A Short History of the End of Our World (II)

A Short History of the End of our World


When the current recession ends (if it ends), economic growth will return and carbon dioxide will continue to accumulate in the atmosphere. (The current rate of accumulation is about 2% a year, or a doubling from the current 385 parts per million to over 700 ppm in less than 50 years.) No one is talking about limiting growth and adjusting developed economies to a new reality. Few people are talking about limiting population. No one is talking about cutting carbon dioxide emissions to a level that would stabilize and then reduce the amount of carbon dioxide in the atmosphere and slowly let it return to a “normal” level (probably 280 parts per million). Such cuts would amount to 70-90% of carbon emissions in the developed world. That is a monumental project that can only be accomplished by reducing energy use—insulating houses, building very efficient cars, motors, pumps, redesigning cities for public transportation. There are also two safe, relatively inexpensive methods of taking carbon out of the atmosphere in large enough amounts to make a difference: converting crop waste to charcoal (biochar) and spreading it on farmland, where it raises soil fertility, and the carbon remains bound up for approximately 50,000 years; and revegetating degraded lands to forests or grassland (5 billion acres, land equivalent to current cropland, is available). No one is doing either of these on any scale. Most schemes for engineering a lower temperature (seeding the oceans with iron, pumping sulfur dioxide into the atmosphere, launching fleets of tiny reflective sunshades) have serious disadvantages. That is, they are either risky or nuts.

As the atmosphere warms, the sea warms (but more slowly) and sea level rises, partly from more water in the ocean from melting glaciers, partly from the thermal expansion of water already there. A disastrous rise in temperature and sea level will supposedly occur after a global warming of 4˚ Centigrade (within the generally accepted range of temperature predicted for 2100 if we don’t control carbon emissions). However, the most recent time carbon dioxide levels were at 350 ppm, sea level was 80 feet higher, so we may already be there, so to speak, the sea just hasn’t responded yet. What is certain is that the carbon dioxide now in the atmosphere implies much additional warming. The earth responds slowly to the temperature of its atmosphere. Both land and sea have great thermal inertia. The ocean has bulges and hollows and because of changing currents and jet stream winds and shifting gravitational pulls from collapsing ice sheets, sea level rise will vary considerably from place to place.

Ecosystems and climates flip. That is, a slow change turns into a new regime. Feedback processes kick in. The forests in the western United States and across the boreal regions of Canada and Russia are collapsing from drought, insect damage and warmer temperatures. Drought stresses the trees, thawing permafrost uproots them, and insects are many times more abundant in the shorter winters and warmer summers. These dying forests will decay, or more likely, burn, putting hundreds of millions, or billions, of tons of carbon dioxide into the atmosphere. As the permafrost below them thaws, it emits methane and carbon dioxide. So do warming boreal peat bogs. The tundra lakes, filled with water from the last ice age, expand as the ice beneath them melts, then drain away, exposing more bare ground to the sun. This soil also emits methane and carbon dioxide. As the sea ice melts in the Arctic, the ocean warms from the sun. Along the east Siberian coast, methane, produced by bacteria and locked in a water/ice lattice by cold and the weight of the sea water, bubbles up from the seabed. Such lattices store perhaps 400 billion tons of carbon as methane. As they warm and dry further, the tropical peat-swamp forests of Indonesia burn. (Burning tropical peat swamps to plant palm oil plantations has been a major contributor over the last 20 years to global warming.) The Amazon rain forest burns more frequently and as transpiration from the trees falls, and then rainfall fails, begins to collapse. These are all positive feedback processes put in place by a small amount of warming (and some additional human interference).

Melting large glaciers like the Greenland ice sheet or the Antarctic glaciers takes time (millennia or centuries, one century for the Greenland ice sheet under the most calamitous and respectable of recent scenarios), so sealevel rise beyond 6-10 feet by 2100 is unlikely but 80 feet is possible. A sea level rise of 10 feet would displace tens of millions of people (in Long Island, Florida, the Gulf Coast, Bangladesh, Southeast Asia, the Rhine Delta). Higher seas push river floods back upstream, into areas that didn’t flood before, and makes the rice fields in the deltas of the great south Asian rivers (the Ganges, the Mekong, the Irrawaddy, the Red, the Pearl) unusable. The fields will become brackish estuaries and produce shrimp and fish. Barrier islands will move to the coast and coastal aquifers (such as the Magothy under Long Island) will become too salty to drink. Mountain glaciers, smaller and fed by yearly snows, melt more quickly than continental ones. Those in the Andes that water the high terraces of Peru (most cultivable land in Peru is over 9000 feet) are almost gone. When they are gone and ground water levels fall, many crops will no longer be grown. The Himalayan glaciers that feed the great rivers of India, Pakistan, China and Southeast Asia, are also melting. Without them, spring floods will be greater and summer flows lower. Much land now irrigated by these rivers will no longer be cultivable. Two billion people depend on its crops. Since groundwaters in India and China are already overpumped, the only way to maintain agricultural production will be with older water harvesting techniques, such as the bunds and valley tanks that once caught the rains in monsoon India. But rising temperatures and a failing or flooding monsoon may make that effort difficult, or fruitless.

