe, the European forest (as impressive as that of Ohio or Kentucky), once as familiar to its inhabitants as the taiga to this woman, had become an alien one to its present inhabitants, a home of spirits and devils. If possible, Europeans took their domestic landscape with them, and so could live far from the apple orchards and barnyards of Europe as long as wheat could be grown, fruit trees planted, and communication with Europe (the spiritual center of the world) existed. Being marooned on an island like Robinson Carusoe was one of the mythic fears of the time; and not without precedent. But the whole colonization of the earth by people had consisted of journeys something like that woman’s; with small bands of people who could make do with what was around them, and whose spiritual lives were connected to the landscape about them.
Where did the modern system of resource exploitation come from? Before the world was marketable, it was edible, and humans, like all plants and animals, were part of that world.
About 13,000 years ago, amidst the retreat of the glaciers that had covered much of northern North America, signs of human occupation appear. In some places, signs appear much earlier: in southern Chile perhaps 30,000 years ago, somewhat less in a cave in western Pennsylvania (the age of the Pennsylvania remains is still disputed). Some writers claim the diversity of North American Indian languages would have taken 50,000 years to evolve. In the present-day United States undisputed signs of people appear as fluted stone points embedded in the bones of the so-called Pleistocene megafauna, the larger (greater than a 100 pounds) grazers and browsers and their predators (also large) that inhabited that slightly earlier earth, 400 to 600 human generations removed from us. So-called Folsom points were found with the bones of ice-age bison in Folsom, New Mexico, and with those of woolly mammoths and mastodons in the Ohio Valley and in New York State. The eastern landscapes would have been just south of the glacier’s edge. During the next few thousand years most of these large animals would become extinct. (Some writers claim the extinctions occurred much faster, over a period of 300 years, from 13,200 to 12,900 years ago.) In North America the Pleistocene megafauna included species of hairy elephant like the herb-eating mammoth (animals of the tundra) and the forest-browsing mastadon, a fierce carnivorous bear (which some claim kept many people from crossing the Bering Plains), 4 genera of giant ground sloth, a large wolf, a tiger, several kinds of horse and donkey, a camel, a moose-elk, a tapir, a cheetah, 2 types of llama, a yak, a giant beaver, 3 kinds of ox. All these animals disappeared. Most of them were larger than those that succeeded them.
In the eastern half of North America, the area south of the glacial front was an open tundra of grasses and sedges, with scattered clumps of balsam poplar and black spruce. This belt was 50 to 100 miles wide. Modern deciduous trees like oak, hickory, beech and birch grew near the glacier in favorable locations (within 100 miles in the Northeast, 15 miles in south central Illinois), along with white-tailed deer. The tundra was more productive than the modern tundra because of its more southerly location and thus its warmer summers. The grassland extended south along the Appalachians to Georgia. Here, lower elevations supported an open and parklike boreal forest, with deciduous trees in south-facing coves. In Georgia this forest merged into a closed oak and hickory forest like that of the Middle West today. West of the Mississippi, the Plains and Southwest were wetter. Much of the Plains was a humid forest; the water in the Ogallala aquifer was still accumulating. Sea levels were 300 feet lower and grazing and browsing land extended some ways out onto the continental shelves, though less far off the coasts of North America than off those of Europe, whose shallow continental shelves were extensive. What would become cod banks in the Gulf of Maine were forested islands. The climate that favored the steppe was created by the mile-high ice, which held a constant high pressure system over it. This kept the climate cool and dry. As the glacier had advanced, trees had retreated south, finally reaching their so-called southern refugia. Trees move a few hundred to a thousand feet a year, depending on how they are dispersed (gravity, wind, the guts of seed-eating birds, the beaks of blue jays, the mouths of squirrels). Oaks in Europe returned north at 500 meters a year, in North America perhaps two-thirds of that, or 200 miles a millennium. (While jays will carry an acorn several kilometers in a trip, it takes several decades for that tree to bear acorns.) The seeds of North American wild ginger are dispersed by ants up to 35 meters a year, so ginger could theoretically move north only 10 to 11 kilometers (6 miles) in 16,000 years; but ginger probably moved north 450 kilometers (250 miles) in that time. Many herbs and trees seem to have moved faster than observation would support, an indication that uncommon occurrences (such as seed transport by floods, windstorms or tornadoes) become relatively common ones over a long period of time. Fish also retreated south along favorable drainages and disappeared from rivers and lakes under the ice. The north-south alignment of the Mississippi is one reason that river is so rich in fish species. But oak, hickory and white-tailed deer were found within a hundred miles of the glacial wall in New England; and oak, elm and ash (the last two nutrient-demanding species that require good soils) amidst clumps of black spruce within 15 miles of the glacier in south-central Illinois. Such trees would re-occupy the landscape when the climate ameliorated.
In North America, as the ice began to retreat, and incontrovertible signs of people appear, the Pleistocene megafauna began to disappear. Its disappearance was worldwide, except in Africa, where modern people and large animals evolved together. The extinctions took much longer in northern Eurasia, where people had also lived with the animals for a long time. Were the extinctions caused by people or the changing climate? People may have been new to the Americas but people had been hunting mammoths in central Europe and Russia for tens of thousands of years. In Australia and South America large mammal species also disappeared when humans arrived. In Australia this happened 50,000 years ago and corresponded with a long-term drying of the climate and also with the modification of the habitat by fire. Fire set by humans changed large portions of Australia’s semi-arid zone from a mosaic of trees, shrubs and grasslands to fire-adapted scrub. With the grassland also disappeared a large flightless bird and the marsupial lions and carnivorous kangaroos that preyed on it and a 7 meter long lizard. One of the more ingenious theories to explain the extinction of the Pleistocene megafauna in North America puts animal behavior, climate change and human predation together. As the glaciers retreat and the climate grows wetter (and more favorable to trees), the large grazers help maintain the grass, through the fertilizing effects of their dung and the constant re-creation of new grass shoots, whose high transpiration rates dry and oxygenate the soil. Mastodons, like modern elephants, fed on trees, breaking off branches and stripping bark. They kept forests open. Mammoths and mastodons recycle nutrients quickly, eating 250 to 300 pounds of vegetation a day, much of it of poor quality (that is, woody: only large animals with large fermenting stomachs can eat such poor quality vegetation). Thus they maintain the habitat. Continual hunting pressure reduces the number of large grazers somewhat. A relatively small kill rate may accomplish this since the large animals mature slowly and have widely spaced young. While in Asia, these animals had evolved with increasingly skilled human hunters, in North America game animals had lived without people for tens or hundreds of thousands of years and had little fear of them, and so, despite their size, may have been easy to hunt. As grazing pressure falls, parts of the grassland begin to be replaced by forbs and shrubs, then with willow, aspen, birch, black spruce. With a climate less and less favorable to grassland, and continuing predation on the large animals, such changes accelerate. At the same time a rapidly rising ocean eliminates more of the grazers’ habitat. So this scenario turns into a downward spiral for the grassland and its inhabitants. For the most part, the large animals were replaced by smaller modern grazers and browsers, all adapted to predation by man: the modern bison, elk, big-horn sheep. Many of these animals came with people across the Bering Strait. Because of the extinctions, some niches are still open. The Southwest could support more browsers on its thorny scrub. The fruits of some species of large-fruited trees in the American tropics are eaten nowadays only by a few species of large-beaked birds. Once they were eaten by elephants and their relatives (or several other genera of megafaunal fruiteaters), the seeds that survived passage through the animal’s gut getting a good start in a pile of dung. (This trick was used by a biologist to re-establish dry tropical forest in Central America; he fed the tree fruits to horses, who shed the seeds in their dung; the seeds sprouted in the manure.)
While the demise of large, tame animals under human hunting has happened in many places (California Indians eliminated large sea mammals from their coasts, New Zealand Polynesians the moas, the Australians their large mammals), matters may have been complicated in North America by a comet that struck 12,900 years ago. The explosion caused immense wildfires, and would have reduced or eliminated both the peoples of the Clovis culture and the large mammals on which those peoples depended. This would explain why Clovis points disappear abruptly from the fossil record about the time the comet struck, while stone points of a different make (reflecting another wave of immigration) appear some time later. The comet may also have triggered the massive release of glacial meltwater from the center of the continent to the North Atlantic that slowed the Gulf Stream, causing 1500 years of Younger Dryas cooling in Europe (12,800 to 11,500 years ago).
Deglaciation took 8000 years. It was a time of flood stories, biblical or Abenaki. The melting ice raised sea levels about 360 feet. During some periods the sea rose as much as 10 feet in 70 years; depending on the slope of the coastline, this could mean the sea moved inland hundreds of yards during a man’s lifetime. But there were more catastrophic events. One reading of the geological data indicates that approximately 7600 years ago, the rising waters of the Mediterranean broke through a natural dam in the Bosporus and flowed into the basin of the Black Sea. At that time the lands around the Black Sea were occupied by Neolithic farmers. The rising flood waters moved over the grainfields and villages of the lakeside plains at a quarter mile a day. The refilling of the Sea happened in a year or two. An alternative theory claims that the rise in the Sea was much slower and was caused by glacial meltwater draining into it from the north; and that the Black Sea then broke through the dam and flowed into the Mediterranean. At any rate a flood, and almost within sight of Ararat. Rising sea levels invaded Hudson’s Bay and floated the remains of the Laurentide ice sheet about 12,800 years ago. Icebergs sailed out through Hudson and Davis Straits and drifted 1900 miles across the Atlantic toward the coast of France, dropping behind them over the ocean floor the rocks and mud of the Bay that had been frozen to their bottoms, thus letting us read of their passage. The melting of the ice sheet changed the air circulation pattern over North America, and let a more modern climate develop. The glacial grassland of eastern North America became an open woodland of boreal conifers, with paper birch, balsam poplar, alder and willow; and then a forest of northern hardwoods, such as sugar and red maple, quaking aspen, and yellow birch, together with hemlock, red and white pine, and red spruce. The more nutrient-demanding species such as white ash, elm, and basswood arrived last. Some species, like red oak, continue to move north and upslope. Meanwhile the boreal conifers continued their move north, overshooting the modern treeline by 175 miles during the Hypsithermal, 9000 years ago, when the climate was warmer and drier than today. A fully modern climate was dependent on the return of the Gulf Stream, which was shut off by massive meltwater drainage into the North Atlantic during the final collapse of the North American ice sheet.
With the return of the Gulf Stream came the establishment of a modern air circulation pattern over North America. East of the Rocky Mountains the climate is controlled by three air streams: warm, moist air from the Gulf of Mexico; cold, dry air from the Canadian Arctic; and moderate maritime air from the Pacific. Precipitation in the East for most of the year depends largely on the converging streams from Canada and the Gulf, one cold and dry, one warm and moist, meeting along the axis of the jet stream. Summer precipitation is often convective: moisture rising from the sun-warmed landscape and transpired by trees and grasses condenses into clouds as it rises into the cooler upper atmosphere. Condensation occurs about marine salt particles and methyl sulfate nuclei produced by marine algae, as well as about other natural and industrial aerosols, and falls as rain. (Condensation droplets that form around sulfur dioxide particles from the burning of fossil fuels are usually too small to fall as raindrops and remain as clouds.) The Pacific air loses its moisture over the mountain chains of the western United States (the Sierra Nevada, the Rocky Mountains): thus the broad arrow of modern grassland that pushes east from the rain shadow of the Rockies over the plains of the Dakotas and the prairies of Illinois and Ohio into western Pennsylvania, and along the shores of the Great Lakes into New York State. With a modern climate, a modern forest developed in the eastern United States between 6000 and 8000 years ago. None of this is static; more warmth loving trees (oaks, hemlock, hickory, chestnut) kept moving north and upslope; and red spruce, a slightly more boreal species than its companions in the northern forest, and a signature tree of the higher elevations of the Appalachians during Euro-American settlement, only became abundant there 2000 years ago.
People had inhabited this landscape for at least 11,000 years. They had hunted the large animals and watched the glaciers retreat. They had begun to influence forests long before the trees came into equilibrium with their soils. Were these prairies, newly created, with their buffalo and elk, entirely natural? Some argue that by helping to eliminate the Pleistocene megafauna, human hunters also helped create the modern grazers, partly through hunting pressure, partly by opening the ecosystem to animals that migrated with the people from Eurasia. Hunting pressure by humans tends to favor early-maturing, smaller animals: the modern bison, as compared to the larger earlier species, whose bones are found at the bottoms of the boneyards beneath buffalo jumps. The grasslands of North America were once thought to be a creation of climate and topography alone; of atmospheric circulation patterns, a mountain rain shadow. Now it seems more likely that in parts of the landscape climate and topography only set the scene. Much of the Plains are too dry and windy for trees, and the wet prairies of Illinois were too wet for too long in the spring and then too dry in the late summer and fall; these wet prairies were inhabitated paradoxically by drought-resistant plants. But grazing (by buffalo, elk, bighorn sheep, prairie dogs) and browsing and grazing (by antelope and by jackrabbits in the drier short-grass and sagebrush steppes) as well as burning (by lightning strikes and Native Americans) maintained and extended the reach of the prairie. In part, both the landscape and the large grazers that inhabited it were man-made. Former prairies in Illinois or Minnesota that are not burned today are invaded by trees. Burning was a major tool of landscape modification by gathering and hunting peoples. Modern studies indicate that burning every 2 to 5 years maximizes prairie productivity. The Kentucky barrens (called barrens by the Americans because they were treeless) consisted of 6000 square miles of buffalo and elk pasture kept open by grazing and browsing by the animals and by burning by their Native American hunters. Some eastern prairie landscapes still existed at the time of European contact, when most of the natives who maintained them were already dead of European diseases. LaSalle saw buffalo grazing along the south shores of the Great Lakes. These would have been the Pennsylvania buffalo, larger and blacker than the Plains buffalo. There were still an estimated 12,000 of these animals in Pennsylvania in the 1700s. (Since the modern buffalo crossed the Mississippi in their movement east only 1000 years ago, these animals may have been there only a few hundred years.) Buffalo, New York, was named for a buffalo trail that went along Lake Erie. Such trails, following the easiest route between two points, may have been quite old; perhaps migrating mammoths laid out the original paths. At any rate, during a period of damper climate, burning would have held back the forests in places where they would have otherwise invaded. Thus the “oak openings” of Ohio and western Pennsylvania; the buffalo along the southern shores of the Great Lakes; the elk in Michigan and New York State; the populations of buffalo along parts of the Atlantic coastal plain. The oak scrub and blueberry barrens used by prairie chickens in New England and New York State were also maintained by fire, and may have been (like the vegetation on mountaintops) relics from glacial times, kept open by humans for their plants and animals. All these animal pastures, which had existed for thousands of years, many since the melting of the glaciers, would be cleared of wild animals in no time by the Euro-Americans, who had no intention of pasturing communally-owned wild animals. They were capitalists and agriculturists, with visions of a privately-owned landscape of barns, fields, woodlots, iron plantations, gristmills, cattle.
Edible landscapes provide food, shelter, clothes, tools and fuel in a renewable way, and in amounts that support a more or less constant human population. While the human population increased steadily up to the time of the adoption of agriculture 10,000 to 11,000 years ago, most of this increase is thought to have been because of the occupation of new habitats. For most of human time (perhaps 160,000 years), the landscape was renewable and edible; edibility was its function. A buffalo hunter sitting on the edge of the Plains in Wyoming a thousand years ago would have been aware of animal traps as far as he could see. A trap might consist of a log enclosure at the foot of a low bank. The animals would be driven over the bank into the pen; the injured, frantic animals caught inside were then speared, shot with arrows, battered with stone mauls, slashed with hatchets. Converging lines of piles of stones (the stones for the piles and the logs for the trap had to be gathered and carried by hand, perhaps for miles, from wherever they might be found) extended back from the brink of the bank for a thousand yards or more, forming a chute up which the animals would be driven. People would jump out from behind the stones waving hides to drive the beasts on. The problem for hunters on foot was getting the animals into the chute. Buffalo have poor vision but are curious and approachable upwind; one might decoy them by pretending to be buffalo, or wolves. In the early spring the grass near a chute might be burned: this would provide new grass to lure the animals. A tall enough bank or cliff wouldn’t need a pen since the animals would be sufficiently hurt in the fall so as not be able to escape. Some sites are quite old; some cliff drives have bones from the larger, Pleistocene bison that preceded the modern “dwarf” bison of the Plains. Hunting in this way was a group endeavor. Once dead, the animals had to be tended to immediately or their flesh would spoil. The meat from four adult bison (about 1600 pounds) would yield about 160 pounds of dried meat (depending on how dry one got it, the amount could be double that), which would keep for several months, and feed a family of six for two months on a ration of half a pound a person a day. (Fresh meat was consumed at six to eight pounds per person per day.) Most of the animal was used. The Plains Indians were buffalo gourmands: delicacies included the stomach contents (a sort of salad), unborn fetuses, the milk from nursing cows, bone marrow, nose gristle. Hunters in a hurry took only the hump and tongue. A green soup was made from drowned and rotten buffalo. What was left at a kill site, which would vary with the number of animals killed and the number of people and the state of their food supply, turned into bait for scavenging bears, wolves, golden eagles, coyotes, skunks, badgers, and bobcats, all of which fed and were ambushed at kill sites. The buffalo returned to the prairie not only through their dung and remains but through the dung and bodies of their predators. Cliff drives were undoubtedly wasteful, when more animals were killed than the people could use.
Animal traps varied with location and prey. The Pit River, the longest tributary of the Sacramento River of northern California, was named for the abundance of pit traps for deer (steep-sided holes in the ground, lightly covered with brush) in its valley. In historic times mountain sheep were trapped in pens in Rocky Mountain pastures by the Shoshone. The drives exploited the animals’ tendency to run down from a look-out area and then up again; and from there off a bank and into the pen. Nursing herds, which formed more tractable groups, were usually driven. Animals in the pen were killed with clubs, which have been found in caves. Eight thousand years before this, when the climate on the Plains was wetter, and some anthropologists think the hunters came by sailing canoe from Pacific islands rather than by foot across the Bering Strait, mountain sheep were netted with nets of juniper bark cordage. Nets 50 to 60 meters long and 1.5 to 2 meters high have been found folded in mountain caves. In the Great Basin, pronghorn antelope, which can be restrained by a visual fence, were lured into brushwood enclosures and driven round and round until exhausted, then clubbed to death. Their numbers in the Great Basin may have been kept artificially low by this method. On the North American taiga, frozen lakes were used to set up traps for caribou. The chute for the drive was made from small evergreens set out on the ice, the trap constructed in the forest on shore. Samuel Hearne reports trap enclosures reached a mile around and the chute would reach out for a mile or more. Openings in the trap’s brush fence were fitted with snares. Animals that weren’t snared were shot with bows and arrows or speared. If possible, in all these cases, no trapped animals were spared, as people thought that escaped animals would warn the others. Modern peoples of the eastern woodland, such as the Huron, drove white-tailed deer into similar pens, on land.
People who depended mostly on hunting and gathering moved often. Some of the plains hunters of the time before the horse moved every second or third day. Because of the lack of water, only the edges of the plains, along the rivers and creeks, were habitable. (But seasonal pools, seeps, and wallows were more abundant in the pre-settlement plains, letting individual hunters travel further.) The technology of drying meat was one of the things that made the lives of hunters on foot possible, as were dogs, used for transport. Whether such cultures had any effect on the numbers of game animals is uncertain. Before the plains hunters began trading with the Americans, their effect on the buffalo was probably negligible. Antelope may have been suppressed in the Great Basin, but probably not in California (where the Central Valley had a herd of a million or more animals). In the East some writers think the population of white-tailed deer was kept artificially low. The Iroquois take of deer has been estimated at 11,000 animals, while the annual deer kill in New York State by automobiles is now about 60,000 animals, and the herd numbers over a million; the kill by hunters is around 200,000. The farmed, logged-over and developed habitat of the State is now much more suitable for deer, which like most game animals prefer early successional (some would say partly destroyed) landscapes. (White-tailed deer are one of the few large mammals in North America more numerous now than at European contact.) But villages could keep the populations of game animals near them low.
Most hunters and gatherers get the bulk of their calories from gathering and the buffalo hunters also gathered wild plants: young stems and leaves of Balsamorrhiza and Chenopodium; bitter-root roots; sego lily bulbs; wild onions; fruits of chokecherry, buffalo berry, gooseberry. Such wild fruits, bitter-sweet and rich in vitamin C, would be beaten up with fat and dried meat into pemmican, a calorie-rich, easily transportable winter food. In the Great Basin, seeds of yucca, Indian ricegrass, wild rye, limber pine, saltbush, and Chenopodium were collected, the small-seeded grasses beaten off the stem into baskets, the pine cones with their large seeds collected before the seeds had fallen and let open in baskets or on mats in the sun or around the fire; some cones, like those of the sugar pine, were set alight so they would open and shed their seeds. Sometimes rodents collected the food: the Pawnee and Winnebago stole caches of ground beans from meadow voles, the Northwest Indians robbed caches of aquatic arrowheads from muskrat nests, the Seri and Yaqui robbed caches of mesquite pods from pack rats. In the Great Basin, Mormon crickets, an abundant, large insect, were driven into shallow trenches, grass was set over the top of the trench and lit, the roasted insects then collected and stored. A woman could collect several bushels in a day, the caloric equivalent of a year’s supply of pizza. Harvesting can increase the abundance of some plants. Grizzly bears create lily gardens above timberline by digging and eating the lily bulbs in the fall. Digging loosens the sod in which the lilies grow. Some of the sod is left exposed and rots, releasing nutrients to the ground. The lilies reproduce by bulb scales on the sides of the bulb, which fall off when they are handled, thus starting new lily plants; the bears also leave many bulbs (especially smaller ones) in the ground. The result is a thicker growth of lilies in the dug-over ground (a lily garden), more forage for animals like mountain goats (which eat the blooms), more spectacular scenery for the hiker, a greater resource for the bears. Bitter-root and sego lily (as well as roots like camas and groundnut in other regions) probably responded this way for the Native Americans, as ramps (wild onions) are said to increase yearly when gathered by modern commercial collectors. The point of course is not to take all the bulbs. Australian aborigines replanted the tops of the wild yams they dug, so the plants would regrow. In general, harvesting seeds and wild fruits tends to spread the plants around. Some plants however require other techniques: California Indians burned stands of wild rice grass in the fall to increase the yield. Burning volatilizes some nutrients but cycles others through the system more rapidly, increasing yields. With some species of perennial plants, lightly harvesting young stems for food, as the Californians did with their native clovers, increases the size of the underground parts, which then produce more stems. Using the landscape by gathering thus subtly changed it, often for the better, from the point of view of the gatherers.
Other landscapes demanded other forms of accommodation. In the boreal woodland south and east of Hudson’s Bay, a more difficult landscape fed the Cree. The Cree ate mammals and fish, greens, berries. One of their prey animals, the varying hare, has a strong population cycle with a 7 year period. Such cycles are typical of many northern animals. In this case, the rise and fall of the hare was followed, at a slight remove, by that of the lynx that ate them. The lynx is a furbearer, so records of lynx skins sold to traders provide a record of varying hare populations. The Cree would eat more hare when they were available, taking hunting pressure off the moose, their other major meat resource and the big game animal of the snowy regions south of the caribou range, and north of the deer. Beaver were a reliable winter food, if not over-exploited. A hunter knew where to find them, how to trap them. It was said a winter camp smelled of balsam boughs and boiling beaver. The animal’s fur was an added benefit. Anadromous fish like Atlantic salmon, blue-back herring and sea-run trout inhabited the rivers of the St. Lawrence drainage up to Niagara Falls and north around the coast through much of Labrador (when, far enough north, trout and salmon are replaced by Arctic char). Other fishes lived in the drainages of the large inland lakes. Fish were relatively easy to capture in spring and fall, when they made their spawning runs. They could also be caught through the ice in winter. Waterfowl and shorebirds were seasonally abundant. Some bands depended largely on muskrat, which were extremely abundant, and also somewhat cyclical, in large river deltas. The small lakes scattered inland from Hudson’s Bay held large lake trout. They could not be fished every year. Growth of the fish was too slow, so the lakes had to be fished in rotation. Game management was handled by the tribes through the assignment of individual hunting territories. (Individual territories probably replaced those of small hunting bands, a change associated with trapping for fur.) Further north, caribou were taken where their migration paths took them across rivers or through lakes, where the animals could be ambushed and shot with bows and arrows as they approached a river crossing, or speared from canoes while swimming a lake. Berries were often abundant. Blueberry barrens were burned, which increased their yield tenfold, making more food available for people, for foxes and bears, for the chicken-like birds of the barrens (grouse, ptarmigan, prairie chickens). Fires often got away and regrowth of the forest could take a long time. The Cree of northern Alberta set landscape-manipulating fires to produce a mosaic of mature and early successional landscapes attractive to game: berries to lure birds and bears; herbs and grasses for rabbits and mice, and thus martens and foxes. The Cree might renew cattail marshes for muskrats or aspen stands for beaver with fire. Fires in the boreal forest could be destructive. Life under the gray winter sky of Quebec or Maine was perhaps not so hard as one supposes: one old Cree lady told an anthropologist that her rabbit-skin winter clothes were so warm that as a girl she sometimes slept outside in the snow.
