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5 Humanity: An Agent of Global Environmental Change The automobile, one of the most pervasive symbols of mod- ern culture, serves as an apt metaphor for the ways in which humans change the global environment. Automobiles emit car- bon dioxide that adds to the buildup of greenhouse gases in the atmosphere, nitrogen oxides that react in the atmosphere and rain down as acid deposition, and other gases and particulates that contribute to smog and local air pollution in our urban areas. Today there are 500 million registered automobiles through- out the world, each of which burns an average of nearly 2 gallons of fuel a day. Automobiles consume one third of the world's production of oil. As the population grows, so will the number of automobiles. In addition, the average number of automobiles per person is going up, and the number of au- tomobiles is increasing faster than the population, particularly in developing countries. Some estimate that if current trends continue, by 2025 there will be 4 times as many automobiles as there are today. Paul Ehrlich, a population biologist at Stanford University, 49
50 THE EARTH AS A SYSTEM and John P. Holdren, an expert on energy and resources at Berke- ley, pointed out in the early 1970s that the damage that humans cause to the environment is a product of three factors: the total number of people, how much each person consumes to main- tain his or her standard of living, and how much environmental damage is incurred in producing the goods consumed. To pur- sue the automobile metaphor a moment longer, the same can be said for the environmental damage caused by automobiles or, for that matter, factories or other manifestations of society. For instance, the future environmental damage from automobiles depends not only on the total number of people owning them and the rate at which the number of automobiles per person in- creases but also on how much pollution each automobile emits. There are also signs that trends can be reversed. While ad- vances in technology in the early 1900s made it possible for the automobile to preempt the horse as a mode of transportation, technology has also reduced the amount of pollutants emitted from each automobile. In the United States, for example, ni- trogen oxide emissions from automobiles dropped substantially once catalytic convertors were required In all new cars. Ehrlich and Holdren's equation embodies a simple and powerful truth. Our ability to change the global environment in- creases along with our numbers, our quest for and achievement of affluence, and our technological and institutional capabilities (which can also provide means to alleviate environmental ciam- age). These intertwining factors, the product of decisions made by individuals and societies around the world, are the main forces driving change in the global environment. POPULATION, AFFLUENCE, AND TECHNOLOGY: HOW HUMANS CHANGE THE ENVIRONMENT A discussion of the human causes of global environmental change would not be complete without mention of the pressures that the sheer numbers of people inhabiting the earth place on the environment. Between 1950 and 1987, the global population doubled from 2.5 billion to 5 billion. This increase in the span
HUMANITY 11 10 . _ of 0 7 6 5 CL 4 o _ 9 _ 8 _ 3 _ 2 _ o World ~ Developing Regions' '\\\ 1750 1800 1850 1900 1950 YEAR 51 2000 2050 2100 Population growth, 175~2100. (Reprinted, by permission, from Thomas W. Merrick et al. 1986. "World Population in Transition," Population Bulletin, vol. 42, no. 2, Figure 1, p. 4. Copyright 2) 1986, Population Reference Bureau, Inc.) of less than 40 years equaled the total increase in the worId's population from the time the human species first emergect until the middle of the century. The United Nations estimates that by 2025 our numbers will increase to S.5 billion before stabilizing at over 10 billion by the end of the coming century. N~nety- five percent of the population growth will be in developing countries. This enormous increase in the numbers of people over the past century and the eventual stabilization in the total number of people are the product of the "demographic transition." With the industrialization that began in the last century in what is now the developed world, improvements in public health and medical advances caused death rates to decline. The improved socioeconomic conditions and access to health care and educa- tion that followed led to a drop in birth rates. When declining birth rates catch up with declining death rates, population even- tually stabilizes. Indeed, the current net population growth in developed countries is generally very low. In the developing world, in contrast, death rates have de- clined, but birth rates have not yet fallen enough to compensate.
