Something New under the Sun: An Environmental History of the 20th-Century World

Prologue: Peculiarities of a Prodigal Century

The disadvantage of men not knowing the past is that they do not know the present.
--G. K. Chesterton (1933)

Environmental change on earth is as old as the planet itself, about 4 billion years. Our genus, Homo, has altered earthly environments throughout our career, about 4 million years. But there has never been anything like the twentieth century.
Asteroids and volcanoes, among other astronomical and geological forces, have probably produced more radical environmental changes than we have yet witnessed in our time. But humanity has not. This is the first time in human history that we have altered ecosystems with such intensity, on such scale and with such speed. It is one of the few times in the earth's history to see changes of this scope and pace. Albert Einstein famously refused to "believe that God plays dice with the world." But in the twentieth century, humankind has begun to play dice with the planet, without knowing all the rules of the game.
The human race, without intending anything of the sort, has undertaken a gigantic uncontrolled experiment on the earth. In time, I think, this will appear as the most important aspect of twentieth-century history, more so than World War II, the communist enterprise, the rise of mass literacy, the spread of democracy, or the growing emancipation of women. To see just how prodigal and peculiar this century was, it helps to adopt long perspectives of the deeper past.
In environmental history, the twentieth century qualifies as a peculiar century because of the screeching acceleration of so many processes that bring ecological change. Most of these processes are not new: we have cut timber, mined ores, generated wastes, grown crops, and hunted animals for a long time. In modern times we have generally done more of these things than ever before, and since 1945, in most cases, far more. Although there are a few kinds of environmental change that are genuinely new in the twentieth century, such as human-induced thinning of the ozone layer, for the most part the ecological peculiarity of the twentieth century is a matter of scale and intensity.
Sometimes differences in quantity can become differences in quality. So it was with twentieth-century environmental change. The scale and intensity of changes were so great that matters that for millennia were local concerns became global. One example is air pollution. Since people first harnessed fire half a million years ago, they have polluted air locally. Mediterranean lead smelting in Roman times even polluted air in the Arctic. But lately, air pollution has grown so comprehensive and large-scale that it affects the fundamentals of global atmospheric chemistry (see Chapter 3). So changes in scale can lead to changes in condition.
Beyond that, in natural systems as in human affairs, there are thresholds and so-called nonlinear effects. In the 1930s, Adolf Hitler's Germany acquired Austria, the Sudetenland, and the rest of Czechoslovakia without provoking much practical response. When in September 1939 Hitler tried to add Poland, he got a six-year war that ruined him, his movement, and (temporarily) Germany. Unknowingly--although he was aware of the risk--he crossed a threshold and provoked a nonlinear effect. Similarly, water temperature in the tropical Atlantic can grow warmer and warmer without generating any hurricanes. But once that water passes 26� Celsius, it begins to promote hurricanes: a threshold passed, a switch thrown, simply by an incremental increase. The environmental history of the twentieth century is different from that of time past not merely because ecological changes were greater and faster, but also because increased intensities threw some switches. For example, incremental increases in fishing effort brought total collapse in some oceanic fisheries. The cumulation of many increased intensities may throw some grand switches, producing very basic changes on the earth. No one knows, and no one will know until it starts to happen--if then.

This chapter examines the long-term histories of some of the human actions that change environments. The length of the long term varies from case to case, mainly because of differences in the availability of information. The actions and processes in question are sometimes easily measured, sometimes not. The accuracy of the data is also open to question. Despite these problems, it is possible to make some judgments about how peculiar the last century was, and in what respects it departed sharply from the patterns of the past.