Perhaps this was an exaggeration. In the late 1700s Samuel Hearne records finding a young Western Dog-rib woman living alone on the taiga. (Hearn, an employee of the Hudson’s Bay Company, made several exploratory walks of a thousand miles or more north and west from the Company’s trading settlement on Hudson’s Bay.) She had been captured by a war party of Athapascans and adopted into that tribe. The Athapascans had killed her infant child when she was captured. She had not forgiven them this and had escaped. Her tribe lived far to the west and she didn’t know where she was, so once free of her captors she set up camp on the taiga, certain that sooner or later some of her people would come her way. She lived by snaring ptarmigan, hare and ground squirrels, along with a few beaver and porcupines. She had made fire from two stones and had sewn a new set of rabbit-skin clothes. She also had fashioned a hundred fathoms of line from the inner bark of willow for a fishing net, which she was planning to use when the fish began to run that fall. She lived alone for seven months. What is impressive about the woman is that she could survive so easily and so well; and she apparently didn’t mind being alone. The landscape was her home in a way it could not be for the Europeans; their own natural landscape was not home for them in this way. For Europeans of that time, human life took place on a divine earth, remade by men in god’s image: the cultivated, domesticated landscape of Europe, a landscape whose history went back several thousand pre-Christian years. The natural post-glacial landscape of Europe, the European forest (as impressive as that of Ohio or Kentucky), once as familiar to its inhabitants as the taiga to this woman, had become an alien one to its present inhabitants, a home of spirits and devils. If possible, Europeans took their domestic landscape with them, and so could live far from the apple orchards and barnyards of Europe as long as wheat could be grown, fruit trees planted, and communication with Europe (the spiritual center of the world) existed. Being marooned on an island like Robinson Carusoe was one of the mythic fears of the time; and not without precedent. But the whole colonization of the earth by people had consisted of journeys something like that woman’s; with small bands of people who could make do with what was around them, and whose spiritual lives were connected to the landscape about them.
The Natural History of the Present, Chapter 3
Chapter 3: The Natural World
All forms of life influence their surroundings. Photosynthesizing bacteria and blue-green algae are thought to have created our oxygen-rich atmosphere about 2.5 billion years ago. Before that the atmosphere was a reducing one, carbon-rich and oxygen-removing. The creation of an atmosphere dominated by oxygen was a disaster from the point of view of most organisms; some retreated far underground to rock formations from whose chemical elements they could derive energy, some to the anoxic muds of wetlands, ponds and the deep ocean. The current global concentration of carbon dioxide is low thanks partly to the burial of so much carbon in fossil fuels 200 to 300 million years ago, and thus its effective removal from planetary chemistry. Large amounts of carbon are also stored in frozen northern bogs, in ocean sediments and ocean water, in soils, and in standing vegetation. Much of this carbon was sequestered by living things, some by simple chemical processes, and much of it can be released to the atmosphere under the right conditions. We, for instance, free the carbon in fossil fuels by burning them. Eventually that carbon would have been put back in the atmosphere as the continental plates in which it is buried are drawn down into the earth’s mantle and the carbon vaporized and carried back into the atmosphere through the vents of volcanoes. The oxygen content of the atmosphere is now maintained, somewhat mysteriously in the face of constantly exposed, oxydizing minerals (exposed by geological activity and digging humans); fires; and of oxygen-respiring living things, by bacteria and blue-green algae similar to those of 2.5 billion years ago, which live in soils or as photosynthesizing plankton on the ocean’s surface; and by rooted green plants.
It is now known that bacteria live in rock formations up to 3.5 kilometers below the surface of the ground and several miles deep under the ocean. They can tolerate temperatures up to 113º C., 13º C. above boiling. The bacteria in deep ocean muds derive their energy by reacting hydrogen with nitrate to produce ammonia. Some of the organisms that live in the deep, hot biosphere underground also depend on hydrogen fuel: these form the so-called subsurface lithoautotrophic microbial ecosystems; or, SLIMES, the rockeaters. SLIMES were first discovered in drill holes 1000 meters down in Columbia River basalts. It is thought these SLIMES use hydrogen generated by the reaction of water with the ferrous silicates in the basalt for an energy supply. As with the case of the sulfur-reducing bacteria about hot-water deep-sea vents, other organisms show up to eat the first ones; or to use their wastes. The mass of such depth-dwelling organisms, because of the immense size of their habitat, may be greater than that of life on the surface of the earth, much of which is in the first, well-oxygenated foot of soil, the first hundred feet above the soil, and the first half-inch of ocean surface. Whether the underworld life has much influence on the surface one isn’t known. Bacterial life in deep ocean muds has some effect on life on the surface, because what goes on in the muds influences the chemistry of the oceans, and ocean water circulates at greater speeds than crustal rocks (thousands of years rather than tens of millions: the carbon from fossil fuels wouldn’t have turned up in the atmosphere any time soon). At any rate, the living influences on the planet’s surface and atmosphere are set among more general planetary and gravitational ones (such as the output of the sun, the speed of the earth’s spin, its aspect to and distance from the sun); and those of plate tectonics. (Rocks circulate too, but slowly: the burial and rebirth of plates not only help recycle planetary carbon and also reposition continents and oceans; the position of the continents on the globe influences heat distribution, rainfall and other aspects of global climate.) It has become more and more clear that nothing—no climate regime, no ocean shoreline, no level of solar output, no stand of trees—is permanent. Things like the structure of a particular forest are only partly replicable. Ecosystems have histories: different histories explain differences among otherwise similar landscapes—landscapes similar in microclimate, soil, aspect, hydrology, but different in vegetation. Their different histories from, say, fire, grazing or windthrow, nudge them in different directions. Why the atmospheric concentration of oxygen, unlike that of carbon dioxide, remains constant in the face of fossil fuel combustion and the oxidation of exposed soils and rocks has to do with the large volume of atmospheric oxygen, compared to that of carbon and carbon dioxide (so large that burning all the trees on the planet would reduce the concentration of oxygen by only 300 parts per million out of 200,000 parts per million); and with the ability of bacterial populations to respond to small changes in the concentrations of planetary gases.
From a more local perspective, trees create conditions that favor forests: they transpire water from their leaves, cooling the atmosphere and creating mist and rain; their roots penetrate the soil, letting water and oxygen in; the yearly turnover of root hairs and rootlets (approximately one third of the total root mass) adds carbon and other nutrients to the soil. These nutrients are recycled by soil organisms and the trees. The damp, shaded, more temperate forest soils (not so hot in summer, not so cold in winter) become a home for insects, rodents, soil arthropods, bacteria, fungi. Fungi are important in all forests but especially so in evergreen forests, which are noted for their survival in poor soils, and whose needle-fall tends to resist recycling by the arthropods and bacteria, thus locking up nutrients for long periods of time. In some Pacific Northwest forests, soil fungi constitute half the soil biomass. Some evergreens won’t survive without specific fungi in the soil. Clear-cutting causes a dramatic decline in soil arthropods and fungi, which helps explain why some clear cut western sites, especially dry, south or west facing sites, are so difficult to reforest. The fungal hyphae provide water and other nutrients to the tree and increase its effective root area by 1000 to 10,000 times. They secrete enzymes that extract nitrogen and phosphorus directly from humus, eliminating the bacterial food chain. Hyphae secrete chemicals that break down the surfaces of stones and transport trace metals to the tree. They help protect tree roots from acid soils. (So firs will grow on piles of mine spoil.) They secrete growth hormones to increase tree root growth and antibiotics to protect tree roots from bacterial infection. Hyphae connect trees of the same and different species, and by providing nutrients from overstory to understory trees, help make forest succession possible. They turn the forest into a single organism. Such services are not free; approximately 40% of the photosynthesate produced by the leaves seeps out of the roots to the mycorrhizal and bacterial ecosystem that lies within a few millimeters of the root hairs (the so-called rhizosphere); the photosynthesate includes nutrients (sugars) and vitamins. Processes like this are the sort that commercial foresters (or farmers, in another situation) try to short-circuit, by using herbicides and commercial fertilisers to alter ecosystem function, and thus allocate more of the products of photosynthesis to plant growth. This approach ignores the place of the tree in the whole soil and forest community. By providing trees with water, fungi help them better withstand droughts. Polysaccharides secreted by the bacteria and fungi of the rhizosphere also change the soil’s structure, making it better aerated and better adapted to the movement and absorption of water (thus better adapted to tree growth). In test plots in a tropical forest in Guinea, trees responded better to a mulch of wood chips than to chemical fertilizers. In general, trees with mycorrhizal connections grow more vigorously than those without them.
The rest of the soil community is also important. The arthropod communities of Pacific Northwest forests include the grinders of successively smaller size that break down litterfall (five tons per acre per year in old growth forests), until the material, successive levels of bug poop, finally reaches the scale of the plant cell. Bacteria scavenge the available nutrients, die, or are eaten by other organisms, which excrete them, their nutrients becoming available to the trees; the nutrients are also transferred by fungal hyphae to the trees directly. Logs are broken down in a similar fashion. Total incorporation of a Douglas fir log into the soil can take 400 years. Because of the log’s inhabitants, while 5% of a tree consists of living cells, 20% of a rotting log is living tissue. Such soil arthropods can be used to define a site. From the structure of the arthropod community one can tell the time of year, the altitude of the collecting site, its aspect (north or south slope), the understory plants, the forest’s successional stage, whether it is old or second growth, its mix of trees. The arthropod community has a turnover time measured in weeks (compared to days for the soil bacteria and centuries for the trees) and so is a much better indicator of subtle changes than the trees, whose long lifetimes put them at a distinct disadvantage in terms of short-term changes. (Along the same lines, Douglas fir needles have fungi that live in them and manufacture chemicals that suppress the growth of needle-grazing insects. The fungi, unlike the tree, can evolve at a rate similar to the insects. As with the soil fungi, these fungi live on nutrients from the needles as well as on nutrients scavenged from killed insects.)
Forests intercept and soften rainfall. Rainwater splatters into a mist as it hits the canopy, drips off leaves and branches and runs down trunks, enters the soil along channels left by rotted roots, dead fungal hyphae, rodent burrows, the smaller burrows of soil invertebrates, cracks left by drying or ice. Rainwater is absorbed into the space that occupies 50-60% of a healthy forest soil. A considerable percent of rainwater evaporates from the trees. In grasslands, where much the same thing happens but on a smaller vertical scale, more water evaporates and runs off into streams, and less enters the ground, than in forests. In older forests, those over say, 150 years in the Pacific Northwest, which is about average for the beginning of maturity in temperate forests, the changing microclimate in the forest begins to favor the growth of lichens on the branches and trunks of the trees. In time, the lichens and other epiphytes on an old-growth tree may weigh four times its foliage. A tree may have 1000 species of affiliated fungi. The lichens gather their nutrients from the air. Rainwater leaches nutrients from them down to the forest floor, where they become available to the tree (pieces also break off and fall to the floor). Lobaria lichens are the largest single source of nitrogen in old-growth forests of the Pacific Northwest and fix several times the nitrogen they need for their growth and maintenance. Roughly speaking, the excess is what is available for the rest of the forest. Lobaria appear in Douglas fir forests at 100 years (20 years after the last of the planted trees in a plantation is cut) and become abundant at 200 years. A full range of all species develops at 400 years. Thus old-growth forests begin a new nutrient cycle, harvesting nutrients from the air to supplement what is available from the soil, much of which by then has been locked up in the trees. The lichens are a food source for arboreal rodents, and the rodents food for predatory birds, creating a new loop on the new nutrient cycle. More growth means more carbon stored in forest soils. Flying squirrels and red-backed voles, among whose main foods are the fruiting heads of the fungi of the forest floor, those valuable edible mushrooms, are the prey of Spotted Owls, a bird whose precipitous decline has led to the controversy over cutting the remaining old-growth forests of the Pacific Northwest.
The spongy forest soil, clumpy with polysaccharides secreted by tree roots and soil organisms, draws in the water it receives. Rainwater is naturally slightly acidic because of carbon dioxide in the air. In the soil it is enriched with more carbon dioxide exuded by respiring tree roots and soil micro-organisms. This increased acidity accelerates the process of subsoil erosion (or weathering), releasing nutrient minerals from rocks and rock particles under the tree. Water also carries rock-dissolving fungal enzymes. Most of the nutrients are taken up immediately by the forest community. Some of the soil water, stripped of its nutrients, sinks through the vadose zone to ground water, some is pulled up by the tree leaves and transpired. The 50-65% that evaporates or is transpired from the canopy to the atmosphere will fall on the landscape nearby in the convective rainfalls of spring and summer. Trees grow tall not so as to produce straight sawlogs, but because gravity tells them to and also to compete for sunlight, their source of energy. Another function is to intercept water. Precipitation under coastal redwoods in California is two to three times the yearly rainfall measured above the trees, thanks to the redwoods’ fog-catching abilities. Trees high on mountainsides may get half their moisture from cloud water condensing on their leaves and branches. Some of the moisture in both cases runs into the ground and feeds perennial streams. (The process supports forests on oceanic islands whose main source of water is fogs.) The great mass of the large trees of the American West Coast may be related to water storage, in a region of summer drought. For the most part, the dead heartwood tissue of trees is thought to be useless, and hazardous as the tree gets larger and its great weight, relative to its root area, increases its liability to fall. Some biologists have theorized that heart-rot fungi, which help the heartwood decay without harming the living outer shell of the tree, are adaptive mechanisms on the part of the tree to reduce its weight and convert the nutrients stored in the heartwood to something the living parts of the tree can use; thus the tree continues to produce seeds, which is the tree’s goal—surely a horrible notion to foresters. (Some old broad-leaved trees send adventitious roots from their branches down into their hollow cavities or into the soil that accumulates along their branches.)
Forests are part of the larger hydrologic and biogeochemical cycles of earth, and of the earth’s energy relationships with the sun. Through photosynthesis, evapotranspiration, and the absorption, reflection, and re-radiation of sunlight, forests affect the flow of solar energy through them and determine the forms in which this energy is dispersed. They change the form, amount and chemistry of the water that flows through them, the chemistry and speed of the wind-driven air, and help determine the amount and kinds of dust and sediment released to these fluids. They govern in some degree the behavior of the interconnected streams, rivers, lakes, and ocean estuaries. They affect local, regional and global climate. In temperate regions, forests, through the evapotranspiration of water from their canopies, have a cooling effect on the summer climate. In snowy regions, certainly in winter, and probably overall, forests have a warming effect on the climate, because they absorb more heat than bare or snow-covered ground. (Locally, this warming exceeds the global cooling effect caused by their absorption of carbon dioxide. So the movement of the taiga forests north as the climate warms will likely reinforce the warming.) But cutting the European forest seems to have raised midwinter temperatures in Europe by 2-3° C., while cutting the forest on Vancouver Island raised summer temperatures there by 2° C.
The storage of carbon in the tissues and soils of forests connects them to the global carbon cycle. One scheme to lower global carbon dioxide levels has been to plant millions of square kilometers of new forests, which while young and growing absorb much carbon dioxide. Existing older forests would be cut down to do this. Cutting down an existing forest releases large amounts of carbon dioxide from the logs, the soil and from rotting vegetation. In temperate forests, it takes 10 to 40 years before more carbon dioxide has been taken up by the growing trees than was released by decomposition. (Tropical forests take much longer.) Once the forest has grown to the point of maturity (that is, to the point where its increase in mass has slowed, and thus the storage of carbon in trunks and branches slowed), the problem is how to log the forest without releasing a high percentage of the carbon. Most of the carbon stored in the wood of a logged forest will return to the atmosphere within a decade. Much of it goes into paper or other short-lived products, and maybe a third is waste, which is burned or decomposes. Since it now appears that forest soils continue to absorb considerable carbon dioxide even as the trees themselves increase in mass more slowly, the likely answer is never to log the forest, or to log it very carefully, so that the soils themselves continue to absorb, or at least limit, their release of carbon. In this case, the choice of lands to reforest becomes important. We should choose more environmentally vulnerable or valuable ones, such as river floodplains, very steep slopes, watersheds used for water supply, and aquifer recharge areas. We should reforest connected areas of sufficient size for the birds and animals characteristic of a region. New forests on deforested or destroyed lands (such as worn-out agricultural lands or strip-mined lands) constitute an advantage from the start; establishing them may be difficult but involves no initial loss of carbon. Tropical forests cool the local climate and continue to store carbon over their lifetimes. They have a large influence on local rainfall and should not be cut, or be cut and reforested very carefully, without much disturbing the canopy, and thus kept from releasing their carbon. (Restored degraded grasslands, such as the American Plains or African savannahs, are other good candidates for carbon storage.)
Forests are connected to the larger world by the water and air that move through them, by the animals that graze on them, and by the plants and animals that otherwise take advantage of the habitat. Insect depredation is usually kept below 20% of leaf mass, partly by insect diseases, partly by chemicals secreted by the trees (24 hours after a caterpillar bites into an aspen leaf, the leaf has five times the amount of poisonous phenols), partly by predatory insects, and partly by insect-eating birds. While losses to insects are a serious matter, much of the energy in the grazed leaves returns to the trees through the insects’ dung and bodies. Summer bird densities in the mesic forests of the eastern United States can be startingly large. Eastern deciduous forests average 863 pairs of songbirds per square kilometer (in effect, about one pair per 1200 square meters, a square 30 by 40 meters on a side). Of these, 587 pairs migrate here from the tropics. Eastern coniferous forest averages 644 pairs, 412 of which are neotropical migrants. Riparian woodland in California averages 1596 pairs per square kilometer, 399 of them neotropical migrants. (California has a more moderate year-round climate and more year-round resident birds.) The neotropical migrants come to take advantage of the summer burst of insect life in the temperate and arctic regions. Birds of one species divide up the suitable areas of the forest into separate territories. A given plot of forest is however shared by many different species; the different species divide it into distinct feeding zones, which are gone over daily and intensively. Intensively, since the birds are feeding not only themselves but several growing young. Birds specialize by focussing on different parts of the forest (the forest floor, the mid-level, the canopy), in how they search those areas for food (scratching in the leaf litter, searching under fallen leaves, hawking for flying insects), in what they choose to eat. (Among wood warblers that forage in the conifers of the northeastern forests, for instance, one species forages in the outer surface, one near the trunk, one along a vertical axis, one horizontally, one chooses the upper third of the tree, one the lower third; some are specialists in specific insects, such as spruce budworm.) The winter territories of these birds are thousands of miles away. Between are the lands that are traversed during migration, slowly in the spring, where, in Central America, the birds’ northward movement corresponds with the ripening of some species of tree fruits, whose seeds the birds disperse. Along the East Coast of North America, spring migration follows the hatch of geometrid moth larvae, at bud break, up the Appalachian Mountains. The leisurely spring migration, during which the birds feed on abundant, protein-rich, nontoxic leafeating caterpillars, is quite different from the birds’ abrupt autumn departure from the Atlantic capes for flights over the ocean to the Caribbean islands or the northern coast of South America. The demanding autumn flights require abundant food supplies concentrated in small areas, that is, easy-to-find fruits, insects, or arthropods, as well as shelter.
To be effective in their job of insect control, the birds must be numerous; ideally they must flood their breeding territories, so that their summer densities are limited primarily by competition for food. This means their “winter” territories must also be optimal, as well as those lands used during migration. All these areas (summer territories, winter territories, migratory corridors) have been considerably degraded in the last 50 years. The Atlantic capes have been developed, reducing their supplies of food and shelter. Breeding areas suffer from fragmentation. Most neotropical migrants do best in large areas of unbroken forest. Smaller areas reduce the amount of their insect prey, as the drying effect of forest edges reaches into the forest and reduces its invertebrate life. Smaller woodlands also make neotropical migrants, most of which are small, brightly colored, and build rather visible cup nests, more vulnerable to nest predators and parasites. Cowbirds, the most important nest parasite in North America, lay their eggs in other birds’ nests and let those birds raise their young. As they grow, the large young cowbirds push the natural offspring out of the nest. Cowbirds, once a bird of the prairie, have increased tremendously and spread throughout the eastern United States with the fragmentation of the forest. (Other prairie birds, such as the clay-colored sparrow, are following them east.) Most neotropical migrants are too small to deter nest predators like crows, raccoons, blue jays, oppossums, house cats and skunks, all of which are abundant in forest edges. More and more winter range is being lost in southern Mexico, Central America and the West Indies to agriculture, logging, and development for tourism. Species that winter in tropical second growth, that is, cut-over woodland (these include northern parula warblers, indigo buntings, rose-breasted grosbeaks), are increasing in number, while those that winter in tropical primary forest (such as wood thrushes, blackburnian warblers, chestnut-sided warblers, hooded warblers) are declining. The quality of winter habitat makes a difference. American redstarts that winter in tropical forest in Jamaica and Honduras gain weight in winter and return early in spring, while those that winter in cutover dry scrub lose weight and return later. Lighthouses and lighted towers (TV towers, cellphone towers) kill 100 to 300 million migrating birds in North America each year, lighted windows 100 to 1000 million (dimming the lights in downtown skyscrapers during migration reduces deaths by 80% and saves millions of kilowatt-hours of electricity); cats 500 to 5000 million (a modest 5 to 10 per cat); ingested lead shot 300,000; hunters 120 million; cars perhaps a million a week. (There are perhaps 20 billion birds in North America in late summer.) The night sky through which songbirds fly south is no longer an empty ether, lit by moon and stars, but probed by beacons, crisscrossed by radio waves, swept by thundering engines, lit by the urban glow from below. Development removes roosting places, meadows and shrublands rich in food, forests from migratory corridors. Habitat degradation, along with pollution of the Northern Hemisphere by heavy metals and hydrocarbons (such as mercury, oil, benzene, DDT), and the depletion of calcium from forest soils by acid rain (which reduces the abundance and nutritional quality of their insect life), helps explain the falling numbers of neotropical migrants in North America. One count puts numbers of migrating songbirds at 5% of pre-Columbian populations, with a fall of perhaps 50% since the 1950s.
Migrating birds extend a forest’s reach into a larger realm, as does the water transpired from the trees (which enters the hydrological cycle, both local and global); or the chemicals exuded by the trees into the atmosphere. Some of these chemicals are part of the trees’ cooling mechanism, some function as warning signals of the presence of grazing insects to other trees (which also begin to secrete them, spreading the warning). Predatory insects are attracted by these deterent-and-warning chemicals, and eat the grazers or lay their eggs on them. (Some species of bean plants secrete chemicals attractant to predatory insects when the eggs of foliage-eating insects are laid on them.) Such chemicals are secreted in sufficient concentration to effect local atmospheric chemistry; in the presence of automobile exhaust and ultra-violet light, they form low level ozone and add to photochemical smogs. At least 120 chemicals are found in the air of California’s high Sierras. Among the most abundant are monoterpenes, which have a role in preventing and curing cancer. Such chemicals enter the bloodstream through the lungs or the limbic system through the olfactory nerves. So a breath of mountain air is a good thing.
A forest’s watery connections lead to the sea, whose nutrients may feed it. After Pacific salmon spawn, they die, and the nutrients in their bodies leach out into headwater streams and lakes. Up to 30% of the nitrogen and carbon in algae and aquatic invertebrates in the steep, nutrient-poor streams where Coho salmon spawn come from dying Coho. The Coho also contribute up to 18% of the nitrogen in streamside vegetation (up to 50% of the nitrogen in some old growth trees. Trees grow 3 times faster along salmon streams. Spawned-out fish contribute 25-40% of the nitrogen and carbon in juvenile Coho, a direct parental contribution to growth. Most of these nutrients come from the sea, so the Coho are part of an accumulated pool of nutrients shared among the sea, streamside forests, and the fish, and to a lesser extent with the bears, martins, otters, beetles, fly larvae, white-tailed deer, red squirrels and eagles that eat the salmon carcasses, and which spread the bounty from the sea further into the landscape through their own bodies and dung. In the salmon-fed rain forests of the Pacific coast, ancient murrelets nest among the roots of the trees and marbled murrelets in the tops: both are seabirds which contribute the nutrients in their droppings to the forest. East Coast streams also had abundant runs of anadromous fish (herring, sea-run trout, striped bass, shad, Atlantic salmon, eels) and so took part in a similar exchange of nutrients; 90% of Atlantic salmon also die after spawning. Fish that didn’t die contributed their voided wastes (and their milt and eggs), which correlated in amount with their body masses, much of which derived from the nutrients of the sea.
