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Updated 11 November 2004

Consequences Vol. 1, No. 3, Autumn 1995








The Environment Since 1970

by Jesse H. Ausubel, David G. Victor, and Iddo K. Wernik

In the minds of many, 1970 marked the beginning of the modern environmental movement, symbolized by the first observance of "Earth Day" in the spring of that year. In the ensuing quarter century we have built personal computers and engineered genes. We have ended the Cold War, the Berlin Wall and apartheid in South Africa. And we have felt deepening environmental concern, punctuated by drought in the Sahel, accidents in Bhopal and Chernobyl, and spilt oil in France, Ireland, and Alaska.

It would seem a good time to take stock of what has happened in these twenty-five years insofar as the environment is concerned. This review considers environmental change in three ways. The first assesses the underlying forces of economic and population growth. The second includes indicators of the environment itself. The third examines changes in management and institutions. In all cases, we seek quantifiable, objective measures while recognizing that not all important changes are or can be measured. We deal mainly with averages over large areas and the twenty-five year period under consideration. Averages by definition sum fluctuations and mix the bad and sad with the good and happy. We observe what people have done rather than what they say. We recognize the great interest in changes in moods and attitudes with respect to the environment. These may generate and amplify the actions on which we report. However, we limit ourselves here to a factual survey of phenomena that can be recognized and counted in a relatively impartial way.

The data on which we rely are mostly collected by national governments. They are compiled periodically in reports of the U.S. government, United Nations organizations, the Organization for Economic Cooperation and Development (OECD), the World Resources Institute, and other groups. The most important of the sources are identified at the end of the article.

Underlying Forces of Environmental Change


In 1970 the population of the Earth was estimated at 3.7 billion. In 1995 it is believed to have reached 5.7 billion, with more than 90 percent of the growth in developing countries. Population growth slowed in the last two and a half decades, but only to a rate that leads demographers to hope that global population may eventually stabilize between double and triple current levels. While in 1970 about 65 percent of the world's population remained rural, by 1995 that fraction had dropped to 55 percent, with the ever-growing remainder concentrated in towns and cities. Urbanization has been fastest in developing countries, where cities grew by almost one billion people. The continuing heavy toll from "natural" disasters is strongly associated with large and growing populations in risk-prone areas, such as flood plains and low-lying coastal regions. The frequency of natural hazards, such as earthquakes and severe storms, has not changed, nor has their apparent take of human lives. However, increased human wealth and unwise development have caused property loss from such events to rise several fold.

Energy use

Total commercial energy consumption grew at the same rate as population, from the equivalent of a little over five billion tons of oil in 1970 to just under eight each year today. Thus, global per capita commercial energy consumption has remained roughly constant. Per capita commercial energy consumption in low-income countries more than doubled. Still, absolute consumption remains concentrated in the wealthy industrialized nations, where 15 percent of the world's population consume over half the energy used.

While energy use has increased, so have estimates of the energy available, in the form of resources that might eventually be tapped. Contrary to expectations that the world would begin to exhaust its supply of so-called fossil fuels, proven reserves of oil have increased from 600 billion barrels in 1970 to 1,000 billion today, even though over 500 billion barrels have been pumped from the ground in that time. Proven reserves of natural gas have tripled over the last twenty-five years. The possibility that environmental concerns such as the build-up of atmospheric greenhouse gases would diminish because of the depletion of exhaustible resources has thus become more remote.

In some respects, the global energy system has evolved in a cleaner direction in the last twenty-five years. While many were predicting increased reliance on "dirty" fossil fuels such as coal and oil shale, the reverse is taking place. The share of world primary energy derived from natural gas--the cleanest fossil fuel--has increased by more than 25 percent. Compared with coal and oil, burning natural gas releases lower quantities of carbon dioxide and of pollutants such as sulfur dioxide and the solid particles formed in smoke.

Between the early 1970s and 1990, the energy intensity, measured in energy used per dollar of gross domestic product (GDP), decreased in fits and starts in nineteen of twenty-four advanced industrialized nations belonging to the Organization for Economic Cooperation and Development (OECD). Energy efficiency has increased, spurred by the 'oil price shocks' of 1973 and 1979. The continuing, average rate of improvement in the OECD nations doubles efficiency in about thirty years. Still, the overall efficiency of energy production remains extremely low: on average, more than 90 percent of energy consumed is lost or wasted in the process of conversion from raw materials such as coal to the final energy service such as the light to read a book. The energy efficiencies today in India and China are similar to that of Europe early in the Industrial Revolution. Further large increases in energy efficiency are clearly attainable through the dissemination and use of practices that now exist and through expected technological progress.

