Another Scenario for the End of our World
Or, we could impose a substantial tax on emitted carbon dioxide, with the goal of reducing emissions by 80% by 2050, and so increased periodically. (A bill something like this is currently before the U.S. Congress, proposed by Mr. Larson, with the tax starting at $15 per metric ton of carbon dioxide, and increasing by $10 per ton per year; and increasing by $5 more per ton per year after five years if interim goals are not met.) The tax ideally would be on carbon dioxide produced by burning fossil fuels; on agricultural emissions from the soil (carbon dioxide, nitrous oxide, methane); on emissions from forestry practices; and from pipelines, manure lagoons and landfills (methane). At least 75% of the tax would be rebated to the general population through a reduction in payroll taxes (or a reduction in the income tax, or an increase in the earned income tax credit), in a progressive way. A carbon tax is a regressive tax, like the sales tax, and hits people hardest who must spend most of their income. Despite the rebates, gas costing $4-$10 a gallon speeds the development of efficient cars, and of efficient public transportation—like the street cars of Central European cities, which come often, on time, with their routes and destinations clearly marked. Expensive oil and electricity makes insulating houses more profitable or, in hotter climates, in order to reduce or eliminate air conditioning, designing houses to take advantage of night-time cooling, the coolness of the earth, breezes and natural airflow. More expensive carbon-based energy makes energy from the sun, wind, and deep hot rocks economically competitive and eliminates the need for subsidies for such new energy supplies. The 25% of the tax money left over would support the reforestation or revegetation of degraded lands (in the U.S. or elsewhere); the management of forests or agricultural soils so as to limit their release of greenhouse gases; the preservation of natural or logged over tropical forests; the management of temperate forests and grasslands for carbon capture; the education of women in third world countries so as to allow them to control their destinies and reproductive lives; the development of agriculture and renewable energy in the undeveloped world; birth control; and other schemes to capture carbon and limit the human population. Reforestation or revegetation of degraded lands worldwide would capture all the carbon dioxide we are currently emitting and so (as energy conservation took hold and we emitted less) slow the warming of the earth. Feedback processes would slow and eventually reverse, as the continental glacier that began reforming several thousand years ago in northeast Labrador melted under the influence of human agricultural activity in Eurasia. Arctic ice would reform and cool the Arctic Ocean and provide habitat for creatures that live on or under the ice. Dry western and cold subarctic forests would regrow and begin absorbing carbon dioxide. The sea would lose carbon dioxide to its sediments and, as the carbon dioxide content of the atmosphere fell, to the atmosphere, so its acidity would fall back to normal levels. All this would take some time, perhaps 800 years, perhaps less.
Governments in developed countries would let populations decline, as they would already be without immigration. Funding agricultural and energy development, the education of women, birth control, and good government in developing countries would help reduce the movement of populations from the poor to the rich world. The goal would be a world population of 1-2 billion people (reachable in a century if women restricted themselves to one child, longer if they have two). Getting through the demographic transition would be difficult but planning for it would make it possible.
The world would still warm. Much depends on how quickly feedback processes already in place (melting arctic ice, collapsing forests, methane bubbling up from the seabed along the arctic coasts) can be slowed or reversed. A sea level rise of 3-10 feet, and perhaps 80 feet, is already built into the atmosphere. Flood insurance for most coastal and riverside properties would be phased out and the houses demolished (they contain much useful material, which would be reclaimed if materials dumped in landfills paid their true costs) or moved away from the shore. Some very developed areas might be worth protecting.
As populations fell, agriculture, like forestry, would focus on the landscape as a whole (only partly an agricultural landscape). Agriculture would try to become carbon neutral or (in the case of grazed grasslands, buffalo or antelope commons) carbon storing. People would live among connected, more or less wild landscapes, in a more or less functioning natural world.
Management of the economy would not focus on growth but on the relationship of man to the natural environment, and thus on avoiding dangerous practices and chemistries, redistributing income, and maintaining a more or less steady economic state, with a constant eye on human relations to the natural world. The growth and death of individual businesses would constitute the creative destruction of capitalism. Toxic industrial chemistries would be phased out and replaced by nontoxic, non bio-accumulating chemistries. (A tax similar to the carbon tax would do the trick.) Waste would become a resource: the waste from one industry would feed another, in a circle of plenty. All manufactured materials would be recyclable or biodegradable. Our landfills would be mined for their methane, metals and composts.
Saturday, April 18, 2009
Natural History of the Present, Chapt.11
Chapter 11: The Land Trip Revisited: the Capitalist Landscape in the Settlement of “New Lands”
Madeira entered European history in 1419 when it was sighted by Portuguese sailors blown out into the Atlantic, though the genetics of its mice indicate it may have been visited earlier by Scandinavians. Madeira was an uninhabited island about 350 miles off the North African coast, on the latitude of Morocco. Legend has it that the island’s woods were set alight by the discoverers, who then sailed away. For 7 years the pillar of smoke was a beacon for ships. Madeira is among the first examples of the modern capitalist settlement of “new lands,” that is, lands newly settled by Europeans. A few of these lands were uninhabited (most weren’t); some had inhabitants who were subdued by force of arms, or by arms and diplomatic pressure. (The 80,000 Guanches on the Canary Islands, another island group in the subtropical Atlantic, nearer to the North African coast, took a century to subdue.) The Americas, whose inhabitants had been isolated from the Eurasian landmass for the last 10 to 30 millennia, were emptied by European diseases that flew miles and years ahead of the Europeans themselves. Ideally, such lands were adaptable to European animals and plants. Some newly discovered lands were not really conquerable; some were not possible to settle for other reasons. Tropical Africa was difficult because its climate and its long occupation by humans made it a home for diseases and parasites to which the Europeans had no resistance. (In some colonies half the Europeans died the first year. The survival rate of colonial administrators in West Africa was calculated, so that sufficient replacements could be trained.) Asia could be dominated, but its dense population made much of it difficult to settle. Settlement of abandoned or un-used lands, and the turning of marshland into farmland through drainage schemes, were still taking place in Europe; but by 1400 Europe was already largely settled, and traditional rights and attitudes also tended to limit what could be done there. Madeira on the other hand was empty. It was a mountainous island, and so work there had to be done by hand. The island’s near-tropical location made it suitable for sugarcane, which had been introduced to Europe by the Arabs, who had got it from India. The Crusaders had adopted the crop for the areas they conquered and invented the plantation system using slave labor to grow it, but in the Mediterranean a shortage of fuelwood to refine it was a problem. Sugar was a delicacy in Europe, whose only previous sweetener was honey. Candied fruits in Renaissance Europe had been sweetened by boiling in lead vessels; the reaction of the acidic fruit with lead from the vessel sweetened the fruit with lead acetate. This is a process that dates at least to Roman times, and some writers have implicated the fondness of Romans for such sweets, and the subsequent level of lead poisoning among Roman elites, in the fall of Rome. On Madeira sugar cane was grown in narrow terraced fields, irrigated with water brought down from the top of the island in channels cut out of the rock. Its mountains gave Madeira many microclimates and its high mountaintop plateau caught a constant supply of water from rain and clouds. This made reservoirs not necessary. Most of the water in the system was stored in the channels and canals. Over time the island was more or less remade into an agricultural landscape. Some of the development was financed by outsiders (again the Genoese) and much of the work was done by African slaves. Sugar was already being grown by the Portuguese with African slave labor on the Cape Verde Islands. The Cape Verdes are located off the African coast, but are hotter and drier. They were used primarily as a staging ground for the export of slaves.
Madeira’s production of sugar showed a typical curve for the capitalist exploitation of a new resource. The beginning was slow. Production reached 640,000 pounds in 1470 (about 45 years after construction of the irrigation system began), rose to 2,560,000 pounds in 1490, 3,360,000 pounds in 1494, and peaked at 4,508,000 pounds in 1506. By 1500, the population of Madeira numbered 20,000, including several thousand slaves, and Madeira was the world’s largest producer of sugar. Madeiran sugar production had caused the price of sugar in Europe to fall by 50% and sugar had begun its journey downward through the European class structure. (Sugarcane is now the world’s largest crop and sugar from cane, beets and corn a major source of calories for the poor.) The move from use by a select few to use by the whole population, the so-called democratization of the market, is typical of modern capitalist enterprise: consider cars, electricity, computer use, internet access, or, more hopefully, the market for organic food (currently 1-2% of food production in the United States, but growing at 10-20% per year). What then happened to Madeiran sugar production was also typically capitalist: production stabilized at about 2,240,000 pounds a year after 1500; and other places began producing sugar. Madeira’s dominance of the market would be taken over by Brazil after 1570. The price of sugar kept falling as production rose, and as demand rose to meet it. Brazil, with its endless flat areas suitable for sugar production, its limitless timber resources, and its huge importation of African slaves would eventually make sugar production uneconomic on Madeira. Madeira had additional expenses compared with Brazil: the irrigation system, the difficult terrain that required more manpower per unit of production. But Madeiran yields were also falling from soil erosion, and from depredations by rats, insects, and introduced diseases of the cane plant. The tremendous yields of earlier years were probably the result of new land being brought into cultivation. Because of its different elevational micro-climates, Madeira had always grown some wheat, wine grapes and tree fruits, and had exported furniture made from the trees that had escaped the initial conflagration. (Many trees must have been left. Sawn boards 15 inches wide and double the length of those available in Europe were exported to Portugal; it is said these planks made possible the large ships the Portuguese sent around Africa to the East. Sugar production also requires a great deal of fuelwood.) Agricultural competition began to change Madeira into a wine island: vines and trees are less demanding crops, require less labor, and are better at maintaining their soils, though with the proper mycorrhizal inoculants sugar cane can be grown without fertiliser, and with the return of the composted bagasse (the crushed stalks), or their ashes, to the soil, sugar cane may not be bad at maintaining its soils either. In the rest of the world, sugar production would continue its upward trajectory for some centuries. As the price of sugar continued to fall, and it became a staple food, profits moved more and more from the tropical producers to the trading houses of Europe. In the seventeenth century, Caribbean islands under the control of the English and the Dutch (such as Barbadoes and Antigua) were cleared to grow cane (on Antigua almost no natural vegetation remains), and the Caribbean began to compete with Brazil as the center of sugar production.
The settlement of Madeira shows the extent to which Europeans of the fifteenth century had the idea of landscape as something marketable. The idea of commodifying nature is not new in history. The Romans saw wilderness as something to be domesticated and so presumably did earlier agriculturalists. (The Greeks saw the conflict between wilderness and civilization.) In an agricultural or a capitalist world, developing a landscape greatly increases the value of the land itself. In North America relative real estate values would become prime considerations in how landscapes were used. Sugar was much more valuable than the productions of the natural landscape of Madeira, whatever they would have been, and sugar’s high value per unit volume also made it profitable to ship in the fifteenth century; timber from Madeira (one product of the natural landscape) was shipped as sawn lumber or chairs. Logs were too bulky to ship profitably. (But things change: by the late 1700s hand-squared white pine timbers 60 feet long were being loaded onto timber ships in the Port of Montreal for shipment to England, where they would be resawed into planks in English pits.) So under capitalist management the natural landscapes of Madeira (its associations of trees, herbs, insects, animals, natural watercourses) were restricted to areas too cold or steep to develop. The ecological functions of the landscape did not enter into the economic calculation. Of course capitalist development runs along a continuum, and some natural landscapes had economic value for some people. The Atlantic salmon that ran up Lake Ontario streams to spawn were considered part of the value of a farm in early nineteenth century western New York State. The salmon didn’t last long: they were overfished; clearing of the landscape for fields made the streams too warm in summer; and silt eroding from the farmland covered the river gravels in which they laid their eggs. Farm woodlots, though forced more and more into poorer, steeper, uncultivable land, were useful in the northeastern United States for a long time as sources of fencing material, logs and fuelwood. The woodlots protected the headwaters of streams and provided some natural habitat among the cultivated ground.
The search for profit helps explain why the meeting of the Huron and the French was such a collision. The material lives of a seventeenth century Abenaki in New England or a Huron in Ontario were not that different from those of a seventeenth century European farmer; and better than the material life of a landless agricultural worker. The well-off European peasant was entirely dependant on his fields for food, owned some metal tools, a table, chairs and a bed, a more or less permanent house, chickens, a cow, perhaps a plow. The North American had better clothes, of animal skins rather than cloth, a safer water supply, was less liable to chronic injury from heavy agricultural labor, suffered from fewer diseases, had a less permanent house, a less laborious daily round and a better diet. He was taller, stronger, and probably lived longer. The Abenaki’s winter wickiup of bark or skins was small, dark, warm, and smoky (the indoor air of the communal long houses of the Iroquois may have been better). European houses were larger, drafty, cold, also dark (because of the expense of window glass), and smoky (fireplaces with chimneys were just coming into use). Native bows were more accurate, more powerful and carried further than blunderbusses; and canoes were faster and more maneuverable than wooden dories. Mocassins were drier and more comfortable than European boots.
It was the direction of such lives that was different. The colonies in Massachusetts were financed by investors who expected to be paid back. The Pilgrims, trading with the native women for their used beaver cloaks (furs 2 to 3 years old, with the guard hairs worn off, were preferred by the London hatters); gathering casks of sassafras and sumac; splitting pine logs into clapboards, or oak logs into barrel staves; filling a ship with this material, must have looked very odd to the Abenaki. The Pilgrims were soon replaced by the tall-hatted, less tolerant Puritans. What drove these people? In the 1920s, the chiefs at Taos Pueblo in New Mexico told the psychologist C.G. Jung that all white men looked mad. In the 1620s, trade was what made Europe work. The goal of all this activity for a Massachusetts Bay Puritan was a big house in town, a life free of the daily round of a farmer or a retail businessman: not the life of a shopkeeper but that of a capitalist, an investor who lived off holdings in real estate or ventures in timber or shipping. The idea was to approach the status of the nobility (always unattainable, since that was a matter of blood). For the Indian gatherer and horticulturalist the chief value of the landscape was its edibility and the daily round with its stones, trees, sweat, nuts and wild animals was life. Life existed in the physical landscape, which was encompassed in myth and in the structure of language. The thousands of petroglyphs tapped into stones below the three ancient volcanoes on the western edge of Albuquerque, New Mexico, commemorate the entrance to the underworld from which, in mythic times, the tribes came out onto the earth. Direction in the language of one Californian tribe was indicated by one’s position with respect to a sacred mountain. The Navaho homeland is delineated by the four sacred mountains. This is not to say that a landcape might not be improved, say by an annual burning, the building of buffalo jumps, the digging of pitfalls along deer trails, the clearing of fields (which lost nutrients and eroded); such matters always fall along a continuum. But the notion of a marketable landscape opened another door. A marketable landscape is no longer important in itself, or in what it can produce by itself in biological perpetuity, or in how it works together with other landscapes up or down the watershed. (These anyway are ideas of modern biology, that sometimes correspond with edible or tribal notions.) A marketable landscape’s value is in what it can produce for sale, as quickly as market demand allows (beaver skins, freshwater pearls, gold), and in its later potential for transformation into a landscape of greater value (a farm, inland waterway, factory site, house lot), with its natural productions reduced or removed.
Agricultural use moves a landscape further along the continuum towards the marketable. Most agriculturalists have some variety of property rights. They may not own the land they cultivate in our sense (that is, be able to sell it) but the right to farm it cannot be taken from them easily, they control what it yields, they can let others use it. The development of modern western ideas of private property rights can be traced back to the European commune: the walled town that managed to separate itself by economic leverage and force of arms from the countryside and the nobility that ruled it. Such towns were comparatively rich by the thirteenth and fourteenth centuries, especially in Italy. Merchants were financing trade in grain, silks, and spices; land reclamation schemes; public works; and (under duress) wars. In the medieval countryside, the nobility rode and hunted where they wished, and took what they wanted by force of arms; the Church also had a growing amount of land and various rights. (By the 1400s, the Church had more land than the nobility, much left it by pious parishioners.) Such things had to be regulated if a person was to invest in farmland or other development projects, such as mines. The right of unobstructed use of one’s property, the right to use it without interference, was a necessary precursor to capitalist investment. This was not always a simple matter. Some land uses were objectionable. Iron mines and foundries, for instance, were almost as unpopular among the peasantry as among the nobility. Their noise was appalling; their logging and run-off polluted rivers; and their smoke poisoned nearby farmland.
For an Inuit or a Huron, private property in our sense was more or less limited to what one held in one’s hand. Cornfields among the Iroquois descended in the female line, but were temporary, and were not sold, though they might be lent or given away. One could say (following Locke) that they were created by their user’s labor. A Chippewa matron would have the use of a particular sugar bush, also in a sense created by labor. In some California tribes, the right to the acorns from certain oaks, or groves of oaks, was passed on by families. The grapevines of the coastal New England villages remarked on by the early explorers, that were located in favored spots, trellised on trees, kept clear of shading by shrubs or other trees, may have been individually owned. Groups of families had the right to certain hunting territories but this was also a limited right, under the supervision of the tribe. (The assignment of discrete hunting territories to smaller and smaller family groups among the tribes of boreal North America was probably a product of the economic pressures of the fur trade.) All this wasn’t very different from medieval, rural Europe, with a village’s common plowland, divided into individual allotments, and common waste and woodlot, pastured and cut by communal agreement. But common lands in Europe after 1200 would slowly become private lands: freehold property, to be farmed, enclosed, mined, sold to another party, that is, developed, as the owner wished, without interference from other landowners or from a state power. Advances in agriculture, along with the constant increase in human population, made such lands valuable. The motive behind the enclosure of common lands in England from the 1600s through the 1800s was the desire of large landowners to profit from the increased value of their land’s agricultural production. The development of private property rights made the landscape marketable, and the lack of traditional restraints in the “new lands” meant capitalist land development would reach its greatest extent there.