Forests are also influenced by the presence of large predatory animals. Ungulates such as deer and elk are capable of rapid increases in population. If unchecked by weather or predation, the animals overshoot their food supplies, their populations crash, and then cycle up and down at a much lower density, in a degraded habitat. Deer at densities greater than 10 per square mile inhibit regeneration in favored species such as hemlock, yew, and white cedar. Browsing that eliminates the understory reduces the value of the forest as habitat for many animals (including nesting birds). White-tailed deer densities in the eastern United States range from 5 per square mile in mature deciduous forest to 20 to 30 per square mile after logging; with protection, populations can reach 70 per square mile. High densities prevent forest reproduction and result in a permanent reduction in food supply for deer. In Yellowstone Park, before the wolf was re-introduced, browsing by elk had prevented regrowth in stands of cottonwoods along streams. Most of the cottonwoods were 60 years old or older and dated from the time wolves were eliminated from Yellowstone. Reintroducing wolves cut the elk population from 5% up to 30%. (Elk numbers are more influenced by food supply and weather than predation. Elk continue to increase during a period of mild winters even as the wolves increase.) But the presence of wolves changed the elks’ behavior. Elk now spent much less time in stream bottoms, where they were more vulnerable to ambush by wolves. This reduced their browsing there and let young willows and cottonwoods regrow. The regrowing forest improved habitat for nesting songbirds and also for beaver (another food animal of wolves). The trees stabilized stream banks and shaded the water. Trout became bigger and more abundant. The ponds the beaver built on small streams provided more habitat for birds and amphibians, slowed water flow, raised ground water tables, and let stream beds build up (aggrade) rather than downcut. Wolf predation also halved the coyote population, so numbers of smaller predators like red foxes and raptors that prey on rodents rose. Wolves control deer and elk by taking animals too sick, too hungry, too old or too young (or whose mothers are less powerful or aware) to defend themselves. (This is the usual story. In prairie dogs predation also falls on males obsessed with sex and on pregnant females, who are probably slightly slower. Predation on young deer or elk can become a problem if the prey population is reduced or otherwise stressed.) Thus animals like wolves exert different evolutionary pressures from those of human hunters on their prey. Human hunters take healthy animals of breeding age. To stabilize deer populations human hunters must take 35-45% of the females annually, not a small number. The difference in predatory behavior is thought to be one reason why prey populations tend to fall in body size under human predation but remain the same or rise under predation by wolves. Healthy wolf populations depend on migration of wolves from other regions, and thus on extensive connected areas of plains or forest.
The plants, animals, fungi and the invisible life of a landscape’s soil are influences on the landscape as important as its topography, climate, and mineral composition (all of which, on a local and a global scale, are modified by life). Natural landscapes are connected largely by the movement of water and its associated nutrients, but also by the flow of the atmosphere and the movements of nutrients and energy through seeds, fish, and other migratory animals. Through such connections, changes in one habitat (such as logging a part of a forest) can affect the whole landscape’s cycling of water, soil, or nutrients, that is, affect the rate of flow of these materials through the larger landscape. When the landscape was edible and its major purpose was to provide food, people were in most cases a less obtrusive part of this landscape. They altered it less, or in less disturbing ways than now, partly by influencing the abundance of large grazing animals, partly by small-scale horticulture, mostly through the use of fire. People were another part of the biota, comparable to an efficient predator like a wolf or a cougar, or to a transformer of soils like a prairie dog, an important but not an overwhelming influence on the landscape, not like now, a cometary impact.
All forms of life influence their surroundings. Photosynthesizing bacteria and blue-green algae are thought to have created our oxygen-rich atmosphere about 2.5 billion years ago. Before that the atmosphere was a reducing one, carbon-rich and oxygen-removing. The creation of an atmosphere dominated by oxygen was a disaster from the point of view of most organisms; some retreated far underground to rock formations from whose chemical elements they could derive energy, some to the anoxic muds of wetlands, ponds and the deep ocean. The current global concentration of carbon dioxide is low thanks partly to the burial of so much carbon in fossil fuels 200 to 300 million years ago, and thus its effective removal from planetary chemistry. Large amounts of carbon are also stored in frozen northern bogs, in ocean sediments and ocean water, in soils, and in standing vegetation. Much of this carbon was sequestered by living things, some by simple chemical processes, and much of it can be released to the atmosphere under the right conditions. We, for instance, free the carbon in fossil fuels by burning them. Eventually that carbon would have been put back in the atmosphere as the continental plates in which it is buried are drawn down into the earth’s mantle and the carbon vaporized and carried back into the atmosphere through the vents of volcanoes. The oxygen content of the atmosphere is now maintained, somewhat mysteriously in the face of constantly exposed, oxydizing minerals (exposed by geological activity and digging humans); fires; and of oxygen-respiring living things, by bacteria and blue-green algae similar to those of 2.5 billion years ago, which live in soils or as photosynthesizing plankton on the ocean’s surface; and by rooted green plants.
It is now known that bacteria live in rock formations up to 3.5 kilometers below the surface of the ground and several miles deep under the ocean. They can tolerate temperatures up to 113º C., 13º C. above boiling. The bacteria in deep ocean muds derive their energy by reacting hydrogen with nitrate to produce ammonia. Some of the organisms that live in the deep, hot biosphere underground also depend on hydrogen fuel: these form the so-called subsurface lithoautotrophic microbial ecosystems; or, SLIMES, the rockeaters. SLIMES were first discovered in drill holes 1000 meters down in Columbia River basalts. It is thought these SLIMES use hydrogen generated by the reaction of water with the ferrous silicates in the basalt for an energy supply. As with the case of the sulfur-reducing bacteria about hot-water deep-sea vents, other organisms show up to eat the first ones; or to use their wastes. The mass of such depth-dwelling organisms, because of the immense size of their habitat, may be greater than that of life on the surface of the earth, much of which is in the first, well-oxygenated foot of soil, the first hundred feet above the soil, and the first half-inch of ocean surface. Whether the underworld life has much influence on the surface one isn’t known. Bacterial life in deep ocean muds has some effect on life on the surface, because what goes on in the muds influences the chemistry of the oceans, and ocean water circulates at greater speeds than crustal rocks (thousands of years rather than tens of millions: the carbon from fossil fuels wouldn’t have turned up in the atmosphere any time soon). At any rate, the living influences on the planet’s surface and atmosphere are set among more general planetary and gravitational ones (such as the output of the sun, the speed of the earth’s spin, its aspect to and distance from the sun); and those of plate tectonics. (Rocks circulate too, but slowly: the burial and rebirth of plates not only help recycle planetary carbon and also reposition continents and oceans; the position of the continents on the globe influences heat distribution, rainfall and other aspects of global climate.) It has become more and more clear that nothing—no climate regime, no ocean shoreline, no level of solar output, no stand of trees—is permanent. Things like the structure of a particular forest are only partly replicable. Ecosystems have histories: different histories explain differences among otherwise similar landscapes—landscapes similar in microclimate, soil, aspect, hydrology, but different in vegetation. Their different histories from, say, fire, grazing or windthrow, nudge them in different directions. Why the atmospheric concentration of oxygen, unlike that of carbon dioxide, remains constant in the face of fossil fuel combustion and the oxidation of exposed soils and rocks has to do with the large volume of atmospheric oxygen, compared to that of carbon and carbon dioxide (so large that burning all the trees on the planet would reduce the concentration of oxygen by only 300 parts per million out of 200,000 parts per million); and with the ability of bacterial populations to respond to small changes in the concentrations of planetary gases.
From a more local perspective, trees create conditions that favor forests: they transpire water from their leaves, cooling the atmosphere and creating mist and rain; their roots penetrate the soil, letting water and oxygen in; the yearly turnover of root hairs and rootlets (approximately one third of the total root mass) adds carbon and other nutrients to the soil. These nutrients are recycled by soil organisms and the trees. The damp, shaded, more temperate forest soils (not so hot in summer, not so cold in winter) become a home for insects, rodents, soil arthropods, bacteria, fungi. Fungi are important in all forests but especially so in evergreen forests, which are noted for their survival in poor soils, and whose needle-fall tends to resist recycling by the arthropods and bacteria, thus locking up nutrients for long periods of time. In some Pacific Northwest forests, soil fungi constitute half the soil biomass. Some evergreens won’t survive without specific fungi in the soil. Clear-cutting causes a dramatic decline in soil arthropods and fungi, which helps explain why some clear cut western sites, especially dry, south or west facing sites, are so difficult to reforest. The fungal hyphae provide water and other nutrients to the tree and increase its effective root area by 1000 to 10,000 times. They secrete enzymes that extract nitrogen and phosphorus directly from humus, eliminating the bacterial food chain. Hyphae secrete chemicals that break down the surfaces of stones and transport trace metals to the tree. They help protect tree roots from acid soils. (So firs will grow on piles of mine spoil.) They secrete growth hormones to increase tree root growth and antibiotics to protect tree roots from bacterial infection. Hyphae connect trees of the same and different species, and by providing nutrients from overstory to understory trees, help make forest succession possible. They turn the forest into a single organism. Such services are not free; approximately 40% of the photosynthesate produced by the leaves seeps out of the roots to the mycorrhizal and bacterial ecosystem that lies within a few millimeters of the root hairs (the so-called rhizosphere); the photosynthesate includes nutrients (sugars) and vitamins. Processes like this are the sort that commercial foresters (or farmers, in another situation) try to short-circuit, by using herbicides and commercial fertilisers to alter ecosystem function, and thus allocate more of the products of photosynthesis to plant growth. This approach ignores the place of the tree in the whole soil and forest community. By providing trees with water, fungi help them better withstand droughts. Polysaccharides secreted by the bacteria and fungi of the rhizosphere also change the soil’s structure, making it better aerated and better adapted to the movement and absorption of water (thus better adapted to tree growth). In test plots in a tropical forest in Guinea, trees responded better to a mulch of wood chips than to chemical fertilizers. In general, trees with mycorrhizal connections grow more vigorously than those without them.
The rest of the soil community is also important. The arthropod communities of Pacific Northwest forests include the grinders of successively smaller size that break down litterfall (five tons per acre per year in old growth forests), until the material, successive levels of bug poop, finally reaches the scale of the plant cell. Bacteria scavenge the available nutrients, die, or are eaten by other organisms, which excrete them, their nutrients becoming available to the trees; the nutrients are also transferred by fungal hyphae to the trees directly. Logs are broken down in a similar fashion. Total incorporation of a Douglas fir log into the soil can take 400 years. Because of the log’s inhabitants, while 5% of a tree consists of living cells, 20% of a rotting log is living tissue. Such soil arthropods can be used to define a site. From the structure of the arthropod community one can tell the time of year, the altitude of the collecting site, its aspect (north or south slope), the understory plants, the forest’s successional stage, whether it is old or second growth, its mix of trees. The arthropod community has a turnover time measured in weeks (compared to days for the soil bacteria and centuries for the trees) and so is a much better indicator of subtle changes than the trees, whose long lifetimes put them at a distinct disadvantage in terms of short-term changes. (Along the same lines, Douglas fir needles have fungi that live in them and manufacture chemicals that suppress the growth of needle-grazing insects. The fungi, unlike the tree, can evolve at a rate similar to the insects. As with the soil fungi, these fungi live on nutrients from the needles as well as on nutrients scavenged from killed insects.)
Forests intercept and soften rainfall. Rainwater splatters into a mist as it hits the canopy, drips off leaves and branches and runs down trunks, enters the soil along channels left by rotted roots, dead fungal hyphae, rodent burrows, the smaller burrows of soil invertebrates, cracks left by drying or ice. Rainwater is absorbed into the space that occupies 50-60% of a healthy forest soil. A considerable percent of rainwater evaporates from the trees. In grasslands, where much the same thing happens but on a smaller vertical scale, more water evaporates and runs off into streams, and less enters the ground, than in forests. In older forests, those over say, 150 years in the Pacific Northwest, which is about average for the beginning of maturity in temperate forests, the changing microclimate in the forest begins to favor the growth of lichens on the branches and trunks of the trees. In time, the lichens and other epiphytes on an old-growth tree may weigh four times its foliage. A tree may have 1000 species of affiliated fungi. The lichens gather their nutrients from the air. Rainwater leaches nutrients from them down to the forest floor, where they become available to the tree (pieces also break off and fall to the floor). Lobaria lichens are the largest single source of nitrogen in old-growth forests of the Pacific Northwest and fix several times the nitrogen they need for their growth and maintenance. Roughly speaking, the excess is what is available for the rest of the forest. Lobaria appear in Douglas fir forests at 100 years (20 years after the last of the planted trees in a plantation is cut) and become abundant at 200 years. A full range of all species develops at 400 years. Thus old-growth forests begin a new nutrient cycle, harvesting nutrients from the air to supplement what is available from the soil, much of which by then has been locked up in the trees. The lichens are a food source for arboreal rodents, and the rodents food for predatory birds, creating a new loop on the new nutrient cycle. More growth means more carbon stored in forest soils. Flying squirrels and red-backed voles, among whose main foods are the fruiting heads of the fungi of the forest floor, those valuable edible mushrooms, are the prey of Spotted Owls, a bird whose precipitous decline has led to the controversy over cutting the remaining old-growth forests of the Pacific Northwest.
The spongy forest soil, clumpy with polysaccharides secreted by tree roots and soil organisms, draws in the water it receives. Rainwater is naturally slightly acidic because of carbon dioxide in the air. In the soil it is enriched with more carbon dioxide exuded by respiring tree roots and soil micro-organisms. This increased acidity accelerates the process of subsoil erosion (or weathering), releasing nutrient minerals from rocks and rock particles under the tree. Water also carries rock-dissolving fungal enzymes. Most of the nutrients are taken up immediately by the forest community. Some of the soil water, stripped of its nutrients, sinks through the vadose zone to ground water, some is pulled up by the tree leaves and transpired. The 50-65% that evaporates or is transpired from the canopy to the atmosphere will fall on the landscape nearby in the convective rainfalls of spring and summer. Trees grow tall not so as to produce straight sawlogs, but because gravity tells them to and also to compete for sunlight, their source of energy. Another function is to intercept water. Precipitation under coastal redwoods in California is two to three times the yearly rainfall measured above the trees, thanks to the redwoods’ fog-catching abilities. Trees high on mountainsides may get half their moisture from cloud water condensing on their leaves and branches. Some of the moisture in both cases runs into the ground and feeds perennial streams. (The process supports forests on oceanic islands whose main source of water is fogs.) The great mass of the large trees of the American West Coast may be related to water storage, in a region of summer drought. For the most part, the dead heartwood tissue of trees is thought to be useless, and hazardous as the tree gets larger and its great weight, relative to its root area, increases its liability to fall. Some biologists have theorized that heart-rot fungi, which help the heartwood decay without harming the living outer shell of the tree, are adaptive mechanisms on the part of the tree to reduce its weight and convert the nutrients stored in the heartwood to something the living parts of the tree can use; thus the tree continues to produce seeds, which is the tree’s goal—surely a horrible notion to foresters. (Some old broad-leaved trees send adventitious roots from their branches down into their hollow cavities or into the soil that accumulates along their branches.)
Forests are part of the larger hydrologic and biogeochemical cycles of earth, and of the earth’s energy relationships with the sun. Through photosynthesis, evapotranspiration, and the absorption, reflection, and re-radiation of sunlight, forests affect the flow of solar energy through them and determine the forms in which this energy is dispersed. They change the form, amount and chemistry of the water that flows through them, the chemistry and speed of the wind-driven air, and help determine the amount and kinds of dust and sediment released to these fluids. They govern in some degree the behavior of the interconnected streams, rivers, lakes, and ocean estuaries. They affect local, regional and global climate. In temperate regions, forests, through the evapotranspiration of water from their canopies, have a cooling effect on the summer climate. In snowy regions, certainly in winter, and probably overall, forests have a warming effect on the climate, because they absorb more heat than bare or snow-covered ground. (Locally, this warming exceeds the global cooling effect caused by their absorption of carbon dioxide. So the movement of the taiga forests north as the climate warms will likely reinforce the warming.) But cutting the European forest seems to have raised midwinter temperatures in Europe by 2-3° C., while cutting the forest on Vancouver Island raised summer temperatures there by 2° C.
The storage of carbon in the tissues and soils of forests connects them to the global carbon cycle. One scheme to lower global carbon dioxide levels has been to plant millions of square kilometers of new forests, which while young and growing absorb much carbon dioxide. Existing older forests would be cut down to do this. Cutting down an existing forest releases large amounts of carbon dioxide from the logs, the soil and from rotting vegetation. In temperate forests, it takes 10 to 40 years before more carbon dioxide has been taken up by the growing trees than was released by decomposition. (Tropical forests take much longer.) Once the forest has grown to the point of maturity (that is, to the point where its increase in mass has slowed, and thus the storage of carbon in trunks and branches slowed), the problem is how to log the forest without releasing a high percentage of the carbon. Most of the carbon stored in the wood of a logged forest will return to the atmosphere within a decade. Much of it goes into paper or other short-lived products, and maybe a third is waste, which is burned or decomposes. Since it now appears that forest soils continue to absorb considerable carbon dioxide even as the trees themselves increase in mass more slowly, the likely answer is never to log the forest, or to log it very carefully, so that the soils themselves continue to absorb, or at least limit, their release of carbon. In this case, the choice of lands to reforest becomes important. We should choose more environmentally vulnerable or valuable ones, such as river floodplains, very steep slopes, watersheds used for water supply, and aquifer recharge areas. We should reforest connected areas of sufficient size for the birds and animals characteristic of a region. New forests on deforested or destroyed lands (such as worn-out agricultural lands or strip-mined lands) constitute an advantage from the start; establishing them may be difficult but involves no initial loss of carbon. Tropical forests cool the local climate and continue to store carbon over their lifetimes. They have a large influence on local rainfall and should not be cut, or be cut and reforested very carefully, without much disturbing the canopy, and thus kept from releasing their carbon. (Restored degraded grasslands, such as the American Plains or African savannahs, are other good candidates for carbon storage.)
Forests are connected to the larger world by the water and air that move through them, by the animals that graze on them, and by the plants and animals that otherwise take advantage of the habitat. Insect depredation is usually kept below 20% of leaf mass, partly by insect diseases, partly by chemicals secreted by the trees (24 hours after a caterpillar bites into an aspen leaf, the leaf has five times the amount of poisonous phenols), partly by predatory insects, and partly by insect-eating birds. While losses to insects are a serious matter, much of the energy in the grazed leaves returns to the trees through the insects’ dung and bodies. Summer bird densities in the mesic forests of the eastern United States can be startingly large. Eastern deciduous forests average 863 pairs of songbirds per square kilometer (in effect, about one pair per 1200 square meters, a square 30 by 40 meters on a side). Of these, 587 pairs migrate here from the tropics. Eastern coniferous forest averages 644 pairs, 412 of which are neotropical migrants. Riparian woodland in California averages 1596 pairs per square kilometer, 399 of them neotropical migrants. (California has a more moderate year-round climate and more year-round resident birds.) The neotropical migrants come to take advantage of the summer burst of insect life in the temperate and arctic regions. Birds of one species divide up the suitable areas of the forest into separate territories. A given plot of forest is however shared by many different species; the different species divide it into distinct feeding zones, which are gone over daily and intensively. Intensively, since the birds are feeding not only themselves but several growing young. Birds specialize by focussing on different parts of the forest (the forest floor, the mid-level, the canopy), in how they search those areas for food (scratching in the leaf litter, searching under fallen leaves, hawking for flying insects), in what they choose to eat. (Among wood warblers that forage in the conifers of the northeastern forests, for instance, one species forages in the outer surface, one near the trunk, one along a vertical axis, one horizontally, one chooses the upper third of the tree, one the lower third; some are specialists in specific insects, such as spruce budworm.) The winter territories of these birds are thousands of miles away. Between are the lands that are traversed during migration, slowly in the spring, where, in Central America, the birds’ northward movement corresponds with the ripening of some species of tree fruits, whose seeds the birds disperse. Along the East Coast of North America, spring migration follows the hatch of geometrid moth larvae, at bud break, up the Appalachian Mountains. The leisurely spring migration, during which the birds feed on abundant, protein-rich, nontoxic leafeating caterpillars, is quite different from the birds’ abrupt autumn departure from the Atlantic capes for flights over the ocean to the Caribbean islands or the northern coast of South America. The demanding autumn flights require abundant food supplies concentrated in small areas, that is, easy-to-find fruits, insects, or arthropods, as well as shelter.
To be effective in their job of insect control, the birds must be numerous; ideally they must flood their breeding territories, so that their summer densities are limited primarily by competition for food. This means their “winter” territories must also be optimal, as well as those lands used during migration. All these areas (summer territories, winter territories, migratory corridors) have been considerably degraded in the last 50 years. The Atlantic capes have been developed, reducing their supplies of food and shelter. Breeding areas suffer from fragmentation. Most neotropical migrants do best in large areas of unbroken forest. Smaller areas reduce the amount of their insect prey, as the drying effect of forest edges reaches into the forest and reduces its invertebrate life. Smaller woodlands also make neotropical migrants, most of which are small, brightly colored, and build rather visible cup nests, more vulnerable to nest predators and parasites. Cowbirds, the most important nest parasite in North America, lay their eggs in other birds’ nests and let those birds raise their young. As they grow, the large young cowbirds push the natural offspring out of the nest. Cowbirds, once a bird of the prairie, have increased tremendously and spread throughout the eastern United States with the fragmentation of the forest. (Other prairie birds, such as the clay-colored sparrow, are following them east.) Most neotropical migrants are too small to deter nest predators like crows, raccoons, blue jays, oppossums, house cats and skunks, all of which are abundant in forest edges. More and more winter range is being lost in southern Mexico, Central America and the West Indies to agriculture, logging, and development for tourism. Species that winter in tropical second growth, that is, cut-over woodland (these include northern parula warblers, indigo buntings, rose-breasted grosbeaks), are increasing in number, while those that winter in tropical primary forest (such as wood thrushes, blackburnian warblers, chestnut-sided warblers, hooded warblers) are declining. The quality of winter habitat makes a difference. American redstarts that winter in tropical forest in Jamaica and Honduras gain weight in winter and return early in spring, while those that winter in cutover dry scrub lose weight and return later. Lighthouses and lighted towers (TV towers, cellphone towers) kill 100 to 300 million migrating birds in North America each year, lighted windows 100 to 1000 million (dimming the lights in downtown skyscrapers during migration reduces deaths by 80% and saves millions of kilowatt-hours of electricity); cats 500 to 5000 million (a modest 5 to 10 per cat); ingested lead shot 300,000; hunters 120 million; cars perhaps a million a week. (There are perhaps 20 billion birds in North America in late summer.) The night sky through which songbirds fly south is no longer an empty ether, lit by moon and stars, but probed by beacons, crisscrossed by radio waves, swept by thundering engines, lit by the urban glow from below. Development removes roosting places, meadows and shrublands rich in food, forests from migratory corridors. Habitat degradation, along with pollution of the Northern Hemisphere by heavy metals and hydrocarbons (such as mercury, oil, benzene, DDT), and the depletion of calcium from forest soils by acid rain (which reduces the abundance and nutritional quality of their insect life), helps explain the falling numbers of neotropical migrants in North America. One count puts numbers of migrating songbirds at 5% of pre-Columbian populations, with a fall of perhaps 50% since the 1950s.
Migrating birds extend a forest’s reach into a larger realm, as does the water transpired from the trees (which enters the hydrological cycle, both local and global); or the chemicals exuded by the trees into the atmosphere. Some of these chemicals are part of the trees’ cooling mechanism, some function as warning signals of the presence of grazing insects to other trees (which also begin to secrete them, spreading the warning). Predatory insects are attracted by these deterent-and-warning chemicals, and eat the grazers or lay their eggs on them. (Some species of bean plants secrete chemicals attractant to predatory insects when the eggs of foliage-eating insects are laid on them.) Such chemicals are secreted in sufficient concentration to effect local atmospheric chemistry; in the presence of automobile exhaust and ultra-violet light, they form low level ozone and add to photochemical smogs. At least 120 chemicals are found in the air of California’s high Sierras. Among the most abundant are monoterpenes, which have a role in preventing and curing cancer. Such chemicals enter the bloodstream through the lungs or the limbic system through the olfactory nerves. So a breath of mountain air is a good thing.
A forest’s watery connections lead to the sea, whose nutrients may feed it. After Pacific salmon spawn, they die, and the nutrients in their bodies leach out into headwater streams and lakes. Up to 30% of the nitrogen and carbon in algae and aquatic invertebrates in the steep, nutrient-poor streams where Coho salmon spawn come from dying Coho. The Coho also contribute up to 18% of the nitrogen in streamside vegetation (up to 50% of the nitrogen in some old growth trees. Trees grow 3 times faster along salmon streams. Spawned-out fish contribute 25-40% of the nitrogen and carbon in juvenile Coho, a direct parental contribution to growth. Most of these nutrients come from the sea, so the Coho are part of an accumulated pool of nutrients shared among the sea, streamside forests, and the fish, and to a lesser extent with the bears, martins, otters, beetles, fly larvae, white-tailed deer, red squirrels and eagles that eat the salmon carcasses, and which spread the bounty from the sea further into the landscape through their own bodies and dung. In the salmon-fed rain forests of the Pacific coast, ancient murrelets nest among the roots of the trees and marbled murrelets in the tops: both are seabirds which contribute the nutrients in their droppings to the forest. East Coast streams also had abundant runs of anadromous fish (herring, sea-run trout, striped bass, shad, Atlantic salmon, eels) and so took part in a similar exchange of nutrients; 90% of Atlantic salmon also die after spawning. Fish that didn’t die contributed their voided wastes (and their milt and eggs), which correlated in amount with their body masses, much of which derived from the nutrients of the sea.