52 THE EARTH AS A SYSTEM The result is the very rapid population growth in developing countries that we see today. However, birth rates in many devel- oping countries have begun to taper off in the past few decades, although the rate of decline differs among countries. In many African countries, for example, demographers expect that rates of population growth will not decline until at least the end of this century. Demographers base their predictions of the world's future population on assumptions about how quickly birth rates will decline. If the rates do not decline as rapidly as assumed, the world's population will grow even faster than the United Na- tions currently predicts. The explosion in the numbers of people inhabiting the earth is significant because, at the very least, each of these people re- quires food, clothing, and shelter. Growing numbers of people cut forests for land to grow food or graze cattle, with global consequences for the hydrologic cycle, the ability of the land to sustain agricultural productivity, and the earth's genetic re- sources as millions of plant and animal species are driven to extinction. Growing numbers of people in industrialized and industrializing societies use energy derived from fossil fuels to travel, produce goods, and apply advanced agricultural tech- nologies, with global consequences for atmospheric concentra- tions of greenhouse gases, climate, and ecosystems. But the impacts that the expanding numbers of people are having on the global environment are not solely a matter of the numbers of people; they also reflect how humans and the societies they live in use natural resources (which is, in turn, driven by economic and political structures as well as social values and norms). Societies use the air, water, and land as repositories for the waste products from industries that produce the goods that are consumed. They use fuel to drive cars, heat homes, and power industries. They convert raw materials such as wood and metals into consumer products and allocate land and fodder for animals that become food. If these resources are used in ways that emit excessive pollutants, clear forests, or deplete the soil of nutrients, the more societies consume to
HUMANITY 53 satisfy their standard of living, the greater the damage to the environment. The earth's inhabitants clo not exert equal pressure on the environment. Each person in an industrialized country uses far more natural resources and generates far more waste through- out his or her lifetime than a person in a developing country. The wealthy countries of the world constitute about one quarter of the global population but consume 80 percent of the worId's commercial energy. Stated another way, each person in a devel- oped country consumes on average about 32 barrels of crude of} per year, whereas a person in a developing country con- sumes only about 3.5 barrels. Energy use in many developing countries has been growing faster than population growth, but developing countries still consume 4 to 7 times less energy per person than their counterparts in the developed world. Thus carbon dioxide, the predominant greenhouse gas pro- duced as fossil fuel is burned for energy, is disproportionately emitted as a result of energy consumed in the industrialized countries. About 40 percent of all carbon dioxide builcting up in the atmosphere is emitted from seven wealthy countries in North America and Western Europe. These seven countries make up only I! percent of the worId's population. While the numbers of people and their levels of affluence clearly influence the environment, the kind of technology used ultimately determines how much pollution is emitted or what kinds of and how much raw materials are used. In many in- dustrialized countries, technologies to control emissions have in recent decades led to significant improvements in the air quality of many cities and the water quality in many lakes and rivers. Meanwhile, the amount of energy used to produce a unit of gross national product known as the energy intensity- has declined in the industrialized world, by one fifth between 1973 and 1985. In the United States, according to John H. Gibbons, director of the U.S. Congress's Office of Technology Assessment, and colleagues, the gross national product grew 40 percent in these years while energy consumption remained constant. Many who study technological trends perceive industrial
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HUMANIl-Y 55 economies to be undergoing a process of "dematerialization," a decline in the weight of materials and the amount of energy con- sumed in providing a given product or service. Undoubtedly, many consumer products such as automobiles, televisions, and calculators have become lighter and smaller. This trend means people can maintain a certain standard of living while using smaller amounts of raw materials and energy and creating less waste. But, as Robert Herman, of the University of Texas at Austin, and colleagues Siamak Ardekani, of the University of Texas at Arlington, and Jesse Ausubel, of The Rockefeller Uni- versity in New York City, note, some trends may counterbalance these benefits. People migrating from urban to suburban areas require more roacts, single-unit houses, and automobiles and demand more products as the definition of "basic necessities" changes. Such tendencies could offset some of the savings in waste, energy, and raw materials achieved through dematerial · - Gabon. Continued industrial development has serious implications for the future global environment, particularly if developing countries adopt older technologies that generate more pollu- tion and consume more energy than more modern technologies. Clearly, though, economic growth is required to break the cycle of poverty and high birth rates that itself causes severe environ- mental damage to the soils, water, forests, and wildlife in many developing countries around the world. The experiences of de- veloped and developing countries alike indicate that improved standards of living-adequate shelter, fuel, and clothing, as well as access to education, health care, and employment led to a sustained reduction in birth rates. Whether this was because of improved access to birth control or greater rights for women or because with socioeconomic development parents no longer need many children to ensure financial security is a complex question. Nevertheless, the fact remains: As economies have grown and standards of living have improved, birth rates have declined.