Economic Growth since 1500

Most of the things people do that change environments count as economic activity. Economists habitually measure the size of economies by summing the total value of goods and services brought to market or otherwise officially noted. The addition yields a single figure, the gross domestic product, or GDP. This is a very imperfect procedure, especially for times and places where significant production (and delivery of services) take place outside of markets. Economic historians are keenly aware of the drawbacks of this measurement, and have tried to adjust their figures accordingly.
Five hundred years ago the world's annual GDP (converted into 1990 dollars) amounted to about $240 billion, slightly more than Poland's or Pakistan's today, slightly smaller than Taiwan's or Turkey's. Up to 1500 the world economy had grown extremely slowly over the millennia, mainly because (as we shall see) population had grown only slowly and improvements in productive technologies came very slowly by recent standards. After 1500, leading technologies were applied to the Americas and other regions, shipping became truly oceanic, and international trade grew. By 1820, the world's GDP had reached $695 billion (more than Canada's or Spain's, less than Brazil's in 1990s terms). The Industrial Revolution, further improvements in transport, and further development of frontier lands increased the rate of growth after 1820 so that in 1900, world GDP reached $1.98 trillion (less than 1990s Japan's). Indeed the period 1870 to 1913 remains one of spectacular growth spurts in the history of the world economy, faster than any that went before, and faster than much of what followed. After three decades of repressed growth (1914-1945) the world economy surged again, so that in 1950, world GDP attained $5.37 trillion (as large as the United States's economy in 1991). A long boom followed, based on more-open international trade, fast development of technology, and rapid population growth. By 1992, world GDP was about $28 trillion. This miraculous period of economic history, with all its upheaval, invention, organization, and suppression, is reduced to index numbers and growth rates in Table 1.1.

Table 1.1 Evolution of World GDP, 1500-1992 Date
1500
1820
1870
1900
1913
1929
1950
1973
1992
World GDP(a)
100
290
470
823
1,136
1,540
2,238
6,693
11,664
Source: Maddison 1995:19, 227.
(a) GDP figures are given in index numbers relative to A.D. 1500.

The world's economy in the late twentieth century was about l20 times larger than that of 1500. Most of this growth took place after 1820. The fastest growth came in 1950 to 1973, but the whole period since the World War II saw economic growth at rates entirely unprecedented in human experience.
Most of this economic expansion was driven by world population growth. The rest is owing to more productive technologies and organization (and perhaps harder work). Per capita figures (Table 1.2) show that while the world economy has grown 120-fold since 1500, average income for individuals has grown only 9-fold. This of course is a global average, and disguises huge variations among regions, countries, and persons.

Table 1.2 Per Capita World GDP since 1500 Year
1500
1820
1900
1950
1992
Per Capita World GDP
(1990 dollars)
565
651
1,263
2,138
5,145
Index Numbers
(A.D. 1500 = 100)
100
117
224
378
942
Source: Elaborated from Maddison 1995:228.

On average, we have nine times more income per capita than our ancestors had in 1500, and four times as much as our forebears had in 1900. Despite gross inequities in the distribution of this income growth--the average Mozambican today has an income well under half the global average of 1500--it must count as a great achievement of the human race over the past 500 years, and especially over the past century. The achievement has come at a price, of course. The social price, in the form of people enslaved, exploited, or killed so that "creative destruction" could make way for economic growth, is enormous. So is the environmental price. Historians in the past thirty years have appropriately paid great attention to the social price of economic growth and modernization; the environmental price deserves their attention too.

Population Growth since 10,000 B.C.

Population is much easier to measure than economic activity, so although estimates prior to 1900 must be treated with caution for most parts of the world, the following reconstruction is more reliable than the previous one.
When humans first invented agriculture (around, say, 8000 B.C.), global population was probably between 2 and 20 million. We were outnumbered by some other primates, such as baboons. But with agriculture came the first great surge in human numbers. Population grew much faster, probably between 10 and 1,000 times as fast as before, but nonetheless very slowly, by tiny fractions of a percent per year. By A.D. l, the globe supported around 200 or 300 million people (roughly equivalent to today's Indonesia or United States). By 1500, world population had reached 400 or 500 million. It had taken about a millennium and a half to double, and grew at a rate well under 0.1 percent per year. After 1500, world population continued to grow quite slowly, reaching 700 million around 1730. At this point it began to rise more quickly, beginning the long boom still in progress today. By 1820, human population reached a billion or so. Our spectacular biological success since then is sketched by the figures in Table 1.3.

