Can the present interglacial time be legitimately distinguished from preceding interglacial intervals of the Pleistocene? Geologists often call this the Holocene, the “completely new” epoch. It was in 1839 that English geologist Charles Lyell coined this term and others from the Greek to designate different ages of the Quaternary period: Pleistocene—the most recent, Pliocene—more recent, Miocene—less recent, and Eocene—the dawn of the recent. Lyell’s completely new epoch now is part of our recent past, and in fact, the major distinction between the present Holocene and previous interglacial intervals—the most recent of which was 120,000 years ago—lies in the growing global impact of human activities. Without this new factor, the ice would almost certainly advance again, sometime in the next 20,000 years. Following that, for more than 100,000 years, climate could be expected to alternate between cold and very cold. After a new glacial paroxysm similar to the last one 18,000 years ago, ice would finally retreat and climate switch back to an interglacial interval similar to that of the last 10,000 years. Will the ice come back? Human activities are something new under the Sun. If indeed anthropogenic reinforcement of the greenhouse effect prevents the return of the ice, we shall indeed be entering truly new times, a Holocene epoch in the full sense, an epoch that should perhaps even be called “anthropocene.”
It’s hard enough to see clearly what is likely to happen in the next few decades; does it make any sense to theorize about coming millennia? If the ice caps return to Canada and Europe in twenty thousand years, there will have been ample time for humans to have exhausted all fossil fuels and to see (if any humans are still around to see) the CO2 added to the atmosphere taken up again by vegetation and the oceans. With global warming induced by the anthropogenic intensification of the greenhouse effect, the ice caps may well melt completely away (but probably over a period of 3,000 years rather than 60 or 300) and sea level may rise, but since in past ages the ice returned many times to cover land from which it had retreated, why should it not do so again, once or twice or even twenty times?
FROM THE TWENTIETH TO THE 21ST CENTURY
Enough time spent on the millennia. What about the next century or two? Thirty years ago, rather than greenhouse warming, some scientists feared a rapid return of the ice, with a sort of “snowblitz” covering large areas of Eurasia and North America with a strongly reflecting layer of snow too thick to melt away in the spring.1 Since 1957, however, the measurements have revealed the continuing increase of atmospheric carbon dioxide, while over the same period temperature fluctuations switched from irregular to a marked warming trend since 1975. Since the 1980s, discussion of the risks associated with continued dependence on fossil fuels refers to scenarios and climate model simulations for the entire 21st century and in some cases up to the year 2400. I often wonder what people will think of our predictions then. Still, land use planning and investments in equipment and facilities having long lifetimes—dams, roads, bridges, power plants—must make a gamble on what the future will be like. Although predictions of change for the coming century are inevitably full of uncertainties, they are certainly not less likely than the implicit scenario of absence of change that the merchants of coal and oil would have us take for granted.
Climate models cannot yet give reliable predictions of how distributions of rainfall, evaporation, and soil moisture will change, even for a date as close as 2050. To reduce the uncertainties calls for sustained monitoring and research, especially since improved understanding of what becomes of the water falling on the land will make it possible to use the water resource more effectively. In fact, enormous advances have been made. In 1900 wheat production barely exceeded one ton per hectare (about two tons per acre). And in India, where wheat production was only 0.83 ton per hectare in 1965, the “green revolution” multiplied total production by a factor 5 without doubling cultivated land area. Even today, however, less than one ton per hectare is produced in many dry areas of Africa. Chemical fertilizers count as a major contribution of modern technology to such agricultural productivity gains not requiring additional water. Of course, that involves new risks, especially when too much fertilizer is applied, and it does not eliminate the need for water; optimum application requires tradeoffs between protection of the water table, increase of agricultural productivity, and safeguard of tomorrow’s soils.
Let’s not forget another contribution of technology to production of food for the human population. Tractors have taken the place of horses, mules, donkeys, and oxen, who used to do most of the heavy work, and large draft animal populations are no longer needed. In 1910 production of animal feed required 30 percent of the farm acreage in the United States. Of course, populations of cattle, sheep, and pigs continue to increase to satisfy growing demand for meat and milk, but farmers in advanced countries no longer need to set aside a significant part of their production to feed draft animals. In the Third World countries, by contrast, hundreds of millions of oxen, water buffalo, camels, donkeys, horses, and mules eat food that could otherwise feed 700 million persons. Note also that production of meat eaten by a fairly small minority of the world’s people requires food that could otherwise feed some three billion people. To each of these figures corresponds a figure giving the needs in water and farmland. Only by increasing the amount of food produced per hectare (or acre, or dunam, or feddan) has it been possible to nourish (not always well) the growing human population, without farming the entire land surface of the planet. Have these enormous gains in productivity been attained without damage to the “sustainability” of agriculture, by erosion or by deleterious chemical alteration of the soil? Some agronomists believe that productivity can still be multiplied by another factor 5, whereas others believe that modern agricultural methods cannot safely be pursued for many decades more. A vital debate.