Madeira entered European history in 1419 when it was sighted by Portuguese sailors blown out into the Atlantic, though the genetics of its mice indicate it may have been visited earlier by Scandinavians. Madeira was an uninhabited island about 350 miles off the North African coast, on the latitude of Morocco. Legend has it that the island’s woods were set alight by the discoverers, who then sailed away. For 7 years the pillar of smoke was a beacon for ships. Madeira is among the first examples of the modern capitalist settlement of “new lands,” that is, lands newly settled by Europeans. A few of these lands were uninhabited (most weren’t); some had inhabitants who were subdued by force of arms, or by arms and diplomatic pressure. (The 80,000 Guanches on the Canary Islands, another island group in the subtropical Atlantic, nearer to the North African coast, took a century to subdue.) The Americas, whose inhabitants had been isolated from the Eurasian landmass for the last 10 to 30 millennia, were emptied by European diseases that flew miles and years ahead of the Europeans themselves. Ideally, such lands were adaptable to European animals and plants. Some newly discovered lands were not really conquerable; some were not possible to settle for other reasons. Tropical Africa was difficult because its climate and its long occupation by humans made it a home for diseases and parasites to which the Europeans had no resistance. (In some colonies half the Europeans died the first year. The survival rate of colonial administrators in West Africa was calculated, so that sufficient replacements could be trained.) Asia could be dominated, but its dense population made much of it difficult to settle. Settlement of abandoned or un-used lands, and the turning of marshland into farmland through drainage schemes, were still taking place in Europe; but by 1400 Europe was already largely settled, and traditional rights and attitudes also tended to limit what could be done there. Madeira on the other hand was empty. It was a mountainous island, and so work there had to be done by hand. The island’s near-tropical location made it suitable for sugarcane, which had been introduced to Europe by the Arabs, who had got it from India. The Crusaders had adopted the crop for the areas they conquered and invented the plantation system using slave labor to grow it, but in the Mediterranean a shortage of fuelwood to refine it was a problem. Sugar was a delicacy in Europe, whose only previous sweetener was honey. Candied fruits in Renaissance Europe had been sweetened by boiling in lead vessels; the reaction of the acidic fruit with lead from the vessel sweetened the fruit with lead acetate. This is a process that dates at least to Roman times, and some writers have implicated the fondness of Romans for such sweets, and the subsequent level of lead poisoning among Roman elites, in the fall of Rome. On Madeira sugar cane was grown in narrow terraced fields, irrigated with water brought down from the top of the island in channels cut out of the rock. Its mountains gave Madeira many microclimates and its high mountaintop plateau caught a constant supply of water from rain and clouds. This made reservoirs not necessary. Most of the water in the system was stored in the channels and canals. Over time the island was more or less remade into an agricultural landscape. Some of the development was financed by outsiders (again the Genoese) and much of the work was done by African slaves. Sugar was already being grown by the Portuguese with African slave labor on the Cape Verde Islands. The Cape Verdes are located off the African coast, but are hotter and drier. They were used primarily as a staging ground for the export of slaves.
Madeira’s production of sugar showed a typical curve for the capitalist exploitation of a new resource. The beginning was slow. Production reached 640,000 pounds in 1470 (about 45 years after construction of the irrigation system began), rose to 2,560,000 pounds in 1490, 3,360,000 pounds in 1494, and peaked at 4,508,000 pounds in 1506. By 1500, the population of Madeira numbered 20,000, including several thousand slaves, and Madeira was the world’s largest producer of sugar. Madeiran sugar production had caused the price of sugar in Europe to fall by 50% and sugar had begun its journey downward through the European class structure. (Sugarcane is now the world’s largest crop and sugar from cane, beets and corn a major source of calories for the poor.) The move from use by a select few to use by the whole population, the so-called democratization of the market, is typical of modern capitalist enterprise: consider cars, electricity, computer use, internet access, or, more hopefully, the market for organic food (currently 1-2% of food production in the United States, but growing at 10-20% per year). What then happened to Madeiran sugar production was also typically capitalist: production stabilized at about 2,240,000 pounds a year after 1500; and other places began producing sugar. Madeira’s dominance of the market would be taken over by Brazil after 1570. The price of sugar kept falling as production rose, and as demand rose to meet it. Brazil, with its endless flat areas suitable for sugar production, its limitless timber resources, and its huge importation of African slaves would eventually make sugar production uneconomic on Madeira. Madeira had additional expenses compared with Brazil: the irrigation system, the difficult terrain that required more manpower per unit of production. But Madeiran yields were also falling from soil erosion, and from depredations by rats, insects, and introduced diseases of the cane plant. The tremendous yields of earlier years were probably the result of new land being brought into cultivation. Because of its different elevational micro-climates, Madeira had always grown some wheat, wine grapes and tree fruits, and had exported furniture made from the trees that had escaped the initial conflagration. (Many trees must have been left. Sawn boards 15 inches wide and double the length of those available in Europe were exported to Portugal; it is said these planks made possible the large ships the Portuguese sent around Africa to the East. Sugar production also requires a great deal of fuelwood.) Agricultural competition began to change Madeira into a wine island: vines and trees are less demanding crops, require less labor, and are better at maintaining their soils, though with the proper mycorrhizal inoculants sugar cane can be grown without fertiliser, and with the return of the composted bagasse (the crushed stalks), or their ashes, to the soil, sugar cane may not be bad at maintaining its soils either. In the rest of the world, sugar production would continue its upward trajectory for some centuries. As the price of sugar continued to fall, and it became a staple food, profits moved more and more from the tropical producers to the trading houses of Europe. In the seventeenth century, Caribbean islands under the control of the English and the Dutch (such as Barbadoes and Antigua) were cleared to grow cane (on Antigua almost no natural vegetation remains), and the Caribbean began to compete with Brazil as the center of sugar production.
The settlement of Madeira shows the extent to which Europeans of the fifteenth century had the idea of landscape as something marketable. The idea of commodifying nature is not new in history. The Romans saw wilderness as something to be domesticated and so presumably did earlier agriculturalists. (The Greeks saw the conflict between wilderness and civilization.) In an agricultural or a capitalist world, developing a landscape greatly increases the value of the land itself. In North America relative real estate values would become prime considerations in how landscapes were used. Sugar was much more valuable than the productions of the natural landscape of Madeira, whatever they would have been, and sugar’s high value per unit volume also made it profitable to ship in the fifteenth century; timber from Madeira (one product of the natural landscape) was shipped as sawn lumber or chairs. Logs were too bulky to ship profitably. (But things change: by the late 1700s hand-squared white pine timbers 60 feet long were being loaded onto timber ships in the Port of Montreal for shipment to England, where they would be resawed into planks in English pits.) So under capitalist management the natural landscapes of Madeira (its associations of trees, herbs, insects, animals, natural watercourses) were restricted to areas too cold or steep to develop. The ecological functions of the landscape did not enter into the economic calculation. Of course capitalist development runs along a continuum, and some natural landscapes had economic value for some people. The Atlantic salmon that ran up Lake Ontario streams to spawn were considered part of the value of a farm in early nineteenth century western New York State. The salmon didn’t last long: they were overfished; clearing of the landscape for fields made the streams too warm in summer; and silt eroding from the farmland covered the river gravels in which they laid their eggs. Farm woodlots, though forced more and more into poorer, steeper, uncultivable land, were useful in the northeastern United States for a long time as sources of fencing material, logs and fuelwood. The woodlots protected the headwaters of streams and provided some natural habitat among the cultivated ground.
The search for profit helps explain why the meeting of the Huron and the French was such a collision. The material lives of a seventeenth century Abenaki in New England or a Huron in Ontario were not that different from those of a seventeenth century European farmer; and better than the material life of a landless agricultural worker. The well-off European peasant was entirely dependant on his fields for food, owned some metal tools, a table, chairs and a bed, a more or less permanent house, chickens, a cow, perhaps a plow. The North American had better clothes, of animal skins rather than cloth, a safer water supply, was less liable to chronic injury from heavy agricultural labor, suffered from fewer diseases, had a less permanent house, a less laborious daily round and a better diet. He was taller, stronger, and probably lived longer. The Abenaki’s winter wickiup of bark or skins was small, dark, warm, and smoky (the indoor air of the communal long houses of the Iroquois may have been better). European houses were larger, drafty, cold, also dark (because of the expense of window glass), and smoky (fireplaces with chimneys were just coming into use). Native bows were more accurate, more powerful and carried further than blunderbusses; and canoes were faster and more maneuverable than wooden dories. Mocassins were drier and more comfortable than European boots.
It was the direction of such lives that was different. The colonies in Massachusetts were financed by investors who expected to be paid back. The Pilgrims, trading with the native women for their used beaver cloaks (furs 2 to 3 years old, with the guard hairs worn off, were preferred by the London hatters); gathering casks of sassafras and sumac; splitting pine logs into clapboards, or oak logs into barrel staves; filling a ship with this material, must have looked very odd to the Abenaki. The Pilgrims were soon replaced by the tall-hatted, less tolerant Puritans. What drove these people? In the 1920s, the chiefs at Taos Pueblo in New Mexico told the psychologist C.G. Jung that all white men looked mad. In the 1620s, trade was what made Europe work. The goal of all this activity for a Massachusetts Bay Puritan was a big house in town, a life free of the daily round of a farmer or a retail businessman: not the life of a shopkeeper but that of a capitalist, an investor who lived off holdings in real estate or ventures in timber or shipping. The idea was to approach the status of the nobility (always unattainable, since that was a matter of blood). For the Indian gatherer and horticulturalist the chief value of the landscape was its edibility and the daily round with its stones, trees, sweat, nuts and wild animals was life. Life existed in the physical landscape, which was encompassed in myth and in the structure of language. The thousands of petroglyphs tapped into stones below the three ancient volcanoes on the western edge of Albuquerque, New Mexico, commemorate the entrance to the underworld from which, in mythic times, the tribes came out onto the earth. Direction in the language of one Californian tribe was indicated by one’s position with respect to a sacred mountain. The Navaho homeland is delineated by the four sacred mountains. This is not to say that a landcape might not be improved, say by an annual burning, the building of buffalo jumps, the digging of pitfalls along deer trails, the clearing of fields (which lost nutrients and eroded); such matters always fall along a continuum. But the notion of a marketable landscape opened another door. A marketable landscape is no longer important in itself, or in what it can produce by itself in biological perpetuity, or in how it works together with other landscapes up or down the watershed. (These anyway are ideas of modern biology, that sometimes correspond with edible or tribal notions.) A marketable landscape’s value is in what it can produce for sale, as quickly as market demand allows (beaver skins, freshwater pearls, gold), and in its later potential for transformation into a landscape of greater value (a farm, inland waterway, factory site, house lot), with its natural productions reduced or removed.
Agricultural use moves a landscape further along the continuum towards the marketable. Most agriculturalists have some variety of property rights. They may not own the land they cultivate in our sense (that is, be able to sell it) but the right to farm it cannot be taken from them easily, they control what it yields, they can let others use it. The development of modern western ideas of private property rights can be traced back to the European commune: the walled town that managed to separate itself by economic leverage and force of arms from the countryside and the nobility that ruled it. Such towns were comparatively rich by the thirteenth and fourteenth centuries, especially in Italy. Merchants were financing trade in grain, silks, and spices; land reclamation schemes; public works; and (under duress) wars. In the medieval countryside, the nobility rode and hunted where they wished, and took what they wanted by force of arms; the Church also had a growing amount of land and various rights. (By the 1400s, the Church had more land than the nobility, much left it by pious parishioners.) Such things had to be regulated if a person was to invest in farmland or other development projects, such as mines. The right of unobstructed use of one’s property, the right to use it without interference, was a necessary precursor to capitalist investment. This was not always a simple matter. Some land uses were objectionable. Iron mines and foundries, for instance, were almost as unpopular among the peasantry as among the nobility. Their noise was appalling; their logging and run-off polluted rivers; and their smoke poisoned nearby farmland.
For an Inuit or a Huron, private property in our sense was more or less limited to what one held in one’s hand. Cornfields among the Iroquois descended in the female line, but were temporary, and were not sold, though they might be lent or given away. One could say (following Locke) that they were created by their user’s labor. A Chippewa matron would have the use of a particular sugar bush, also in a sense created by labor. In some California tribes, the right to the acorns from certain oaks, or groves of oaks, was passed on by families. The grapevines of the coastal New England villages remarked on by the early explorers, that were located in favored spots, trellised on trees, kept clear of shading by shrubs or other trees, may have been individually owned. Groups of families had the right to certain hunting territories but this was also a limited right, under the supervision of the tribe. (The assignment of discrete hunting territories to smaller and smaller family groups among the tribes of boreal North America was probably a product of the economic pressures of the fur trade.) All this wasn’t very different from medieval, rural Europe, with a village’s common plowland, divided into individual allotments, and common waste and woodlot, pastured and cut by communal agreement. But common lands in Europe after 1200 would slowly become private lands: freehold property, to be farmed, enclosed, mined, sold to another party, that is, developed, as the owner wished, without interference from other landowners or from a state power. Advances in agriculture, along with the constant increase in human population, made such lands valuable. The motive behind the enclosure of common lands in England from the 1600s through the 1800s was the desire of large landowners to profit from the increased value of their land’s agricultural production. The development of private property rights made the landscape marketable, and the lack of traditional restraints in the “new lands” meant capitalist land development would reach its greatest extent there.
Thursday, March 26, 2009
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 to over 700 parts per million in less than 50 years. No one is talking about limiting growth and adjusting developed economies to a new reality. No one is talking about cutting carbon dioxide emissions to a level that would stabilize the amount of carbon dioxide in the atmosphere and slowly let it return to a “normal” level (probably 280 parts per million: the current level is 385 ppm). 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, building 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 revegetating degraded lands to forests or grassland (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 sunshades) have serious disadvantages. That is, they are either risky or nuts.
As the atmosphere warms, the sea warms (but more slowly) and sealevel 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 sealevel will supposedly occur after a global warming of 4˚ Centigrade (within the generally accepted range of that predicted for 2100 if we don’t control carbon emissions). However, the most recent time carbon dioxide levels were at 350 ppm, sealevel 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.
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 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, now bubbles up from the seabed. As they warm and dry, the tropical peat-swamp forests of Indonesia burn, as they have been for two decades (burning tropical peat swamps are a major contributor to global warming). The Amazon rain forest burns more frequently and as transpiration from the trees falls, and rainfall fails, begins to collapse. These are all positive feedback processes put in place by a small global warming and, in most cases, some additional human interference.
Melting large glaciers like the Greenland ice sheet or the Antarctic glaciers takes time (millennia or centuries, at least one century, say, for a quarter of the Greenland ice sheet, even under the more calamitous scenarios), so sealevel rise beyond a meter or two by 2100 is unlikely. Mountain glaciers, smaller and fed by yearly snows, melt more quickly. 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 and the countries of 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. A billion people depend on its crops. Since groundwaters in India are already overpumped, the only way to maintain agricultural production in the subcontinent will be to reconstruct the valley tanks and water structures that once served to catch the monsoon rains. But rising temperatures and a failing or flooding monsoon will soon make that effort difficult, or fruitless.
Except for island nations, sea level rise will 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 bottom of food chains 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 hydrogen sulfide, a toxic gas. 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, much of South America south of the Amazon, parts of southeast Africa, much of Southeast Asia and the Himalayas) 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 the 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, as the Arctic islands were once covered by redwood forests. Most flowering plants and large animals, unable to migrate quickly enough, 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 contaminated by radioactivity from the Soviet nuclear program), Iceland, New Zealand, Tasmania, southern Patagonia, western Antarctica, the west coast of Greenland. 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 (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, from entirely different causes, in Mexico and Central America. 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, fueling itself with solar panels, pumping oil out of the ground, 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 (if the water in the ponds has not already evaporated and radioactive material melted into the earth), oil refineries with their stored oil and chemicals, 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. In 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 have filled 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 human habitations (much of it now under water), and the great savannahs and forests of the Arctic coast.
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 to over 700 parts per million in less than 50 years. No one is talking about limiting growth and adjusting developed economies to a new reality. No one is talking about cutting carbon dioxide emissions to a level that would stabilize the amount of carbon dioxide in the atmosphere and slowly let it return to a “normal” level (probably 280 parts per million: the current level is 385 ppm). 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, building 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 revegetating degraded lands to forests or grassland (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 sunshades) have serious disadvantages. That is, they are either risky or nuts.
As the atmosphere warms, the sea warms (but more slowly) and sealevel 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 sealevel will supposedly occur after a global warming of 4˚ Centigrade (within the generally accepted range of that predicted for 2100 if we don’t control carbon emissions). However, the most recent time carbon dioxide levels were at 350 ppm, sealevel 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.
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 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, now bubbles up from the seabed. As they warm and dry, the tropical peat-swamp forests of Indonesia burn, as they have been for two decades (burning tropical peat swamps are a major contributor to global warming). The Amazon rain forest burns more frequently and as transpiration from the trees falls, and rainfall fails, begins to collapse. These are all positive feedback processes put in place by a small global warming and, in most cases, some additional human interference.
Melting large glaciers like the Greenland ice sheet or the Antarctic glaciers takes time (millennia or centuries, at least one century, say, for a quarter of the Greenland ice sheet, even under the more calamitous scenarios), so sealevel rise beyond a meter or two by 2100 is unlikely. Mountain glaciers, smaller and fed by yearly snows, melt more quickly. 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 and the countries of 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. A billion people depend on its crops. Since groundwaters in India are already overpumped, the only way to maintain agricultural production in the subcontinent will be to reconstruct the valley tanks and water structures that once served to catch the monsoon rains. But rising temperatures and a failing or flooding monsoon will soon make that effort difficult, or fruitless.
Except for island nations, sea level rise will 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 bottom of food chains 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 hydrogen sulfide, a toxic gas. 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, much of South America south of the Amazon, parts of southeast Africa, much of Southeast Asia and the Himalayas) 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 the 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, as the Arctic islands were once covered by redwood forests. Most flowering plants and large animals, unable to migrate quickly enough, 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 contaminated by radioactivity from the Soviet nuclear program), Iceland, New Zealand, Tasmania, southern Patagonia, western Antarctica, the west coast of Greenland. 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 (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, from entirely different causes, in Mexico and Central America. 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, fueling itself with solar panels, pumping oil out of the ground, 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 (if the water in the ponds has not already evaporated and radioactive material melted into the earth), oil refineries with their stored oil and chemicals, 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. In 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 have filled 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 human habitations (much of it now under water), and the great savannahs and forests of the Arctic coast.