Table 1.3 World Population since 1820 Year
1820
1850
1900
1950
1990
2000
Population (billion)
1
1.2
1.6
2.5
5.3
6.0
Annual Growth Rate (%)
--
0.5 (1820-1849)
0.6 (1850-1899)
0.8 (1900-1949)
1.8 (1950-1989)
1.5 (1990-1999)
Source: Cohen 1995:79 and app. 2.

Since the eighteenth century our numbers have grown extremely quickly by previous standards. And in the period since 1950, population has increased at roughly 10,000 times the pace that prevailed before the first invention of agriculture, and 50 to 100 times the pace that followed. If twentieth-century rates of population growth had prevailed since the invention of agriculture, the earth would now be encased in a squiggling mass of human flesh, thousands of light-years in diameter, expanding outward with a radial velocity many times greater than the speed of light. Clearly we will not keep the twentieth-century pace up for long. We are in the final stages of the second great surge in human population history. Demographers expect at most one more doubling to come. The twentieth century's global population history will be peculiar not only in light of the past, but in light of the future as well.
Another way to conceive of the extraordinary demographic character of the modern era is to estimate how many people have ever lived, and (with estimates about life expectancy) how many human-years have ever been lived. Such estimates require extra caution, of course. Some European demographic historians have made the heroic assumptions and subsequent calculations. They figure that about 80 billion hominids have been born in the past 4 million years. All together, those 80 billion have lived about 2.16 trillion years. Now for the astonishing part: 28 percent of those years were lived after 1750, 20 percent after 1900, and 13 percent after 1950. Although the twentieth century accounts for only 0.00025 of human history (l00 out of 4 million years), it has hosted about a fifth of all human-years.
Like the long-term course of economic growth, our population history also represents a triumph of the human species. It too, of course, has come at a price. In any case, it is an amazing development, an extreme departure from the patterns of the past--even though we tend to take our present experience for granted and regard modern rates of growth as normal. Bizarre events that last for more than a human lifetime are easy to misunderstand.
The long-term trajectories of economic growth and population growth followed one another closely for millennia. Only around 1820 did they begin to diverge sharply, with economic growth outstripping population growth--hence the rising per capita incomes. What made this possible were new technologies and systems of economic organization that allowed people to make far greater use of energy.

Energy History since 10,000 B.C.