Forests are also influenced by the presence of large predatory animals. Ungulates such as deer and elk are capable of rapid increases in population. If unchecked by weather or predation, the animals overshoot their food supplies, their populations crash, and then cycle up and down at a much lower density, in a degraded habitat. Deer at densities greater than 10 per square mile inhibit regeneration in favored species such as hemlock, yew, and white cedar. Browsing that eliminates the understory reduces the value of the forest as habitat for many animals (including nesting birds). White-tailed deer densities in the eastern United States range from 5 per square mile in mature deciduous forest to 20 to 30 per square mile after logging; with protection, populations can reach 70 per square mile. High densities prevent forest reproduction and result in a permanent reduction in food supply for deer. In Yellowstone Park, before the wolf was re-introduced, browsing by elk had prevented regrowth in stands of cottonwoods along streams. Most of the cottonwoods were 60 years old or older and dated from the time wolves were eliminated from Yellowstone. Reintroducing wolves cut the elk population from 5% up to 30%. (Elk numbers are more influenced by food supply and weather than predation. Elk continue to increase during a period of mild winters even as the wolves increase.) But the presence of wolves changed the elks’ behavior. Elk now spent much less time in stream bottoms, where they were more vulnerable to ambush by wolves. This reduced their browsing there and let young willows and cottonwoods regrow. The regrowing forest improved habitat for nesting songbirds and also for beaver (another food animal of wolves). The trees stabilized stream banks and shaded the water. Trout became bigger and more abundant. The ponds the beaver built on small streams provided more habitat for birds and amphibians, slowed water flow, raised ground water tables, and let stream beds build up (aggrade) rather than downcut. Wolf predation also halved the coyote population, so numbers of smaller predators like red foxes and raptors that prey on rodents rose. Wolves control deer and elk by taking animals too sick, too hungry, too old or too young (or whose mothers are less powerful or aware) to defend themselves. (This is the usual story. In prairie dogs predation also falls on males obsessed with sex and on pregnant females, who are probably slightly slower. Predation on young deer or elk can become a problem if the prey population is reduced or otherwise stressed.) Thus animals like wolves exert different evolutionary pressures from those of human hunters on their prey. Human hunters take healthy animals of breeding age. To stabilize deer populations human hunters must take 35-45% of the females annually, not a small number. The difference in predatory behavior is thought to be one reason why prey populations tend to fall in body size under human predation but remain the same or rise under predation by wolves. Healthy wolf populations depend on migration of wolves from other regions, and thus on extensive connected areas of plains or forest.
The plants, animals, fungi and the invisible life of a landscape’s soil are influences on the landscape as important as its topography, climate, and mineral composition (all of which, on a local and a global scale, are modified by life). Natural landscapes are connected largely by the movement of water and its associated nutrients, but also by the flow of the atmosphere and the movements of nutrients and energy through seeds, fish, and other migratory animals. Through such connections, changes in one habitat (such as logging a part of a forest) can affect the whole landscape’s cycling of water, soil, or nutrients, that is, affect the rate of flow of these materials through the larger landscape. When the landscape was edible and its major purpose was to provide food, people were in most cases a less obtrusive part of this landscape. They altered it less, or in less disturbing ways than now, partly by influencing the abundance of large grazing animals, partly by small-scale horticulture, mostly through the use of fire. People were another part of the biota, comparable to an efficient predator like a wolf or a cougar, or to a transformer of soils like a prairie dog, an important but not an overwhelming influence on the landscape, not like now, a cometary impact.
The Natural History of the Present, Chapter 1
The Natural History of the Present
Part I: The Problem with Economics
Chapter 1
Some people trace the state of our warming, polluted world to capitalism, with its ability to motivate human effort towards ever more elaborate material lives. Long before capitalism, agriculture greatly increased our effect on the natural world, largely through allowing the human population to increase by many times. The first southerly breath of global warming most likely came from the clearance of forests for agriculture. Fossil evidence suggests human hunters with spears caused a major wave of extinction of large animals 11,500 years ago in the Americas; and that humans using spears, throwing sticks and fire caused one 40,000 years before that in Australia. The fundamental problem with human influence on the natural world is not capitalism (state or corporate) but the human evolutionary imperative to multiply and thus to occupy every possible environment. Like any plant or animal, we remake our environment to make it more suitable for us. Digging sticks, fiber carrying bags, stone blades, fire, crops, the development of machines, the use of fossil fuels, the organizing and motivating abilities of the state, just increased these abilities. How far we can go isn’t clear. There may indeed be limits: we need space to lie down, to move around, and in which to grow food (even if the food is grown in stainless steel fermenters on nutrients derived from sewage). But we could build huge steel and glass above-ground cities (the linear cities of Paolo Soleri), faced with solar cells, their size limited only by the materials, or excavate caverns many hundreds of yards or kilometers underground, like those of ancient Cappadocia or modern Norway (so employing geothermal heat), or build marine cities, powered by wind, or by the difference in temperatures between ocean currents, on floating platforms tethered to the bottom of the sea. None of this interests me here. What interests me here are the possibilities of a modern life in a working natural world, surrounded by and supported by working ecosystems. Ideally, half or less of any landscape would be used by people for the production of commodities of economic value. Some equilibrium would exist between the tribe of humans, the tribe of mice, the tribe of herons, the tribe of salmon. There would be restraints. We would eat salmon but we wouldn’t eat all of them; and we wouldn’t destroy their habitat.
In any case, the practice of pure capitalism is a myth. It exists in no society. Life under it for most of the population would be nasty, brutish and short. The move from an agricultural to an industrial economy, which exacerbated the economic and social failures of capitalism in practice, led to the idea of the social welfare state, with free public education, universal health care, old age and unemployment insurance, some redistribution of wealth from the rich to the poor. Modern western societies vary in how far they go toward establishing such a state. Among those societies that go the farthest—the democracies of northern Europe—are the richest.
Capitalism can also be modified to save the natural environment. A focus on water helps. So do two legal doctrines: the Law of Nuisance, under which an individual may not use his property to cause legally recognized difficulties for his neighbor (consider the rain of metals from the atmosphere, or the warming planet, as well as plumes of industrial discharges in waterways); and the Public Trust Doctrine, which puts the use of certain landscapes, such as riverbanks and shorelines, along with their related benefits (such as swimmable waters and fisheries) under the protection of the state, which must maintain them for the common good. Public Trust landscapes, such as riverbanks, groundwater reserves and shorelines, are only partly controllable by people. In practice, both these doctrines are difficult and expensive for individuals to use, since specific harms must be traced to specific causes. Some writers argue that the notions behind the Public Trust Doctrine form the basis for protecting ecosystem functions in general.
My motives in writing this book are unabashedly sentimental. I am attached to the green world in which, where I live, the ground freezes up in early November (better have your shovel out of the ground), and the wood warblers return in early May. My attachment is something of a misperception on my part, since this green world is recent (at least in its details), certainly no more than 6000 years old. It is also much less abundant than the one I remember from 50 years ago, when as a boy the robin chorus woke me up at dawn. The world for the last 10,000 years has been one of shifting baselines: my world is less abundant than the one my father saw in the 1920s, when he shot ducks from a harbor breakwall on Lake Erie; and his less abundant than my grandfather’s in the 1880s, when deer were extinct in Vermont and Rhode Island, but shorebirds were still shot on the New England beaches for market. (An amateur ornithologist, as a boy my grandfather amassed a collection of bird skins.) Without the heat-trapping gases of modern civilization, my world would probably have been replaced by several hundred feet of ice within another few thousand years. It will now probably be replaced with a warmer and greener world. (‘Probably’ because the results of modifying climate are unpredictable.) This must be fine with me, as long as such changes remain within the limits to which living things can adjust, and as long as the ecosystems that support the green world continue to function.
* * *
The usefulness of market economics comes from its reduction of human activity to matters of efficiency and profit. Reductionism has a long history in modern life: children are educated in school, not the home (reducing the influence of parents); work and life are separate activities; one does not grow one’s food or sew one’s clothes (farmers grow food and garment workers sew clothes); and entertainers provide entertainment. Specialization of economic and social roles goes along with economic development. Social roles, such as schooling and child care, become economic professions, performed by teachers and nannies. Thus new jobs are created and parents work outside the home. One could argue that economic specialization makes economic development possible. Distinctions among work, entertainment, and schooling are obscure in peasant, or gathering and hunting cultures, where all or none of one’s activities might be considered work, and few, if any, yielded a profit; but together they constituted a life: that whole life was what children learned. While economic development has made possible the continuing elaboration of modern life, economic development also requires that elaboration. Without increasing consumption, how can capital grow?
In early modern times in Europe, walking was replaced by riding in carriages, then carriages were replaced by trains, which were replaced by automobiles and airplanes. A long time ago people drank from streams, then from hand-dug wells or public fountains, then had piped household water, then drinkable piped water; now people choose from a thousand kinds of carbonated drinks and bottled waters. All this costs the individual more: soda or apple juice costs more than tap water, or a sip from the local brook, which is anyway no longer drinkable because of the side effects of economic development. In New York City, maintaining a car costs 8 to 10 times more than taking public transportation, and despite the state of traffic in the city, where in 1960 cars moved at half the speed of horse-cars in 1907, about half the households have one. (The number is close to 100% in the suburbs.) The additional costs per person mean that each person supports a higher level of economic activity, and that the cost of necessities has fallen relative to total income. Late twentieth-century Americans spend 8% of their income on food, while the figure for eighteenth-century France was 90%. Much improvement has been recent: in turn-of-the-century America food, clothing and shelter accounted for 80% of a family’s budget; in 2000 one-third. So more income is available for other things. Spending income on other things employs the people who provide them; as their incomes rise, they also spend more, and the general level of economic activity rises further—the capitalist gift of growth.
Economic growth has some counter-intuitive consequences. If you earn more than, say $6 an hour, it is probably not worth your while to grow your own food: carrots and cabbage are too cheap. Walking across the United States, a journey of 200 to 300 days, is much more expensive than flying. A one-way ticket from New York to San Francisco costs $150. Food and drink for 200 days costs several times that. (Even biking, which takes 30 days, costs considerably more.) Partly, the direct costs of walking are so high because one can no longer drink the water one comes across, hunt or gather one’s food, camp out beside the road, or sew new shoes from animal skins. Capitalist development has made flying cheap and walking expensive, and travel more polluting; walking generates no extra carbon dioxide, and flying somewhat more than driving (6 times more than taking the train). A Sioux or a Tewa would have set out on foot on a trading journey of some hundreds of miles to realize what he or she considered a profit (perhaps a change of scene was also a benefit); or a medieval Frenchman walk from Arras in northern France to Saint James of Campostella in Spain for the good of his soul. Along the road the pilgrim would have been given food and lodging by others for the good of their souls. To walk the length of France at that time took 40 days. It was somewhat faster by horse: 20 to 22 days from Flanders to Navarre in the fourteenth century. For capitalist traders the time such journeys took represented a cost. Some profited by it; the distances allowed bankers in Florence and Sienna (such as the Medicis) to use the different rates of exchange in local currencies as a substitute for charging interest. Charging interest constituted usury, a sin. Periodic improvements in transport would give a tremendous boost to trade.
While capitalist development divides up the social and material world to create more scope for profit, scientific investigation divides up the natural world in order to understand it. Science cannot yet deal with whole views of the world, though some scientists are trying. So our world is made up of many pieces that don’t fit together. We have many worlds, not one whole. Such disconnectedness is a rather recent development. Most pre-industrial conceptions of the world were wholes. The Sumerians, one of the earliest irrigation societies, lived in the valley of the Tigris and Euphrates rivers, in the flat, hot countryside of what is now Iraq. All agriculturists, but especially irrigators, have to be able to predict the seasons, and the Sumerians, like all irrigators, were astronomers. They mathematically interpreted (explained, in modern terms) the cyclical movements of the planets and stars. These predictable heavenly cycles were used to predict the cycles of earthly life—the time of the river floods, the time to plant, the time to clean the canals; the time to build new ones. The cycles of the heavens determined the cycles of human society, and the cyclic life of the society that of the man or woman in it, one life within another, microcosm within macrocosm. Like the stars, the people were fixed in their professions and social classes, the son of a farmer became a farmer, the son of a potter a potter; the society was one whole in its place under the night sky. While such ancient worlds are wholes, they have their limitations. Doubters are banished to other worlds. The Catholic Church came close to banishing Galileo to the world of the dead for teaching that the earth circled the sun. (It didn’t help that he had a bad attitude toward the Church.) Tribal groups banish those whose behavior isn’t socially acceptable. Banishment in this case usually means death from starvation or loneliness. Many have pointed out that the word for non-Greeks in Greek is barbarian. This is true in many languages, where the word for man is often the same as that for a member of the tribal or linguistic group. Fundamentalist Christians and Muslims banish non-believers to hell. So wholeness has its price.
While the idea of an unfettered market economy is a modern sort of whole outlook, examples of the destructiveness of market economics are many. (To paraphrase another writer, markets are a great way to organize economic activity but need adult supervision.) One is the abundance of abandoned downtowns throughout the United States. City downtowns, built for streetcars and foot traffic, were unadaptable to automobile transportation. Automobiles require parking space, which didn’t exist downtown. Land was cheaper outside the city, so shops and investment moved to the suburbs. Another is the abundance of leaking mines: 40% of rivers in the western United States are polluted by mines. Reclamation of surface coal mines comes to 4% of production costs in a free market, and is therefore affordable, while reclamation of hard rock mines (most of those in the West) is not economically possible at current prices for metals. From a market point of view, reclamation costs are costs without returns. Then there is the continuing failure of the Atlantic right whale population to recover, despite the end of hunting. The cause is probably high levels of anthropogenic nitrogen in coastal waters; these, together with overfishing, have shifted the plankton soup the whales feed on to mostly plants, rather than a mix of plants and animals, and put the whales on a vegetarian diet—which doesn’t allow them to put on sufficient weight to breed. (They are also killed in collisions with ships and get entangled in fishing gear.) There are the silty rivers of the American Middle West, once full of game fish, waterfowl, and turtles, now used for barge transport, hydroelectric power, sewage disposal, disposal of industrial effluent, and water supply. Under the same agricultural region lie pools of ground water contaminated with fertiliser and pesticide, some with pools of perchloroethylene collecting below, and pools of motor oil and gasoline sitting on top. Such hydrocarbons don’t mix well with water (though fats and oils take them up). The chloroethylenes are solvents, degreasers, dry cleaning fluids. Much ground and surface water and most processed foods are contaminated with them. Perchloroethylene interferes with the action of hormones, attaches to chromosomes, cripples immune systems, and over-stimulates the activity of some enzymes. About half the population of the United States gets its drinking water from ground water. Ground water eventually becomes river water, and thus everybody else’s drinking water, and the water in which fish and amphibians live and waterbirds swim. Bacteria will eventually break down most of these chemicals but not before they have accumulated in our bodies (the process takes too long in nature).
There is acid precipitation, a side effect of the combustion of fossil fuels, which has resulted in the dying trees, declining birds, acidified lakes and calcium-leached soils of the higher elevations of the eastern United States, Central Europe, and Scandinavia. About 70% of soils in the eastern United States are calcium poor. As the rain leaches more calcium out and the soils further acidify, aluminum ions are released from their oxydized (and harmless) state. Aluminum is the most abundant positive ion in the soil and once it is available, trees take it up instead of calcium, and transfer it to their crowns in an attempt to neutralize the acidic water condensing on their needles, which degrades chlorophyll (and if it forms trichloroacetic acid, acts as a defoliant). But aluminum is toxic to plants and animals and interferes with the trees’ metabolism. Leaves lower in calcium are less nutritious for grazing insects and the insects make less nutritious meals for birds, who must accumulate calcium for their eggshells. Nesting songbirds lay fewer eggs in acidified northern European woodlands. With less calcium available, soil animals such as earthworms, millipedes, pillbugs and snails, food for thrushes and other birds of the forest floor, decline. Such effects may explain the strong declines of nesting songbirds on the high plateaus of the eastern United States. The first snowmelt in the spring carries much of the winter’s acid precipitation (the accumulated snow and rain) into streams, and mobilizes the bio-accumulated acids from the soil, killing young trout and essentially sterilizing the water.
Research increasingly implicates the human environment in the growing epidemics of asthma, autism, adult onset diabetes and attention deficit disorder. The increase in diabetes is probably caused by changes in diet, specifically by the rise in the use of corn syrup, cheaper than cane or beet sugar, to sweeten ever-larger bottles of soft drinks, while the incidence of the other three disorders is likely influenced by the chemical soup in which we live. There are also inexplicable clusters of childhood leukemia and breast cancer. Virtually all the atrazine (an herbicide) used on cornfields in the Great Lakes Basin is still in the Great Lakes, as is most of the DDT that periodically wells up from their depths; in very small doses (one thirtieth of the Environmental Protection Agency’s standard for drinking water) atrazine makes male northern leopard frogs hermaphroditic. Atrazine is also an immune suppressant. Its use is probably the main reason for the collapse of amphibian populations in the Middle West in the 1970s. The capacity to act as a hormone in very small doses is characteristic of many chlorinated hydrocarbons. Very low levels of 2,4-D (one seventh of the Environmental Protection Agency’s recommendation for drinking water) has the greatest effect in reducing fertility in mice. Larger doses of the same chemical are ignored by the endocrine system, which normally responds to very low levels of blood-borne hormones.
Some cancer clusters may really be inexplicable (so-called statistical artifacts common to small sample populations), and some increases in disease a matter of better diagnosis. Some may be the result of atmospheric circulation having concentrated radioactive fallout in certain places during the testing of nuclear weapons 40 years ago. (One argument for this is an apparent rise in the incidence of breast cancer in American women who were adolescents living in downwind locations from 1957 to 1963). Two rather interesting explanations have been put forward to explain clusters of childhood leukemia. One suggests such clusters may be related to the ease of movement of modern people. Genetic studies indicate that many people in rural areas of Europe are descendants of people who have lived there for hundreds or thousands of years. If a nuclear powerplant or nuclear fuel reprocessing facility is built in such a place (remote places are favored and nuclear facilities are always suspect in terms of cancer-related diseases), people move into the area for the jobs, from hundreds or thousands of miles away. Their newly born children are exposed to leukemia-causing viruses endemic to the area, for which their mothers—not from the area—have transmitted to them no immunuty. In this case connections with radioactive hazards are incidental.
So the hazards of development are not obvious. A second explanation concerns clusters of leukemia in children who live near industrialized river estuaries in Britain. Such children have unusual levels of alpha radiation in their tissues and two to three times the normal rate of childhood leukemia. Large river estuaries like the Severn which are surrounded by fossil fuel burning industry, by a large car and truck traffic, and much space and water heating, end up with a considerable load of hydrocarbons in the water. They fall into the water from the air, or wash in off the land. Hydrophobic, the hydrocarbons tend to float on the surface and are concentrated by tidal action at the interface of fresh and salt water. The chemicals are mobilized in spray, which is carried inland by the wind and inhaled by people, settles out on their clothes and migrates into their houses. The hydrocarbons contain uranium and radon as contaminants. (Radioactive materials are natural contaminants of oil and coal.) These materials or their radioactive daughters (radioactively unstable lead) are concentrated in bone and fat. The release of alpha particles during further radioactive breakdown irradiates developing blood cells in bone marrow, and is thought to cause the leukemias. Children, whose cells divide more rapidly, are more sensitive to ionizing radiation.
Economics is concerned with prices, not with intrinsic values, so things of little intrinsic use—diamonds, gold, Cabbage Patch dolls—may be priced highly by the market. Production of such goods, like that of necessities, generates toxic materials and carbon dioxide. In general, scarcity sets prices. Social goods become valuable only when they threaten market stability, and ecological ones (like clean water) only when they become scarce. Abundant resources (including labor in some markets, and timber, land and water in many developed societies until recently) are cheap. Disposal of the waste products of production into air or water is free. The social problems of capitalist societies are more likely to be ameliorated than the biological ones. Social problems of capitalist, or market, societies include (in addition to those described above) the working homeless, who don’t earn enough for shelter; the non-working homeless, often mentally ill, who live on the street; the great spread of incomes in many capitalist or capitalist-socialist countries, which reduces growth; the unaffordability of medical care. Biological problems include the upward curve of man-made carbon dioxide in the atmosphere and the rising level of nitrogen in coastal ecosystems, which degrades them back to more primitive ecological structures: more algae and jellyfish, fewer oysters and salmon. Capitalist systems are open but not inherently democratic: without state direction, capitalism inevitably produces inequality in incomes that is likely to undermine democractic systems of government.
To keep up with the present rate of global warming, plants and animals would have to move poleward at 30 feet a day. But as far as global warming goes, the colder, less populated regions have experienced it most. High latitudes respond more quickly to temperature changes because of the feedback effects of snow cover. New snow reflects 80% of incoming sunlight, while water absorbs 90%, bare earth somewhat less, and thus leads to more snow and cooler temperatures. Less snow leads to bare ground, more absorption of heat, and warmer ones. In the modern Arctic, spring comes 10 days earlier, summers are warmer, sea ice is less abundant and thinner, permafrost is thawing, and the pulse of summer productivity on land is greater, than 20 years ago. Red squirrels in the Yukon give birth 18 days earlier than 10 years ago. (Some of this change may be genetic, that is, evolved change favoring earlier breeders, and not behavioral.) In 1998 Arctic terns were laying eggs 18 days earlier than in 1929. Robins and barn swallows visit Banks Island in the Canadian Arctic, and the Island has thunderstorms: birds and weather for which the Inuit have no words. Sea ice is melting. Annual fluctuations in the extent of Arctic sea ice corresponds almost exactly with the length of the melting season, which has been increasing by 5 days per decade. The Arctic without sea ice will be warmer and wetter. Since the 1970s Alaskan mean temperatures have risen 5° Fahrenheit (F.) in summer, 10° F. in winter. Legal travel days for heavy equipment on the tundra of the Arctic Slope (requiring six inches of snow and ground frozen to a foot) have fallen from 200 days a year to 100. Bark beetles, now able to produce two generations a summer rather than one, and whose females lay many more eggs in warmer temperatures, have killed 95% of the spruce trees on Alaska’s Kenai Peninsula. For a time, this was the largest insect infestation in North America. Now pine and spruce trees are dying throughout the forests of the west. Forests covering 150 million acres of the western United States and Canada have died from warming-related beetle infestations over the last ten years. As they burn or decay, the trees release more carbon dioxide to the atmosphere, creating a positive feedback. The situation is not only hard on seals and polar bears, which live on sea ice. Gray jays at the southern edge of their range in the Canadian province of Ontario are declining. Fall temperatures in this region have risen 5° F. in the last 30 years. The jays breed at the end of winter and in the autumn lay up a supply of perishable food (up to 50 pounds a bird: berries, mushrooms, insects, small mammals) for the winter and for the breeding season. In the warmer temperatures the stored foods rot, leaving the jays starving and in poor condition for breeding.
Being animals of the subtropics who carry our climate with us in clothes or buildings, we find the perennial polar ice with its noise and movement threatening. But for many animals the pack ice provides a basis for life. It lets mammals like seals and polar bears inhabit an open ocean, parts of which are rich in fish and squid. Algae live throughout the ice but are concentrated in the bottom half inch or so, which, saturated with seawater, is soft. The algae remain dormant during the lightless winters but begin to grow with the return of sunlight, eventually exceeding the number of algae in the water, and providing a concentrated and accessible food resource for krill, the basis of many food webs in both Arctic and Antarctic oceans, and also for nematodes (non-swimmers, but very abundant in some locations), ciliates, bacteria, rotifers, copepods. So the ice helps support the abundant avian and mammalian life (whales, penguins, bears, seals arctic foxes, ravens, scavenging gulls) of Arctic and Antarctic waters. The colored algae, by absorbing the sun’s heat, may speed the melting of pack ice in the spring. Melting ice seeds the water with algae, which reproduce in a bloom (marking the recent ice); crustaceans and zooplankton feed on the algae, and fish on all three. So loss of the ice is likely to reduce the biotic abundance of the polar regions, as well as—by changing currents and the transport of cold water out of the polar oceans—influence weather patterns thousands of miles away. (The spring thawing of sea ice in the Antarctic influences rainfall on the soybean fields in southern Brazil, the anchovy harvest off Peru, Sahel winds.) The disappearance of 20% of the pack ice about Antarctica since 1950 corresponds with a reduction of krill of 40% per decade since 1976 (when the disappearing ice was noticed) and a decline of emperor penguins of 50%, of adelie penguins 70% in the last 30 years. Ways of coping with ice vary: spectacled eiders winter in small openings in the Bering Sea, kept open by the warmth of their bodies (aggregations can reach tens of thousands of birds). They remain amid the ice in order to feed on the rich invertebrate fauna of the shallow sea bottom.