Wednesday, March 11, 2009
The Natural History of the Present, Chapter 10
Chapter 10: Europe until 1800: Limits of a Fully Settled Agricultural World
Using the natural production of the forest or waste to increase the fertility of cropland is a common strategy of folk agricultures. It usually depends on domestic animals that eat leaves or grass from the surrounding uncultivated land and whose manure is then used on the fields. In a modern African variant of this system, branches from leguminous trees, grown in hedgerows between the fields, are directly used to mulch, and thus also to fertilize, crops; no animals are involved. The rapid decay rates of the tropics make this system possible.
Overexploitation of systems that depend on the surrounding forest or wasteland for a portion of their fertility is easy. While usually caused by over-population, over-exploitation can also be caused by an increase in market demand for timber, grain or fuel. An example is trekkers seeking food and shelter in Nepal. Villagers build small hotels of native lumber to take them in. They also grow more food to feed them, and more fuel to warm them, thus increasing their income at the cost of over-cutting the forest for timber, fuel and fodder. This increases erosion and the risk of landslides in steep areas. (Much of upland Nepal is steep, its slopes held in place by shrubs and trees; under traditional management, firewood was taken from dead vegetation.) The rise in the number of ski areas in Swiss mountain valleys is a more high-tech example of market-based over-exploitation of steep forestlands (which 250 years ago in the French Alps were cleared for farmland, with catastrophic erosion); now not for food or fuel but (similarly to the Nepalese) for business income. In such cases the demand for wealth magnifies the effect of population.
In the grain-and-cow culture of the Near-Eastern agriculturists who settled Europe 7000 years ago, using products of the wasteland to fertilize fields already had a long history. Fertility of upland fields is maintained on the one hand by in-situ weathering. This is the release of mineral elements from the soil by bacterial and fungal action and the erosive effect of natural rainfall, which is slightly acidic (root secretions make it more so and increase the release of minerals). Fields have much simpler plant, animal, fungal and microbial populations than forests or grasslands, and lack their nutrient cycling ability. Leaving them bare for much of the year exposes them to extensive leaching and erosion. They also have less sophisticated systems for releasing nutrients from soils. Cereal crops use nutrients equivalent to the forests or grasslands they replace, but much of their growth, along with the nutrients, is removed in the annual harvest. Nitrogen in fields is provided by free-living nitrogen-fixing bacteria in the soil, and those living in nodules on the roots of leguminous plants. The annual pulse of nitrogen may be greater in fields than in grasslands or forest, because of the warmer temperatures of the cleared ground. A good part of this nitrogen is leached out by rainfall, even from hayfields, that is, cultivated grassland. The problem is that in such simple systems, the bacterial activity that releases nutrients, and nutrient uptake by the plants, do not always coincide; then nutrients escape. For instance, bacteria may mobilize nutrients before crop plants have been seeded in the spring, or after they are done growing (or have been plowed under) in the fall. The fertility of fields depends on the balance among what is removed—by crops, by leaching, by soil erosion—and on what nutrients are produced within the field or added to it. If the soil is inherently fertile, and soil erosion is not too great, the crops not too demanding, and leaching of nutrients by rainfall remains within bounds, a field will retain a low level of fertility indefinitely. (Temperate loess soils are good here.) But the steady fall in fertility after the clearing of the natural vegetation is the reason for rotating fields back into forest. The earliest agriculturalists in Europe cultivated river floodplains with hoes (such soils were good to begin with and are renewed by floods and by soil washing down from the hillsides), but the slash-and-burn agriculturalists of upland Europe apparently moved on, with their cattle and stores of grain, when the fertility of their fields fell. Denser populations require permanent fields, however, and with the manure from domestic animals the fertility of fields can be maintained. Animals are pastured in the woods and kept nights on the fallow; fed cut branches, hay, and grain straw; and put to graze on grain stubble (where they also deposit their urine and manure). The biological productivity of uncultivated lands is a major support of such continuous grain-growing systems.
The introduction of cattle was a tremendous innovation in Neolithic agriculture. Milk provides 4 to 5 times the protein and energy for the same amount of feed as meat; cattle provide traction power; and manure for grain crops. The development of lactose tolerance in adults (the ability to digest milk usually disappears after childhood in humans) is thought to have increased the number of a person’s descendants several times (perhaps 10). In Neolithic Europe each person needed 20 hectares (48 acres) for cropland, fallowland, pasture, hay meadows, firewood, building material, and forest browse. (Branches were lopped and brought to the animals, sometimes stored in piles by the trees for the winter. This is still done in parts of the Mediterranean.) A village of 30 people needed a herd of 40 cattle, 40 sheep or goats, 13 hectares of wheat or other grain, and about 5 square kilometers of forest for firewood, timber, and animal pasture. As in Medieval times, the cropland (hoeland, plowland: the plow was invented about 6500 years ago on the Sumerian plain) was probably communal and divided into two: one field was used for winter grain, the other rested, its stubble and weeds grazed by the domestic stock, which were also kept there at night. The fallow period allowed for the build-up of nutrients from bacteria, decayed plants, and animal manure.
A variation on this system in medieval and renaissance Europe was provided by the so-called transhumance pastoralists who took their flocks of sheep up into the mountain pastures of the Alps or Pyrenees during spring and summer, returning in fall and winter to the grain-growing lowlands: Spanish wheat growers paid for the privilege of having such flocks kept on their fields for a night or a week (as long as the stubble and the roadside grass would support the animals); manuring by the sheep is thought to have doubled wheat yields. While the manure produced by the flocks came from the immediate surroundings (the wasteland, steep banks, roadside ditches, and grain stubble), the animals themselves were at least partly supported by the mountain pastures and the landscapes in between. That is, their total biomass was much greater than the local landscape would have supported. Sheep are good at converting biomass to dung, producing 10 times their weight in dung annually. So this was a way of bringing the biological productivity of the mountains to the plains and making the mountains useful to people at lower elevations. (All the same, overgrazing during the medieval period by huge flocks of sheep in La Mancha and Estremadura—those impoverished lands that produced the American conquistadores—converted large parts of central Spain to poor quality grass and scrub; and the general decline in Mediterranean forests after the Middle Ages is thought to have been caused by overgrazing by sheep.) Whether such grain-growing systems were sustainable over the long run depended on the underlying fertility of the soil (a gift of nature) and the rate of erosion (a matter of climate, soils and management), but they supported (or helped support) many of the Mediterranean and Near Eastern high civilizations.
The organized settlement systems (an early state capitalism?) of the Greeks, with their colonies in Turkey, Sicily, Egypt, the Black Sea, the Mediterranean coast of France, provided surplus grain for mainland Greece. By 400 B.C. perhaps half the food eaten in Greek cities was imported. Were such colonies a sign of erosion in Greek agricultural soils? Many Greek sites show thousand year cycles of use and abandonment. Cycles of expansion and contraction of agriculture and population during the Neolithic and Bronze ages occurred throughout the Mediterranean basin and central and western Europe, especially on upland sites. As people filled the better soils of the river valleys and lower slopes, the population continued moving up to the poorer soils of the surrounding hills. Such settlement was followed by massive erosion (visible in cores from lakes or swamps), followed by the abandonment of land, depopulation, the regrowth of scrub or forest, until some centuries later, when the soils had rebuilt themselves, settlement began again. Many European and Mediterranean landscapes were thus deforested and cleared several times over 7000 years. Such cycles continued into the classical and medieval periods.
Greek colonies were followed by those of Rome, the citizens of whose capital were entitled to a daily ration of grain, and whose grain-shed included most of the Mediterranean basin. Egypt was called the granary of Rome; there were also the more or less new lands along the North African littoral, in Turkey, and in southern France. Under a law of 111 B.C., any Roman citizen could claim up to 20 acres of public land to cultivate; by bringing it under cultivation he established ownership. This was 10 times the size of the individual holdings Romulus passed out during the settlement of Rome 600 years before, an indication either that agriculture had become more commercial or soils had become less productive. In 750 BC a man with a hoe could cultivate two acres of olives, grapes, vegetables, cereals, and fodder crops. The multistory canopy saved labor, prevented erosion and took half the land to feed the same number of people as plowing with an ox; but for large landlords plowing with an ox was more profitable. At any rate cultivation in Italy expanded; the land near Rome, once full of orchards, became large grain-growing estates, and then, as the soil declined or eroded away, uncultivated wasteland. Wood use in Rome has been estimated at 1 to 1.5 cubic meters per person per year, in total about the wood in 30 square kilometers of forest. Is such a number high or low? Per capita wood use in North America before the Revolution was 17 cubic meters a year, about 4.5 full cords, that is 11 to 17 times as much. (Two hundred years later modern people in the northeastern United States use 4 to 5 cords per winter to heat their houses; less than 1 cord if their houses are super-insulated.) Deforestation for metal smelting, pottery-making, brick and lime burning, building material, for new agricultural land, for pastureland, meant the continuous exposure of bare and overgrazed soils to the elements; and led to slow, massive, cumulative soil erosion. Composting, crop rotation, and the use of manures in maintaining soil fertility were known to the Romans (and probably to earlier peoples: the slow charring of vegetation, along with composting, began producing black earth soils in the Amazon Basin 2500 years ago), but such practices were not widely followed, and soil exhaustion and erosion imposed long cycles of settlement, abandonment, and re-settlement on river valleys throughout the Mediterranean, and influenced the larger empires of which they were a part (thus, the colonies, the importation of grain). Many former Greek and Roman port cities now lie several kilometers from the ocean. Some of this erosion would have occurred without human intervention, as the Mediterranean climate became drier, and the landscape more susceptible to erosion from its intense rainstorms, but human manipulation of the landscape speeded things up. Some Mediterranean uplands have little soil left to erode. The vine and olive, with winter wheat on flat ground, the tree fruits that date from Roman times (many brought from Persia), and the sheep pastured on the aromatic but not very palatable herbs of the once forested mountains of Crete or Lebanon constitute the modern and beautiful Mediterranean landscape. Springs and streams dry up in summer; the total run-off from the landscape is greater. On hilly land near Rome, farmers plant hazelnuts by blasting small holes in the light volcanic rock, then plant the shrubs, and water them until they take or die. Those that die (perhaps half of the first planting) are replanted. No natural topsoil is left. Such persistance constitutes land rehabilitation: the re-creation of soil with dynamite, tree roots, tree litter, hope, and hard labor.
The agricultural remaking of Europe has left various signs, some of which we can read. Pollen cores from English ponds show pollen of oaks replaced by that of weeds, wheat, rye, hazel and birch. Hazel and birch are early successional species; hazel was often coppiced for fuelwood, that is, cut at short intervals from stands that sprout from stumps. Agriculture, by baring and stirring the soil, mobilizes the soil’s lead in airborn dust. Airborn lead from Roman silver smelting shows up in cores from the Greenland icecap. Cores from peat bogs in the Jura Mountains of France show variations in airborn lead in the surrounding landscape over the last several thousand years. An initial rise 8000 years ago corresponds with a volcanic eruption in France. Soon afterward Neolithic agricultural activity tripled the relatively constant, post-glacial background level. A further rise in lead 3000 years ago corresponds with smelting at Phoenician lead mines in Spain. There were rises corresponding with Roman and Greek metallurgical activity (a layer of lead from Roman silver smelting is found in lake muds all over Europe), a decline from those heights in the Middle Ages, and a rise with the Industrial Revolution that peaked in 1905, the rise in this case caused by coal burning as well as metal smelting. Total airborn lead peaked again in 1967, from lead in gasoline, on top of all the other sources, when it reached 85 parts per million. The post-glacial background concentration was 0.28 parts per million. So anthropogenic lead in the modern atmosphere is something like 250 to 300 times that of the hunting and gathering background, that to which one assumes modern people and animals are adapted.
The two-field system helped support Greece and Rome. The fields, fallow or cropland, were plowed in spring, summer and fall (they were planted in the fall). Together with Egypt’s Nile Valley, and some irrigated lands, the two-field system supported the Islamic civilizations of Turkey, the Middle East, and North Africa. (“Some irrigated lands” includes lands watered by qanats, underground tunnels that collect groundwater from mountain slopes. Qanats are found in the Middle East, Cyprus, Iran, Central Asia, and in parts of North Africa. Their design makes them self-regulating, though they must effect surface waters. Their flow in Iran in 1960, to provide urban water and to irrigate farmland, has been estimated at that of 12 Nile Rivers. For the most part qanats have been replaced by pumps, that is, water taken from deep wells and rivers, but the cities of Bam and Irbil still use water from qanats dug by the slaves of Sennacherib 2700 years ago.) The two-field system supported the civilization that followed Rome in Europe north of the Alps: its surpluses (wheat yielded only twice the seed sown) built Romanesque churches, fortified castles, early walled towns. About 800 A.D., when Charlemagne was crowned king of a united Europe in Aachen, a three-field system had come into use in some villages in northeastern France. The common ploughland was divided in three parts. One field was planted in autumn with a winter grain (wheat or rye); this is the traditional method of Mediterranean or Near-Eastern agriculture that had been brought to Europe several thousand years ago. Another field was planted in spring with a summer crop of oats, barley or peas (the last a nitrogen-fixing legume); this was new. The third section was left fallow. This system increased total crop yields, putting two-thirds of the plowland into crops yearly. It increased the land in crops by a sixth. It also increased crop variety, provided more fodder for the animals and spread work more evenly over the year. More fodder meant more manure and greater yields, a positive feedback. In later centuries a winter fodder crop, often turnips, would be planted for the animals.
The re-settlement of Europe that followed the crowning of Charlemagne was intended to remake the European landscape into a holy and cultivated earth. Charlemagne renamed the months (then, as now, named for Roman gods and goddesses) for their agricultural activities (the month to plow, the month to plant, the month to cut wood). Around 1000, the wheeled iron plow, pulled by a yoke of 8 oxen, came into common use. This implement, invented several centuries earlier, made possible the conversion of Europe’s heavier soils (the clays on which the oaks grew) to agriculture. The invention of the shoulder harness and the nailed horseshoe led to the growing use of the horse for traction power. Horses are several times more expensive to maintain than oxen and must be shod to protect their hooves from the northern European damp, but can exert more force and work faster for a longer time. Such developments in agriculture opened up new lands in Europe and by 1100 led to prosperity across the continent from the Atlantic to the Dnieper. The 1100s brought the first European manufacturing age, powered by wind and water mills. Europe had abundant resources of wood, flowing water and minerals. Water mills were used to mill grain, full cloth, process hemp, for tanning, laundering, milling logs, crushing and grinding ores, sieving, turning, polishing, stamping, for iron-making (operating bellows, puddling and beating iron, drawing wire). Watermills averaged one per 50 families in England.
So the Dark and Middle Ages that followed the death of Charlemagne were a time of boom: in population, in land clearance (sometimes of land abandoned after the collapse of Rome), iron manufacture, stock raising, the founding of new towns. Fields were 5% of Europe in the sixth century, 30-40% in the later Middle Ages. Religious orders established monasteries in the wilderness and granted colonists their forestland to clear and cultivate. Interested in increasing their income, the nobility also established colonizing settlements and began the reclamation of marshland and heath. Forest cover in Europe was reduced from 80% (95% originally) in 500AD to 50% or less in 1300. (Some writers claim only 20% of the forest was left by 1400, that in France perhaps 25% of the forest remained.) That forest was heavily exploited for fuel and timber. Land use had fallen to 2 hectares per capita from 16 to 20 in Neolithic times. The climate was also good. During the so-called Medieval Climate Optimum (from about 1000 A.D. to 1400 A.D.; some writers now put it a century earlier) temperatures in Europe were about 1º C. warmer. This lengthened the growing season by a month. The climate change was worldwide. The warm period in Europe coincided with a warm period in the Arctic (southwestern Greenland was settled by the Norse and grain was grown in Iceland), while most of the earth was slightly cooler and civilizations in Central America, the Andes, and the American Southwest collapsed from droughts.
Population in Europe doubled from 1000 to 1220, from 38.5 million to 75.5 million; from a base of 18 million in 600. New land was gone by 1300, and the population was reaching the limits of its renewable resources. Overall yields fell as more and more marginal lands were brought into cultivation; wages fell. By 1300 Europe’s expanding population had overwhelmed its productive capacities. Trade was still a small part of the economy, which was largely agricultural. Roads were poor and travel unsafe. Religious views discouraged much economic activity (for instance, lending money at interest—usury—was a sin). Land in the medieval economy was held by right of occupation and was difficult to sell. Labor could be hired but was governed by a customary web of rights and obligations. Many of the so-called prerequisites for economic growth did not exist. These include secure property rights, the rule of law, more or less working markets, some social mobility, a desire by the individual for financial improvement. The Hundred Year’s War, a general European war, began in 1337. Catastrophe arrived 11 years later as a plague. The plague turned out to be a blessing in disguise.
Europe in 1300 still depended on renewable resources. The primary limit was food. Production per acre would rise 2.5 times during the succeeding centuries, with better forage crops and legumes, animal breeding (which produced more milk or flesh from the same amount of feed), more complex rotations, new crops and animals from Asia, Africa, India and the Americas; but yields never kept up with population, and periodic starvation in Europe continued until the Industrial Revolution. Death from famine and cold were common in Europe in the 1700s. Many episodes of starvation were local, a matter of food distribution rather than absolute shortage (as is still the case in Africa now). The last famine in Europe caused by an absolute shortage of food was in the early 1800s, when the eruption of Krakakoa in Indonesia injected enough dust into the stratosphere to cause two years of climate cooling worldwide. In New England in the year following the eruption, frost occurred in every month. The Irish potato famine, which followed this, was not caused by an absolute shortage of food (Ireland exported food throughout the famine), but by the failure of the British government to distribute food to a starving population. The Irish famine was an unexpected problem of industrialization: that of the introduction of new organisms to new environments. The blight that destroyed the potato crop was brought to Belgium on American seed potatoes imported by steam ship. The rapidity of the trip across the Atlantic allowed the fungus to arrive on the potatoes alive, and the damp summer that followed allowed it to spread all over northern Europe.