Before the Industrial Revolution began, we had at our disposal the muscle power of our bodies and of some domesticated animals; the power (very inefficiently harnessed) of wind and water; and (for heat but not for power) the chemical energy stored in wood and other biomass. The Industrial Revolution changed everything because it brought engines that could convert into mechanical power the biomass energy stocks accumulated in the earth's crust over hundreds of millions of years: fossil fuels.
Physicists agree that the total quantity of energy in the universe is constant. On earth, energy is held in rough balance: what arrives from the sun as radiant energy is equivalent to what dissipates into space as heat. Energy can neither be created nor destroyed. Yet we commonly speak of energy production or consumption. The word "energy" is imprecise; the stuff hard to measure. The following reconstruction aims to be precise about what is meant by energy, but its quantitative elements deserve as much or more caution as the section on economic growth.
All our energy, ultimately, is nuclear energy, in that it comes from a nuclear fusion reaction in the sun. It exists on earth in several forms, the important ones for people being mechanical (or kinetic), chemical, heat (or thermal), and radiant. The problem for us is to get energy in a useful form in the right place and the right time for whatever we might wish to do. We do this by means of converters, which change energy from one form to another, making it easier to store, transport, or use for work. Many economic operations make use of several converters. Each conversion involves some practical loss, in that a proportion of the preconverted energy is dissipated (usually as heat) or otherwise rendered into a form that is useless, impossible to capture. Hence converters have efficiency ratings. Human beings, for instance, are about 18 percent efficient: for every 100 calories I eat as food (chemical energy), only about 18 are converted into mechanical energy; the rest are lost for practical purposes, mostly as heat. Horses' efficiency is only about 10 percent.
Before the Industrial Revolution, the only important converters were biological ones. The first human societies used only their own muscle power, derived from chemical energy stored in plants and animal flesh. Eventually, with a few tools, the deployment of this muscle power grew more efficient. The use of fire helped a great deal in heating, of course, and, when cooking was invented, rendered some otherwise inedible energy sources edible. But until roughly 10,000 years ago, for mechanical energy our ancestors depended on their own bodies in what one might call the "somatic energy regime."
Agriculture allowed people greater control over the plant converters we call food crops. Shifting agriculture probably increased energy availability 10-fold over that available through hunting and gathering, and settled agriculture another 10-fold. This translated into greater population densities. Then, as big animals were domesticated, people acquired more muscle power, more mechanical energy, in more concentrated form. Oxen for haulage and horses or camels for transport marked great improvements. Oxen could plow heavy soils, opening up new food possibilities, which in turn allowed for more people and more oxen in a positive feedback loop that extended and strengthened the somatic energy regime. Societies that did not domesticate large animals labored at a disadvantage. New crops, wheels, and horse collars improved the energy efficiency of societies over subsequent millennia, but even at the outset of the Industrial Revolution in Europe (c.1800), more than 70 percent of the mechanical energy used was supplied by human muscle. The fundamental energy constraints remained the amount of arable land and the amount of water to produce crops.
Agriculture and animal domestication did create an energy surplus. Controlling that surplus, applying it as one wished, and enjoying the returns from it constituted the stuff of politics--directing the somatic energy regime. If applied judiciously, in war or irrigation for instance, surplus might create a windfall of increasing returns that made someone rich or powerful indeed--pharaohs, for instance. Since people are more efficient than horses and far better than oxen as converters of chemical into mechanical energy, big domesticated animals were something of a luxury in preindustrial times. Slavery was the most efficient means by which the ambitious and powerful could become richer and more powerful. It was the answer to energy shortage. Slavery was widespread within the somatic energy regime, notably in those societies short on draft animals. They had no practical options for concentrating energy other than amassing human bodies.
An interesting feature of the somatic energy regime was its success in storing energy. In the form of heat or light or even electricity, energy is hard to store. Wind and direct solar power remain hard to store even with late twentieth-century technologies. Chemical energy in the form of plants is also hard to store, although with favorable conditions and appropriate techniques some crops can be stored for a few years, albeit with considerable wastage.
The vagaries of weather and crop pests caused the supply of food to vary greatly from season to season and year to year in preindustrial societies. This created a problem for society as a whole, and for its rulers, in that the available energy supply fluctuated uncontrollably and unpredictably over time. For rulers, the stock of human and domestic animal populations served as an energy store, a flywheel in the society's energy system. They could be put to work whether the primary energy source--plant crops--was bountiful or scarce. The stock could be built up in fat times and drawn down in lean times, but at virtually all times rulers could lay their hands on people and animals for their enterprises.
For ordinary people, livestock served the same purpose. They were a store of energy, one that could be raided when necessary to even out energy flows despite the inevitably uneven supply of staple foods. This provided households a flywheel in their domestic energy systems, proportional in size to the quantity of animals they owned (or could buy when needed).
The limits of the somatic energy regime were stringent. In a burst of effort, the human body can muster 100 watts of power. The most any society could devote to a given task, say ditch digging, dam building, or fighting, was--with people and animals as the main sources of mechanical power--a few hundred thousand watts. The Ming emperors and Egyptian pharaohs had no more power available to them than does a single modern bulldozer operator or tank captain. Expanding their territorial domain might increase rulers' total energy supply, a goal vigorously pursued, but it could not raise the total that they could apply to a single task since it was usually impossible to concentrate more than a few thousand bodies on a given construction project or battle.
The Industrial Revolution first augmented and then quickly outstripped human muscle power. Wherever it spread, it ended the somatic energy regime, replacing it with a much more complex set of arrangements that one might call the "exosomatic energy regime," but might better be called the fossil fuel age: to date the lion's share of energy deployed since 1800 has come from fossil fuels.
From ancient times forward, notably in Persia, China, and Europe, sails, windmills, and watermills added slightly to the somatic energy supply of agrarian societies. Incremental improvements followed for many centuries. But in the eighteenth century, steam engines tapped hundreds of millions of years' worth of photosynthesis, burning coal to convert chemical into mechanical energy. Coal of course had found uses for centuries, mainly as a fuel for heating. But the steam engine's capacity to convert that heat into mechanical energy capable of doing work opened up new possibilities.
The first steam engines were notoriously inefficient, losing more than 99 percent of their energy. But gradual improvements by 1800 allowed efficiency of about 5 percent and a capacity of 20 kilowatts of power in a single engine, the equivalent of 200 men. By 1900, engineers had learned how to handle high-pressure steam, and engines became 30 times as powerful as those of 1800. On top of this, steam engines, unlike watermills and windmills, could be put anywhere, even on ships and railroad locomotives. This created another positive feedback loop, in that it allowed transport of coal on a massive scale, providing the fuel for yet more steam engines. Nineteenth-century industrialization rested on this fact. World coal production, about 10 million tons in 1800, shot up 110-fold by 1900.
By 1900 another major departure was underway: internal combustion engines using refined oil. A Scot, James Young, figured out how to refine crude oil in the 1850s, and an American, Edwin Drake, proved in 1859 that oil could be drilled through deep rock. The oil age had begun, albeit in a small way. Internal combustion engines, developed mainly in Germany after 1880, furthered the transition. They weighed less than coalfired steam engines, they were much more efficient, especially at small scales. On larger scales they could deliver much more power than steam engines. The provision of electricity needed power on such a scale; and automobiles required lightweight and efficient engines.
So from 1900 forward, biomass, coal, and oil provided large quantities of energy. In terms of usable energy, fossil fuels overshadowed biomass from the 1890s forward, even though the great majority of the world's population used no fossil fuels directly. Production and use of all three fuels grew throughout the twentieth century, although oil use grew much faster so that in proportional terms the other two declined. Some estimates of world fuel production and the usable energy derived therefrom appear in Tables 1.4 and 1.5. Not only did fossil fuels largely replaced biomass in the global energy mix in the twentieth century, but the total energy harvest skyrocketed. The electrification of the globe, begun around 1890 and still in train, boosted demand and use of energy. Electric motors are highly flexible and have countless uses. Electricity also is good at providing light and heat. Lenin famously defined communism as electrification plus Soviet power, and rural electrification was a major achievement of Franklin Roosevelt's presidency.