But the effects of warming are worldwide. In general, the north temperate zone has earlier springs, later falls, and more intense rains than 40 or 50 years ago. Summer temperatures in the southern parts of the United States are now 4° F. higher than optimal for seed formation in grains. Increased storminess causes more frequent high tides in the Mediterranean. (More frequent very high tides constitute much of Venice’s flooding problem, not rising sea levels: the level of the Mediterranean is falling because of less water inflow.) There is heavier wave action in the North Atlantic and more frequent and more violent storms in the tropics. Since 1980, 18 new species of warm water fish have been caught off the coast of Cornwall, England. Fish can swim anywhere in the ocean, and thus are a good mark of changes in sea temperature; no new species had been caught off Cornwall between 1940 and 1980. Oceans are rising at about 8 inches per century, partly from thermal expansion of the warmer water, partly from the melting of glaciers and from increased continental drainage. (Continental drainage includes the lowering of water tables for agriculture and construction and the pumping of ancient groundwater not renewed by rain.) Melting of the Greenland ice cap would raise sea levels by about 23 feet, of the West Antarctic ice sheet by 20 feet; or 43 feet total. Such events are becoming more likely. Ice is an excellent insulator and for a long time it was thought glaciers would take thousands of years to melt, since for half the effect of a rise in surface temperature to penetrate 3000 feet down into an ice sheet takes 7000 years, but summer meltwater streams on the ice’s surface drain down through cracks to the bottom of the ice sheet, melting ice as they go. The meltwaters pool at the bottom, lubricate the mass, find an outlet, and help the glacier slide more rapidly towards the sea. Once floating in the sea, ice melts. A rise in sea level of one to three feet in the next 30-40 years no longer looks farfetched. A 33 foot rise in sea level would inundate land with a population of one billion people and much of the world’s most fertile farmland. Three million years ago the temperature was 2° C. to 3º C. higher than now (this much temperature rise is already built into the atmosphere) and sealevel was 75 feet higher. Getting there may take centuries; or it may not. (Since the oceans are not perfectly connected, some places may see more sealevel rise earlier. Meltwater from the Greenland glacier will tend to stay in the North Atlantic for some time. For the first 50-100 years of melting, the sealevel rise along Greenland and the east coast of North America would be 30 times as great as that in the Pacific, that along the European coast 6 times as great. And the strong circumferential currents about Antarctica may prevent Antarctic meltwaters from reaching the rest of the world for centuries.)
Ecological disasters eventually become human disasters. Inuit women who eat a traditional diet of fish, whale blubber, seal meat, birds, berries and caribou, produce breast milk with 10 times the load of chlorinated hydrocarbons (PCBs, DDT, and their metabolites and relatives) than women who live 1000 miles to the south. These materials are implicated in causing cancers and birth defects and suppressing immune systems. Heavy metals, such as mercury, in the milk are also high. Mercury causes impaired neurological development in children. Sources of the chemicals are probably global, but some of the chemicals in the Inuit near Hudson’s Bay have been traced to industrial installations in the state of Alabama. Does this raise a question of liability?
Perhaps Inuit women should no longer nurse their babies. Breast milk helps ward off diabetes and cancer in later life; its fatty acids boost brain growth and its antibodies prime the immune system, so breast-fed babies have fewer infections. Breast-feeding protects the mother from breast and ovarian cancer and reduces her level of stress. But the Inuit are not alone: 10-15% of American women of childbearing age have more mercury in their blood than the Environmental Protection Agency considers safe. The mercury is transferred through the placenta to the fetus, where it affects the development of the brain, kidneys and liver. Approximately 600,000 children a year in the United States are born with unsafe mercury levels. A quarter of all North American women have levels of toxic compounds in their breast milk that would make it unfit for human consumption if it were cow’s milk or apple juice. These include anti-bacterial agents in cleaning compounds, pesticides, chemicals from detergents, from artificial musks in perfumes, from inks, paints, cosmetics and plastics. Most mothers don’t know this. If such mothers nurse their babies, they help purge their bodies of these materials, transmitting 20% of their body burden of fat-soluble chemicals to the (much smaller) child in six months. In a sense, nursing protects female mammals from chemicals in the environment. While the levels of chlorinated hydrocarbons in male seals grow throughout their lives, those in females level off once they reach reproductive age and start transferring the chemicals to their young. Such transfers are already a serious problem in some fish. Small amounts of PCBs, transferred by a female eel to her eggs, are fatal to developing eel embryos. This explains the crash in European eel populations.
The chemical industry, like the coal-fired electric power industry, is a cornerstone of the modern world. Many industrial chemicals and metals accumulate in human fatty tissue. These include pesticides, metals from burning coal (such as mercury, cadmium and lead), fire retardants, additives to detergents and plastics, and musk fragrances in perfumes. They accumulate through diet or through exposure to them in air and water. One breathes in waterborn chemicals with the steam of the shower, or absorbs them directly through the skin. The fat of a middle-aged American male contains 177 detectable organochlorines. A small fraction of the population, perhaps 5%, accumulate metals more efficiently and so are more at risk. (Such people, for instance, are probably at risk from mercury amalgam fillings in their teeth.) In general, once exposure to bio-accumulating chemicals ceases, a person sheds half of his load of fat-stored material every seven years. A large fraction comes out in faeces and thus remains in the environment, though bacteria will eventually break down most of the chemicals and immobilize the metals. In the Inuit (as with people in more temperate regions) their diet continues to concentrate these materials, and the metabolites of PCBs in their body fat increase 10 times from age 18 to age 66. Sooner or later, much of this will be expressed in disease. PCBs affect sexual development, among other things. Concentrations of PCBs comparable to those in human breast milk in industrialized countries turn the eggs of red-eared slider turtles from male to female. Polar bears in the Norwegian Arctic, where air pollution from Europe concentrates, develop both male and female genitals. Seals and dolphins in the North Atlantic basin, at the top of fishy food chains that accumulate the rain of chemicals falling on the North Atlantic (and washed into it through rivers) are dying of diseases their depressed immune systems can no longer handle. Several persistent organic pollutants, such as DDT and dioxins and their breakdown products, suppress the immune system. The population of beluga whales in the St. Lawrence estuary has fallen from 30,000 animals to about 30. Originally reduced by hunting, the population hasn’t recovered. The remaining belugas are full of tumors and virtually infertile. Their bodies have among the highest recorded levels of toxic chemicals found in living organisms. (This distinction is shared with the killer whales that eat salmon and seals off the northwest coast of the United States.) Most of these chemicals are industrial and agricultural materials washed into the Great Lakes. The chemicals in the water are taken up by planktonic algae. The algae are eaten by zooplankton, which are eaten by small fish, and eventually concentrated in the larger fish and eels the whales eat. Two toxins found in very high concentrations in the beluga, the insecticides chlordane and toxaphene, have no history of use in the St. Lawrence Basin. However, the St. Lawrence Basin occupies 500,000 square miles, so its waters concentrate airborn chemicals from a wide area. Chlordane and toxaphene probably arrived on the wind from the American South, where they were once used extensively.
One way or another, the environment is implicated in 80% of cancers. Some effects come through choice, as with smoking and diet; and some not, or at least not so obviously. (An example of the nonobvious comes from epigenetic effects on genes. Epigenetic effects involve environmentally mediated changes in genes—through such things as a mother’s diet, or a grandfather’s smoking, or his exposure to the chemicals in smoke—and may skip a generation or continue for several. Things like diet affect the methylation of genes and thus their expression. Epigenetic effects are thought to explain why fathers who started smoking before puberty have prepubertal sons who are heavier than normal; and why women whose grandmothers were short of food between the ages of 9 and 12 live longer. Other such transgenerational effects include the effects of DES, a synthetic estrogen, taken by pregnant women on the reproductive organs of their daughters.) Industrially produced chlorinated hydrocarbons are implicated in many cancers. Now widespread in the environment, chlorinated hydrocarbons are produced naturally by forest fires, volcanoes and some marine algae (traces of halogenated hydrocarbons have been found in the oil of whales killed before such compounds were manufactured), but most of them are produced by people. Some are harmful, some not. (The natural compounds seem to be less harmful.) Some may be involved in epigenetic effects. Many of the several thousand varieties of chlorinated hydrocarbons in the Great Lakes come from the chlorine bleaching of paper. Other chlorinated hydrocarbons include the dry cleaning chemicals and solvents dichloroethylene, trichloroethylene and perchloroethylene, which are found in about a third of American surface waters and also in about a third of American drinking water and in most American processed foods. Polynuclear aromatic hydrocarbons or PAHs are found in the haze of dust, tire dust and unburned gasoline that hangs over freeways in Los Angeles, glinting red in the dusk; PAHs are ubiquitous in lake sediments in North America and Europe; PAHs saturating the air downwind of coal burning power plants cause genetic mutations in mice and birth defects in birds (thus the crossed beaks and other abnormalities in the herring gulls of the lower Great lakes). The nonylphenols used in detergents and in the manufacture of plastics act as hormone mimics; their effect on the developing brains of larval fish has resulted in the fish inhabiting some British rivers being overwhelmingly female; such so-called estrogenic chemicals are also implicated in breast cancers. Nonylphenols leach out of things like plastic toys into human skin and out of food containers into food. They seem to affect larval fish by stimulating an enzyme that converts testosterone to estrogen. (Atrazine, a common herbicide, also an estrogen mimic, may work the same way.) The unpronounceable phthalates are used as plasticisers; phthalates are one of the most abundant industrial chemicals in the environment; some are estrogenic, some carcinogenic.
Then there are the heavy metals. As an anthropologist has pointed out, high lead levels (along with increased fire frequencies, eutrophicated lakes, soils disturbed by cultivation, and early successional forest vegetation) are signs of human occupation. Increasing metal contamination of northern hemisphere lake sediments during the twentieth century has been found wherever studies have been done. Cadmium, used in automobile greases, washes from roadways into rivers; cadmium is used also as a stabiliser in plastics, from which people can absorb it directly. Cadmium is not necessary for life but is implicated in some cancers. Mercury, a nerve toxin, is used as a biocide in paper making (it prevents those dark bacterial streaks I saw in classroom paper as a schoolchild). It is still sent, though much less than formerly, with the wastewater from paper manufacture into waterways, where bacteria convert it to methyl mercury, in which form it enters the food chain and accumulates in fish. (About 90% of mercury can be profitably removed from wastewater streams, the rest not.) The major environmental sources of mercury are the burning of fossil fuels, especially coal, for electricity generation; of gasoline and diesel for transportation; metal smelting; and garbage incineration (the last because of unrecycled mercury batteries in trash). Since the 1970s mercury has been increasing in the atmosphere at 2% a year (so in a few years its concentration will have doubled). Mercury contamination of forest soils is thought to be the reason all species of forest thrushes in North America, except the hermit, are declining. Inactive metallic mercury falling from the air is changed to methyl mercury by bacteria in damp forest soils; biologically active methyl mercury ends up in the invertebrates the thrushes eat.
Industrial chemicals are distributed worldwide by the same processes that distribute the sun’s heat from the tropics to the temperate regions and poles. The earth’s atmosphere insulates the earth and raises its average temperature from -2º F. (earth’s temperature as a radiative black body, determined by its albedo and distance from the sun) to 59º F. (its temperature thanks to the heat absorbing gases in its atmosphere). Air heated by the sun rises at the equator, along with much water vapor (a line of clouds marks its rise along the Intertropical Convergence Zone) and sinks as compressionally heated dry air at about 30º North and South. Thus the deserts that circle the earth at those latitudes. Cooled by radiation to space, air sinks at the poles. The tropical and polar circulations, driven by the relative strength and weakness of sunlight in these places, drive an indirect circulation over the North and South Temperate Zones. The spin of the earth and the placement of oceans and continents drive other, smaller convection cells. Heavy metals, radioactive materials, chlorinated and aromatic hydrocarbons, nitrates and sulfates enter the atmosphere from the stacks of power plants, incinerators, metal smelters, car tailpipes. Pesticides and herbicides evaporate from the fields and forests on which they have been sprayed. Warm, rising air lifted by the sun and given a twist by the earth’s spin carries them poleward, until the air begins to cool and sink, or the materials condense out onto droplets of rain or fog, and are carried downward and deposited on the ground, or in the ocean or rivers. If they settle on water they are absorbed into the thin bioactive skin of the sunlit surface that also contains high concentrations of single-celled organisms (plants, animals, viruses, bacteria). The materials are then incorporated into the food chain, usually by being taken up in cellular fats. As these materials pass up the food chain, their concentrations are biomagnified from 10,000 to 1,000,000 times in living tissue; that is, their concentration in living tissue increases geometrically as one organism eats another; the longer the food chain, the greater the concentration. (So lake trout from lakes with short food chains are safer to eat, and small fish are safer to eat than large ones.) The chemicals are also concentrated by wind patterns, by ocean currents (such as the spinning tropical gyres), in the interface of fresh and salt water, by fish migrations (sockeye salmon, which die after spawning, release the PCBs in their bodies into their natal Alaskan lakes, where they enter the food web), by seabird colonies. The ponds below arctic seabird colonies, fertile oases rich in nitrogen and phosphorus from the birds, and thus with plant and animal life, are also contaminated with the chlorinated hydrocarbons and metals the birds accumulate through eating fish, which they take from far at sea. So the distribution of heavy metals and persistant organic chemicals worldwide becomes surprisingly egalitarian but varies with the terminal location (wet and cold are worse) and the length of the food chain (short is better). Mercury from power plants burning coal ends up in Minnesota walleyes far from any power plant, in concentrations making the fish unsafe to eat, and in the arctic char, whitefish, lake trout and pike of Canada’s Northwest Territories, also far from any power plants. The fish-eating loons of the northeastern United States and Canada, downwind of the continent’s industrial chemistry, are much more contaminated by mercury than those in the center of the continent, or those on the West Coast, an advantage that will disappear as China develops; and, thanks to the thoroughness of atmospheric mixing, DDT sprayed on cotton fields in Brazil ends up in lake trout in Lake Michigan. The United States currently exports several tons per day (9 in 1994) of pesticides whose use is banned here; but the atmosphere returns them to us.
The air in the trophosphere, the lowest level of the atmosphere, mixes in each hemisphere (North and South) on a time scale of a few months. It takes about a year for pollutants to cross the Intertropical Convergence Zone and mix through the atmosphere as a whole, during which time many of them settle out. Thus the egalitarian distribution of manmade chemicals, but with fewer of them in the south, which has less land, less industry and fewer people. Material carried by the atmosphere moves inexorably north (south in the Southern Hemisphere), with an eastward component given it by the earth’s rotation; material that settles on land and is not washed by rain into waterways is re-volatilized by sunlight and continues its journey poleward, perhaps going through several more such settlings and re-volatilizations, during each of which it may be concentrated by rain or snowmelt in waterways, until it settles out on the lichens of the barren lands, and is concentrated in the flesh of the herbivores that graze them (lemmings, musk-ox, caribou), or in the northern oceans, lakes or rivers, and ends up in their fish, birds, whales, seals, and finally in the Inuit. The material may be buried for a time in the Arctic ice. Such scenarios were mostly unimaginable by the scientific community in 1948, when use of DDT and other synthetic chemicals was soaring. (Or were they unimaginable? The dangers of tetra-ethyl lead were well understood in the 1920s, when—thanks to pressure from General Motors and the Standard Oil Company, who had built a factory to produce it—it was introduced into gasoline to raise the octane level. Adding lead to gasoline was cheaper than refining gasoline further. When lead was finally banned from American gasoline in 1996, seven million tons of lead had been deposited into the atmosphere and along American roadsides. Seventy million children had been exposed to high blood levels of lead. As for the effects of coal burning on climate, the possibility of global warming from the burning of fossil fuels had been suggested at the end of the nineteenth century, by a Swedish physical chemist who buried the memory of an unhappy love affair in several years of calculations. But the effect on climate of raising the concentration of carbon dioxide in the atmosphere was thought to be small and slow.) Synthetic chemical production in the United States rose from one billion pounds in 1945 to 400 billion pounds in the 1980s and is higher now. Worldwide production is of course many, many times this.
Market economics always functions against a cultural background. This becomes very clear when one looks at different market-oriented societies. In Norway and Japan, countries with standards of living equal to or greater than that of the United States, the spread of incomes between the lowest and highest paid employees of a company rarely exceeds 10 times. That is, if the minimum wage is $15,000 per year, the head of the firm would earn no more than $150,000. In Sweden the ratio is 13 to 1, in France 15 to 1, in Britain 24 to 1. In the United States in 1980 the average CEO earned 40 times the wage of the average manufacturing employee. Now that CEO earns 475 times the employee’s income. Under current law, much of the CEO’s income is sheltered from taxes. The point is not that the American worker is worth that much less, economically speaking, than an American chief executive officer (such facts are probaby incalculable), but that the public ethos allows chief executive officers to ask that much more, and to pay that much less in monies collected for the public good. In the United States getting rich is considered a right. But how rich? A so-called welfare state that guarantees elderly people a livable income, provides for universal medical care, gives people paid vacations, maternity leave, affordable child-care and long-term unemployment insurance, also buffers itself against economic disaster, by providing a reliable, recession-proof flow of income and purchasing power. Redistributing wealth from the wealthy to those who will spend it guarantees a certain level of consumer spending and thus helps moderate market failure. Skewed income distributions, by limiting consumption, tend to inhibit economic development. This is a problem in parts of Africa, Asia and Latin America and may be becoming one in the United States. A common way to counter the development of extremely skewed distributions of wealth is through inheritance taxes. Andrew Carnegie, a self-made nineteenth-century Scottish-American industrialist, supported the notion of inheritance taxes. Carnegie believed in hierarchical societies, but ones in which the individual’s social position depended on his economic merit, not on inherited power or wealth. Inheritance taxes, by recycling wealth, keep the social order fluid. They also mobilize the movement of money.
Capitalist societies exhibit long-term cycles of growth and decline. For 20% of the history of the United States, the gross domestic product contracted. Markets, constantly evolving, can create massive economic instability. So certain sectors of all market economies are supported by the state. In the United States the list is quite long and includes fossil-fuel energy, war materials, real estate, agriculture, and the production of most virgin materials, such as timber and metal ores. Food, fuel and housing are the few necessary productions of a modern economy. As John Kenneth Galbraith has pointed out, the most long-standing, pure market, that in agricultural commodities, must be regulated to prevent the natural cycle of boom and bust from destroying agricultural producers, with the result of food shortages and high food prices. The cycle is simple. As prices for crops rise, farmers increase production, usually taking out loans to do this. As supplies of farm crops increase, prices fall, making the loans difficult to pay back. Farm profit margins are low, much less than 10% (more like 3%), so small changes in prices can have a big effect on farm profits. Superimposed on such human behaviors are weather conditions, which are not uniform over a growing region and can influence crop yields by 20-30%. Thus a particular farmer can face a poor harvest and low prices, while his neighbors, who have also increased their acreages and also face low prices, have normal yields and are able to remain more or less solvent, at least for a while. As farm income falls, profits drop at local businesses, such as banks, hardware stores, farm equipment dealers, coffee shops, doctors, veterinarians, real estate agents, insurance agencies. If bank loans are unrepayable, farms get auctioned off, real estate values fall, and services supported by property taxes, such as schools and roads, are hurt. After a few years of low prices, farm production drops, shortages develop, prices for crops then rise, the surviving farmers buy up the vacant land and production rises again. Corporations with capital, such as insurance companies, also buy up farms, which leads to land being farmed by tenants rather than owners. One solution to this situation is for the government to buy up surplus crops and store them until the price rises. Another is to support crop prices at the cost of production, no matter how much is produced. This is current U.S. policy. It is not necessarily the best social or environmental solution. While its original purpose was to keep food prices low, it has turned into a support system for corporate farmers. Consistently low, but supported, agricultural prices in the United States, along with greater and greater mechanization and chemical use, and the rising cost of land, have created more and more farm consolidation: larger and larger farms, more corporate farms. Because of the cost of land and of installing drainage, the American Corn Belt has always had a high percentage of its land in absentee owners (about half of cultivated land at the turn of the twentieth century); such owners, along with farmers who rent land, are interested primarily in what they can make off the land in the short run; they are not interested in the future of the landscape. Large farm operations, private or corporate, produce most of the country’s food and receive most of the government support payments. Typically, 20-30% of the income of large farms consists of government payments; if the farm is irrigated, the level of government support is over 90% (mostly in the irrigation infrastructure and the cost of water). Agricultural subsidies in 2000 amounted to half of farm income. Large farms also cause most of the environmental problems of agriculture. A side effect of farm consolidation in the agricultural landscape has been a fall in the rural population, and thus a decline in local economies and in public and private services (schools, stores, medical clinics), and also a widening in the income gap between the relatively well-off corporate farmers and the relatively poor laborers. A poorer population results in a further decline in tax-supported local services, just as the need for such services increases.
Most developed societies support the price of agricultural commodities and regulate production. In France, agricultural policy is seen both as supporting the food supply and as supporting the late-medieval French agricultural landscape: the appearance and the taste of the land (in wine, honey, salt, butter) some Frenchmen call the soul of France. The French developed methods of replanting hedgerows in Normandy, for instance. Hedgerows are useful as windbrakes in that windy land, and important as habitat for birds, small mammals, pollinators and other invertebrates. The hedgerows had been removed to make the fields larger and easier to work with modern equipment. Restoring them restores the landscape. Similar small-scale agricultural operations are supported all over France. These include sheepherders, wheat farmers, small wine-makers. Shepherds still follow herds of sheep grazing along the sides of country roads, or in the grassy wastelands near new housing projects. Such government subsidies represent social as much as economic choices. If the United States made similar choices, instead of the ones it now does, it would support biologically appropriate agriculture, distribute income more thoroughly, substitute photo-voltaic and wind power for coal and establish universal health care. The natural landscape would be allowed to recover. One could call the American economy still colonial, in that (in large measure) we trade agricultural and forest products for manufactured goods and oil. The rate of erosion from agricultural land in the United States is 10 to 15 times the background geological rate. Cutover timberland also erodes. The soil and nutrients lost from the land end up in rivers and the sea, shortening the life of dams, making clean water more expensive and eliminating native fisheries. Supporting better agricultural practice, treating abandoned or polluted lands as a resource, redistributing income and developing small-scale renewable energy would lead to an economic boom. As a candidate for election in 1996 suggested, a one-time tax of 15% on the net worth of all Americans worth $30 million or more would raise enough money to pay off the national debt. The money now paid in interest would be freed up to be used elsewhere; and the rich would make their money back in three years.
Economics also functions against a biological background. Plants change levels of atmospheric gases, modify nutrient cycles, engage in chemical warfare, promote (or suppress) wildfires, create shade, alter the temperature and humidity near the ground. Bacteria change the planet through photosynthesis, decomposition, respiration, nutrient cycling and fixation, by initiating processes that allow other organisms to colonize new environments. Fossil fuels, limestone and phosphate deposits, soils, sedimentary iron deposits, the amount of carbon dioxide in the atmosphere, the presence of oxygen—all are signs of life. Photosynthetic cyanobacteria began to oxygenate the atmosphere about 2.7 billion years ago. Iron precipitated out of the anoxic seas; was uplifted over hundreds of millions of years; and weathered of impurities to form concentrated iron ore, or hematite. Oxidation of the iron helped absorb some of the extra oxygen, which was poisonous to much of existing life. Such life, adapted to a world without oxygen, retreated underground, and new life arose. Modern ecosystems, with flowering plants, pollinators and mammals, began during the Jurassic Period 150 million years ago, when the level of oxygen in the atmosphere was close to 12%. Oxygen levels started rising in the middle of the Cretaceous Period about 100 million years ago during a burst of plant growth (never reached again), and reached the modern level of 21% perhaps 50 million years ago. Lower levels would make it hard for large mammals, which have less efficient lungs than dinosaurs and birds, to survive. Dips in the level of atmospheric oxygen correspond to major episodes of extinction. During this time, the stage was set for our cooler glacial world by the evolution, 390 million years ago, of root systems in plants. Roots secrete carbon dioxide into the soil, where it reacts with soil minerals, breaking them down and making them available to plants, and locking much of the carbon up in the process. The death of roots also adds carbon to the soil. Soil storage of carbon may have resulted in a 45% drop in atmospheric carbon dioxide and a slow planetary cooling (reinforced by the absorption of more carbon dioxide by the cooling ocean; much carbon dioxide was also locked up as coal and oil).
This is the ineluctable background of modern life. But economics focuses relentlessly on the human world. Economics assumes that the natural world can be ordered according to market needs and within market time-scales. It assumes that biological goods, such as forests, fish and beach-front property, can be consumed as fast as the market allows, at neglible economic or human cost: wild fish, salamanders, semi-palmated plovers, and other organisms of little economic value, pay the cost. Forests and mangrove swamps are exchangeable for hot dogs and dollar bills. Once a given resource has been exploited, the profits, if any, are invested in other enterprises. Most people don’t lose: wild salmon runs are replaced by farmed salmon; the profits from logging redwoods are invested in setting up web pages. Individuals such as fisherman and loggers may lose, but that is part of the creative destruction of capitalism; they can get other jobs; and the economy as a whole gains. As natural wealth disappears, the creation of wealth depends more and more on human manipulation. The exploitation of natural resources may remain high or even rise, their lower value per acre (as in second-growth timber), or lower unit value (the declining percent of metal in an ore) compensated for by larger machines, shorter rotation times, and greater use of fossil fuel energy. Oil and coal became cheaper and cheaper during the twentieth century thanks to increasing mechanization and ever-increasing use of those (ever cheaper) fossil fuels: a helpful upward spiral. In this abundant world, energy costs, even of energy-producing devices, didn’t really matter. When oil was abundant and accessible, oil production consumed only 2% of the energy the oil contained. Most other energy resources (coal, tar sands, photo-voltaics) require several times that energy investment and, partly because of this, will require a far larger energy infrastructure. (A 1970’s criticism of nuclear power plants was that more energy went into building them than they would ever produce; this turned out to be not quite true.)