56 THE EARTH AS A SYSTEM CHANGING THE FACE OF THE EARTH: AGRICULTURE AND INDUSTRY Humans do not tread softly on the earth. In fact, the effect of human activity is so pervasive that In just a few centuries the earth's surface has been transformed such that in many places its original state is difficult to imagine, much less restore. This transformation wrought by the immensity of human numbers, by increasing affluence, and by technology has captured the popular imagination in recent years as more people realize that their world, and their children's futures, may be jeopardized by unchecked environmental changes. The recognition that hu- mans are a powerful agent in transforming the earth dates back much further, however. George Perkins Marsh in the nineteenth century, the Russian mineralogist W. T. Vernadsky in the first half of this century, and contributors to the now classic work, Man's Role in Changing the Face of the Earth (1956), edited by William L. Thomas, Jr., each expressed the ties between the global environ- ment and human development. B. L. Turner Il. who heads the program on The Earth as Transformed by Human Action, at Clark University, points out that two types of transformations of the earth most affect the global environment: changes in how humans use the land, most notably for agriculture, and changes in industrial capabilities. Over the past three centuries or so, as the area of land used for agriculture spread and the global economy expanded, hu- mans were increasingly prone to adapt land to suit their own purposes. This control is most visible in the profound changes in the vegetation that covers the earth's surface. The land area devoted to cropland has expanded by 450 percent in the past 300 years, amounting to a world increase of about 12.4 million square kilometers. The net loss of forests due to human action from the time humans first began cutting trees amounts to 15 to 20 percent of the worId's forested area, or about ~ million square kilometers. Also in the past three centuries, the popula- tion of the 40 largest urban areas increased about 25-fold, with an even greater increase in estimated urban area. Such changes
HUMANITY 57 have drastically altered the earth's surface, as well as the en- ergy balance, the hydrologic cycle, the emissions of biologically produced gases to the atmosphere, and the vegetation. Industrial clevelopment, too, has a potent effect on a global scale, through pollutants and other materials that are introduced into the biosphere, atmosphere, and oceans. Industrial devel- opment has vastly improved human well-being, but there have been unexpected side effects. ChIorofluorocarbons (CFCs) were invented around 1930 and were hailed, for instance, as safe al ternatives to ammonia and other coolants that had a tendency to leak and cause explosions when used in home refrigerators. No one could foresee the repercussions of these seemingly safe, stable, and inexpensive compounds on the global environment. Certainly, no chemist imagined that CFCs destroy the ozone layer about 25 miles above the earth, which shields us from solar ultraviolet radiation, or that CFCs contribute roughly 25 percent of the warming caused as greenhouse gases build up in the atmosphere. Other examples abound of what Paul Gray, president of the Massachusetts Institute of Technology, calls the "paradox of technological development." Writing in the 1989 National Academy of Engineering publication Technology and Environ- ment, Gray observed that "New technology will be applied in ways that transcend the intentions anc! the purposes of its cre- ators, and new technology will reveal consequences that were not anticipated." A few decades ago, asbestos fibers were hailed as a breakthrough for fireproofing ships, schools, and office buildings, but today they are known to cause Jung cancer. The "green revolution" that improved food production around the world and enabled countries such as India to become net ex porters rather than importers of food has contributed to the chemical pollution of rivers, lakes, and seas because it relies heavily on the use of insecticides and fertilizers. Energy is fundamental to inclustrial development, and the sources used to derive that energy have had particular impli- cations for the environment. With the Industrial Revolution In the early 1800s, fuel wood and water power gave way to coal