Another renewable limit was fuel. Until the 1700s (earlier in England) wood was the primary fuel used for industries and crafts, as well as for cooking and heating. Brick burning, glassmaking, iron smelting, salt evaporation, lime burning, sugar refining, soap making, brewing all required fuel. Heating and cooking probably required the most. Shortages made wood expensive; in 1600 the average city dweller in France spent 10% of his income to keep a fire burning in one room for part of the day. In general, from 1500 to 1700, 7.5% of an ordinary budget went for light and heat. (More efficient brick or stone heating stoves in central and northeastern Europe made it more comfortable in 1700 to winter in Warsaw than Toulouse.) Timber was necessary for buildings, tools, ships and furniture. Hazel and oak, species that sprout well from stumps, were cut on short-term rotations to provide fuel and also materials like tanbark. Some oak stems (the standards) were allowed to mature for timber. But supplies were limited to what forest growth provided. In the European wars of the eighteenth century, English blast furnaces, needed to forge cannon shot, could only operate intermittently; when they ran out of charcoal, they had to shut down. (Eight tons of wood made two tons of charcoal, which would smelt just under a ton of pig iron.) Similar shortages occurred all over Europe. Since iron making depended on a renewable resource, production of iron had to remain at or below what the wood supply could handle. If production were increased to meet an increase in demand, the supply of wood in the future would be reduced. Future production of iron would have to be lowered, or stopped altogether. Everything depended on the growth of the trees, which put an inexorable limit on production. Where available, coal could be used for cooking, heating, and processes such as brewing that simply required a source of heat. Coal was commonly used for such purposes in England, where wood shortages developed early and coal was abundant. Coal had largely replaced wood for household heating and cooking in England by 1700. The adaptation of essentially unlimited European coal supplies to iron smelting was a fundamental factor in the rise of the Industrial Revolution.
There were other problems related to an overexploitation of a renewable environment. One of the more serious was soil erosion. This reduced soil fertility (nutrients were lost with the soil and the depth of topsoil was also reduced); caused the siltation of streams, which increased flooding; and ruined freshwater fisheries. (The gravels in which the fish laid their eggs silted over. Mill dams also destroyed fisheries. Riverine fisheries were failing in Europe by 1000 and were replaced by the cultivation of fish in ponds — many fishponds in the 1100s and 1200s were the dammed sections of rivers and streams, but with different species of fish.) Eroded soil also filled waterways and harbors. Harborworks of cities in the Rhine delta suffered. Bruges in present-day Belgium, the commercial center of northern Europe in the 1300s, watched its harbor on the Zwin disappear, silted past the ability of the city to clear it. Rivers were also polluted by metal works, dye works, tanneries and sewage. Wells were polluted with seepage from cesspits and from rotting bodies in churchyards. The smell of cellars about the cemetery of Les Innocents in Paris was notorious.
Overfishing followed population growth, as marine fish began to replace freshwater fish in the European diet; the trawl was invented in the 1300s, with disastrous effects on fish stocks and the life of the seafloor. With the trawl, cod off the English coast became so easy to catch that the surplus was fed to pigs. Diking to reclaim land in the Rhine Delta caused major losses in sturgeon, once a key item in the European diet, by destroying its spawning habitat. By 1500 stocks of herring in the Baltic and of cod in the seas about Europe were failing. (Except for the Danish herring fishery, which collapsed with finality in the 1300s, the cod and herring fisheries would recover to fail again.) The Baltic and North Sea herring fisheries originally amounted to billions of fish annually. Fish was one of the sources of wealth of the cities of the Hanseatic League. (Even in the late 1600s, work in the herring fishery constituted 20% of the Dutch economy.) In the late 1400s fishermen from Bristol sailing west of Iceland discovered the Newfoundland cod fisheries. Did they stop to take on some of the Norse colonists in southern Greenland, whose culture was failing? By 1600, 20,000 European fishermen were salting and drying cod off Newfoundland. Dried cod from the North American banks would provide a cheap source of protein for Europe for 500 years.
Until the Industrial Revolution, the European world was Malthusian. That is, its population tended to increase faster than its food supply. In a downward spiral, more people meant more demand for grain, less crop rotation, less fodder for the animals, not enough manure to raise grain yields, the animals dying from parasites and malnutrition in late winter and spring. People died from hunger and exposure. Infant mortality was 25-30% until the late eighteenth century, life expectancy was 30 to 40 years, epidemics were common, most of the population was undernourished and depended on vegetable foods (bread, gruel, potatoes). Much of the population was very poor. At the time of the French Revolution, 80% of the population of France is thought to have been poor or destitute; that is, they owned the clothes on their backs. Many were more or less homeless, not being able to afford both food and lodging. In Medieval and Early Modern Europe four-fifths of disposable income went for food. The nobles and the members of the middle-class ate well. These distinctions lasted in England long into the period of industrialization: in 1800, boys taken into the Royal Navy from the slums of London or Liverpool were 8 inches shorter than boys from the upper classes; in 1940, working class draftees were still 4 inches shorter than boys who had gone to elite schools. So one could recognize an officer by his stature. Until about 1700, periods of growth in the standard of living of the common people were followed by periods of reversal (the long waves in the economy were cyclical), so the standard of living of an agricultural worker in Europe in 1500 or 1600 was only slightly higher than in Roman times. When Europeans came to North America, where food was plentiful, their numbers, instead of doubling every 150 years, began to double every 23 years. (Most of the first-born children in Puritan families were illegitimate.)
This is not a portrait that leads to a progressive view of history (constant progess onward and upward). That view would come out of the cascading improvements in material life with the Industrial Revolution (railroads, steam power, gas lights) and their consolidation and elaboration in the twentieth century (electricity, cars, radio, penicillin, TV). In the United States, more egalitarian and less bound by social traditions than Europe, especially after the Civil War, markets expanded with the population and economic productivity grew at 2% a year from 1870 to 1970. (In general, a more widespread prosperity increases the rate of economic growth.) But it is also not the whole picture. From 1200 to 1800, during a period of worsening climate, agricultural yields in Europe rose 2.5 times, while population rose 10 times. Land under cultivation increased several fold. During the so-called Little Ice Age, from 1430 until 1850, the climate was 1º - 2º C. lower than during the Medieval Optimum. A severe famine from 1315 to 1322 may have set the stage for the Black Death of the 1340s and 1350s (fetal malnutrition interferes with the development of the immune system) and killed outright perhaps 10-15% of the population. The Black Death killed a third to a half of the population. Recurrent epidemics followed for the next century and there was another famine in the 1430s. For the most part crops near their natural temperature limits (at high altitudes or latitudes) failed. During the Little Ice Age cereals could no longer be grown on the hills of northern and western Britain, glaciers and the tree line descended in the Alps, and the northern limits of vinyards in France and Germany retreated 300 kilometers south. Yields of grain on newly cleared land during the warm summers of the Optimum had been twice those of late Roman times but inevitably fell as soils eroded and fell further as the weather worsened. Most of the cooling took place in winter (this was a time of ice-skating and ice festivals) but summers were also 0.8º C. cooler.
After the calamitous 1300s, with disease, famine and continual low level war, came a period of recovery. Europeans rebuilt their water mills for water-powered industry. Tenants gained heritable rights to their land in return for rents. Some common lands began to be enclosed to create rentable tracts. (In the late 1500s, it was said a living was three acres and a cow. People were still saying that in upstate New York in 1850.) Towns, supported by agricultural surpluses, grew into small industrial centers. Industry in late medieval Europe was for the most part cloth, of wool or linen, woven on hand looms at home. By establishing chartered political units, surrounding themselves with walls, and mobilising their citizens into a defensive force, towns established a degree of political independence, both from the church (many towns were founded as the seats of bishops) and from the countryside and the nobility that ruled it. Intellectual life bloomed as paper replaced skin parchment in books (paper was 13 times cheaper than parchment at the time) and printing (also much cheaper) replaced hand copying. Books became more affordable; before the printing press, a professional man’s annual salary bought two cows or four books (and nothing else). After the printing press, a middle class person could afford a couple of books a year. As land became more valuable, property rights became more exclusive, and began to extinguish the traditional rights of the nobility, such as that to ride or hunt where they pleased, and those of the peasantry, which included the right to common grazing land and to fuelwood gathered from the forest. Trade spread once again (memories lingered of the fairs of the 1300s), its bankers and merchants operating under the protection of the towns. Some of this trade was for commodities like Baltic timber and grain and some for luxury products like the silks and spices of Asia, to which the caravan routes, closed for some centuries by drought and the expansion of Islam, were once more open. Imitating the nobility, families of the middle class tried to keep their wealth through such devices as late marriage (thus limiting their fertility); by advantageous marriages between families; or by restricting inheritance to first-born sons. A writer has said that among the wealthy, population control was positive, while among the poor, population was controlled by starvation. In Paris at the time of the Revolution one-quarter of all children are thought to have been abandoned for adoption. Such infants were taken in by church orphanages, where the great majority of them died.
The medieval boom had ended with the famine of 1315 to 1322. Every season of 1315 was wet. Crop yields were half of normal. Hay was put up wet and rotted in the barns. During the winter and spring of 1316 people ate their seed grain. The year 1316 continued wet with another crop failure. The price of wheat tripled, when it could be bought. The famine continued until 1322. Twenty-five years later, after several warm, wet springs favorable to the spread of plague among the rodents of Central Asia, the Black Death arrived with people on ships from trading posts on the Black Sea fleeing the Mongol invasion and killed a third or more of the population of Europe. Parts of Europe would not see the population reached during the Climate Optimum for another 450 years. But the decline in population was followed by a period of development and prosperity: the Renaissance. The average age of death for adults was still something like 35. Still hemmed in by the Islamic world, Europe began probing its limits. Genoese bankers (who had financed the trading cities on the Black Sea) now financed Portuguese explorations around Africa to the Spice Islands of the East and out into the Atlantic, where large semi-tropical islands were discovered. New crops had been appearing in Europe thanks to trade with Asia and contact with the Moors in Spain; these included rice and sugar cane and the new livestock of silkworms. After 1492 came American crops. The yields of Mexican corn and Andean potatoes would dwarf those of European grains. A writer has speculated that the introduction of maize, peanuts and manioc from the Americas to Africa, which substantially increased the human population there, made the trans-Atlantic slave trade possible. New diseases (such as yellow fever) came with trade and with the Africans to Europe and the New World.
The high point of European row-crop agriculture was reached in England in the eighteenth and nineteenth centuries. The development of rotations between cereals and crops of legume hays (which raised the yield of grain per acre), the raising of animals on legume hays (which increased the numbers of animals that could be kept), and the use of animal manures on the fields (which further raised the yields of grain), together with plant and animal breeding that resulted in higher yielding varieties of plants and animals (more meat, wool, or grain for the same nutritional input) — all raised European upland agriculture toward the heights of successful overflow agriculture (such as in the Nile Delta), the ditched fields of Tiahuanaco, or paddy rice. That is, it became a high-yielding, self-sustaining agricultural system, less dependent on inputs from the wasteland, capable of supporting many more people per acre. Enclosure laws in England, enacted partly to ensure an adequate supply of manure for cropland (the relation of pastureland to cropland is important in manure-dependent cropping systems), better equipment, and better capitalized farms put many agricultural laborers and small tenant farmers out of work; some went to poorhouses, some to Australia or the Americas, some to work in the shops of the Industrial Revolution. Agricultural prosperity showed in that in the 1800s horses replaced oxen in Europe as the main source of agricultural power. (Horses are able to work faster for a longer time but are several times more expensive to maintain.) Environmentally speaking, such mixed agricultures were a high point of upland agriculture; they were sustainable as long as they occupied a more or less limited place in the larger ecosystem. Similar agricultures flourished briefly on the American prairies, and in the German settlements of the Shenandoah Valley of Pennsylvania and Virginia. One finds them still among the American Amish.
What ended the European dependence on the renewable world was the use of fossil fuels. England was the European nation most short of wood. It was largely deforested, probably not for the first time, when the Domesday Book was compiled in 1089 AD. (For instance, deforestation of the English downlands had begun in Neolithic times 5500 years before and had continued through the Roman invasion of AD 43. Deforestation, erosion and grazing converted the original downland woodland of oak, alder, willow, hazel, birch and rowan into the thin-soiled grasslands of today.) England was also the country most in need of wood for its imperial ambitions and it was here the Industrial Revolution began. (While some developments came from the continent, the English most thoroughly exploited their economic possibilities, probably thanks to their better developed markets.) A writer has summarized the reasons for the development of the Industrial Revolution in Britain: the greater size and efficiency of British markets (many of the export markets created and maintained by Britain’s sea power); Britain’s commercially minded society; Britain’s openness to innovation; and its accumulation of natural resources from around the globe (also a function of its sea power). In the late eighteenth century machines were developed that, powered by water, would spin cotton thread; other machines wove the thread into cloth. The mechanical advantage of the machinery was so great, the multiplication of the value of the labor and investment so enormous, that the major limits on cloth manufacture became the availability of waterpower, of raw cotton, and of the ability to market the cloth. The manufacturing process was so cheap, compared to hand spinning and weaving, that the manufacturers were able to lower the price until demand met supply. Once cloth fell within reach of the poor, an enormous market was created and demand exploded. Profits were still enormous. The invention of the cotton gin, which mechanically cleaned cotton (previously slaves had picked out the seeds by hand) had a similar advantage: one didn’t just double or triple the value of labor, one increased it by orders of magnitude, powers of ten. During the 1780s, as the English were losing their American colonies, industrial growth in England rose from 1% to 4% a year. It remained near 4% (some writers claim 2%) for a century.
It was the use of fossil fuels to smelt iron ore and power steam engines that finally changed everything. In England in the late eighteenth century processed coal (coke), rather than wood, was first used successfully to smelt iron ore. Unprocessed coal had too many impurities compared with charcoal and the iron smelted with it was too brittle. The coke-making process eliminated these. Coke was much cheaper than charcoal. And coal to make it was available for the mining, as was iron ore. Coal fired the steam engines, made of coke-smelted iron, that pumped the water from English mines and let the miners produce more coal. Coal-powered locomotives, built of iron and running on iron rails, hauled coal and iron ore to where they were needed. Coal-powered spinning machines took over from water-powered ones, removing another constraint from the manufacture of cotton. Coal was later joined by oil and natural gas, useful because they were fluids rather than solids, and so flow under gravity or pressure. Such fossil fuels became unlimited sources of energy in an otherwise renewable and limited world. Fossil fuels will likely remain available for a long time. (For coal the current guess is another 200 to 400 years.)
Coal-powered steam engines eliminated the limits set by floods or frozen waterways in water transportation, by replacing canal and river traffic with rail. In the 1860s coal-powered steamships, built of coal-tempered steel, carried three times the cargo twice as fast as sail. With transportation faster and cheaper, Europe reached out to the rest of the world for its resources. From 1860 to 1920 one billion acres of new land was converted to agriculture, 40% in the United States (much of it in the Corn Belt), 20% in the Russian Black Earths, 20% in Asia. Grain was imported from the “new lands” in the Ukraine, North and South America, and Australia. (Land clearing would continue, with another billion acres added to agricultural lands from 1920 to 1980, mostly in Latin America.) Refrigeration and pasteurization of milk made milk more saleable and its production rose enormously, with beneficial effects on the European diet. Milk now constitutes 20% of the value of agricultural production in Europe and the United States. Imported fertilisers such as rock phosphate and Peruvian guano increased the fertility of European soils. But it was primarily cheap imported food, its cheapness made possible by the exploitation of fossil fuels, that ended starvation in Europe. The pre-industrial European diet in 1800 was worse than that of the European hunter-gatherers of 12,000 years before. The diet worsened further during the early years of industrialization (the average height of men in both America and Europe fell in the 1830s) but improved after about three generations of industrialization. (By the 1920s the shortfall in height was gone.) By 1900 England was importing 80% of its grain, 75% of its dairy products, and 50% of its meat.
Coal also made the chemical industry possible. Coal provided the energy to run the reactions; while coal, oil and natural gas replaced wood as a feedstock. The Haber process, which synthesizes ammonia from atmospheric nitrogen, led to the manufacture of synthetic nitrogen fertiliser, which further increased the yield of soils. Artificial fertilisers and further developments in crops and animals would make Europe nearly self-sufficient in food by the mid-twentieth century. However the excess nitrogen used on crops would cause tremendous pollution problems. Anthropogenic nitrogen lies behind the biological degradation of marine estuaries and (along with phosphorus) of fresh waters. Nitrate pollution in the Thames and Rhine are now two orders of magnitude (100 times) above the mean values of unpolluted streams. (Not all of this is due to agriculture; some nitrogen and phosphorus come from sewage effluent and some nitrogen from the combustion of fossil fuels.)
By the end of the nineteenth century coal was being used to generate electricity. By two decades into the twentieth century coal and oil had produced the modern world, where the problem is not that of producing enough, but of creating demand for all that can be produced. Through gaslight and electricity, fossil fuels had eliminated night. They ameliorated the seasons through heating in cold climates, cooling in hot ones. Fast, cheap transportation eliminated the agricultural seasons, so that now any modern expects fresh fish, fresh lettuce and fresh grapes to be available anytime, whenever he or she wants them. The human habitat in developed countries, even in rural areas, is almost entirely a built one, of roads, telephones, powerlines, fields, houses, internet communication. The cost of food has kept falling until it is now less than 10% of income in developed countries. Such development comes at a cost. In 1850 every Englishman used the equivalent of 1.7 tons of coal a year; this rose to 4 tons by 1919, where it remained until 1950, despite considerable economic growth, when the number began rising once again. Such energy use brings us other problems. But the notion of man’s independence from nature and its constraints is a hallmark of the modern.