Some sectors of the economy, such as the service sector, are less dependent on natural resources. The medical industry (15% of the United States’ economy) or the educational industry (another good-sized chunk) are examples of wealth-creating industries that don’t require such high levels of resource exploitation per unit of output; at any rate less than mining, logging, metal smelting or agriculture. Of course, modern physicians and teachers depend on the already high level of resource exploitation that the society itself requires (some of that mining, logging and agriculture). Computer software development is an almost purely intellectual effort, but behind it lie customers and computers, power plants, chip manufacturing facilities, heated or air-conditioned buildings, trucks, tremendous quantities of polluted groundwater. In 20 years computers have risen to consume 10% of the American electricity supply. In no time the person at the desk becomes part of the whole petrochemical stream.
Our world is constantly recreated by living things. Climate is partly regulated by the amount of carbon dioxide in the atmosphere and thus by the storage of carbon in vegetation, soils, peat bogs and carbonate rocks. Plants absorb carbon dioxide from the air, turn some of it into plant tissue and pump some of it into soils, where it is absorbed by the breakdown of rocks into useful plant nutrients (so-called, in-place weathering). Soil invertebrates, bacteria and fungi immobilize the carbon left behind in dying plant roots. (A considerable percent of the fine roots of trees and perennial grasses die and regrow every year.) Physical processes in the oceans would precipitate out absorbed carbon dioxide as calcium carbonate (limestone), but living things do it first, so limestone is mostly formed of shells and corals. Uplifted limestones from the sea form 10% of continental crusts. One day, as the earth’s continental crusts are slowly recycled, they will be subducted into the earth’s fiery mantle and their vaporized carbon returned to the atmosphere through volcanoes. Fossil fuels are probably the product of one major past storage event of tens of millions of years duration during a warm wet period especially favorable to vegetation. (Coal certainly is; some writers claim oil and gas are not, but are continually regenerated from inorganic matter by physical processes in the earth’s mantle.) At present, peat bogs and grasslands are both better than forests at long term storage of carbon and tropical forests are better than temperate ones.
The main absorption band of carbon dioxide corresponds with the earth’s peak thermal emissions, which explains its role as a greenhouse gas. Carbon dioxide levels in the atmosphere have been declining for tens of millions of years, and as a result, the earth has been slowly cooling, despite the increasing radiance of the sun. (The increasing radiance of the sun is a very long-term process.) A cooler climate tends to be a drier one, because less water evaporates from the oceans, and so declining carbon dioxide levels favor grasslands over forests, which need more moisture. The rise of carbon-storing grasslands and grazers over the last several million years has corresponded with our cooler glacial ages and, by absorbing more carbon dioxide into the soil, creates a positive feedback for a cooling earth. Some writers argue that under present planetary conditions, carbon dioxide (and the related gas methane, which oxidizes to it) acts as a natural thermostat. Carbon dioxide is stored as a gas in the atmosphere, as a weak solution of carbonic acid in the oceans, as clathrate hydrates near the poles, as carbonate minerals in the earth’s crust, in oil and natural gas. Cooling of the earth causes the reactions that store carbon dioxide in the oceans and soil to slow down, thus moderating the cooling. Continuing volcanic activity releases carbon dioxide from fossil fuels, carbonate minerals and other sources, slowly rewarming the earth. But under current planetary conditions carbon storage slowly increases overall, so the activity of the thermostat is superimposed on the slow cooling of the last several millions of years.
Besides carbon dioxide and oxygen (whose level is maintained by photosynthesis, largely of cyanobacteria and blue-green algae, but also by higher plants), gases of biological origin in the atmosphere include methane, nitrous oxide, and dimethyl sulfide. All are produced by bacteria or algae; methane and nitrous oxide are heat-absorbing gases that work at different wavebands than carbon dioxide; dimethyl sulfide, produced by marine organisms, is important in cloud formation (as are bacteria, which use the atmosphere for dispersal, and whose DNA is found in rain and snow); clouds are also important in regulating climate. (Such facts are taken by some to support the argument that earth’s climate is, within limits, self-regulating.) Without life, the composition of the atmosphere would be very different: the amount of carbon dioxide would be much greater, the turnover of nitrogen gas 10 to 20 times slower, the amount of oxygen very small. Atmospheric methane would not vary with the expansion and contraction of termite habitat or of methane-producing tropical wetlands (whose size is controlled by the strengths of summer monsoons, those a function of plate tectonics, ice cover in the Arctic, ocean currents, earth’s orbital cycles, and the intensity of the summer sun.)
The particular state of our world is maintained by its ecosystem services. The living world’s influence on climate (a sort of regulation) is its most dramatic ecosystem service. Others include maintaining the natural water cycle (regulating the heights of ground water tables and floods; to some extent, regulating the amount of rainfall); cleaning the air and water (forests filter the air passing through them; most ecosystems scavenge nutrients and toxic chemicals from water passing through them and influence its temperature, its siltiness, its chemistry, its rate of flow); maintaining the relative composition of the gases in the atmosphere (such as oxygen and carbon dioxide); creating and maintaining soils (the structure, water-holding capacity, and nutrient levels of soils are all functions of the living things in them as much as of their mineral composition and their location in the landscape); the cycling of nutrients essential for life, including human life, among the atmosphere, the oceans, plants, animals and soils; detoxifying pollutants (the workers here include the many organisms of decay, including those micro-organisms that can reduce human hormones and chlorinated hydrocarbons to more benign chemicals); on a smaller scale, pollination of plants and the regulation of plant and animal populations. The yearly value of such services has been put between $3 trillion and $33 trillion dollars (the latter about equal to the world’s gross domestic product, the former—given a yield of 5%—implying an investment of around $60 trillion). While such calculations are economically useful, ecosystem services are essentially irreplaceable. Both estimates are likely way too low. We can’t create systems that perform the services natural ones perform. Even on small scales, as in space ships or sewage treatment plants, this is difficult. Partly this is because of their size (and therefore their cost, both in wealth and in energy consumption) and partly because we don’t understand how the systems work.
We all share in our effects on the natural world. Any permanent human settlement changes plant cover and the local water cycle, and modern settlements require energy use and chemical output far above those of a few centuries or a few decades back. The footprint of a modern person—the acreage of farm, forestland, mines, manufacturing plants, roads, oil wells, waste dumps needed to sustain his or her life—is much larger, about 24 acres for the average American. Our combined demand requires more land than the United States contains. Is this necessary? Certainly not for human life. The energy use of a hunter-gatherer society, which is mostly food, plus some fuelwood, is little more than their caloric requirements, about 2000 kilocalories per person per day, all of it recyclable. Agriculturalists, who often grow a surplus of food, and also may use draft animals, irrigation water, and derive power from wind and water, use between 5 and 10 times as much, 10,000 to 20,000 kilocalories per person per day. While such societies are sun-powered and potentially sustainable, they may not be so in practice. (They may overcut their forests or overexploit their soils.) Industrial peoples of the nineteenth century with their railroads, steam engines, piped water and gas light, used about 70,000 kilocalories per person per day, much of it from coal, a fossil fuel, that is, a fuel whose energy comes from stored solar energy; burning a fossil fuel returns its carbon to the atmosphere from which it came, in general at a rate too fast for the land and oceans to absorb and neutralize. Late twentieth-century people in the developed world, with their automobiles, large houses, electric lights, airplanes, televisions and computers use about 120,000 kilocalories per person per day, or 60 times that of hunter-gatherers, and twice that of industrial populations in the nineteenth century. North Americans use twice that; but live no better than Europeans. The difference is thought to be partly extravagance (bigger cars, larger, warmer houses, a larger military establishment), partly more energy-intensive industries, and partly North America itself, with its more extreme climates and longer driving distances. The footprint of the developed world, if applied to a population of 6 billion, is not sustainable: that many people living a western life would require several earths. Astronauts, because of the energy demands of escaping earth’s gravitational pull (and those of recreating earth in space), use 2.7 million kilocalories per person per day. Most of the energy used by the developed world comes from the combustion of fossil fuels.
Fuel use is not the only way to measure the environmental impact of a society; synthetic chemical production and patterns of human settlement are others. The size of the American corn crop is a measure of the environmental impact of American agriculture. (The picture is one of relentless growth: corn yields are up 31% since 1995, 72% since 1975, that is from about 4 billion bushels in 1970 to 10 billion in 2000, largely because of genetic improvements, even as the land planted to corn shrank; each bushel requires 1.25 quarts of oil and one or more bushels of eroded topsoil to grow.) However extraction and combustion of fossil fuels constitute one of the most important causes of land degradation and water pollution, as well as a leading source of man-made greenhouse gases. Compared to natural energy fluxes on earth, human fossil fuel use is small, amounting to .11 calories per square meter per day. Input from the sun is 4900 calories per square meter per day, primary production by plants 7.8 calories, weather 100 calories. The outsize effect of fossil fuel use on natural systems derives from several factors. Water use by electric power plants constitutes the largest use after irrigation. While it is not a consumptive use like irrigation (water is pumped through the plants to cool them), it warms rivers and changes their flow regimes, simplifies their flora and fauna, and ruins their fisheries. (New plants can cut water use by 90%, at a small increase in the cost of power.) Obtaining fossil fuels takes up land for wells, roads, mines and pipelines and through spills or disposal of wastes, contaminates land and water. Burning them puts the products of combustion into the atmosphere: carbon dioxide (the gas of global warming), heavy metals like arsenic and mercury, dioxins and other hydrocarbons, sulfur, and radioactive materials. The heavy metals, sulfur, and radioactive materials are natural contaminants of the fuels. While arsenic, lead, mercury and radioactive elements are present in small concentrations in the natural environment, current man-made fluxes of them are comparable to, often greater than, the natural ones. For instance, the flux of mercury produced by people is 10 times the natural flux.
It is the production of carbon dioxide by the burning of fossil fuels whose effects may turn out to be the most dramatic, and perhaps the most catastrophic, for us. Carbon dioxide from the clearing of woodland, the cultivation of soil, and the burning of fossil fuels has apparently reversed the slow fall in the atmospheric concentration of this gas during the last several million years. Sunlight falls through the earth’s atmosphere with little absorption (a little is absorbed as heat) to strike the earth, where it is absorbed or reflected. When reflected (re-radiated) from the earth as infrared radiation (radiant energy of a different wavelength), it is captured by several gases in the atmosphere, including carbon dioxide, methane, nitrous oxide, and water vapor. Water vapor is the most abundant and most important greenhouse gas. By capturing a small amount of additional heat, man-made carbon dioxide raises the temperature of the atmosphere and increases the evaporation of water vapor from the oceans; this creates a positive feedback that raises the temperature of the atmosphere further; the climate warms. Since the ability of the atmosphere to hold water vapor increases rapidly with temperature, a small rise in temperature caused by carbon dioxide can end up having a large effect on atmospheric temperature.
The gases that absorb visible or infra-red radiation are not the only factors that influence the earth’s balance between incoming and outgoing solar radiation. The amount of dust in the atmosphere, clouds, the reflectivity of the earth’s surface (that is, whether it tends to reflect or absorb sunlight: ice reflects light, water absorbs it) also alter that balance, warming or cooling the planet. The global temperature is currently up 0.74º C. (1.33ºF.) from the pre-industrial level, though it is now thought that the pre-industrial level had been raised slightly above the “natural” level by human influences beginning several thousand years ago, including forest clearance for agriculture and wet rice cultivation (rice paddies produce methane). Clearing forests and cultivating soils releases carbon dioxide that would otherwise be stored. To keep global warming below 2º C. (considered a “safe“ level) carbon dioxide in the atmosphere must stay below 450 parts per million; this corresponds to an average carbon emission of half a ton of carbon dioxide per person per year. (2º C. is still a level at which the permafrost boundary will move 400 to 600 kilometers north and sea level rise several feet. Current measurements of methane released from thawing permafrost, and of carbon released from peat bogs, implies we are already at an unsafe level of warming.) A person in India currently produces 0.3 tons, an American 6 tons, a European 2 tons. Thus stabilising the climate implies large cuts in carbon dioxide emissions in developed countries, as countries like China and India develop; 70% in Europe, 90% in North America. This is not necessarily a disaster. Carbon dioxide from stationary sources (such as power plants) can be immobilized, at costs estimated at 2 to 4 cents per kilowatt hour, or 10-20% of current electricity costs. This would come to about $15 a month on the average American bill. (What we would do with a several billion tons a year of magnesium carbonate blocks is another matter.) Norwegian offshore oil and gas production is currently taxed at $38 per metric ton for the carbon dioxide associated with the burning of the fuels; to avoid this tax the state oil company reinjects the carbon dioxide stripped from its gas wells into salt formations under the North Sea. Renewable sources of energy work; and efficiency gains in the use of energy of far greater than 50% are possible, probably 1000% in the case of cars. The French and Japanese in the early 1960s supported themselves on energy usage one-seventh that of the United States today. They certainly lived modern lives (they made better movies), and because of tremendous increases in energy efficiency to date would lead even better ones on the same amount of energy today. By that measure the world today produces enough energy; the problem, as with food, is one of distribution. Even lower energy consumptions than those of France or Japan in the 1960s will support societies with low infant mortality, high life expectancies, varied diets, good medical care, and good educational opportunity. People in the Indian state of Kerala are said to live such lives on per capita incomes of less than $400 a year. (Since other writers claim that an adequate diet, that is, one that allows full expression of one’s genetic potential for growth, arrives only during the early stages of modernization, at per capita incomes of about $4000 a year, ten times that in Kerala, one must wonder at such claims.)
The direction of market-ruled societies is upward; their purpose is growth; their citizens constantly strive to increase their incomes. The notion of constant material improvement in human life is recent, probably foolish, and undoubtedly unsustainable. What is clear is that our current way of increasing our wealth is too much for the biological world to bear. All high civilizations fail; and their people die or disperse to lead simpler lives. (Four to six million people disappeared when the Maya collapsed.) In the past such failures have occurred when climates changed, rains failed, trade routes disappeared, soils grew less fertile. Since people took up agriculture and began to settle in villages 10,000 years ago, societies have created wealth from the extraction of virgin resources and the clearing of new land. For the most part, such societies occupied relatively small areas of the earth and used relatively small amounts of easily available natural resources (timber, soil, coal, copper, iron ore). While all societies fail in the end, none will take as much of the world with them as we will.
Part I: The Problem with Economics
Chapter 1
Some people trace the state of our warming, polluted world to capitalism, with its ability to motivate human effort towards ever more elaborate material lives. Long before capitalism, agriculture greatly increased our effect on the natural world, largely through allowing the human population to increase by many times. The first southerly breath of global warming most likely came from the clearance of forests for agriculture. Fossil evidence suggests human hunters with spears caused a major wave of extinction of large animals 11,500 years ago in the Americas; and that humans using spears, throwing sticks and fire caused one 40,000 years before that in Australia. The fundamental problem with human influence on the natural world is not capitalism (state or corporate) but the human evolutionary imperative to multiply and thus to occupy every possible environment. Like any plant or animal, we remake our environment to make it more suitable for us. Digging sticks, fiber carrying bags, stone blades, fire, crops, the development of machines, the use of fossil fuels, the organizing and motivating abilities of the state, just increased these abilities. How far we can go isn’t clear. There may indeed be limits: we need space to lie down, to move around, and in which to grow food (even if the food is grown in stainless steel fermenters on nutrients derived from sewage). But we could build huge steel and glass above-ground cities (the linear cities of Paolo Soleri), faced with solar cells, their size limited only by the materials, or excavate caverns many hundreds of yards or kilometers underground, like those of ancient Cappadocia or modern Norway (so employing geothermal heat), or build marine cities, powered by wind, or by the difference in temperatures between ocean currents, on floating platforms tethered to the bottom of the sea. None of this interests me here. What interests me here are the possibilities of a modern life in a working natural world, surrounded by and supported by working ecosystems. Ideally, half or less of any landscape would be used by people for the production of commodities of economic value. Some equilibrium would exist between the tribe of humans, the tribe of mice, the tribe of herons, the tribe of salmon. There would be restraints. We would eat salmon but we wouldn’t eat all of them; and we wouldn’t destroy their habitat.
In any case, the practice of pure capitalism is a myth. It exists in no society. Life under it for most of the population would be nasty, brutish and short. The move from an agricultural to an industrial economy, which exacerbated the economic and social failures of capitalism in practice, led to the idea of the social welfare state, with free public education, universal health care, old age and unemployment insurance, some redistribution of wealth from the rich to the poor. Modern western societies vary in how far they go toward establishing such a state. Among those societies that go the farthest—the democracies of northern Europe—are the richest.
Capitalism can also be modified to save the natural environment. A focus on water helps. So do two legal doctrines: the Law of Nuisance, under which an individual may not use his property to cause legally recognized difficulties for his neighbor (consider the rain of metals from the atmosphere, or the warming planet, as well as plumes of industrial discharges in waterways); and the Public Trust Doctrine, which puts the use of certain landscapes, such as riverbanks and shorelines, along with their related benefits (such as swimmable waters and fisheries) under the protection of the state, which must maintain them for the common good. Public Trust landscapes, such as riverbanks, groundwater reserves and shorelines, are only partly controllable by people. In practice, both these doctrines are difficult and expensive for individuals to use, since specific harms must be traced to specific causes. Some writers argue that the notions behind the Public Trust Doctrine form the basis for protecting ecosystem functions in general.
My motives in writing this book are unabashedly sentimental. I am attached to the green world in which, where I live, the ground freezes up in early November (better have your shovel out of the ground), and the wood warblers return in early May. My attachment is something of a misperception on my part, since this green world is recent (at least in its details), certainly no more than 6000 years old. It is also much less abundant than the one I remember from 50 years ago, when as a boy the robin chorus woke me up at dawn. The world for the last 10,000 years has been one of shifting baselines: my world is less abundant than the one my father saw in the 1920s, when he shot ducks from a harbor breakwall on Lake Erie; and his less abundant than my grandfather’s in the 1880s, when deer were extinct in Vermont and Rhode Island, but shorebirds were still shot on the New England beaches for market. (An amateur ornithologist, as a boy my grandfather amassed a collection of bird skins.) Without the heat-trapping gases of modern civilization, my world would probably have been replaced by several hundred feet of ice within another few thousand years. It will now probably be replaced with a warmer and greener world. (‘Probably’ because the results of modifying climate are unpredictable.) This must be fine with me, as long as such changes remain within the limits to which living things can adjust, and as long as the ecosystems that support the green world continue to function.
* * *
The usefulness of market economics comes from its reduction of human activity to matters of efficiency and profit. Reductionism has a long history in modern life: children are educated in school, not the home (reducing the influence of parents); work and life are separate activities; one does not grow one’s food or sew one’s clothes (farmers grow food and garment workers sew clothes); and entertainers provide entertainment. Specialization of economic and social roles goes along with economic development. Social roles, such as schooling and child care, become economic professions, performed by teachers and nannies. Thus new jobs are created and parents work outside the home. One could argue that economic specialization makes economic development possible. Distinctions among work, entertainment, and schooling are obscure in peasant, or gathering and hunting cultures, where all or none of one’s activities might be considered work, and few, if any, yielded a profit; but together they constituted a life: that whole life was what children learned. While economic development has made possible the continuing elaboration of modern life, economic development also requires that elaboration. Without increasing consumption, how can capital grow?
In early modern times in Europe, walking was replaced by riding in carriages, then carriages were replaced by trains, which were replaced by automobiles and airplanes. A long time ago people drank from streams, then from hand-dug wells or public fountains, then had piped household water, then drinkable piped water; now people choose from a thousand kinds of carbonated drinks and bottled waters. All this costs the individual more: soda or apple juice costs more than tap water, or a sip from the local brook, which is anyway no longer drinkable because of the side effects of economic development. In New York City, maintaining a car costs 8 to 10 times more than taking public transportation, and despite the state of traffic in the city, where in 1960 cars moved at half the speed of horse-cars in 1907, about half the households have one. (The number is close to 100% in the suburbs.) The additional costs per person mean that each person supports a higher level of economic activity, and that the cost of necessities has fallen relative to total income. Late twentieth-century Americans spend 8% of their income on food, while the figure for eighteenth-century France was 90%. Much improvement has been recent: in turn-of-the-century America food, clothing and shelter accounted for 80% of a family’s budget; in 2000 one-third. So more income is available for other things. Spending income on other things employs the people who provide them; as their incomes rise, they also spend more, and the general level of economic activity rises further—the capitalist gift of growth.
Economic growth has some counter-intuitive consequences. If you earn more than, say $6 an hour, it is probably not worth your while to grow your own food: carrots and cabbage are too cheap. Walking across the United States, a journey of 200 to 300 days, is much more expensive than flying. A one-way ticket from New York to San Francisco costs $150. Food and drink for 200 days costs several times that. (Even biking, which takes 30 days, costs considerably more.) Partly, the direct costs of walking are so high because one can no longer drink the water one comes across, hunt or gather one’s food, camp out beside the road, or sew new shoes from animal skins. Capitalist development has made flying cheap and walking expensive, and travel more polluting; walking generates no extra carbon dioxide, and flying somewhat more than driving (6 times more than taking the train). A Sioux or a Tewa would have set out on foot on a trading journey of some hundreds of miles to realize what he or she considered a profit (perhaps a change of scene was also a benefit); or a medieval Frenchman walk from Arras in northern France to Saint James of Campostella in Spain for the good of his soul. Along the road the pilgrim would have been given food and lodging by others for the good of their souls. To walk the length of France at that time took 40 days. It was somewhat faster by horse: 20 to 22 days from Flanders to Navarre in the fourteenth century. For capitalist traders the time such journeys took represented a cost. Some profited by it; the distances allowed bankers in Florence and Sienna (such as the Medicis) to use the different rates of exchange in local currencies as a substitute for charging interest. Charging interest constituted usury, a sin. Periodic improvements in transport would give a tremendous boost to trade.
While capitalist development divides up the social and material world to create more scope for profit, scientific investigation divides up the natural world in order to understand it. Science cannot yet deal with whole views of the world, though some scientists are trying. So our world is made up of many pieces that don’t fit together. We have many worlds, not one whole. Such disconnectedness is a rather recent development. Most pre-industrial conceptions of the world were wholes. The Sumerians, one of the earliest irrigation societies, lived in the valley of the Tigris and Euphrates rivers, in the flat, hot countryside of what is now Iraq. All agriculturists, but especially irrigators, have to be able to predict the seasons, and the Sumerians, like all irrigators, were astronomers. They mathematically interpreted (explained, in modern terms) the cyclical movements of the planets and stars. These predictable heavenly cycles were used to predict the cycles of earthly life—the time of the river floods, the time to plant, the time to clean the canals; the time to build new ones. The cycles of the heavens determined the cycles of human society, and the cyclic life of the society that of the man or woman in it, one life within another, microcosm within macrocosm. Like the stars, the people were fixed in their professions and social classes, the son of a farmer became a farmer, the son of a potter a potter; the society was one whole in its place under the night sky. While such ancient worlds are wholes, they have their limitations. Doubters are banished to other worlds. The Catholic Church came close to banishing Galileo to the world of the dead for teaching that the earth circled the sun. (It didn’t help that he had a bad attitude toward the Church.) Tribal groups banish those whose behavior isn’t socially acceptable. Banishment in this case usually means death from starvation or loneliness. Many have pointed out that the word for non-Greeks in Greek is barbarian. This is true in many languages, where the word for man is often the same as that for a member of the tribal or linguistic group. Fundamentalist Christians and Muslims banish non-believers to hell. So wholeness has its price.
While the idea of an unfettered market economy is a modern sort of whole outlook, examples of the destructiveness of market economics are many. (To paraphrase another writer, markets are a great way to organize economic activity but need adult supervision.) One is the abundance of abandoned downtowns throughout the United States. City downtowns, built for streetcars and foot traffic, were unadaptable to automobile transportation. Automobiles require parking space, which didn’t exist downtown. Land was cheaper outside the city, so shops and investment moved to the suburbs. Another is the abundance of leaking mines: 40% of rivers in the western United States are polluted by mines. Reclamation of surface coal mines comes to 4% of production costs in a free market, and is therefore affordable, while reclamation of hard rock mines (most of those in the West) is not economically possible at current prices for metals. From a market point of view, reclamation costs are costs without returns. Then there is the continuing failure of the Atlantic right whale population to recover, despite the end of hunting. The cause is probably high levels of anthropogenic nitrogen in coastal waters; these, together with overfishing, have shifted the plankton soup the whales feed on to mostly plants, rather than a mix of plants and animals, and put the whales on a vegetarian diet—which doesn’t allow them to put on sufficient weight to breed. (They are also killed in collisions with ships and get entangled in fishing gear.) There are the silty rivers of the American Middle West, once full of game fish, waterfowl, and turtles, now used for barge transport, hydroelectric power, sewage disposal, disposal of industrial effluent, and water supply. Under the same agricultural region lie pools of ground water contaminated with fertiliser and pesticide, some with pools of perchloroethylene collecting below, and pools of motor oil and gasoline sitting on top. Such hydrocarbons don’t mix well with water (though fats and oils take them up). The chloroethylenes are solvents, degreasers, dry cleaning fluids. Much ground and surface water and most processed foods are contaminated with them. Perchloroethylene interferes with the action of hormones, attaches to chromosomes, cripples immune systems, and over-stimulates the activity of some enzymes. About half the population of the United States gets its drinking water from ground water. Ground water eventually becomes river water, and thus everybody else’s drinking water, and the water in which fish and amphibians live and waterbirds swim. Bacteria will eventually break down most of these chemicals but not before they have accumulated in our bodies (the process takes too long in nature).