Except for island nations, and a few tens of millions of coastal dwellers, sea level rise will likely be a problem for the future, but other things will happen in the ocean. Its rising acidity will cause its fisheries to collapse, as the shell-forming algae at the center of food webs die. (All commercial fish stocks are already predicted to collapse from overfishing by 2048, so we may have caught the last fish just in time.) Coral reefs will melt away and animals with calcium carbonate shells (clams, oysters, mussels) will go extinct. Whales and other sea mammals will go extinct. The Gulf Stream will slow greatly or shut down, ending the circulation of oxygenated water to the deep sea and suffocating the animals of the depths. As the sea stagnates, it will become perfused with toxic hydrogen sulfide. The change in ocean currents and surface temperatures will change weather patterns and make many parts of the earth (the east coast of North America, much of Mexico and Central America, South America south of the Amazon, parts of southeast Africa, much of Southeast Asia) uninhabitable from constant storms, floods and drought.

The land warms more quickly than the sea. Much of the land on earth is between 30˚ north and 30˚ south (that is, about the equator). Some of this is now desert, some tropical forest and savannah. As the climate warms these forests and grasslands will be replaced by desert (though some pockets of vegetation in favored locations may remain). Desert conditions will spread south and north, encompassing most of the United States, southern Europe up to the latitude of Paris, northern South America, most of Africa, India, Southeast Asia and all of China: most of the inhabited world. The boreal forests and tundra of North America and Eurasia be replaced by mixed deciduous woodland and grassland. (Not long ago, the Arctic islands were covered by redwood forests.) Most flowering plants and large animals, unable to migrate quickly enough, or their way blocked by human settlements, will go extinct. The habitable parts of the world, where large animals can live and crops grow, will consist of the boreal regions (an immense landscape, its Siberian section unfortunately contaminated by radioactivity from the Soviet nuclear program), the west coast of Greenland, Iceland, New Zealand, Tasmania, southern Patagonia, western Antarctica. Some writers imagine high rise cites amidst intensively cultivated stony Arctic soils.

What will happen to people? Most, in both undeveloped and developed parts of the world, will die, probably not catastrophically, but slowly, from starvation and despair, as death rates climb by 15-20%. This happened in Russia recently (with a lesser rise in the death rate) after the collapse of the Soviet Union, and is still happening there today. (The collapse of the Soviet system explains why Russian troops stationed far from their home bases must return in spring to plant, and in fall to harvest, their potatoes.) It probably happened with the collapse of the Maya and the Aztec civilizations in Mexico and Central America, or the Sumerians in Mesopotamia. Industrial civilization can maintain itself in a desert, desalinating seawater, growing crops in greenhouses cooled by seawater and watered by its sweet condensation, mining copper, pumping oil out of the sand, fueling itself largely with solar panels, living underground where daytime temperatures average 150˚ Fahrenheit. Would it? As the economic blows worsen, and food, water and electricity become scarce, I doubt whether the retreat from the present will be orderly. Farmers will not plant with perennial cover crops the fields they abandon. For one thing, they will have no money to do so. People imagine an orderly retreat to the Arctic coasts (forget about national boundaries) but this ignores the difficulties of feeding large populations, purifying polluted surface water, maintaining the infrastructure necessary to build roads, power stations, vehicles, cement plants in the north. As the seas rise, the water will flood the containment ponds of abandoned nuclear power stations, where the spent fuel rods are stored, oil refineries with their stored oil and chemicals, private houses with their toxic cleaners and pesticides. This material will spread to river deltas and inshore waters. Public zoos and private animal shelters will release their animals rather than let them starve: lions, tigers, elephants, camels, yaks may once again populate North America. Tropical plants will escape from botanical gardens into the new tropical habitat. Over a long time (20,000-100,000 years?), the ocean, finally cleansed of man-made and natural toxins, its circulation restored, will return to something like normal, and after another million years or more, new adaptive radiations will fill it with new creatures.

Perhaps people will watch some of this, as they wander the corners of the deserts with palms and springs, carrying their bows and arrows, and digging tools scavenged from former habitations (much of it now under water), and the great savannahs and woods of the Arctic and Antarctic coasts.