Using the natural production of the forest or waste to increase the fertility of cropland is a common strategy of folk agricultures. It usually depends on domestic animals that eat leaves or grass from the surrounding uncultivated land and whose manure is then used on the fields. In a modern African variant of this system, branches from leguminous trees, grown in hedgerows between the fields, are directly used to mulch, and thus also to fertilize, crops; no animals are involved. The rapid decay rates of the tropics make this system possible.
Overexploitation of systems that depend on the surrounding forest or wasteland for a portion of their fertility is easy. While usually caused by over-population, over-exploitation can also be caused by an increase in market demand for timber, grain or fuel. An example is trekkers seeking food and shelter in Nepal. Villagers build small hotels of native lumber to take them in. They also grow more food to feed them, and more fuel to warm them, thus increasing their income at the cost of over-cutting the forest for timber, fuel and fodder. This increases erosion and the risk of landslides in steep areas. (Much of upland Nepal is steep, its slopes held in place by shrubs and trees; under traditional management, firewood was taken from dead vegetation.) The rise in the number of ski areas in Swiss mountain valleys is a more high-tech example of market-based over-exploitation of steep forestlands (which 250 years ago in the French Alps were cleared for farmland, with catastrophic erosion); now not for food or fuel but (similarly to the Nepalese) for business income. In such cases the demand for wealth magnifies the effect of population.
In the grain-and-cow culture of the Near-Eastern agriculturists who settled Europe 7000 years ago, using products of the wasteland to fertilize fields already had a long history. Fertility of upland fields is maintained on the one hand by in-situ weathering. This is the release of mineral elements from the soil by bacterial and fungal action and the erosive effect of natural rainfall, which is slightly acidic (root secretions make it more so and increase the release of minerals). Fields have much simpler plant, animal, fungal and microbial populations than forests or grasslands, and lack their nutrient cycling ability. Leaving them bare for much of the year exposes them to extensive leaching and erosion. They also have less sophisticated systems for releasing nutrients from soils. Cereal crops use nutrients equivalent to the forests or grasslands they replace, but much of their growth, along with the nutrients, is removed in the annual harvest. Nitrogen in fields is provided by free-living nitrogen-fixing bacteria in the soil, and those living in nodules on the roots of leguminous plants. The annual pulse of nitrogen may be greater in fields than in grasslands or forest, because of the warmer temperatures of the cleared ground. A good part of this nitrogen is leached out by rainfall, even from hayfields, that is, cultivated grassland. The problem is that in such simple systems, the bacterial activity that releases nutrients, and nutrient uptake by the plants, do not always coincide; then nutrients escape. For instance, bacteria may mobilize nutrients before crop plants have been seeded in the spring, or after they are done growing (or have been plowed under) in the fall. The fertility of fields depends on the balance among what is removed—by crops, by leaching, by soil erosion—and on what nutrients are produced within the field or added to it. If the soil is inherently fertile, and soil erosion is not too great, the crops not too demanding, and leaching of nutrients by rainfall remains within bounds, a field will retain a low level of fertility indefinitely. (Temperate loess soils are good here.) But the steady fall in fertility after the clearing of the natural vegetation is the reason for rotating fields back into forest. The earliest agriculturalists in Europe cultivated river floodplains with hoes (such soils were good to begin with and are renewed by floods and by soil washing down from the hillsides), but the slash-and-burn agriculturalists of upland Europe apparently moved on, with their cattle and stores of grain, when the fertility of their fields fell. Denser populations require permanent fields, however, and with the manure from domestic animals the fertility of fields can be maintained. Animals are pastured in the woods and kept nights on the fallow; fed cut branches, hay, and grain straw; and put to graze on grain stubble (where they also deposit their urine and manure). The biological productivity of uncultivated lands is a major support of such continuous grain-growing systems.
The introduction of cattle was a tremendous innovation in Neolithic agriculture. Milk provides 4 to 5 times the protein and energy for the same amount of feed as meat; cattle provide traction power; and manure for grain crops. The development of lactose tolerance in adults (the ability to digest milk usually disappears after childhood in humans) is thought to have increased the number of a person’s descendants several times (perhaps 10). In Neolithic Europe each person needed 20 hectares (48 acres) for cropland, fallowland, pasture, hay meadows, firewood, building material, and forest browse. (Branches were lopped and brought to the animals, sometimes stored in piles by the trees for the winter. This is still done in parts of the Mediterranean.) A village of 30 people needed a herd of 40 cattle, 40 sheep or goats, 13 hectares of wheat or other grain, and about 5 square kilometers of forest for firewood, timber, and animal pasture. As in Medieval times, the cropland (hoeland, plowland: the plow was invented about 6500 years ago on the Sumerian plain) was probably communal and divided into two: one field was used for winter grain, the other rested, its stubble and weeds grazed by the domestic stock, which were also kept there at night. The fallow period allowed for the build-up of nutrients from bacteria, decayed plants, and animal manure.
A variation on this system in medieval and renaissance Europe was provided by the so-called transhumance pastoralists who took their flocks of sheep up into the mountain pastures of the Alps or Pyrenees during spring and summer, returning in fall and winter to the grain-growing lowlands: Spanish wheat growers paid for the privilege of having such flocks kept on their fields for a night or a week (as long as the stubble and the roadside grass would support the animals); manuring by the sheep is thought to have doubled wheat yields. While the manure produced by the flocks came from the immediate surroundings (the wasteland, steep banks, roadside ditches, and grain stubble), the animals themselves were at least partly supported by the mountain pastures and the landscapes in between. That is, their total biomass was much greater than the local landscape would have supported. Sheep are good at converting biomass to dung, producing 10 times their weight in dung annually. So this was a way of bringing the biological productivity of the mountains to the plains and making the mountains useful to people at lower elevations. (All the same, overgrazing during the medieval period by huge flocks of sheep in La Mancha and Estremadura—those impoverished lands that produced the American conquistadores—converted large parts of central Spain to poor quality grass and scrub; and the general decline in Mediterranean forests after the Middle Ages is thought to have been caused by overgrazing by sheep.) Whether such grain-growing systems were sustainable over the long run depended on the underlying fertility of the soil (a gift of nature) and the rate of erosion (a matter of climate, soils and management), but they supported (or helped support) many of the Mediterranean and Near Eastern high civilizations.
The organized settlement systems (an early state capitalism?) of the Greeks, with their colonies in Turkey, Sicily, Egypt, the Black Sea, the Mediterranean coast of France, provided surplus grain for mainland Greece. By 400 B.C. perhaps half the food eaten in Greek cities was imported. Were such colonies a sign of erosion in Greek agricultural soils? Many Greek sites show thousand year cycles of use and abandonment. Cycles of expansion and contraction of agriculture and population during the Neolithic and Bronze ages occurred throughout the Mediterranean basin and central and western Europe, especially on upland sites. As people filled the better soils of the river valleys and lower slopes, the population continued moving up to the poorer soils of the surrounding hills. Such settlement was followed by massive erosion (visible in cores from lakes or swamps), followed by the abandonment of land, depopulation, the regrowth of scrub or forest, until some centuries later, when the soils had rebuilt themselves, settlement began again. Many European and Mediterranean landscapes were thus deforested and cleared several times over 7000 years. Such cycles continued into the classical and medieval periods.
Greek colonies were followed by those of Rome, the citizens of whose capital were entitled to a daily ration of grain, and whose grain-shed included most of the Mediterranean basin. Egypt was called the granary of Rome; there were also the more or less new lands along the North African littoral, in Turkey, and in southern France. Under a law of 111 B.C., any Roman citizen could claim up to 20 acres of public land to cultivate; by bringing it under cultivation he established ownership. This was 10 times the size of the individual holdings Romulus passed out during the settlement of Rome 600 years before, an indication either that agriculture had become more commercial or soils had become less productive. In 750 BC a man with a hoe could cultivate two acres of olives, grapes, vegetables, cereals, and fodder crops. The multistory canopy saved labor, prevented erosion and took half the land to feed the same number of people as plowing with an ox; but for large landlords plowing with an ox was more profitable. At any rate cultivation in Italy expanded; the land near Rome, once full of orchards, became large grain-growing estates, and then, as the soil declined or eroded away, uncultivated wasteland. Wood use in Rome has been estimated at 1 to 1.5 cubic meters per person per year, in total about the wood in 30 square kilometers of forest. Is such a number high or low? Per capita wood use in North America before the Revolution was 17 cubic meters a year, about 4.5 full cords, that is 11 to 17 times as much. (Two hundred years later modern people in the northeastern United States use 4 to 5 cords per winter to heat their houses; less than 1 cord if their houses are super-insulated.) Deforestation for metal smelting, pottery-making, brick and lime burning, building material, for new agricultural land, for pastureland, meant the continuous exposure of bare and overgrazed soils to the elements; and led to slow, massive, cumulative soil erosion. Composting, crop rotation, and the use of manures in maintaining soil fertility were known to the Romans (and probably to earlier peoples: the slow charring of vegetation, along with composting, began producing black earth soils in the Amazon Basin 2500 years ago), but such practices were not widely followed, and soil exhaustion and erosion imposed long cycles of settlement, abandonment, and re-settlement on river valleys throughout the Mediterranean, and influenced the larger empires of which they were a part (thus, the colonies, the importation of grain). Many former Greek and Roman port cities now lie several kilometers from the ocean. Some of this erosion would have occurred without human intervention, as the Mediterranean climate became drier, and the landscape more susceptible to erosion from its intense rainstorms, but human manipulation of the landscape speeded things up. Some Mediterranean uplands have little soil left to erode. The vine and olive, with winter wheat on flat ground, the tree fruits that date from Roman times (many brought from Persia), and the sheep pastured on the aromatic but not very palatable herbs of the once forested mountains of Crete or Lebanon constitute the modern and beautiful Mediterranean landscape. Springs and streams dry up in summer; the total run-off from the landscape is greater. On hilly land near Rome, farmers plant hazelnuts by blasting small holes in the light volcanic rock, then plant the shrubs, and water them until they take or die. Those that die (perhaps half of the first planting) are replanted. No natural topsoil is left. Such persistance constitutes land rehabilitation: the re-creation of soil with dynamite, tree roots, tree litter, hope, and hard labor.
The agricultural remaking of Europe has left various signs, some of which we can read. Pollen cores from English ponds show pollen of oaks replaced by that of weeds, wheat, rye, hazel and birch. Hazel and birch are early successional species; hazel was often coppiced for fuelwood, that is, cut at short intervals from stands that sprout from stumps. Agriculture, by baring and stirring the soil, mobilizes the soil’s lead in airborn dust. Airborn lead from Roman silver smelting shows up in cores from the Greenland icecap. Cores from peat bogs in the Jura Mountains of France show variations in airborn lead in the surrounding landscape over the last several thousand years. An initial rise 8000 years ago corresponds with a volcanic eruption in France. Soon afterward Neolithic agricultural activity tripled the relatively constant, post-glacial background level. A further rise in lead 3000 years ago corresponds with smelting at Phoenician lead mines in Spain. There were rises corresponding with Roman and Greek metallurgical activity (a layer of lead from Roman silver smelting is found in lake muds all over Europe), a decline from those heights in the Middle Ages, and a rise with the Industrial Revolution that peaked in 1905, the rise in this case caused by coal burning as well as metal smelting. Total airborn lead peaked again in 1967, from lead in gasoline, on top of all the other sources, when it reached 85 parts per million. The post-glacial background concentration was 0.28 parts per million. So anthropogenic lead in the modern atmosphere is something like 250 to 300 times that of the hunting and gathering background, that to which one assumes modern people and animals are adapted.
The two-field system helped support Greece and Rome. The fields, fallow or cropland, were plowed in spring, summer and fall (they were planted in the fall). Together with Egypt’s Nile Valley, and some irrigated lands, the two-field system supported the Islamic civilizations of Turkey, the Middle East, and North Africa. (“Some irrigated lands” includes lands watered by qanats, underground tunnels that collect groundwater from mountain slopes. Qanats are found in the Middle East, Cyprus, Iran, Central Asia, and in parts of North Africa. Their design makes them self-regulating, though they must effect surface waters. Their flow in Iran in 1960, to provide urban water and to irrigate farmland, has been estimated at that of 12 Nile Rivers. For the most part qanats have been replaced by pumps, that is, water taken from deep wells and rivers, but the cities of Bam and Irbil still use water from qanats dug by the slaves of Sennacherib 2700 years ago.) The two-field system supported the civilization that followed Rome in Europe north of the Alps: its surpluses (wheat yielded only twice the seed sown) built Romanesque churches, fortified castles, early walled towns. About 800 A.D., when Charlemagne was crowned king of a united Europe in Aachen, a three-field system had come into use in some villages in northeastern France. The common ploughland was divided in three parts. One field was planted in autumn with a winter grain (wheat or rye); this is the traditional method of Mediterranean or Near-Eastern agriculture that had been brought to Europe several thousand years ago. Another field was planted in spring with a summer crop of oats, barley or peas (the last a nitrogen-fixing legume); this was new. The third section was left fallow. This system increased total crop yields, putting two-thirds of the plowland into crops yearly. It increased the land in crops by a sixth. It also increased crop variety, provided more fodder for the animals and spread work more evenly over the year. More fodder meant more manure and greater yields, a positive feedback. In later centuries a winter fodder crop, often turnips, would be planted for the animals.
The re-settlement of Europe that followed the crowning of Charlemagne was intended to remake the European landscape into a holy and cultivated earth. Charlemagne renamed the months (then, as now, named for Roman gods and goddesses) for their agricultural activities (the month to plow, the month to plant, the month to cut wood). Around 1000, the wheeled iron plow, pulled by a yoke of 8 oxen, came into common use. This implement, invented several centuries earlier, made possible the conversion of Europe’s heavier soils (the clays on which the oaks grew) to agriculture. The invention of the shoulder harness and the nailed horseshoe led to the growing use of the horse for traction power. Horses are several times more expensive to maintain than oxen and must be shod to protect their hooves from the northern European damp, but can exert more force and work faster for a longer time. Such developments in agriculture opened up new lands in Europe and by 1100 led to prosperity across the continent from the Atlantic to the Dnieper. The 1100s brought the first European manufacturing age, powered by wind and water mills. Europe had abundant resources of wood, flowing water and minerals. Water mills were used to mill grain, full cloth, process hemp, for tanning, laundering, milling logs, crushing and grinding ores, sieving, turning, polishing, stamping, for iron-making (operating bellows, puddling and beating iron, drawing wire). Watermills averaged one per 50 families in England.
So the Dark and Middle Ages that followed the death of Charlemagne were a time of boom: in population, in land clearance (sometimes of land abandoned after the collapse of Rome), iron manufacture, stock raising, the founding of new towns. Fields were 5% of Europe in the sixth century, 30-40% in the later Middle Ages. Religious orders established monasteries in the wilderness and granted colonists their forestland to clear and cultivate. Interested in increasing their income, the nobility also established colonizing settlements and began the reclamation of marshland and heath. Forest cover in Europe was reduced from 80% (95% originally) in 500AD to 50% or less in 1300. (Some writers claim only 20% of the forest was left by 1400, that in France perhaps 25% of the forest remained.) That forest was heavily exploited for fuel and timber. Land use had fallen to 2 hectares per capita from 16 to 20 in Neolithic times. The climate was also good. During the so-called Medieval Climate Optimum (from about 1000 A.D. to 1400 A.D.; some writers now put it a century earlier) temperatures in Europe were about 1º C. warmer. This lengthened the growing season by a month. The climate change was worldwide. The warm period in Europe coincided with a warm period in the Arctic (southwestern Greenland was settled by the Norse and grain was grown in Iceland), while most of the earth was slightly cooler and civilizations in Central America, the Andes, and the American Southwest collapsed from droughts.
Population in Europe doubled from 1000 to 1220, from 38.5 million to 75.5 million; from a base of 18 million in 600. New land was gone by 1300, and the population was reaching the limits of its renewable resources. Overall yields fell as more and more marginal lands were brought into cultivation; wages fell. By 1300 Europe’s expanding population had overwhelmed its productive capacities. Trade was still a small part of the economy, which was largely agricultural. Roads were poor and travel unsafe. Religious views discouraged much economic activity (for instance, lending money at interest—usury—was a sin). Land in the medieval economy was held by right of occupation and was difficult to sell. Labor could be hired but was governed by a customary web of rights and obligations. Many of the so-called prerequisites for economic growth did not exist. These include secure property rights, the rule of law, more or less working markets, some social mobility, a desire by the individual for financial improvement. The Hundred Year’s War, a general European war, began in 1337. Catastrophe arrived 11 years later as a plague. The plague turned out to be a blessing in disguise.
Europe in 1300 still depended on renewable resources. The primary limit was food. Production per acre would rise 2.5 times during the succeeding centuries, with better forage crops and legumes, animal breeding (which produced more milk or flesh from the same amount of feed), more complex rotations, new crops and animals from Asia, Africa, India and the Americas; but yields never kept up with population, and periodic starvation in Europe continued until the Industrial Revolution. Death from famine and cold were common in Europe in the 1700s. Many episodes of starvation were local, a matter of food distribution rather than absolute shortage (as is still the case in Africa now). The last famine in Europe caused by an absolute shortage of food was in the early 1800s, when the eruption of Krakakoa in Indonesia injected enough dust into the stratosphere to cause two years of climate cooling worldwide. In New England in the year following the eruption, frost occurred in every month. The Irish potato famine, which followed this, was not caused by an absolute shortage of food (Ireland exported food throughout the famine), but by the failure of the British government to distribute food to a starving population. The Irish famine was an unexpected problem of industrialization: that of the introduction of new organisms to new environments. The blight that destroyed the potato crop was brought to Belgium on American seed potatoes imported by steam ship. The rapidity of the trip across the Atlantic allowed the fungus to arrive on the potatoes alive, and the damp summer that followed allowed it to spread all over northern Europe.