There is acid precipitation, a side effect of the combustion of fossil fuels, which has resulted in the dying trees, declining birds, acidified lakes and calcium-leached soils of the higher elevations of the eastern United States, Central Europe, and Scandinavia. About 70% of soils in the eastern United States are calcium poor. As the rain leaches more calcium out and the soils further acidify, aluminum ions are released from their oxydized (and harmless) state. Aluminum is the most abundant positive ion in the soil and once it is available, trees take it up instead of calcium, and transfer it to their crowns in an attempt to neutralize the acidic water condensing on their needles, which degrades chlorophyll (and if it forms trichloroacetic acid, acts as a defoliant). But aluminum is toxic to plants and animals and interferes with the trees’ metabolism. Leaves lower in calcium are less nutritious for grazing insects and the insects make less nutritious meals for birds, who must accumulate calcium for their eggshells. Nesting songbirds lay fewer eggs in acidified northern European woodlands. With less calcium available, soil animals such as earthworms, millipedes, pillbugs and snails, food for thrushes and other birds of the forest floor, decline. Such effects may explain the strong declines of nesting songbirds on the high plateaus of the eastern United States. The first snowmelt in the spring carries much of the winter’s acid precipitation (the accumulated snow and rain) into streams, and mobilizes the bio-accumulated acids from the soil, killing young trout and essentially sterilizing the water.
Research increasingly implicates the human environment in the growing epidemics of asthma, autism, adult onset diabetes and attention deficit disorder. The increase in diabetes is probably caused by changes in diet, specifically by the rise in the use of corn syrup, cheaper than cane or beet sugar, to sweeten ever-larger bottles of soft drinks, while the incidence of the other three disorders is likely influenced by the chemical soup in which we live. There are also inexplicable clusters of childhood leukemia and breast cancer. Virtually all the atrazine (an herbicide) used on cornfields in the Great Lakes Basin is still in the Great Lakes, as is most of the DDT that periodically wells up from their depths; in very small doses (one thirtieth of the Environmental Protection Agency’s standard for drinking water) atrazine makes male northern leopard frogs hermaphroditic. Atrazine is also an immune suppressant. Its use is probably the main reason for the collapse of amphibian populations in the Middle West in the 1970s. The capacity to act as a hormone in very small doses is characteristic of many chlorinated hydrocarbons. Very low levels of 2,4-D (one seventh of the Environmental Protection Agency’s recommendation for drinking water) has the greatest effect in reducing fertility in mice. Larger doses of the same chemical are ignored by the endocrine system, which normally responds to very low levels of blood-borne hormones.
Some cancer clusters may really be inexplicable (so-called statistical artifacts common to small sample populations), and some increases in disease a matter of better diagnosis. Some may be the result of atmospheric circulation having concentrated radioactive fallout in certain places during the testing of nuclear weapons 40 years ago. (One argument for this is an apparent rise in the incidence of breast cancer in American women who were adolescents living in downwind locations from 1957 to 1963). Two rather interesting explanations have been put forward to explain clusters of childhood leukemia. One suggests such clusters may be related to the ease of movement of modern people. Genetic studies indicate that many people in rural areas of Europe are descendants of people who have lived there for hundreds or thousands of years. If a nuclear powerplant or nuclear fuel reprocessing facility is built in such a place (remote places are favored and nuclear facilities are always suspect in terms of cancer-related diseases), people move into the area for the jobs, from hundreds or thousands of miles away. Their newly born children are exposed to leukemia-causing viruses endemic to the area, for which their mothers—not from the area—have transmitted to them no immunuty. In this case connections with radioactive hazards are incidental.
So the hazards of development are not obvious. A second explanation concerns clusters of leukemia in children who live near industrialized river estuaries in Britain. Such children have unusual levels of alpha radiation in their tissues and two to three times the normal rate of childhood leukemia. Large river estuaries like the Severn which are surrounded by fossil fuel burning industry, by a large car and truck traffic, and much space and water heating, end up with a considerable load of hydrocarbons in the water. They fall into the water from the air, or wash in off the land. Hydrophobic, the hydrocarbons tend to float on the surface and are concentrated by tidal action at the interface of fresh and salt water. The chemicals are mobilized in spray, which is carried inland by the wind and inhaled by people, settles out on their clothes and migrates into their houses. The hydrocarbons contain uranium and radon as contaminants. (Radioactive materials are natural contaminants of oil and coal.) These materials or their radioactive daughters (radioactively unstable lead) are concentrated in bone and fat. The release of alpha particles during further radioactive breakdown irradiates developing blood cells in bone marrow, and is thought to cause the leukemias. Children, whose cells divide more rapidly, are more sensitive to ionizing radiation.
Economics is concerned with prices, not with intrinsic values, so things of little intrinsic use—diamonds, gold, Cabbage Patch dolls—may be priced highly by the market. Production of such goods, like that of necessities, generates toxic materials and carbon dioxide. In general, scarcity sets prices. Social goods become valuable only when they threaten market stability, and ecological ones (like clean water) only when they become scarce. Abundant resources (including labor in some markets, and timber, land and water in many developed societies until recently) are cheap. Disposal of the waste products of production into air or water is free. The social problems of capitalist societies are more likely to be ameliorated than the biological ones. Social problems of capitalist, or market, societies include (in addition to those described above) the working homeless, who don’t earn enough for shelter; the non-working homeless, often mentally ill, who live on the street; the great spread of incomes in many capitalist or capitalist-socialist countries, which reduces growth; the unaffordability of medical care. Biological problems include the upward curve of man-made carbon dioxide in the atmosphere and the rising level of nitrogen in coastal ecosystems, which degrades them back to more primitive ecological structures: more algae and jellyfish, fewer oysters and salmon. Capitalist systems are open but not inherently democratic: without state direction, capitalism inevitably produces inequality in incomes that is likely to undermine democractic systems of government.
To keep up with the present rate of global warming, plants and animals would have to move poleward at 30 feet a day. But as far as global warming goes, the colder, less populated regions have experienced it most. High latitudes respond more quickly to temperature changes because of the feedback effects of snow cover. New snow reflects 80% of incoming sunlight, while water absorbs 90%, bare earth somewhat less, and thus leads to more snow and cooler temperatures. Less snow leads to bare ground, more absorption of heat, and warmer ones. In the modern Arctic, spring comes 10 days earlier, summers are warmer, sea ice is less abundant and thinner, permafrost is thawing, and the pulse of summer productivity on land is greater, than 20 years ago. Red squirrels in the Yukon give birth 18 days earlier than 10 years ago. (Some of this change may be genetic, that is, evolved change favoring earlier breeders, and not behavioral.) In 1998 Arctic terns were laying eggs 18 days earlier than in 1929. Robins and barn swallows visit Banks Island in the Canadian Arctic, and the Island has thunderstorms: birds and weather for which the Inuit have no words. Sea ice is melting. Annual fluctuations in the extent of Arctic sea ice corresponds almost exactly with the length of the melting season, which has been increasing by 5 days per decade. The Arctic without sea ice will be warmer and wetter. Since the 1970s Alaskan mean temperatures have risen 5° Fahrenheit (F.) in summer, 10° F. in winter. Legal travel days for heavy equipment on the tundra of the Arctic Slope (requiring six inches of snow and ground frozen to a foot) have fallen from 200 days a year to 100. Bark beetles, now able to produce two generations a summer rather than one, and whose females lay many more eggs in warmer temperatures, have killed 95% of the spruce trees on Alaska’s Kenai Peninsula. For a time, this was the largest insect infestation in North America. Now pine and spruce trees are dying throughout the forests of the west. Forests covering 150 million acres of the western United States and Canada have died from warming-related beetle infestations over the last ten years. As they burn or decay, the trees release more carbon dioxide to the atmosphere, creating a positive feedback. The situation is not only hard on seals and polar bears, which live on sea ice. Gray jays at the southern edge of their range in the Canadian province of Ontario are declining. Fall temperatures in this region have risen 5° F. in the last 30 years. The jays breed at the end of winter and in the autumn lay up a supply of perishable food (up to 50 pounds a bird: berries, mushrooms, insects, small mammals) for the winter and for the breeding season. In the warmer temperatures the stored foods rot, leaving the jays starving and in poor condition for breeding.
Being animals of the subtropics who carry our climate with us in clothes or buildings, we find the perennial polar ice with its noise and movement threatening. But for many animals the pack ice provides a basis for life. It lets mammals like seals and polar bears inhabit an open ocean, parts of which are rich in fish and squid. Algae live throughout the ice but are concentrated in the bottom half inch or so, which, saturated with seawater, is soft. The algae remain dormant during the lightless winters but begin to grow with the return of sunlight, eventually exceeding the number of algae in the water, and providing a concentrated and accessible food resource for krill, the basis of many food webs in both Arctic and Antarctic oceans, and also for nematodes (non-swimmers, but very abundant in some locations), ciliates, bacteria, rotifers, copepods. So the ice helps support the abundant avian and mammalian life (whales, penguins, bears, seals arctic foxes, ravens, scavenging gulls) of Arctic and Antarctic waters. The colored algae, by absorbing the sun’s heat, may speed the melting of pack ice in the spring. Melting ice seeds the water with algae, which reproduce in a bloom (marking the recent ice); crustaceans and zooplankton feed on the algae, and fish on all three. So loss of the ice is likely to reduce the biotic abundance of the polar regions, as well as—by changing currents and the transport of cold water out of the polar oceans—influence weather patterns thousands of miles away. (The spring thawing of sea ice in the Antarctic influences rainfall on the soybean fields in southern Brazil, the anchovy harvest off Peru, Sahel winds.) The disappearance of 20% of the pack ice about Antarctica since 1950 corresponds with a reduction of krill of 40% per decade since 1976 (when the disappearing ice was noticed) and a decline of emperor penguins of 50%, of adelie penguins 70% in the last 30 years. Ways of coping with ice vary: spectacled eiders winter in small openings in the Bering Sea, kept open by the warmth of their bodies (aggregations can reach tens of thousands of birds). They remain amid the ice in order to feed on the rich invertebrate fauna of the shallow sea bottom.
But the effects of warming are worldwide. In general, the north temperate zone has earlier springs, later falls, and more intense rains than 40 or 50 years ago. Summer temperatures in the southern parts of the United States are now 4° F. higher than optimal for seed formation in grains. Increased storminess causes more frequent high tides in the Mediterranean. (More frequent very high tides constitute much of Venice’s flooding problem, not rising sea levels: the level of the Mediterranean is falling because of less water inflow.) There is heavier wave action in the North Atlantic and more frequent and more violent storms in the tropics. Since 1980, 18 new species of warm water fish have been caught off the coast of Cornwall, England. Fish can swim anywhere in the ocean, and thus are a good mark of changes in sea temperature; no new species had been caught off Cornwall between 1940 and 1980. Oceans are rising at about 8 inches per century, partly from thermal expansion of the warmer water, partly from the melting of glaciers and from increased continental drainage. (Continental drainage includes the lowering of water tables for agriculture and construction and the pumping of ancient groundwater not renewed by rain.) Melting of the Greenland ice cap would raise sea levels by about 23 feet, of the West Antarctic ice sheet by 20 feet; or 43 feet total. Such events are becoming more likely. Ice is an excellent insulator and for a long time it was thought glaciers would take thousands of years to melt, since for half the effect of a rise in surface temperature to penetrate 3000 feet down into an ice sheet takes 7000 years, but summer meltwater streams on the ice’s surface drain down through cracks to the bottom of the ice sheet, melting ice as they go. The meltwaters pool at the bottom, lubricate the mass, find an outlet, and help the glacier slide more rapidly towards the sea. Once floating in the sea, ice melts. A rise in sea level of one to three feet in the next 30-40 years no longer looks farfetched. A 33 foot rise in sea level would inundate land with a population of one billion people and much of the world’s most fertile farmland. Three million years ago the temperature was 2° C. to 3º C. higher than now (this much temperature rise is already built into the atmosphere) and sealevel was 75 feet higher. Getting there may take centuries; or it may not. (Since the oceans are not perfectly connected, some places may see more sealevel rise earlier. Meltwater from the Greenland glacier will tend to stay in the North Atlantic for some time. For the first 50-100 years of melting, the sealevel rise along Greenland and the east coast of North America would be 30 times as great as that in the Pacific, that along the European coast 6 times as great. And the strong circumferential currents about Antarctica may prevent Antarctic meltwaters from reaching the rest of the world for centuries.)
Ecological disasters eventually become human disasters. Inuit women who eat a traditional diet of fish, whale blubber, seal meat, birds, berries and caribou, produce breast milk with 10 times the load of chlorinated hydrocarbons (PCBs, DDT, and their metabolites and relatives) than women who live 1000 miles to the south. These materials are implicated in causing cancers and birth defects and suppressing immune systems. Heavy metals, such as mercury, in the milk are also high. Mercury causes impaired neurological development in children. Sources of the chemicals are probably global, but some of the chemicals in the Inuit near Hudson’s Bay have been traced to industrial installations in the state of Alabama. Does this raise a question of liability?
Perhaps Inuit women should no longer nurse their babies. Breast milk helps ward off diabetes and cancer in later life; its fatty acids boost brain growth and its antibodies prime the immune system, so breast-fed babies have fewer infections. Breast-feeding protects the mother from breast and ovarian cancer and reduces her level of stress. But the Inuit are not alone: 10-15% of American women of childbearing age have more mercury in their blood than the Environmental Protection Agency considers safe. The mercury is transferred through the placenta to the fetus, where it affects the development of the brain, kidneys and liver. Approximately 600,000 children a year in the United States are born with unsafe mercury levels. A quarter of all North American women have levels of toxic compounds in their breast milk that would make it unfit for human consumption if it were cow’s milk or apple juice. These include anti-bacterial agents in cleaning compounds, pesticides, chemicals from detergents, from artificial musks in perfumes, from inks, paints, cosmetics and plastics. Most mothers don’t know this. If such mothers nurse their babies, they help purge their bodies of these materials, transmitting 20% of their body burden of fat-soluble chemicals to the (much smaller) child in six months. In a sense, nursing protects female mammals from chemicals in the environment. While the levels of chlorinated hydrocarbons in male seals grow throughout their lives, those in females level off once they reach reproductive age and start transferring the chemicals to their young. Such transfers are already a serious problem in some fish. Small amounts of PCBs, transferred by a female eel to her eggs, are fatal to developing eel embryos. This explains the crash in European eel populations.
The chemical industry, like the coal-fired electric power industry, is a cornerstone of the modern world. Many industrial chemicals and metals accumulate in human fatty tissue. These include pesticides, metals from burning coal (such as mercury, cadmium and lead), fire retardants, additives to detergents and plastics, and musk fragrances in perfumes. They accumulate through diet or through exposure to them in air and water. One breathes in waterborn chemicals with the steam of the shower, or absorbs them directly through the skin. The fat of a middle-aged American male contains 177 detectable organochlorines. A small fraction of the population, perhaps 5%, accumulate metals more efficiently and so are more at risk. (Such people, for instance, are probably at risk from mercury amalgam fillings in their teeth.) In general, once exposure to bio-accumulating chemicals ceases, a person sheds half of his load of fat-stored material every seven years. A large fraction comes out in faeces and thus remains in the environment, though bacteria will eventually break down most of the chemicals and immobilize the metals. In the Inuit (as with people in more temperate regions) their diet continues to concentrate these materials, and the metabolites of PCBs in their body fat increase 10 times from age 18 to age 66. Sooner or later, much of this will be expressed in disease. PCBs affect sexual development, among other things. Concentrations of PCBs comparable to those in human breast milk in industrialized countries turn the eggs of red-eared slider turtles from male to female. Polar bears in the Norwegian Arctic, where air pollution from Europe concentrates, develop both male and female genitals. Seals and dolphins in the North Atlantic basin, at the top of fishy food chains that accumulate the rain of chemicals falling on the North Atlantic (and washed into it through rivers) are dying of diseases their depressed immune systems can no longer handle. Several persistent organic pollutants, such as DDT and dioxins and their breakdown products, suppress the immune system. The population of beluga whales in the St. Lawrence estuary has fallen from 30,000 animals to about 30. Originally reduced by hunting, the population hasn’t recovered. The remaining belugas are full of tumors and virtually infertile. Their bodies have among the highest recorded levels of toxic chemicals found in living organisms. (This distinction is shared with the killer whales that eat salmon and seals off the northwest coast of the United States.) Most of these chemicals are industrial and agricultural materials washed into the Great Lakes. The chemicals in the water are taken up by planktonic algae. The algae are eaten by zooplankton, which are eaten by small fish, and eventually concentrated in the larger fish and eels the whales eat. Two toxins found in very high concentrations in the beluga, the insecticides chlordane and toxaphene, have no history of use in the St. Lawrence Basin. However, the St. Lawrence Basin occupies 500,000 square miles, so its waters concentrate airborn chemicals from a wide area. Chlordane and toxaphene probably arrived on the wind from the American South, where they were once used extensively.
One way or another, the environment is implicated in 80% of cancers. Some effects come through choice, as with smoking and diet; and some not, or at least not so obviously. (An example of the nonobvious comes from epigenetic effects on genes. Epigenetic effects involve environmentally mediated changes in genes—through such things as a mother’s diet, or a grandfather’s smoking, or his exposure to the chemicals in smoke—and may skip a generation or continue for several. Things like diet affect the methylation of genes and thus their expression. Epigenetic effects are thought to explain why fathers who started smoking before puberty have prepubertal sons who are heavier than normal; and why women whose grandmothers were short of food between the ages of 9 and 12 live longer. Other such transgenerational effects include the effects of DES, a synthetic estrogen, taken by pregnant women on the reproductive organs of their daughters.) Industrially produced chlorinated hydrocarbons are implicated in many cancers. Now widespread in the environment, chlorinated hydrocarbons are produced naturally by forest fires, volcanoes and some marine algae (traces of halogenated hydrocarbons have been found in the oil of whales killed before such compounds were manufactured), but most of them are produced by people. Some are harmful, some not. (The natural compounds seem to be less harmful.) Some may be involved in epigenetic effects. Many of the several thousand varieties of chlorinated hydrocarbons in the Great Lakes come from the chlorine bleaching of paper. Other chlorinated hydrocarbons include the dry cleaning chemicals and solvents dichloroethylene, trichloroethylene and perchloroethylene, which are found in about a third of American surface waters and also in about a third of American drinking water and in most American processed foods. Polynuclear aromatic hydrocarbons or PAHs are found in the haze of dust, tire dust and unburned gasoline that hangs over freeways in Los Angeles, glinting red in the dusk; PAHs are ubiquitous in lake sediments in North America and Europe; PAHs saturating the air downwind of coal burning power plants cause genetic mutations in mice and birth defects in birds (thus the crossed beaks and other abnormalities in the herring gulls of the lower Great lakes). The nonylphenols used in detergents and in the manufacture of plastics act as hormone mimics; their effect on the developing brains of larval fish has resulted in the fish inhabiting some British rivers being overwhelmingly female; such so-called estrogenic chemicals are also implicated in breast cancers. Nonylphenols leach out of things like plastic toys into human skin and out of food containers into food. They seem to affect larval fish by stimulating an enzyme that converts testosterone to estrogen. (Atrazine, a common herbicide, also an estrogen mimic, may work the same way.) The unpronounceable phthalates are used as plasticisers; phthalates are one of the most abundant industrial chemicals in the environment; some are estrogenic, some carcinogenic.
Then there are the heavy metals. As an anthropologist has pointed out, high lead levels (along with increased fire frequencies, eutrophicated lakes, soils disturbed by cultivation, and early successional forest vegetation) are signs of human occupation. Increasing metal contamination of northern hemisphere lake sediments during the twentieth century has been found wherever studies have been done. Cadmium, used in automobile greases, washes from roadways into rivers; cadmium is used also as a stabiliser in plastics, from which people can absorb it directly. Cadmium is not necessary for life but is implicated in some cancers. Mercury, a nerve toxin, is used as a biocide in paper making (it prevents those dark bacterial streaks I saw in classroom paper as a schoolchild). It is still sent, though much less than formerly, with the wastewater from paper manufacture into waterways, where bacteria convert it to methyl mercury, in which form it enters the food chain and accumulates in fish. (About 90% of mercury can be profitably removed from wastewater streams, the rest not.) The major environmental sources of mercury are the burning of fossil fuels, especially coal, for electricity generation; of gasoline and diesel for transportation; metal smelting; and garbage incineration (the last because of unrecycled mercury batteries in trash). Since the 1970s mercury has been increasing in the atmosphere at 2% a year (so in a few years its concentration will have doubled). Mercury contamination of forest soils is thought to be the reason all species of forest thrushes in North America, except the hermit, are declining. Inactive metallic mercury falling from the air is changed to methyl mercury by bacteria in damp forest soils; biologically active methyl mercury ends up in the invertebrates the thrushes eat.
Industrial chemicals are distributed worldwide by the same processes that distribute the sun’s heat from the tropics to the temperate regions and poles. The earth’s atmosphere insulates the earth and raises its average temperature from -2º F. (earth’s temperature as a radiative black body, determined by its albedo and distance from the sun) to 59º F. (its temperature thanks to the heat absorbing gases in its atmosphere). Air heated by the sun rises at the equator, along with much water vapor (a line of clouds marks its rise along the Intertropical Convergence Zone) and sinks as compressionally heated dry air at about 30º North and South. Thus the deserts that circle the earth at those latitudes. Cooled by radiation to space, air sinks at the poles. The tropical and polar circulations, driven by the relative strength and weakness of sunlight in these places, drive an indirect circulation over the North and South Temperate Zones. The spin of the earth and the placement of oceans and continents drive other, smaller convection cells. Heavy metals, radioactive materials, chlorinated and aromatic hydrocarbons, nitrates and sulfates enter the atmosphere from the stacks of power plants, incinerators, metal smelters, car tailpipes. Pesticides and herbicides evaporate from the fields and forests on which they have been sprayed. Warm, rising air lifted by the sun and given a twist by the earth’s spin carries them poleward, until the air begins to cool and sink, or the materials condense out onto droplets of rain or fog, and are carried downward and deposited on the ground, or in the ocean or rivers. If they settle on water they are absorbed into the thin bioactive skin of the sunlit surface that also contains high concentrations of single-celled organisms (plants, animals, viruses, bacteria). The materials are then incorporated into the food chain, usually by being taken up in cellular fats. As these materials pass up the food chain, their concentrations are biomagnified from 10,000 to 1,000,000 times in living tissue; that is, their concentration in living tissue increases geometrically as one organism eats another; the longer the food chain, the greater the concentration. (So lake trout from lakes with short food chains are safer to eat, and small fish are safer to eat than large ones.) The chemicals are also concentrated by wind patterns, by ocean currents (such as the spinning tropical gyres), in the interface of fresh and salt water, by fish migrations (sockeye salmon, which die after spawning, release the PCBs in their bodies into their natal Alaskan lakes, where they enter the food web), by seabird colonies. The ponds below arctic seabird colonies, fertile oases rich in nitrogen and phosphorus from the birds, and thus with plant and animal life, are also contaminated with the chlorinated hydrocarbons and metals the birds accumulate through eating fish, which they take from far at sea. So the distribution of heavy metals and persistant organic chemicals worldwide becomes surprisingly egalitarian but varies with the terminal location (wet and cold are worse) and the length of the food chain (short is better). Mercury from power plants burning coal ends up in Minnesota walleyes far from any power plant, in concentrations making the fish unsafe to eat, and in the arctic char, whitefish, lake trout and pike of Canada’s Northwest Territories, also far from any power plants. The fish-eating loons of the northeastern United States and Canada, downwind of the continent’s industrial chemistry, are much more contaminated by mercury than those in the center of the continent, or those on the West Coast, an advantage that will disappear as China develops; and, thanks to the thoroughness of atmospheric mixing, DDT sprayed on cotton fields in Brazil ends up in lake trout in Lake Michigan. The United States currently exports several tons per day (9 in 1994) of pesticides whose use is banned here; but the atmosphere returns them to us.