58 THE EARTH AS A SYSTEM 50 45 40 3~ 30 m 25 ~ _ 20 15 10 5 o Oil . , ! :r~ Gas · I / Cat - Wood ~ 1860 1880 1900 1920 1940 YEAR 1960 1980 20~00 Trend for U.S. fossil fuel consumption (in British thermal units, BTUs) since 1850. Data for 1850 to 1880 from U.S. Bureau of the Census (1975); data from 1880 to 1932 from U.S. Geological Survey, Yearbooks (1880-1932); data from 1933 to 1980 from U.S. Bureau of Mines, Mineral Yearbooks (1933-1980). (Reprinted from National Research Council. 1986. Acid Deposition: Long-Term Trends. National Academy Press, Washington, D.C.) and coal-based technologies such as iron smelting and steam engines. By the early 19OOs in the United States, coal, which generates large amounts of carbon dioxide and other pollutants, supplied most of the energy for the nation's factories. Industri- alized countries currently generate between 20 and 30 percent of their energy from coal. Natural gas, which currently provides about one fifth of the worId's commercial energy, generates fewer pollutants and less carbon dioxide than any other fossil fuel. Today, fossil fuels (oil, natural gas, and coal) supply SS percent of the worId's commercial energy, and nuclear energy provides the rest. In many poor countries, noncommercial fuels such as wood, dung, and crop waste still provide much of
HUMANITY 59 the energy for cooking and heating. Clearly, the future of the global environment depends to a large extent on the sources of energy for current and future societies and the amount of energy consumed. THE FUTURE The global consequences of industrial development as prac- ticed today cannot be denied. Waterways, soils, and forests bear the signature of acid deposition; the annual hole in the ozone layer marks human-induced depletion of this protective gas. These environmental changes may be unacceptable costs of progress, and yet development must continue, albeit in a less damaging form. The gap between rich and poor can be nar- rowect only by the economic development necessary to meet the needs and aspirations of the worId's poor today, as well as the needs and aspirations of tomorrow's growing population. The challenge, in the words of km MacNeill, director of the Environ- ment and Sustainable Development Program at the Institute for Research on Public Policy in Ottawa, Canada, and a contributor to Our Common Future, the 1987 report of the U.N. World Com- mission on Environment and Development, is to "emphasize the possibilities for a 'new era of growth'-not the type of growth that dominates today but sustainable growth, growth basect on forms and processes of development that do not undermine the integrity of the environment on which they depenct." In one such approach, Robert Frosch and Nicholas Gal- lopoulos, of General Motors, suggested in the 1989 Special Issue of Scientific American that the traditional mode! of industrial activity in which individual manufacturing processes take in raw materials and generate products to be sold and waste to be disposed of should be transformed "into a more Integrated model: an industrial ecosystem." Like its analog in the biolog- ical ecosystem, such an industrial ecosystem would optimize consumption of energy anct materials, minimize waste gener- ation, and use the effluents of one process whether fly and
60 THE EARTH AS A SYSTEM bottom ash from electric-power generation or discarded plas- tic containers from consumer products as raw materials for another process. Just as humans can transform the face of the earth, we can also mitigate some of the adverse effects. Methods exist that could shape the future environment, including regulatory con- tro! and market adjustments in which prices of goods account for the environmental damage they produce (the price of gaso- line could, for instance, reflect the costs associated with smog, global warming, or acid deposition), as well as changes in social values and norms. William Ruckelshaus, former head of EPA, notes that history offers examples in which nations have mobi- lizecl to synthesize short-term interests with longer-term goals. During World War IT, for instance, when people believed that the nation's survival was at stake, seemingly impossible politi- cal and economic changes were accomplished in a remarkably short time. The entire U.S. population was mobilized: Work pat- terns changed, prices and supplies of goods were manipulated and controlled, and the nation's industrial plants were swiftly reorganized. Even though government agencies and international organi- zations are structured to deal with environmental and economic issues separately, these issues are in fact interlocked. "Global warming is a form of feedback from the earth's ecological system to the worId's economic system," MacNeill observes. "So are the ozone hole, acid rain in Europe and eastern North America, soil degradation in the prairies, deforestation and species loss in the Amazon, and many other environmental phenomena." These phenomena are the faces of global change.