Another renewable limit was fuel. Until the 1700s (earlier in England) wood was the primary fuel used for industries and crafts, as well as for cooking and heating. Brick burning, glassmaking, iron smelting, salt evaporation, lime burning, sugar refining, soap making, brewing all required fuel. Heating and cooking probably required the most. Shortages made wood expensive; in 1600 the average city dweller in France spent 10% of his income to keep a fire burning in one room for part of the day. In general, from 1500 to 1700, 7.5% of an ordinary budget went for light and heat. (More efficient brick or stone heating stoves in central and northeastern Europe made it more comfortable in 1700 to winter in Warsaw than Toulouse.) Timber was necessary for buildings, tools, ships and furniture. Hazel and oak, species that sprout well from stumps, were cut on short-term rotations to provide fuel and also materials like tanbark. Some oak stems (the standards) were allowed to mature for timber. But supplies were limited to what forest growth provided. In the European wars of the eighteenth century, English blast furnaces, needed to forge cannon shot, could only operate intermittently; when they ran out of charcoal, they had to shut down. (Eight tons of wood made two tons of charcoal, which would smelt just under a ton of pig iron.) Similar shortages occurred all over Europe. Since iron making depended on a renewable resource, production of iron had to remain at or below what the wood supply could handle. If production were increased to meet an increase in demand, the supply of wood in the future would be reduced. Future production of iron would have to be lowered, or stopped altogether. Everything depended on the growth of the trees, which put an inexorable limit on production. Where available, coal could be used for cooking, heating, and processes such as brewing that simply required a source of heat. Coal was commonly used for such purposes in England, where wood shortages developed early and coal was abundant. Coal had largely replaced wood for household heating and cooking in England by 1700. The adaptation of essentially unlimited European coal supplies to iron smelting was a fundamental factor in the rise of the Industrial Revolution.
There were other problems related to an overexploitation of a renewable environment. One of the more serious was soil erosion. This reduced soil fertility (nutrients were lost with the soil and the depth of topsoil was also reduced); caused the siltation of streams, which increased flooding; and ruined freshwater fisheries. (The gravels in which the fish laid their eggs silted over. Mill dams also destroyed fisheries. Riverine fisheries were failing in Europe by 1000 and were replaced by the cultivation of fish in ponds — many fishponds in the 1100s and 1200s were the dammed sections of rivers and streams, but with different species of fish.) Eroded soil also filled waterways and harbors. Harborworks of cities in the Rhine delta suffered. Bruges in present-day Belgium, the commercial center of northern Europe in the 1300s, watched its harbor on the Zwin disappear, silted past the ability of the city to clear it. Rivers were also polluted by metal works, dye works, tanneries and sewage. Wells were polluted with seepage from cesspits and from rotting bodies in churchyards. The smell of cellars about the cemetery of Les Innocents in Paris was notorious.
Overfishing followed population growth, as marine fish began to replace freshwater fish in the European diet; the trawl was invented in the 1300s, with disastrous effects on fish stocks and the life of the seafloor. With the trawl, cod off the English coast became so easy to catch that the surplus was fed to pigs. Diking to reclaim land in the Rhine Delta caused major losses in sturgeon, once a key item in the European diet, by destroying its spawning habitat. By 1500 stocks of herring in the Baltic and of cod in the seas about Europe were failing. (Except for the Danish herring fishery, which collapsed with finality in the 1300s, the cod and herring fisheries would recover to fail again.) The Baltic and North Sea herring fisheries originally amounted to billions of fish annually. Fish was one of the sources of wealth of the cities of the Hanseatic League. (Even in the late 1600s, work in the herring fishery constituted 20% of the Dutch economy.) In the late 1400s fishermen from Bristol sailing west of Iceland discovered the Newfoundland cod fisheries. Did they stop to take on some of the Norse colonists in southern Greenland, whose culture was failing? By 1600, 20,000 European fishermen were salting and drying cod off Newfoundland. Dried cod from the North American banks would provide a cheap source of protein for Europe for 500 years.
Until the Industrial Revolution, the European world was Malthusian. That is, its population tended to increase faster than its food supply. In a downward spiral, more people meant more demand for grain, less crop rotation, less fodder for the animals, not enough manure to raise grain yields, the animals dying from parasites and malnutrition in late winter and spring. People died from hunger and exposure. Infant mortality was 25-30% until the late eighteenth century, life expectancy was 30 to 40 years, epidemics were common, most of the population was undernourished and depended on vegetable foods (bread, gruel, potatoes). Much of the population was very poor. At the time of the French Revolution, 80% of the population of France is thought to have been poor or destitute; that is, they owned the clothes on their backs. Many were more or less homeless, not being able to afford both food and lodging. In Medieval and Early Modern Europe four-fifths of disposable income went for food. The nobles and the members of the middle-class ate well. These distinctions lasted in England long into the period of industrialization: in 1800, boys taken into the Royal Navy from the slums of London or Liverpool were 8 inches shorter than boys from the upper classes; in 1940, working class draftees were still 4 inches shorter than boys who had gone to elite schools. So one could recognize an officer by his stature. Until about 1700, periods of growth in the standard of living of the common people were followed by periods of reversal (the long waves in the economy were cyclical), so the standard of living of an agricultural worker in Europe in 1500 or 1600 was only slightly higher than in Roman times. When Europeans came to North America, where food was plentiful, their numbers, instead of doubling every 150 years, began to double every 23 years. (Most of the first-born children in Puritan families were illegitimate.)
This is not a portrait that leads to a progressive view of history (constant progess onward and upward). That view would come out of the cascading improvements in material life with the Industrial Revolution (railroads, steam power, gas lights) and their consolidation and elaboration in the twentieth century (electricity, cars, radio, penicillin, TV). In the United States, more egalitarian and less bound by social traditions than Europe, especially after the Civil War, markets expanded with the population and economic productivity grew at 2% a year from 1870 to 1970. (In general, a more widespread prosperity increases the rate of economic growth.) But it is also not the whole picture. From 1200 to 1800, during a period of worsening climate, agricultural yields in Europe rose 2.5 times, while population rose 10 times. Land under cultivation increased several fold. During the so-called Little Ice Age, from 1430 until 1850, the climate was 1º - 2º C. lower than during the Medieval Optimum. A severe famine from 1315 to 1322 may have set the stage for the Black Death of the 1340s and 1350s (fetal malnutrition interferes with the development of the immune system) and killed outright perhaps 10-15% of the population. The Black Death killed a third to a half of the population. Recurrent epidemics followed for the next century and there was another famine in the 1430s. For the most part crops near their natural temperature limits (at high altitudes or latitudes) failed. During the Little Ice Age cereals could no longer be grown on the hills of northern and western Britain, glaciers and the tree line descended in the Alps, and the northern limits of vinyards in France and Germany retreated 300 kilometers south. Yields of grain on newly cleared land during the warm summers of the Optimum had been twice those of late Roman times but inevitably fell as soils eroded and fell further as the weather worsened. Most of the cooling took place in winter (this was a time of ice-skating and ice festivals) but summers were also 0.8º C. cooler.
After the calamitous 1300s, with disease, famine and continual low level war, came a period of recovery. Europeans rebuilt their water mills for water-powered industry. Tenants gained heritable rights to their land in return for rents. Some common lands began to be enclosed to create rentable tracts. (In the late 1500s, it was said a living was three acres and a cow. People were still saying that in upstate New York in 1850.) Towns, supported by agricultural surpluses, grew into small industrial centers. Industry in late medieval Europe was for the most part cloth, of wool or linen, woven on hand looms at home. By establishing chartered political units, surrounding themselves with walls, and mobilising their citizens into a defensive force, towns established a degree of political independence, both from the church (many towns were founded as the seats of bishops) and from the countryside and the nobility that ruled it. Intellectual life bloomed as paper replaced skin parchment in books (paper was 13 times cheaper than parchment at the time) and printing (also much cheaper) replaced hand copying. Books became more affordable; before the printing press, a professional man’s annual salary bought two cows or four books (and nothing else). After the printing press, a middle class person could afford a couple of books a year. As land became more valuable, property rights became more exclusive, and began to extinguish the traditional rights of the nobility, such as that to ride or hunt where they pleased, and those of the peasantry, which included the right to common grazing land and to fuelwood gathered from the forest. Trade spread once again (memories lingered of the fairs of the 1300s), its bankers and merchants operating under the protection of the towns. Some of this trade was for commodities like Baltic timber and grain and some for luxury products like the silks and spices of Asia, to which the caravan routes, closed for some centuries by drought and the expansion of Islam, were once more open. Imitating the nobility, families of the middle class tried to keep their wealth through such devices as late marriage (thus limiting their fertility); by advantageous marriages between families; or by restricting inheritance to first-born sons. A writer has said that among the wealthy, population control was positive, while among the poor, population was controlled by starvation. In Paris at the time of the Revolution one-quarter of all children are thought to have been abandoned for adoption. Such infants were taken in by church orphanages, where the great majority of them died.
The medieval boom had ended with the famine of 1315 to 1322. Every season of 1315 was wet. Crop yields were half of normal. Hay was put up wet and rotted in the barns. During the winter and spring of 1316 people ate their seed grain. The year 1316 continued wet with another crop failure. The price of wheat tripled, when it could be bought. The famine continued until 1322. Twenty-five years later, after several warm, wet springs favorable to the spread of plague among the rodents of Central Asia, the Black Death arrived with people on ships from trading posts on the Black Sea fleeing the Mongol invasion and killed a third or more of the population of Europe. Parts of Europe would not see the population reached during the Climate Optimum for another 450 years. But the decline in population was followed by a period of development and prosperity: the Renaissance. The average age of death for adults was still something like 35. Still hemmed in by the Islamic world, Europe began probing its limits. Genoese bankers (who had financed the trading cities on the Black Sea) now financed Portuguese explorations around Africa to the Spice Islands of the East and out into the Atlantic, where large semi-tropical islands were discovered. New crops had been appearing in Europe thanks to trade with Asia and contact with the Moors in Spain; these included rice and sugar cane and the new livestock of silkworms. After 1492 came American crops. The yields of Mexican corn and Andean potatoes would dwarf those of European grains. A writer has speculated that the introduction of maize, peanuts and manioc from the Americas to Africa, which substantially increased the human population there, made the trans-Atlantic slave trade possible. New diseases (such as yellow fever) came with trade and with the Africans to Europe and the New World.
The high point of European row-crop agriculture was reached in England in the eighteenth and nineteenth centuries. The development of rotations between cereals and crops of legume hays (which raised the yield of grain per acre), the raising of animals on legume hays (which increased the numbers of animals that could be kept), and the use of animal manures on the fields (which further raised the yields of grain), together with plant and animal breeding that resulted in higher yielding varieties of plants and animals (more meat, wool, or grain for the same nutritional input) — all raised European upland agriculture toward the heights of successful overflow agriculture (such as in the Nile Delta), the ditched fields of Tiahuanaco, or paddy rice. That is, it became a high-yielding, self-sustaining agricultural system, less dependent on inputs from the wasteland, capable of supporting many more people per acre. Enclosure laws in England, enacted partly to ensure an adequate supply of manure for cropland (the relation of pastureland to cropland is important in manure-dependent cropping systems), better equipment, and better capitalized farms put many agricultural laborers and small tenant farmers out of work; some went to poorhouses, some to Australia or the Americas, some to work in the shops of the Industrial Revolution. Agricultural prosperity showed in that in the 1800s horses replaced oxen in Europe as the main source of agricultural power. (Horses are able to work faster for a longer time but are several times more expensive to maintain.) Environmentally speaking, such mixed agricultures were a high point of upland agriculture; they were sustainable as long as they occupied a more or less limited place in the larger ecosystem. Similar agricultures flourished briefly on the American prairies, and in the German settlements of the Shenandoah Valley of Pennsylvania and Virginia. One finds them still among the American Amish.
What ended the European dependence on the renewable world was the use of fossil fuels. England was the European nation most short of wood. It was largely deforested, probably not for the first time, when the Domesday Book was compiled in 1089 AD. (For instance, deforestation of the English downlands had begun in Neolithic times 5500 years before and had continued through the Roman invasion of AD 43. Deforestation, erosion and grazing converted the original downland woodland of oak, alder, willow, hazel, birch and rowan into the thin-soiled grasslands of today.) England was also the country most in need of wood for its imperial ambitions and it was here the Industrial Revolution began. (While some developments came from the continent, the English most thoroughly exploited their economic possibilities, probably thanks to their better developed markets.) A writer has summarized the reasons for the development of the Industrial Revolution in Britain: the greater size and efficiency of British markets (many of the export markets created and maintained by Britain’s sea power); Britain’s commercially minded society; Britain’s openness to innovation; and its accumulation of natural resources from around the globe (also a function of its sea power). In the late eighteenth century machines were developed that, powered by water, would spin cotton thread; other machines wove the thread into cloth. The mechanical advantage of the machinery was so great, the multiplication of the value of the labor and investment so enormous, that the major limits on cloth manufacture became the availability of waterpower, of raw cotton, and of the ability to market the cloth. The manufacturing process was so cheap, compared to hand spinning and weaving, that the manufacturers were able to lower the price until demand met supply. Once cloth fell within reach of the poor, an enormous market was created and demand exploded. Profits were still enormous. The invention of the cotton gin, which mechanically cleaned cotton (previously slaves had picked out the seeds by hand) had a similar advantage: one didn’t just double or triple the value of labor, one increased it by orders of magnitude, powers of ten. During the 1780s, as the English were losing their American colonies, industrial growth in England rose from 1% to 4% a year. It remained near 4% (some writers claim 2%) for a century.
It was the use of fossil fuels to smelt iron ore and power steam engines that finally changed everything. In England in the late eighteenth century processed coal (coke), rather than wood, was first used successfully to smelt iron ore. Unprocessed coal had too many impurities compared with charcoal and the iron smelted with it was too brittle. The coke-making process eliminated these. Coke was much cheaper than charcoal. And coal to make it was available for the mining, as was iron ore. Coal fired the steam engines, made of coke-smelted iron, that pumped the water from English mines and let the miners produce more coal. Coal-powered locomotives, built of iron and running on iron rails, hauled coal and iron ore to where they were needed. Coal-powered spinning machines took over from water-powered ones, removing another constraint from the manufacture of cotton. Coal was later joined by oil and natural gas, useful because they were fluids rather than solids, and so flow under gravity or pressure. Such fossil fuels became unlimited sources of energy in an otherwise renewable and limited world. Fossil fuels will likely remain available for a long time. (For coal the current guess is another 200 to 400 years.)
Coal-powered steam engines eliminated the limits set by floods or frozen waterways in water transportation, by replacing canal and river traffic with rail. In the 1860s coal-powered steamships, built of coal-tempered steel, carried three times the cargo twice as fast as sail. With transportation faster and cheaper, Europe reached out to the rest of the world for its resources. From 1860 to 1920 one billion acres of new land was converted to agriculture, 40% in the United States (much of it in the Corn Belt), 20% in the Russian Black Earths, 20% in Asia. Grain was imported from the “new lands” in the Ukraine, North and South America, and Australia. (Land clearing would continue, with another billion acres added to agricultural lands from 1920 to 1980, mostly in Latin America.) Refrigeration and pasteurization of milk made milk more saleable and its production rose enormously, with beneficial effects on the European diet. Milk now constitutes 20% of the value of agricultural production in Europe and the United States. Imported fertilisers such as rock phosphate and Peruvian guano increased the fertility of European soils. But it was primarily cheap imported food, its cheapness made possible by the exploitation of fossil fuels, that ended starvation in Europe. The pre-industrial European diet in 1800 was worse than that of the European hunter-gatherers of 12,000 years before. The diet worsened further during the early years of industrialization (the average height of men in both America and Europe fell in the 1830s) but improved after about three generations of industrialization. (By the 1920s the shortfall in height was gone.) By 1900 England was importing 80% of its grain, 75% of its dairy products, and 50% of its meat.
Coal also made the chemical industry possible. Coal provided the energy to run the reactions; while coal, oil and natural gas replaced wood as a feedstock. The Haber process, which synthesizes ammonia from atmospheric nitrogen, led to the manufacture of synthetic nitrogen fertiliser, which further increased the yield of soils. Artificial fertilisers and further developments in crops and animals would make Europe nearly self-sufficient in food by the mid-twentieth century. However the excess nitrogen used on crops would cause tremendous pollution problems. Anthropogenic nitrogen lies behind the biological degradation of marine estuaries and (along with phosphorus) of fresh waters. Nitrate pollution in the Thames and Rhine are now two orders of magnitude (100 times) above the mean values of unpolluted streams. (Not all of this is due to agriculture; some nitrogen and phosphorus come from sewage effluent and some nitrogen from the combustion of fossil fuels.)
By the end of the nineteenth century coal was being used to generate electricity. By two decades into the twentieth century coal and oil had produced the modern world, where the problem is not that of producing enough, but of creating demand for all that can be produced. Through gaslight and electricity, fossil fuels had eliminated night. They ameliorated the seasons through heating in cold climates, cooling in hot ones. Fast, cheap transportation eliminated the agricultural seasons, so that now any modern expects fresh fish, fresh lettuce and fresh grapes to be available anytime, whenever he or she wants them. The human habitat in developed countries, even in rural areas, is almost entirely a built one, of roads, telephones, powerlines, fields, houses, internet communication. The cost of food has kept falling until it is now less than 10% of income in developed countries. Such development comes at a cost. In 1850 every Englishman used the equivalent of 1.7 tons of coal a year; this rose to 4 tons by 1919, where it remained until 1950, despite considerable economic growth, when the number began rising once again. Such energy use brings us other problems. But the notion of man’s independence from nature and its constraints is a hallmark of the modern.
The Natural History of the Present, Chapter 9
Chapter 9: Were Ancient Marketable Landscapes Sustainable?