Another problem for the future: modern technology depends on harnessing energy, to a large extent by exploiting nonrenewable resources; moreover, it involves new insults to the human or natural environment. We no longer have to clean up tons of horse manure from the streets of our cities and towns, and the clatter of hooves on the pavement has gone, but obstinate insistence on using private automobiles, even in crowded cities, often brings as much or more noise and stink. Outside cities, more and more broad highways crisscross fields and forests and make it harder and harder for whatever wild animals are left to move around. Instead of growing fodder for horses, we import oil. Even those who don’t take seriously the risks of intensification of the greenhouse effect must recognize that our dependence on black gold has its own costs, both for the environment (consider the oil spills by Exxon Valdez off Alaska, by Amoco Cadiz off Brittany) and for society as a whole (the Gulf War). It will take millions of years to renew the oil resource we dilapidate so rapidly. Much more coal still lies in the ground, but mining scars the land and takes lives, and exploitation of some resources such as the Colorado oil shale is impractical considering limited available water resources, at least with today’s technology. Can the world’s energy needs be satisfied without expanding the use of nuclear power? Can enough energy be produced from renewable resources, essentially solar, including biomass burning (but water is needed to grow the plants to be burned) and hydroelectric power from the many still unexploited high-potential sites (as well as wind and waves)? Thermonuclear fusion produces the Sun’s energy, but on Earth is controlled fusion a real option, or a mirage? In any event, it should not be forgotten that for the next few decades, the energy source most easily harnessed, at least in advanced countries, is today’s wasted energy. With truly modern technology, with enough political will to do away with hidden subsidies of outmoded industries and fossil fuel producers, we can do more with less, perhaps ten times less.2
World population will almost certainly pass the eight billion mark sometime in the 21st century, and it may approach twelve billion. Such large populations can be fed, but in the absence of additional water resources, without new ways to multiply water use efficiency, agriculture will have to take over practically all the world’s land and tap all the world’s flowing freshwater. How can anyone find such a prospect acceptable? Even apart from nature lovers nostalgic for wilderness unsullied by humans, how many people really want to live in a world that would end up being nothing but a gigantic agro-industrial complex? Increasing the water resource is conceivable, in particular by going after water flowing in rivers considered inaccessible up to now. The rivers flowing north to the Arctic may well be exploited before the end of the 21st century, although plenty of questions remain unanswered concerning the consequences of such freshwater withdrawals for Arctic ice cover and snowfall on surrounding lands. Hardly anyone evokes anymore the various grandiose projects for the Congo River and Lake Chad basins, and the idea of flooding the vast Saharan Desert areas below sea level. In 1910 such schemes were promoted with the idea of “enhancing the value of Africa as a land for settlement and colonization by Europeans,” without asking what the Africans thought of the idea. In another context, even as late as 1977 there were optimists to write: “During the years of Soviet power, many areas that were ‘dead’ or unproductive deserts only a few decades ago have been turned into flourishing districts of developed industry and agriculture."3 Today, such problems are approached in a new light, both from the political and from the technical and scientific points of view, and specialists and lay citizens alike are more aware of the snares and traps of taming nature. Still, we can learn a lot over the coming century, and the dream of making deserts bloom may well become a more common reality. Not that I would approve of greening all deserts. The stark bright desert landscape, a precious part of our heritage as inhabitants of this planet, reveals clearly the past history of running water on the land. But deserts cover vast territories, and gardens, like the oases created as stopping places for caravans carrying salt in exchange for gold across the Sahara, have their own, human-created beauty. Eden was a garden, not a forest—a God-created garden (Genesis 2:8), but at the same time a garden created by Man (and Woman), to whom the Creator gave the task of working the land so that it would bear fruit.4
How can we make better use of our resources? The Sun is always shining on the Earth, and the Earth must get rid of the solar energy that it absorbs and turns into heat by radiating it away as infrared to space. However, our planet’s water cycle operates in a practically closed circuit, transforming and transporting an enormous (but by no means infinite) stock of water. A space station also operates in this way, with a much more limited water stock; and as cities grow, they will end up by having to operate that way too, as already should factories. Up to now, agriculture has been very different, because even though water transpired by crops ends up in the planetary cycle, it returns to the land only after the long detours of atmospheric circulation, cloud formation, and precipitation in convective or cyclonic disturbances. Certainly the water resource can and must be used more efficiently—for example, using drop-by-drop irrigation to keep evaporative losses to a minimum and to make sure the water benefits the crop. But since we are worried about the greenhouse effect, why not one day grow crops with a much shorter water cycle entirely confined within a greenhouse? Even if such greenhouses were to be horribly technological facilities, wouldn’t they make it possible to leave larger areas of forest, prairie, or desert in their “natural” state? Today, the idea of feeding billions of humans with crops thus grown may appear to be a pipe dream or science fiction, and it may be another crazy idea of a theoretician who has never built a greenhouse, but tomorrow, if we can develop sufficiently light-weight and sturdy materials, transparent to sunlight but opaque to infrared rays, why not? For the most part, twentieth-century science and technology went far beyond the “reasonable” predictions made in 1900, and compared with what is happening with computers and biotechnology, thousand-square-mile greenhouses may one day be considered almost ordinary!
Doomsayers have always been with us. In 1948, when Americans were preparing CARE packages (Cooperative for American Remittances to Europe) to help starving European populations to pick up after the disasters of World War II, New York ornithologist William Vogt published a best-selling book, Road to Survival, in which he argued that Europe as well as Asia would have to reduce their populations substantially if they were to survive. And time and time again, distinguished voices have proclaimed that we are on the way to famine, that the “death of the oceans” is nigh. But catastrophe is not inevitable, except for those who consider our very existence as human beings on this planet to be a catastrophe. I can empathize with nostalgia for an imagined lost state of nature, but I know that nature unsullied by humanity disappeared more than 8,000 years ago when farming began. I also am convinced that the end of that nature has created possibilities that we humans would not gladly give up. There’s no way back. We humans are condemned to exercise stewardship over the Earth, managing the land and the water, and we can do it and protect nature at the same time. But we must accept that a protected nature, even if not a human creation, requires at least that we humans work together with nature and accept our responsibility for it.5