The air in the trophosphere, the lowest level of the atmosphere, mixes in each hemisphere (North and South) on a time scale of a few months. It takes about a year for pollutants to cross the Intertropical Convergence Zone and mix through the atmosphere as a whole, during which time many of them settle out. Thus the egalitarian distribution of manmade chemicals, but with fewer of them in the south, which has less land, less industry and fewer people. Material carried by the atmosphere moves inexorably north (south in the Southern Hemisphere), with an eastward component given it by the earth’s rotation; material that settles on land and is not washed by rain into waterways is re-volatilized by sunlight and continues its journey poleward, perhaps going through several more such settlings and re-volatilizations, during each of which it may be concentrated by rain or snowmelt in waterways, until it settles out on the lichens of the barren lands, and is concentrated in the flesh of the herbivores that graze them (lemmings, musk-ox, caribou), or in the northern oceans, lakes or rivers, and ends up in their fish, birds, whales, seals, and finally in the Inuit. The material may be buried for a time in the Arctic ice. Such scenarios were mostly unimaginable by the scientific community in 1948, when use of DDT and other synthetic chemicals was soaring. (Or were they unimaginable? The dangers of tetra-ethyl lead were well understood in the 1920s, when—thanks to pressure from General Motors and the Standard Oil Company, who had built a factory to produce it—it was introduced into gasoline to raise the octane level. Adding lead to gasoline was cheaper than refining gasoline further. When lead was finally banned from American gasoline in 1996, seven million tons of lead had been deposited into the atmosphere and along American roadsides. Seventy million children had been exposed to high blood levels of lead. As for the effects of coal burning on climate, the possibility of global warming from the burning of fossil fuels had been suggested at the end of the nineteenth century, by a Swedish physical chemist who buried the memory of an unhappy love affair in several years of calculations. But the effect on climate of raising the concentration of carbon dioxide in the atmosphere was thought to be small and slow.) Synthetic chemical production in the United States rose from one billion pounds in 1945 to 400 billion pounds in the 1980s and is higher now. Worldwide production is of course many, many times this.
Market economics always functions against a cultural background. This becomes very clear when one looks at different market-oriented societies. In Norway and Japan, countries with standards of living equal to or greater than that of the United States, the spread of incomes between the lowest and highest paid employees of a company rarely exceeds 10 times. That is, if the minimum wage is $15,000 per year, the head of the firm would earn no more than $150,000. In Sweden the ratio is 13 to 1, in France 15 to 1, in Britain 24 to 1. In the United States in 1980 the average CEO earned 40 times the wage of the average manufacturing employee. Now that CEO earns 475 times the employee’s income. Under current law, much of the CEO’s income is sheltered from taxes. The point is not that the American worker is worth that much less, economically speaking, than an American chief executive officer (such facts are probaby incalculable), but that the public ethos allows chief executive officers to ask that much more, and to pay that much less in monies collected for the public good. In the United States getting rich is considered a right. But how rich? A so-called welfare state that guarantees elderly people a livable income, provides for universal medical care, gives people paid vacations, maternity leave, affordable child-care and long-term unemployment insurance, also buffers itself against economic disaster, by providing a reliable, recession-proof flow of income and purchasing power. Redistributing wealth from the wealthy to those who will spend it guarantees a certain level of consumer spending and thus helps moderate market failure. Skewed income distributions, by limiting consumption, tend to inhibit economic development. This is a problem in parts of Africa, Asia and Latin America and may be becoming one in the United States. A common way to counter the development of extremely skewed distributions of wealth is through inheritance taxes. Andrew Carnegie, a self-made nineteenth-century Scottish-American industrialist, supported the notion of inheritance taxes. Carnegie believed in hierarchical societies, but ones in which the individual’s social position depended on his economic merit, not on inherited power or wealth. Inheritance taxes, by recycling wealth, keep the social order fluid. They also mobilize the movement of money.
Capitalist societies exhibit long-term cycles of growth and decline. For 20% of the history of the United States, the gross domestic product contracted. Markets, constantly evolving, can create massive economic instability. So certain sectors of all market economies are supported by the state. In the United States the list is quite long and includes fossil-fuel energy, war materials, real estate, agriculture, and the production of most virgin materials, such as timber and metal ores. Food, fuel and housing are the few necessary productions of a modern economy. As John Kenneth Galbraith has pointed out, the most long-standing, pure market, that in agricultural commodities, must be regulated to prevent the natural cycle of boom and bust from destroying agricultural producers, with the result of food shortages and high food prices. The cycle is simple. As prices for crops rise, farmers increase production, usually taking out loans to do this. As supplies of farm crops increase, prices fall, making the loans difficult to pay back. Farm profit margins are low, much less than 10% (more like 3%), so small changes in prices can have a big effect on farm profits. Superimposed on such human behaviors are weather conditions, which are not uniform over a growing region and can influence crop yields by 20-30%. Thus a particular farmer can face a poor harvest and low prices, while his neighbors, who have also increased their acreages and also face low prices, have normal yields and are able to remain more or less solvent, at least for a while. As farm income falls, profits drop at local businesses, such as banks, hardware stores, farm equipment dealers, coffee shops, doctors, veterinarians, real estate agents, insurance agencies. If bank loans are unrepayable, farms get auctioned off, real estate values fall, and services supported by property taxes, such as schools and roads, are hurt. After a few years of low prices, farm production drops, shortages develop, prices for crops then rise, the surviving farmers buy up the vacant land and production rises again. Corporations with capital, such as insurance companies, also buy up farms, which leads to land being farmed by tenants rather than owners. One solution to this situation is for the government to buy up surplus crops and store them until the price rises. Another is to support crop prices at the cost of production, no matter how much is produced. This is current U.S. policy. It is not necessarily the best social or environmental solution. While its original purpose was to keep food prices low, it has turned into a support system for corporate farmers. Consistently low, but supported, agricultural prices in the United States, along with greater and greater mechanization and chemical use, and the rising cost of land, have created more and more farm consolidation: larger and larger farms, more corporate farms. Because of the cost of land and of installing drainage, the American Corn Belt has always had a high percentage of its land in absentee owners (about half of cultivated land at the turn of the twentieth century); such owners, along with farmers who rent land, are interested primarily in what they can make off the land in the short run; they are not interested in the future of the landscape. Large farm operations, private or corporate, produce most of the country’s food and receive most of the government support payments. Typically, 20-30% of the income of large farms consists of government payments; if the farm is irrigated, the level of government support is over 90% (mostly in the irrigation infrastructure and the cost of water). Agricultural subsidies in 2000 amounted to half of farm income. Large farms also cause most of the environmental problems of agriculture. A side effect of farm consolidation in the agricultural landscape has been a fall in the rural population, and thus a decline in local economies and in public and private services (schools, stores, medical clinics), and also a widening in the income gap between the relatively well-off corporate farmers and the relatively poor laborers. A poorer population results in a further decline in tax-supported local services, just as the need for such services increases.
Most developed societies support the price of agricultural commodities and regulate production. In France, agricultural policy is seen both as supporting the food supply and as supporting the late-medieval French agricultural landscape: the appearance and the taste of the land (in wine, honey, salt, butter) some Frenchmen call the soul of France. The French developed methods of replanting hedgerows in Normandy, for instance. Hedgerows are useful as windbrakes in that windy land, and important as habitat for birds, small mammals, pollinators and other invertebrates. The hedgerows had been removed to make the fields larger and easier to work with modern equipment. Restoring them restores the landscape. Similar small-scale agricultural operations are supported all over France. These include sheepherders, wheat farmers, small wine-makers. Shepherds still follow herds of sheep grazing along the sides of country roads, or in the grassy wastelands near new housing projects. Such government subsidies represent social as much as economic choices. If the United States made similar choices, instead of the ones it now does, it would support biologically appropriate agriculture, distribute income more thoroughly, substitute photo-voltaic and wind power for coal and establish universal health care. The natural landscape would be allowed to recover. One could call the American economy still colonial, in that (in large measure) we trade agricultural and forest products for manufactured goods and oil. The rate of erosion from agricultural land in the United States is 10 to 15 times the background geological rate. Cutover timberland also erodes. The soil and nutrients lost from the land end up in rivers and the sea, shortening the life of dams, making clean water more expensive and eliminating native fisheries. Supporting better agricultural practice, treating abandoned or polluted lands as a resource, redistributing income and developing small-scale renewable energy would lead to an economic boom. As a candidate for election in 1996 suggested, a one-time tax of 15% on the net worth of all Americans worth $30 million or more would raise enough money to pay off the national debt. The money now paid in interest would be freed up to be used elsewhere; and the rich would make their money back in three years.
Economics also functions against a biological background. Plants change levels of atmospheric gases, modify nutrient cycles, engage in chemical warfare, promote (or suppress) wildfires, create shade, alter the temperature and humidity near the ground. Bacteria change the planet through photosynthesis, decomposition, respiration, nutrient cycling and fixation, by initiating processes that allow other organisms to colonize new environments. Fossil fuels, limestone and phosphate deposits, soils, sedimentary iron deposits, the amount of carbon dioxide in the atmosphere, the presence of oxygen—all are signs of life. Photosynthetic cyanobacteria began to oxygenate the atmosphere about 2.7 billion years ago. Iron precipitated out of the anoxic seas; was uplifted over hundreds of millions of years; and weathered of impurities to form concentrated iron ore, or hematite. Oxidation of the iron helped absorb some of the extra oxygen, which was poisonous to much of existing life. Such life, adapted to a world without oxygen, retreated underground, and new life arose. Modern ecosystems, with flowering plants, pollinators and mammals, began during the Jurassic Period 150 million years ago, when the level of oxygen in the atmosphere was close to 12%. Oxygen levels started rising in the middle of the Cretaceous Period about 100 million years ago during a burst of plant growth (never reached again), and reached the modern level of 21% perhaps 50 million years ago. Lower levels would make it hard for large mammals, which have less efficient lungs than dinosaurs and birds, to survive. Dips in the level of atmospheric oxygen correspond to major episodes of extinction. During this time, the stage was set for our cooler glacial world by the evolution, 390 million years ago, of root systems in plants. Roots secrete carbon dioxide into the soil, where it reacts with soil minerals, breaking them down and making them available to plants, and locking much of the carbon up in the process. The death of roots also adds carbon to the soil. Soil storage of carbon may have resulted in a 45% drop in atmospheric carbon dioxide and a slow planetary cooling (reinforced by the absorption of more carbon dioxide by the cooling ocean; much carbon dioxide was also locked up as coal and oil).
This is the ineluctable background of modern life. But economics focuses relentlessly on the human world. Economics assumes that the natural world can be ordered according to market needs and within market time-scales. It assumes that biological goods, such as forests, fish and beach-front property, can be consumed as fast as the market allows, at neglible economic or human cost: wild fish, salamanders, semi-palmated plovers, and other organisms of little economic value, pay the cost. Forests and mangrove swamps are exchangeable for hot dogs and dollar bills. Once a given resource has been exploited, the profits, if any, are invested in other enterprises. Most people don’t lose: wild salmon runs are replaced by farmed salmon; the profits from logging redwoods are invested in setting up web pages. Individuals such as fisherman and loggers may lose, but that is part of the creative destruction of capitalism; they can get other jobs; and the economy as a whole gains. As natural wealth disappears, the creation of wealth depends more and more on human manipulation. The exploitation of natural resources may remain high or even rise, their lower value per acre (as in second-growth timber), or lower unit value (the declining percent of metal in an ore) compensated for by larger machines, shorter rotation times, and greater use of fossil fuel energy. Oil and coal became cheaper and cheaper during the twentieth century thanks to increasing mechanization and ever-increasing use of those (ever cheaper) fossil fuels: a helpful upward spiral. In this abundant world, energy costs, even of energy-producing devices, didn’t really matter. When oil was abundant and accessible, oil production consumed only 2% of the energy the oil contained. Most other energy resources (coal, tar sands, photo-voltaics) require several times that energy investment and, partly because of this, will require a far larger energy infrastructure. (A 1970’s criticism of nuclear power plants was that more energy went into building them than they would ever produce; this turned out to be not quite true.)
Some sectors of the economy, such as the service sector, are less dependent on natural resources. The medical industry (15% of the United States’ economy) or the educational industry (another good-sized chunk) are examples of wealth-creating industries that don’t require such high levels of resource exploitation per unit of output; at any rate less than mining, logging, metal smelting or agriculture. Of course, modern physicians and teachers depend on the already high level of resource exploitation that the society itself requires (some of that mining, logging and agriculture). Computer software development is an almost purely intellectual effort, but behind it lie customers and computers, power plants, chip manufacturing facilities, heated or air-conditioned buildings, trucks, tremendous quantities of polluted groundwater. In 20 years computers have risen to consume 10% of the American electricity supply. In no time the person at the desk becomes part of the whole petrochemical stream.
Our world is constantly recreated by living things. Climate is partly regulated by the amount of carbon dioxide in the atmosphere and thus by the storage of carbon in vegetation, soils, peat bogs and carbonate rocks. Plants absorb carbon dioxide from the air, turn some of it into plant tissue and pump some of it into soils, where it is absorbed by the breakdown of rocks into useful plant nutrients (so-called, in-place weathering). Soil invertebrates, bacteria and fungi immobilize the carbon left behind in dying plant roots. (A considerable percent of the fine roots of trees and perennial grasses die and regrow every year.) Physical processes in the oceans would precipitate out absorbed carbon dioxide as calcium carbonate (limestone), but living things do it first, so limestone is mostly formed of shells and corals. Uplifted limestones from the sea form 10% of continental crusts. One day, as the earth’s continental crusts are slowly recycled, they will be subducted into the earth’s fiery mantle and their vaporized carbon returned to the atmosphere through volcanoes. Fossil fuels are probably the product of one major past storage event of tens of millions of years duration during a warm wet period especially favorable to vegetation. (Coal certainly is; some writers claim oil and gas are not, but are continually regenerated from inorganic matter by physical processes in the earth’s mantle.) At present, peat bogs and grasslands are both better than forests at long term storage of carbon and tropical forests are better than temperate ones.
The main absorption band of carbon dioxide corresponds with the earth’s peak thermal emissions, which explains its role as a greenhouse gas. Carbon dioxide levels in the atmosphere have been declining for tens of millions of years, and as a result, the earth has been slowly cooling, despite the increasing radiance of the sun. (The increasing radiance of the sun is a very long-term process.) A cooler climate tends to be a drier one, because less water evaporates from the oceans, and so declining carbon dioxide levels favor grasslands over forests, which need more moisture. The rise of carbon-storing grasslands and grazers over the last several million years has corresponded with our cooler glacial ages and, by absorbing more carbon dioxide into the soil, creates a positive feedback for a cooling earth. Some writers argue that under present planetary conditions, carbon dioxide (and the related gas methane, which oxidizes to it) acts as a natural thermostat. Carbon dioxide is stored as a gas in the atmosphere, as a weak solution of carbonic acid in the oceans, as clathrate hydrates near the poles, as carbonate minerals in the earth’s crust, in oil and natural gas. Cooling of the earth causes the reactions that store carbon dioxide in the oceans and soil to slow down, thus moderating the cooling. Continuing volcanic activity releases carbon dioxide from fossil fuels, carbonate minerals and other sources, slowly rewarming the earth. But under current planetary conditions carbon storage slowly increases overall, so the activity of the thermostat is superimposed on the slow cooling of the last several millions of years.
Besides carbon dioxide and oxygen (whose level is maintained by photosynthesis, largely of cyanobacteria and blue-green algae, but also by higher plants), gases of biological origin in the atmosphere include methane, nitrous oxide, and dimethyl sulfide. All are produced by bacteria or algae; methane and nitrous oxide are heat-absorbing gases that work at different wavebands than carbon dioxide; dimethyl sulfide, produced by marine organisms, is important in cloud formation (as are bacteria, which use the atmosphere for dispersal, and whose DNA is found in rain and snow); clouds are also important in regulating climate. (Such facts are taken by some to support the argument that earth’s climate is, within limits, self-regulating.) Without life, the composition of the atmosphere would be very different: the amount of carbon dioxide would be much greater, the turnover of nitrogen gas 10 to 20 times slower, the amount of oxygen very small. Atmospheric methane would not vary with the expansion and contraction of termite habitat or of methane-producing tropical wetlands (whose size is controlled by the strengths of summer monsoons, those a function of plate tectonics, ice cover in the Arctic, ocean currents, earth’s orbital cycles, and the intensity of the summer sun.)
The particular state of our world is maintained by its ecosystem services. The living world’s influence on climate (a sort of regulation) is its most dramatic ecosystem service. Others include maintaining the natural water cycle (regulating the heights of ground water tables and floods; to some extent, regulating the amount of rainfall); cleaning the air and water (forests filter the air passing through them; most ecosystems scavenge nutrients and toxic chemicals from water passing through them and influence its temperature, its siltiness, its chemistry, its rate of flow); maintaining the relative composition of the gases in the atmosphere (such as oxygen and carbon dioxide); creating and maintaining soils (the structure, water-holding capacity, and nutrient levels of soils are all functions of the living things in them as much as of their mineral composition and their location in the landscape); the cycling of nutrients essential for life, including human life, among the atmosphere, the oceans, plants, animals and soils; detoxifying pollutants (the workers here include the many organisms of decay, including those micro-organisms that can reduce human hormones and chlorinated hydrocarbons to more benign chemicals); on a smaller scale, pollination of plants and the regulation of plant and animal populations. The yearly value of such services has been put between $3 trillion and $33 trillion dollars (the latter about equal to the world’s gross domestic product, the former—given a yield of 5%—implying an investment of around $60 trillion). While such calculations are economically useful, ecosystem services are essentially irreplaceable. Both estimates are likely way too low. We can’t create systems that perform the services natural ones perform. Even on small scales, as in space ships or sewage treatment plants, this is difficult. Partly this is because of their size (and therefore their cost, both in wealth and in energy consumption) and partly because we don’t understand how the systems work.
We all share in our effects on the natural world. Any permanent human settlement changes plant cover and the local water cycle, and modern settlements require energy use and chemical output far above those of a few centuries or a few decades back. The footprint of a modern person—the acreage of farm, forestland, mines, manufacturing plants, roads, oil wells, waste dumps needed to sustain his or her life—is much larger, about 24 acres for the average American. Our combined demand requires more land than the United States contains. Is this necessary? Certainly not for human life. The energy use of a hunter-gatherer society, which is mostly food, plus some fuelwood, is little more than their caloric requirements, about 2000 kilocalories per person per day, all of it recyclable. Agriculturalists, who often grow a surplus of food, and also may use draft animals, irrigation water, and derive power from wind and water, use between 5 and 10 times as much, 10,000 to 20,000 kilocalories per person per day. While such societies are sun-powered and potentially sustainable, they may not be so in practice. (They may overcut their forests or overexploit their soils.) Industrial peoples of the nineteenth century with their railroads, steam engines, piped water and gas light, used about 70,000 kilocalories per person per day, much of it from coal, a fossil fuel, that is, a fuel whose energy comes from stored solar energy; burning a fossil fuel returns its carbon to the atmosphere from which it came, in general at a rate too fast for the land and oceans to absorb and neutralize. Late twentieth-century people in the developed world, with their automobiles, large houses, electric lights, airplanes, televisions and computers use about 120,000 kilocalories per person per day, or 60 times that of hunter-gatherers, and twice that of industrial populations in the nineteenth century. North Americans use twice that; but live no better than Europeans. The difference is thought to be partly extravagance (bigger cars, larger, warmer houses, a larger military establishment), partly more energy-intensive industries, and partly North America itself, with its more extreme climates and longer driving distances. The footprint of the developed world, if applied to a population of 6 billion, is not sustainable: that many people living a western life would require several earths. Astronauts, because of the energy demands of escaping earth’s gravitational pull (and those of recreating earth in space), use 2.7 million kilocalories per person per day. Most of the energy used by the developed world comes from the combustion of fossil fuels.
Fuel use is not the only way to measure the environmental impact of a society; synthetic chemical production and patterns of human settlement are others. The size of the American corn crop is a measure of the environmental impact of American agriculture. (The picture is one of relentless growth: corn yields are up 31% since 1995, 72% since 1975, that is from about 4 billion bushels in 1970 to 10 billion in 2000, largely because of genetic improvements, even as the land planted to corn shrank; each bushel requires 1.25 quarts of oil and one or more bushels of eroded topsoil to grow.) However extraction and combustion of fossil fuels constitute one of the most important causes of land degradation and water pollution, as well as a leading source of man-made greenhouse gases. Compared to natural energy fluxes on earth, human fossil fuel use is small, amounting to .11 calories per square meter per day. Input from the sun is 4900 calories per square meter per day, primary production by plants 7.8 calories, weather 100 calories. The outsize effect of fossil fuel use on natural systems derives from several factors. Water use by electric power plants constitutes the largest use after irrigation. While it is not a consumptive use like irrigation (water is pumped through the plants to cool them), it warms rivers and changes their flow regimes, simplifies their flora and fauna, and ruins their fisheries. (New plants can cut water use by 90%, at a small increase in the cost of power.) Obtaining fossil fuels takes up land for wells, roads, mines and pipelines and through spills or disposal of wastes, contaminates land and water. Burning them puts the products of combustion into the atmosphere: carbon dioxide (the gas of global warming), heavy metals like arsenic and mercury, dioxins and other hydrocarbons, sulfur, and radioactive materials. The heavy metals, sulfur, and radioactive materials are natural contaminants of the fuels. While arsenic, lead, mercury and radioactive elements are present in small concentrations in the natural environment, current man-made fluxes of them are comparable to, often greater than, the natural ones. For instance, the flux of mercury produced by people is 10 times the natural flux.
It is the production of carbon dioxide by the burning of fossil fuels whose effects may turn out to be the most dramatic, and perhaps the most catastrophic, for us. Carbon dioxide from the clearing of woodland, the cultivation of soil, and the burning of fossil fuels has apparently reversed the slow fall in the atmospheric concentration of this gas during the last several million years. Sunlight falls through the earth’s atmosphere with little absorption (a little is absorbed as heat) to strike the earth, where it is absorbed or reflected. When reflected (re-radiated) from the earth as infrared radiation (radiant energy of a different wavelength), it is captured by several gases in the atmosphere, including carbon dioxide, methane, nitrous oxide, and water vapor. Water vapor is the most abundant and most important greenhouse gas. By capturing a small amount of additional heat, man-made carbon dioxide raises the temperature of the atmosphere and increases the evaporation of water vapor from the oceans; this creates a positive feedback that raises the temperature of the atmosphere further; the climate warms. Since the ability of the atmosphere to hold water vapor increases rapidly with temperature, a small rise in temperature caused by carbon dioxide can end up having a large effect on atmospheric temperature.
The gases that absorb visible or infra-red radiation are not the only factors that influence the earth’s balance between incoming and outgoing solar radiation. The amount of dust in the atmosphere, clouds, the reflectivity of the earth’s surface (that is, whether it tends to reflect or absorb sunlight: ice reflects light, water absorbs it) also alter that balance, warming or cooling the planet. The global temperature is currently up 0.74º C. (1.33ºF.) from the pre-industrial level, though it is now thought that the pre-industrial level had been raised slightly above the “natural” level by human influences beginning several thousand years ago, including forest clearance for agriculture and wet rice cultivation (rice paddies produce methane). Clearing forests and cultivating soils releases carbon dioxide that would otherwise be stored. To keep global warming below 2º C. (considered a “safe“ level) carbon dioxide in the atmosphere must stay below 450 parts per million; this corresponds to an average carbon emission of half a ton of carbon dioxide per person per year. (2º C. is still a level at which the permafrost boundary will move 400 to 600 kilometers north and sea level rise several feet. Current measurements of methane released from thawing permafrost, and of carbon released from peat bogs, implies we are already at an unsafe level of warming.) A person in India currently produces 0.3 tons, an American 6 tons, a European 2 tons. Thus stabilising the climate implies large cuts in carbon dioxide emissions in developed countries, as countries like China and India develop; 70% in Europe, 90% in North America. This is not necessarily a disaster. Carbon dioxide from stationary sources (such as power plants) can be immobilized, at costs estimated at 2 to 4 cents per kilowatt hour, or 10-20% of current electricity costs. This would come to about $15 a month on the average American bill. (What we would do with a several billion tons a year of magnesium carbonate blocks is another matter.) Norwegian offshore oil and gas production is currently taxed at $38 per metric ton for the carbon dioxide associated with the burning of the fuels; to avoid this tax the state oil company reinjects the carbon dioxide stripped from its gas wells into salt formations under the North Sea. Renewable sources of energy work; and efficiency gains in the use of energy of far greater than 50% are possible, probably 1000% in the case of cars. The French and Japanese in the early 1960s supported themselves on energy usage one-seventh that of the United States today. They certainly lived modern lives (they made better movies), and because of tremendous increases in energy efficiency to date would lead even better ones on the same amount of energy today. By that measure the world today produces enough energy; the problem, as with food, is one of distribution. Even lower energy consumptions than those of France or Japan in the 1960s will support societies with low infant mortality, high life expectancies, varied diets, good medical care, and good educational opportunity. People in the Indian state of Kerala are said to live such lives on per capita incomes of less than $400 a year. (Since other writers claim that an adequate diet, that is, one that allows full expression of one’s genetic potential for growth, arrives only during the early stages of modernization, at per capita incomes of about $4000 a year, ten times that in Kerala, one must wonder at such claims.)
The direction of market-ruled societies is upward; their purpose is growth; their citizens constantly strive to increase their incomes. The notion of constant material improvement in human life is recent, probably foolish, and undoubtedly unsustainable. What is clear is that our current way of increasing our wealth is too much for the biological world to bear. All high civilizations fail; and their people die or disperse to lead simpler lives. (Four to six million people disappeared when the Maya collapsed.) In the past such failures have occurred when climates changed, rains failed, trade routes disappeared, soils grew less fertile. Since people took up agriculture and began to settle in villages 10,000 years ago, societies have created wealth from the extraction of virgin resources and the clearing of new land. For the most part, such societies occupied relatively small areas of the earth and used relatively small amounts of easily available natural resources (timber, soil, coal, copper, iron ore). While all societies fail in the end, none will take as much of the world with them as we will.
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