Westerners are taught that civilization began in the Fertile Crescent of Mesopotamia. This is a matter of cultural focus, for while agricultural civilization reached a more extensive development in Eurasia at an earlier time, agricultural development elsewhere began not much later and eventually reached comparable levels. But those agricultural civilizations (say, in the Americas, or in highland New Guinea) did not lead in a straight line to the modern West. Rather they were all taken over by that bellicose, capitalist, Christian culture that rose in Europe over some 1500 years out of its Mediterranean and Near Eastern roots.
In Mesopotamia, the adoption of agriculture seems more obvious than in many places. Wild annuals like emmer wheat and barley grew in large natural stands; for wild crops, they were exceptionally large-seeded. These plants formed a natural climax in the wet winters and long dry summers of the eastern Mediterranean, in micro-climates where the length of the summer drought made the support of woody vegetation difficult. Especially on fertile sites, these tall annuals grew quickly and used up the available soil moisture, preventing percolation and out-competing trees and shrubs. Their seeds were adapted to survive the long summers and sprout and grow quickly in the returning winter rains. A ton of seeds per hectare could be gathered with a hand sickle from such wild stands. The warming and drying climate at the end of the Pleistocene greatly expanded the range of these plants altitudinally. People could harvest them from month to month as summer proceded up the mountain terraces, and store the surplus. The Middle East also had many other of the wild precursors of modern crops, especially the pulses (the protein-rich lentils, peas, chick-peas and bitter vetch); and also flax, whose stems produced a fiber and whose seeds produced an edible oil. Combining grains and pulses in a dish produces so-called complementary proteins, a mix of proteins that corresponds more closely to what the human body needs—not as good as animal protein, but much better than grains alone: so one has wheat and chickpeas, rice and beans, beans and corn. (Chickpeas also contain tryptofan, a precursor of serotonin, which improves performance under stress and promotes ovulation.) Wild cows, sheep, pigs and goats also lived in the area; animals that were domesticable because of their tractable natures and herding or flocking behaviors. (Other crops soon included barley, oats, grapes, olives, dates, figs, apples, pears and cherries.) So here one can more easily envision how an increased birth rate, thanks to a more sedentary life based on acorns and pistacios, and also on gathered cereals and pulses, carried down to the village in woven woolen bags lashed over the backs of goats and sheep, led to an upward population spiral that then led to more settled agricultural communities: permanent fields, domestic animals (pastured after harvest on the fields), stone or mud-brick dwellings, pottery-making. Such villages, based on hoe culture of grain and on domestic animals, existed in upland Mesopotamia 9000 years ago in areas with sufficient rainfall. By 8000 years ago, in what is now central Jordan, such communities were being abandoned, partly because of soil exhaustion and deforestation, and partly because of a drought associated with another breakdown in the North Atlantic circulation, this one caused by the final meltdown of the Laurentide Glacier in North America. With the end of that drought about 7000 years ago, Europe entered a climatic optimum that lasted 2000 years.
The progression to agriculture is less obvious elsewhere. In eastern North America the Hopewell mound-builders of the Ohio and Illinois valleys were cultivating seven crops about 2500 years ago. Four of them were grains with tiny seeds but good protein and fat content; the other crops were a squash and a sunflower grown for their seeds, and sumpweed, a large oilseed, whose pollen and leaves are often irritating to people. These crops were grown on the floodplains of the rivers after the flood had receded. While seed crops provided a considerable part of the diet, the people in the Hopewell cities also ate fish, shellfish, deer, migratory waterfowl, turtles, passenger pigeons, and wild nuts. They have been called cities of hunters and gatherers. (Cahokia, a later mound-building city near present-day St. Louis, was based on maize. Cahokia was a city of several thousand small farms, apparently without significant trading relations with other places.) Shellfish were very abundant in Middle Western rivers. Nuts and acorns had been important foods for people dwelling in the mesic forests of eastern North America for thousands of years. Most acorns have to be leached of their tannins to be edible. Hickory nuts were pounded shell and all in a mortar, the mass boiled in water, and skimmed of froth and particles of shell. Further boiling reduced the mass to a nutritious, storable paste: hickory milk. In the late 1700s John Bartram watched Creek families in North Carolina store hundreds of bushels of hickory nuts. While corn would transform life in aboriginal North America, the domestication of corn in highland Mexico took thousands of years. The plant that became corn was grown for several thousand years before its seeds became usable as a grain. Corn may have been first grown for its sweet stalks, fermented to make beer. (Modern maize stalks are 16% sugar.) An entire ear of Teosinte, the plant that was turned into corn by generations of middle American women, has less nutritional value than one kernal of modern maize. It took many more years for corn to change its daylength characteristics from tropical to temperate and move north. The advantages of corn over the native domesticates were immediately apparent, and when corn appeared, the tribes adopted it. Corn changed social structures; many societies became more hierarchical and their villages larger. In the Asian subtropics, the cultivation of paddy rice involved the invention of a method of cultivation. The method is not obvious. (The cultivation of upland rice is another matter.) In these cases the immediate advantages of agriculture were more difficult to see, and the process that led to a settled agricultural life more difficult to imagine.
In the Near East, irrigation societies and large cities (50,000 people and up), with their organized hierarchies of nobles, priests, courtiers, warriors, artisans and farmers; their massive public buildings of brick, mud-brick or stone; their calenders based on astronomical observation; their use of writing; and war for the purpose of gaining land and tribute, developed after some thousands of years of upland village agriculture. Early cities were storehouses for grain: a means of distributing food, trading for it, and storing it against a risk of crop failure. (One can regard modern cities as means of maintaining and distributing wealth.) These societies exploited a new environment: the flat and arid Mesopotamian plain, with its high summer temperatures (40º C., 104º F.), high evaporation rates and relatively impermeable soils. Initially agriculture here consisted of the cultivation of rainfed winter grains, but the shift of the Indian monsoon south about 5800 years ago reduced winter rainfall so that winter crops would no longer grow. The timing of high water meant that irrigated crops would have to be grown in the hot summer. So more water was needed and soils accumulated salts more quickly. Irrigation produced a more apparently controllable supply of water than rain (it depended on the reliabability of the river’s flow patterns), and a much larger harvest per unit of land. The agricultural work was seasonal. In the off seasons, farmers could extend and maintain the irrigation system. Thus the surplus per farmer was considerably more and the other levels of the society considerably richer than in the upstream societies that still depended on rainfed agriculture. Irrigation also made large areas of new land cultivable.
The Tigris and Euphrates took parallel courses across the Mesopotamian plain, but at slightly different elevations. The plain was essentially flat; the rivers dropped 30 meters over a distance of 700 kilometers. Overflow channels connected the rivers during spring floods, and the first irrigation schemes exploited these channels. The land between the rivers was a mix of swamps, stands of date palms, forest, shrubs and grassland. Large herds of gazelle, along with other herbivores and their feline and canine predators, originally occupied the plain. The Euphrates carried a lot of silt; its delta moved out into the Persian Gulf at 15 miles per 1000 years, so ancient trading cities near the gulf are now 50 to 70 miles inland. Irrigation agriculture would have had all the disadvantages of rainfed agriculture: a poorer diet (with sufficient calories, but less balanced, with less protein, and less calcium, potassium, and other minerals and vitamins, and thus leading to poorer overall health, more skeletal disease and shorter stature); the diseases and parasites that come from contact with water containing human excreta (various worms, including those that cause schistosomiasis), and those that come from close contact with domestic animals (many of the latter are also crowd diseases that require a sufficient density of human population to maintain themselves and so flourish in cities); the skeletal problems caused by hard physical labor; and earlier death. But at least at first, some of these irrigation societies were rich and grew a wide variety of crops, including pulses and some vegetables and fruits (such as onions and figs, sources of sugars, minerals and vitamins). Animal protein came from herds of goats and sheep that were pastured out on the plains in summer, along the rivers in winter. Wooden rafts supported by inflatable goatskins brought commodities down the Tigris in summer. Timber from the rafts and the commodities, including semi-precious stones and copper, were sold, and the goatskins packed back upstream. The actual extent of nutritional diseases would have depended on how well food was distributed; of waterborn diseases on the city’s organization of things like water supply and sanitation (whether drinking water and human excreta were separated). That is to say, depending on the political situation (the extent to which the needs of the people were taken into account), the jump in agricultural productivity associated with irrigation agriculture might have let these peoples raise their general levels of health (as well as raise the standard of living of their elites), at least for some time.
There were the usual advantages of agricultural societies: a higher birth rate and higher population; permanent dwellings; fine and varied craft work; the development of the sciences of mathematics, engineering and astronomy; the construction of large public buildings; improved methods of war; and writing. In the several times writing has been invented (Sumeria; Mexico; perhaps Egypt; probably China; perhaps Peru) it always flowed from irrigation, or quasi-irrigation, societies. Sumerians seem to have invented writing first, part of the great head start of Eurasia in cultural evolution. This was a gift of geography and biology, as a modern writer has explained. The easily domesticated plants and animals of southwest Asia could be grown without much adaptation north and west through Europe and east through much of Asia, an immense area, which led to societies influencing each other with ideas, new crops, new inventions; thus cultural development was rapid. Writing in Sumeria began, like the knotted strings of the Inca, from the need to keep agricultural accounts. By making possible the recording of knowledge (as well as that of wealth) writing made possible the accumulation of knowledge (in mathematics, biology, astronomy, physics, law, natural history, human history); that is, it made possible the modern world.
Irrigation societies in Mesopotamia would all eventually collapse because of the character of the landscape’s soils and the climate. Failure through saltation, accumulation of toxic minerals, or waterlogging is the fate of virtually all large-scale irrigation schemes in hot, dry climates. The muddy waters of the Tigris and Euphrates had a relatively high salt content. This was partly natural, partly the result of some thousands of years of agricultural erosion and deforestation upstream. The high summer temperatures of the Mesopotamian Plain meant a high rate of evaporation and of water use. The time of spring high water meant that crops, unlike the rainfed grains of the Mediterranean uplands or those in Egypt, where the Nile flood arrived in early autumn, allowing for a late autumn sowing, were grown in the summer heat. Thus they required a lot of water. The high salt content of the water and the relatively impermeable soils meant that the soils would inevitably begin to accumulate salt. Salt interferes with the ability of plants to take up water and thus reduces their growth. This soon became apparent and new land was brought into cultivation as the fertility of the old fields fell. (Modern irrigation schemes in impermeable soils sometimes solve this problem by installing drains to carry away the excess water.) The development of new lands maintained total agricultural productivity and accomodated the rising population for a long time. But the climatic drying that began 5800 years ago continued. As new land ran out, and population pressure prevented the use of long-term fallows, crops in Sumeria shifted from wheat to the more salt-tolerant barley. The cities also needed wood, which had to be within an economical hauling distance (some came down the Tigris in rafts), to smelt metal, fire pottery, brew beer, burn brick, cook the pulses and grains, and for building material. Deforestation added to the salts and silt carried by the river water. The irrigators kept cows, pigs, chickens, and goats, and so the cutover forests were grazed, which prevented their regrowth. Such use slowly transformed the whole landscape within the reach of the Sumerian cities and intensified the load of silts and salts that fed the rivers. Rising silt loads made keeping the canals open a constant problem, and sent the Euphrates migrating across its plain. Such problems take time to develop on a large scale, but unless dealt with, become (like our rising curve of carbon dioxide) more and more inexorable in their effects. About 5500 years ago equal amounts of wheat and barley were grown in Sumeria, by 4500 years ago wheat amounted to 15% of the crop, by 4100 years ago 2%, by 3700 years ago no wheat was grown. Crop yields remained high until 4400 years ago —that is, for 1100 years, far longer than we have been growing industrial grain in the American Middle West. After 4400 years ago, no new land was available and crop yields fell by 40% over the next 300 years. From 4200 to 3900 years ago there was a region-wide drought. Egypt’s Old Kingdom collapsed about 4200 years ago. Water levels in the Euphrates may have fallen below the beds of the canals. The drought was so severe that in fields near the Syrian border the earthworms died. The first external conquest of the region occurred almost concurrently with the end of new land, 4375 years ago. By 3800 years ago yields were less than 20% those of earlier times and the society had effectively collapsed.
Sumerian agriculture might have been sustainable if it had been handled differently, using fields over a long rotation (like the Hohokum of the American Southwest). Some ancient irrigation agricultures were sustainable: Egypt’s; the Mayas’ ditched swamps; the raised beds of the Tiahuanaco; paddy rice in Asia; floodplain agriculture along the lower Mississippi or Amazon. None of these are irrigation agricultures in the classic sense. In the Nile Valley the flood was usually high enough, and the soils beneath were more permeable, so the water washed the salts from the flooded land. Agriculture along the Nile was a sort of improved floodplain agriculture, much like that along the Mississippi and the Amazon. In the swamps of the Maya and the raised fields of Tiahuanaco, the water percolated up from below. Paddy rice involves a constant slow flow over a more or less impenetrable substrate.
Until the building of the dam at Aswan, Egypt’s Nile Valley was probably the most naturally productive agricultural landscape in the world. When invaded by Napolean in the 1790s, Egypt’s wheat yields were twice those of France. By then the valley had been cultivated continuously for 7000 years. Half or more of Egypt’s cultivable land is in the delta. The geology of the lower Nile Valley and the use of its natural overflow basins for agriculture removed the problems of saltation and waterlogging. After the flood, the water table would drop 10 feet below the valley bottom, letting the flood waters drain away. The timing of the overflow also helped. Water from the spring rains in the uplands of east Africa (present-day Ethiopia and Uganda) reached the Nile Delta in September, so crops were sown in late fall and matured in the cooler temperatures of winter. Spring and summer irrigation was restricted by the available technology to areas near the river, which the floods would leach clean of salts every year. Fertility was provided annually by the silt, and also by human and animal manure. Fertilising minerals came with the river water from the highlands of Abyssinia, humus from the jungles of central Africa. As in Mesopotamia, the volume of silt may have been increased by deforestation for agriculture in Ethiopia and for metal smelting in the Ugandan uplands. But the river was also cleaned and regulated by its passage through the swamps of Nubia, before it fell to the lower valley. The Nile also provided fish, both in the river and off the delta. The nutrients and fresh water brought down by the Nile supported fisheries throughout the eastern Mediterranean. The problem with the Nile flood was its unpredictability. Low floods occurred about twice a decade. The heights of Nile floods are connected to El Nino Events, which influence the northward reach of the Indian Ocean monsoon, and thus the extent of spring rains in Ethiopia. Two low floods in a row were a disaster. A flood can also be too great, remaining on the land too long and preventing the sowing of the winter crops. So, loosely speaking, the agricultural area would have supported a population that could store sufficient grain for 2 years. But population control is not the point of high civilisations, the timing of low or high floods wasn’t predictable, and since Early Dynastic times the population kept rising above the food supply. Periodic starvation was common. Of course over such a long period of time Egypt also had more severe climatic disasters. The end of the Old Kingdom was caused by 300 years of low floods. A drought in the eastern Mediterranean 3200 years ago stressed all the civilizations of the area. It helped in the collapse of Mycenaen Crete, already half-destroyed by a tsunami from the volcanic eruption on Santorini. The earthquakes that accompanied the eruption apparently compromised the island’s aquifers. The Cretans traded olive oil and wine for grain from the mainland; they also grew some wheat themselves; the drought reduced their crops and meant less grain was available from the mainland. Even in this lucky landscape, the Egyptians were caught between the constant increase in the human population and the behavior of the river.
Paddy rice constitutes another sustainable agricultural system. Tropical soils in humid climates, once cleared of their natural vegetation, are in general impervious and nutrient poor. The soils are old, and have been depleted by rainfall, plant respiration, and internal erosion. Most of their nutrients are concentrated in the vegetation that is removed. In paddy rice cultivation, the nitrogen that feeds the rice plant comes largely from blue-green algae that colonize the warm, slowly moving water that covers the paddy. The water itself, descending from the uplands, provides some nutrients (phosphorus and other minerals). Trampling and working of the paddy bottom makes the soil more or less watertight, so water and nutrients are retained. Fish and freshwater invertebrates grow in the paddies and the feeder canals. In the Lake Biwa basin of Japan, very old paddy fields are used by the lake’s catfish as a spawning area and nursery: that is, as an extension of the lake itself. This use is a benefit both to the farmers, who harvest some of the fish and whose rice is more productive, and to the fish. In some cases the nutrient-rich overflow from the paddies is led to duck ponds, whose algal and insect life (food for the ducks) is supplemented by grain. The ponds, their bottom muds fertilized by the algal and bacterial growth and by that cycled through the ducks, are periodically drained and planted to vegetables. Fertility of the paddies is also maintained by adding manure from the animals that plow them, human manure, ashes, the walls of demolished mud-brick houses impregnated with soot and grease from cooking.
The water buffalo whose manure ends up on the paddy and increases its yield of rice, is fed from forage cut in the nearby forest. Irrigation water also comes from the forest. So the forest is part of the paddy system. It also provides firewood, small game, material for building and basketry. Lowland rice-growing systems, irrigated by large rivers, also depend on a predictable supply of good quality water. These systems can be overwhelmed by timber cutting in the watershed and the change in the quality, timing and amount of water delivered to the paddies that this causes.
So some agricultural systems of “high” civilizations were sustainable, some not; some landscapes could stand more human development, some less. Any human civilization is a outgrowth of an existing landscape and climate, that is, of levels of rainfall and temperature, of sea levels, flood levels, the likelihood of extreme weather events. All agricultural systems can be pushed over the edge by too much development about them or by small climatic changes. Increase in population is often the problem, though technology also matters, in that technology magnifies the effects of population. In the 1800s, perennial irrigation to grow cotton (three crops a year) began to salinize Egyptian fields. The building of the dam at Aswan, which cut off the natural flow of water and silt, turned the Nile Valley into an unsustainable agricultural system. Salinization is now a problem, the fishery for sardines off the delta has collapsed, and without a yearly influx of silt, the land in the delta is receding.