Table 1.4 World Fuel Production, 1800-1990 Production (millions of metric tons) Type of Fuel
Biomass
Coal
Oil
1800
1,000
10
10
1900
1,400
1,000
20
1990
1,800
5,000
3,000
Source: Elaborated From Smil 1994:185-7.
Note: These figures do not reflected the energy yield of these fuels: a ton of oil gives 5-10 times as much energy as a ton firewood, and perhaps twice as much as a tone of coal.

The worldwide energy harvest increased about fivefold in the nineteenth century under the impact of steam and coal, but then by another sixteenfold in the twentieth century with oil, and (after 1950) natural gas, and, less importantly, nuclear power. No other century--no millennium--in human history can compare with the twentieth for its growth in energy use. We have probably deployed more energy since 1900 than in all of human history before 1900. My very rough calculation suggests that the world in the twentieth century used 10 times as much energy as in the thousand years before 1900 A.D. In the 100 centuries between the dawn of agriculture and 1900, people used only about two-thirds as much energy as in the twentieth century.

Table 1.5 World Energy Use, 1800-1990 1800 1900 1990 Total (millions of metric tons of oil equivalent) 400 1,900 30,000 Indexed (1900 = 100) 21 100 1,580
Source: Elaborated from Smil 1994:187.

This astounding profligacy, too, counts as something of a triumph for the human species, a liberation from the drudgery of endless muscular toil and the opening up of new possibilities well beyond the range of muscles. Even on a per capita basis energy use grew spectacularly, four- or fivefold in the twentieth century. In the 1990s the average global citizen (an abstraction of limited utility) deployed about 20 "energy slaves," meaning 20 human equivalents working 24 hours a day, 365 days a year. The economic growth of the last two centuries, and the population growth too, would have been quite impossible within the confines of the somatic energy regime.