Westerners are taught that civilization began in the Fertile Crescent of Mesopotamia. This is a matter of cultural focus, for while agricultural civilization reached a more extensive development in Eurasia at an earlier time, agricultural development elsewhere began not much later and eventually reached comparable levels. But those agricultural civilizations (say, in the Americas, or in highland New Guinea) did not lead in a straight line to the modern West. Rather they were all taken over by that bellicose, capitalist, Christian culture that rose in Europe over some 1500 years out of its Mediterranean and Near Eastern roots.
In Mesopotamia, the adoption of agriculture seems more obvious than in many places. Wild annuals like emmer wheat and barley grew in large natural stands; for wild crops, they were exceptionally large-seeded. These plants formed a natural climax in the wet winters and long dry summers of the eastern Mediterranean, in micro-climates where the length of the summer drought made the support of woody vegetation difficult. Especially on fertile sites, these tall annuals grew quickly and used up the available soil moisture, preventing percolation and out-competing trees and shrubs. Their seeds were adapted to survive the long summers and sprout and grow quickly in the returning winter rains. A ton of seeds per hectare could be gathered with a hand sickle from such wild stands. The warming and drying climate at the end of the Pleistocene greatly expanded the range of these plants altitudinally. People could harvest them from month to month as summer proceded up the mountain terraces, and store the surplus. The Middle East also had many other of the wild precursors of modern crops, especially the pulses (the protein-rich lentils, peas, chick-peas and bitter vetch); and also flax, whose stems produced a fiber and whose seeds produced an edible oil. Combining grains and pulses in a dish produces so-called complementary proteins, a mix of proteins that corresponds more closely to what the human body needs—not as good as animal protein, but much better than grains alone: so one has wheat and chickpeas, rice and beans, beans and corn. (Chickpeas also contain tryptofan, a precursor of serotonin, which improves performance under stress and promotes ovulation.) Wild cows, sheep, pigs and goats also lived in the area; animals that were domesticable because of their tractable natures and herding or flocking behaviors. (Other crops soon included barley, oats, grapes, olives, dates, figs, apples, pears and cherries.) So here one can more easily envision how an increased birth rate, thanks to a more sedentary life based on acorns and pistacios, and also on gathered cereals and pulses, carried down to the village in woven woolen bags lashed over the backs of goats and sheep, led to an upward population spiral that then led to more settled agricultural communities: permanent fields, domestic animals (pastured after harvest on the fields), stone or mud-brick dwellings, pottery-making. Such villages, based on hoe culture of grain and on domestic animals, existed in upland Mesopotamia 9000 years ago in areas with sufficient rainfall. By 8000 years ago, in what is now central Jordan, such communities were being abandoned, partly because of soil exhaustion and deforestation, and partly because of a drought associated with another breakdown in the North Atlantic circulation, this one caused by the final meltdown of the Laurentide Glacier in North America. With the end of that drought about 7000 years ago, Europe entered a climatic optimum that lasted 2000 years.
The progression to agriculture is less obvious elsewhere. In eastern North America the Hopewell mound-builders of the Ohio and Illinois valleys were cultivating seven crops about 2500 years ago. Four of them were grains with tiny seeds but good protein and fat content; the other crops were a squash and a sunflower grown for their seeds, and sumpweed, a large oilseed, whose pollen and leaves are often irritating to people. These crops were grown on the floodplains of the rivers after the flood had receded. While seed crops provided a considerable part of the diet, the people in the Hopewell cities also ate fish, shellfish, deer, migratory waterfowl, turtles, passenger pigeons, and wild nuts. They have been called cities of hunters and gatherers. (Cahokia, a later mound-building city near present-day St. Louis, was based on maize. Cahokia was a city of several thousand small farms, apparently without significant trading relations with other places.) Shellfish were very abundant in Middle Western rivers. Nuts and acorns had been important foods for people dwelling in the mesic forests of eastern North America for thousands of years. Most acorns have to be leached of their tannins to be edible. Hickory nuts were pounded shell and all in a mortar, the mass boiled in water, and skimmed of froth and particles of shell. Further boiling reduced the mass to a nutritious, storable paste: hickory milk. In the late 1700s John Bartram watched Creek families in North Carolina store hundreds of bushels of hickory nuts. While corn would transform life in aboriginal North America, the domestication of corn in highland Mexico took thousands of years. The plant that became corn was grown for several thousand years before its seeds became usable as a grain. Corn may have been first grown for its sweet stalks, fermented to make beer. (Modern maize stalks are 16% sugar.) An entire ear of Teosinte, the plant that was turned into corn by generations of middle American women, has less nutritional value than one kernal of modern maize. It took many more years for corn to change its daylength characteristics from tropical to temperate and move north. The advantages of corn over the native domesticates were immediately apparent, and when corn appeared, the tribes adopted it. Corn changed social structures; many societies became more hierarchical and their villages larger. In the Asian subtropics, the cultivation of paddy rice involved the invention of a method of cultivation. The method is not obvious. (The cultivation of upland rice is another matter.) In these cases the immediate advantages of agriculture were more difficult to see, and the process that led to a settled agricultural life more difficult to imagine.
In the Near East, irrigation societies and large cities (50,000 people and up), with their organized hierarchies of nobles, priests, courtiers, warriors, artisans and farmers; their massive public buildings of brick, mud-brick or stone; their calenders based on astronomical observation; their use of writing; and war for the purpose of gaining land and tribute, developed after some thousands of years of upland village agriculture. Early cities were storehouses for grain: a means of distributing food, trading for it, and storing it against a risk of crop failure. (One can regard modern cities as means of maintaining and distributing wealth.) These societies exploited a new environment: the flat and arid Mesopotamian plain, with its high summer temperatures (40º C., 104º F.), high evaporation rates and relatively impermeable soils. Initially agriculture here consisted of the cultivation of rainfed winter grains, but the shift of the Indian monsoon south about 5800 years ago reduced winter rainfall so that winter crops would no longer grow. The timing of high water meant that irrigated crops would have to be grown in the hot summer. So more water was needed and soils accumulated salts more quickly. Irrigation produced a more apparently controllable supply of water than rain (it depended on the reliabability of the river’s flow patterns), and a much larger harvest per unit of land. The agricultural work was seasonal. In the off seasons, farmers could extend and maintain the irrigation system. Thus the surplus per farmer was considerably more and the other levels of the society considerably richer than in the upstream societies that still depended on rainfed agriculture. Irrigation also made large areas of new land cultivable.
The Tigris and Euphrates took parallel courses across the Mesopotamian plain, but at slightly different elevations. The plain was essentially flat; the rivers dropped 30 meters over a distance of 700 kilometers. Overflow channels connected the rivers during spring floods, and the first irrigation schemes exploited these channels. The land between the rivers was a mix of swamps, stands of date palms, forest, shrubs and grassland. Large herds of gazelle, along with other herbivores and their feline and canine predators, originally occupied the plain. The Euphrates carried a lot of silt; its delta moved out into the Persian Gulf at 15 miles per 1000 years, so ancient trading cities near the gulf are now 50 to 70 miles inland. Irrigation agriculture would have had all the disadvantages of rainfed agriculture: a poorer diet (with sufficient calories, but less balanced, with less protein, and less calcium, potassium, and other minerals and vitamins, and thus leading to poorer overall health, more skeletal disease and shorter stature); the diseases and parasites that come from contact with water containing human excreta (various worms, including those that cause schistosomiasis), and those that come from close contact with domestic animals (many of the latter are also crowd diseases that require a sufficient density of human population to maintain themselves and so flourish in cities); the skeletal problems caused by hard physical labor; and earlier death. But at least at first, some of these irrigation societies were rich and grew a wide variety of crops, including pulses and some vegetables and fruits (such as onions and figs, sources of sugars, minerals and vitamins). Animal protein came from herds of goats and sheep that were pastured out on the plains in summer, along the rivers in winter. Wooden rafts supported by inflatable goatskins brought commodities down the Tigris in summer. Timber from the rafts and the commodities, including semi-precious stones and copper, were sold, and the goatskins packed back upstream. The actual extent of nutritional diseases would have depended on how well food was distributed; of waterborn diseases on the city’s organization of things like water supply and sanitation (whether drinking water and human excreta were separated). That is to say, depending on the political situation (the extent to which the needs of the people were taken into account), the jump in agricultural productivity associated with irrigation agriculture might have let these peoples raise their general levels of health (as well as raise the standard of living of their elites), at least for some time.
There were the usual advantages of agricultural societies: a higher birth rate and higher population; permanent dwellings; fine and varied craft work; the development of the sciences of mathematics, engineering and astronomy; the construction of large public buildings; improved methods of war; and writing. In the several times writing has been invented (Sumeria; Mexico; perhaps Egypt; probably China; perhaps Peru) it always flowed from irrigation, or quasi-irrigation, societies. Sumerians seem to have invented writing first, part of the great head start of Eurasia in cultural evolution. This was a gift of geography and biology, as a modern writer has explained. The easily domesticated plants and animals of southwest Asia could be grown without much adaptation north and west through Europe and east through much of Asia, an immense area, which led to societies influencing each other with ideas, new crops, new inventions; thus cultural development was rapid. Writing in Sumeria began, like the knotted strings of the Inca, from the need to keep agricultural accounts. By making possible the recording of knowledge (as well as that of wealth) writing made possible the accumulation of knowledge (in mathematics, biology, astronomy, physics, law, natural history, human history); that is, it made possible the modern world.
Irrigation societies in Mesopotamia would all eventually collapse because of the character of the landscape’s soils and the climate. Failure through saltation, accumulation of toxic minerals, or waterlogging is the fate of virtually all large-scale irrigation schemes in hot, dry climates. The muddy waters of the Tigris and Euphrates had a relatively high salt content. This was partly natural, partly the result of some thousands of years of agricultural erosion and deforestation upstream. The high summer temperatures of the Mesopotamian Plain meant a high rate of evaporation and of water use. The time of spring high water meant that crops, unlike the rainfed grains of the Mediterranean uplands or those in Egypt, where the Nile flood arrived in early autumn, allowing for a late autumn sowing, were grown in the summer heat. Thus they required a lot of water. The high salt content of the water and the relatively impermeable soils meant that the soils would inevitably begin to accumulate salt. Salt interferes with the ability of plants to take up water and thus reduces their growth. This soon became apparent and new land was brought into cultivation as the fertility of the old fields fell. (Modern irrigation schemes in impermeable soils sometimes solve this problem by installing drains to carry away the excess water.) The development of new lands maintained total agricultural productivity and accomodated the rising population for a long time. But the climatic drying that began 5800 years ago continued. As new land ran out, and population pressure prevented the use of long-term fallows, crops in Sumeria shifted from wheat to the more salt-tolerant barley. The cities also needed wood, which had to be within an economical hauling distance (some came down the Tigris in rafts), to smelt metal, fire pottery, brew beer, burn brick, cook the pulses and grains, and for building material. Deforestation added to the salts and silt carried by the river water. The irrigators kept cows, pigs, chickens, and goats, and so the cutover forests were grazed, which prevented their regrowth. Such use slowly transformed the whole landscape within the reach of the Sumerian cities and intensified the load of silts and salts that fed the rivers. Rising silt loads made keeping the canals open a constant problem, and sent the Euphrates migrating across its plain. Such problems take time to develop on a large scale, but unless dealt with, become (like our rising curve of carbon dioxide) more and more inexorable in their effects. About 5500 years ago equal amounts of wheat and barley were grown in Sumeria, by 4500 years ago wheat amounted to 15% of the crop, by 4100 years ago 2%, by 3700 years ago no wheat was grown. Crop yields remained high until 4400 years ago —that is, for 1100 years, far longer than we have been growing industrial grain in the American Middle West. After 4400 years ago, no new land was available and crop yields fell by 40% over the next 300 years. From 4200 to 3900 years ago there was a region-wide drought. Egypt’s Old Kingdom collapsed about 4200 years ago. Water levels in the Euphrates may have fallen below the beds of the canals. The drought was so severe that in fields near the Syrian border the earthworms died. The first external conquest of the region occurred almost concurrently with the end of new land, 4375 years ago. By 3800 years ago yields were less than 20% those of earlier times and the society had effectively collapsed.
Sumerian agriculture might have been sustainable if it had been handled differently, using fields over a long rotation (like the Hohokum of the American Southwest). Some ancient irrigation agricultures were sustainable: Egypt’s; the Mayas’ ditched swamps; the raised beds of the Tiahuanaco; paddy rice in Asia; floodplain agriculture along the lower Mississippi or Amazon. None of these are irrigation agricultures in the classic sense. In the Nile Valley the flood was usually high enough, and the soils beneath were more permeable, so the water washed the salts from the flooded land. Agriculture along the Nile was a sort of improved floodplain agriculture, much like that along the Mississippi and the Amazon. In the swamps of the Maya and the raised fields of Tiahuanaco, the water percolated up from below. Paddy rice involves a constant slow flow over a more or less impenetrable substrate.
Until the building of the dam at Aswan, Egypt’s Nile Valley was probably the most naturally productive agricultural landscape in the world. When invaded by Napolean in the 1790s, Egypt’s wheat yields were twice those of France. By then the valley had been cultivated continuously for 7000 years. Half or more of Egypt’s cultivable land is in the delta. The geology of the lower Nile Valley and the use of its natural overflow basins for agriculture removed the problems of saltation and waterlogging. After the flood, the water table would drop 10 feet below the valley bottom, letting the flood waters drain away. The timing of the overflow also helped. Water from the spring rains in the uplands of east Africa (present-day Ethiopia and Uganda) reached the Nile Delta in September, so crops were sown in late fall and matured in the cooler temperatures of winter. Spring and summer irrigation was restricted by the available technology to areas near the river, which the floods would leach clean of salts every year. Fertility was provided annually by the silt, and also by human and animal manure. Fertilising minerals came with the river water from the highlands of Abyssinia, humus from the jungles of central Africa. As in Mesopotamia, the volume of silt may have been increased by deforestation for agriculture in Ethiopia and for metal smelting in the Ugandan uplands. But the river was also cleaned and regulated by its passage through the swamps of Nubia, before it fell to the lower valley. The Nile also provided fish, both in the river and off the delta. The nutrients and fresh water brought down by the Nile supported fisheries throughout the eastern Mediterranean. The problem with the Nile flood was its unpredictability. Low floods occurred about twice a decade. The heights of Nile floods are connected to El Nino Events, which influence the northward reach of the Indian Ocean monsoon, and thus the extent of spring rains in Ethiopia. Two low floods in a row were a disaster. A flood can also be too great, remaining on the land too long and preventing the sowing of the winter crops. So, loosely speaking, the agricultural area would have supported a population that could store sufficient grain for 2 years. But population control is not the point of high civilisations, the timing of low or high floods wasn’t predictable, and since Early Dynastic times the population kept rising above the food supply. Periodic starvation was common. Of course over such a long period of time Egypt also had more severe climatic disasters. The end of the Old Kingdom was caused by 300 years of low floods. A drought in the eastern Mediterranean 3200 years ago stressed all the civilizations of the area. It helped in the collapse of Mycenaen Crete, already half-destroyed by a tsunami from the volcanic eruption on Santorini. The earthquakes that accompanied the eruption apparently compromised the island’s aquifers. The Cretans traded olive oil and wine for grain from the mainland; they also grew some wheat themselves; the drought reduced their crops and meant less grain was available from the mainland. Even in this lucky landscape, the Egyptians were caught between the constant increase in the human population and the behavior of the river.
Paddy rice constitutes another sustainable agricultural system. Tropical soils in humid climates, once cleared of their natural vegetation, are in general impervious and nutrient poor. The soils are old, and have been depleted by rainfall, plant respiration, and internal erosion. Most of their nutrients are concentrated in the vegetation that is removed. In paddy rice cultivation, the nitrogen that feeds the rice plant comes largely from blue-green algae that colonize the warm, slowly moving water that covers the paddy. The water itself, descending from the uplands, provides some nutrients (phosphorus and other minerals). Trampling and working of the paddy bottom makes the soil more or less watertight, so water and nutrients are retained. Fish and freshwater invertebrates grow in the paddies and the feeder canals. In the Lake Biwa basin of Japan, very old paddy fields are used by the lake’s catfish as a spawning area and nursery: that is, as an extension of the lake itself. This use is a benefit both to the farmers, who harvest some of the fish and whose rice is more productive, and to the fish. In some cases the nutrient-rich overflow from the paddies is led to duck ponds, whose algal and insect life (food for the ducks) is supplemented by grain. The ponds, their bottom muds fertilized by the algal and bacterial growth and by that cycled through the ducks, are periodically drained and planted to vegetables. Fertility of the paddies is also maintained by adding manure from the animals that plow them, human manure, ashes, the walls of demolished mud-brick houses impregnated with soot and grease from cooking.
The water buffalo whose manure ends up on the paddy and increases its yield of rice, is fed from forage cut in the nearby forest. Irrigation water also comes from the forest. So the forest is part of the paddy system. It also provides firewood, small game, material for building and basketry. Lowland rice-growing systems, irrigated by large rivers, also depend on a predictable supply of good quality water. These systems can be overwhelmed by timber cutting in the watershed and the change in the quality, timing and amount of water delivered to the paddies that this causes.
So some agricultural systems of “high” civilizations were sustainable, some not; some landscapes could stand more human development, some less. Any human civilization is a outgrowth of an existing landscape and climate, that is, of levels of rainfall and temperature, of sea levels, flood levels, the likelihood of extreme weather events. All agricultural systems can be pushed over the edge by too much development about them or by small climatic changes. Increase in population is often the problem, though technology also matters, in that technology magnifies the effects of population. In the 1800s, perennial irrigation to grow cotton (three crops a year) began to salinize Egyptian fields. The building of the dam at Aswan, which cut off the natural flow of water and silt, turned the Nile Valley into an unsustainable agricultural system. Salinization is now a problem, the fishery for sardines off the delta has collapsed, and without a yearly influx of silt, the land in the delta is receding.
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