Electric power

Much of the expanded consumption of energy has been channeled into electrification, or the use of electric power. World production of electricity increased by 150 percent since 1970. Electricity consumption increased more rapidly than non-electric energy in both industrialized and developing countries. As with growth in primary energy consumption, electrification has been more rapid in developing countries. In Africa, for example, increases in electrification are nearly double the world rate, but from a very low base. In contrast to the experience of industrialized countries, however, most of the increase in electrification in Africa has come through expanded use of fossil fuels.

Generally, with electrification has come a trend toward the diminished use of fossil fuels, primarily through expanded use of nuclear power, especially in industrialized countries. Although national experiences with nuclear programs differ and the future of nuclear power remains uncertain, in one generation the capacity of operating nuclear plants has increased more than twentyfold. The world of the 1990s is much more nuclear than 1970, with 420 nuclear power plants providing 7 percent of the world's primary energy and about a quarter of the electric power in the industrialized nations. Over six nuclear reactors operate today for every one in 1970. There were fifty-five nuclear plants under construction around the world in 1994. Chernobyl and other nuclear accidents increased the fear of nuclear energy, present but less apparent in 1970. The growth of nuclear power combined with the shift from carbon-heavy fuels such as coal and oil to carbon-light gas contribute to the gradual "decarbonization" that is the central tendency of the world energy system (Fig. 1). Decarbonization means we are obtaining more energy and income with fewer carbon atoms. For China the tons of carbon used to produce a Kilowatt-year of electricity fell from 0.72 to 0.65 between 1971-91 and for India from 0.76 to 0.68. The OECD countries have declined to around 0.5 tons carbon per Kilowatt-year, continuing a century-long trend.

Hydropower currently provides about 2.5 percent of world commercial energy, up from a little under 2 percent in 1970. Most potential commercial energy in the world's rivers is now tapped. The oil crises of the 1970s spurred numerous experiments to harness energy from the Sun, and underground thermal reservoirs. The combined output from these sources remains below 1 percent of world commercial energy production.


With more people and energy comes more travel. Global affluence has vastly increased mobility. The number of motor vehicles in use worldwide has more than doubled since 1970, to the now imposing figure of about 600 million cars and trucks. Automobility has increased the fastest in countries with rapid economic growth such as Japan. The U.S. and Canada had slower but substantial absolute growth, expanding their fleet from about 120 million motor vehicles in 1970 to about 220 million in the early 1990s. The number of cars in developing countries has increased steeply, but has typically reached only 10-20 percent of the level of car ownership in the most developed countries. Since the first 747 jet began passenger service in 1970, global air travel, measured in passenger-miles, grew by a factor of five, much faster than car travel.

Agriculture and fisheries

With larger and more affluent populations have come important changes in agriculture that affect the environment. Most of these arise through intensified production, since the total area of arable and permanent cropland, when averaged over the Earth as a whole, has changed little in the twenty-five years since 1970. World fertilizer consumption nearly doubled from 1970 to the mid-1980s and has remained about level since. As with energy consumption, the largest percentage increases were in the developing nations. Currently, low income countries apply fertilizer at about 90 percent of the rate per area in high income countries; in 1970 the ratio was only 17 percent. Averaged over the globe (Fig. 2), due to increased mechanization, irrigation, and other changes, the same area of land that in 1970 yielded thirty bushels of grain in 1994 produced fifty. The use of pesticides does not appear to have expanded, as feared, in industrialized nations, and in some countries it has decreased; in Asia, however, it has more than doubled. Few data exist for pesticide and herbicide trends in developing countries, although the use of both of these helpful but environmentally-detrimental substances has almost certainly risen substantially.

Several cycles of more productive seeds have been bred and put into use for many crops since 1970, and the number of gene banks, which store the sources of genetic materials out of which better crops grow, has multiplied tenfold. Yields from staple crops such as wheat and rice have grown faster than human population. Overall, food production has kept pace with population, even in parts of Sub-Saharan Africa, in countries as diverse as Zimbabwe, Chad, and Nigeria. Still, perhaps one-fifth of the world population remains hungry. The volume of cereal aid from donor countries to sub-Saharan Africa more than trebled from 1975 to 1990, and many nations in the region also increased commercial food imports.

Trade in agricultural products has expanded dramatically. World sales of cereal grains to Asia for food and feed are almost double those of 1970. Global trends in dietary behavior continue as before, toward higher meat consumption (including fish and poultry) with higher income.

The reported world harvest of marine and freshwater fish since 1970 has risen at one and a half times the rate of world population growth, with the commercial, wild catch reaching a peak in 1989. Meanwhile several major marine fisheries have collapsed: Peruvian anchoveta (in the early 1970s), North Sea herring (late 1970s) and Georges and Grand Banks cod (early 1990s). While the conditions of many fish stocks are not known accurately and natural conditions cause stocks to fluctuate, commercial harvesting has brought definite changes in what is caught. The makeup of the catch has moved down the food chain as the stock of higher and generally more desired species, such as tuna, decrease. Nations have made numerous national fisheries management plans, extended their exclusive economic zones to 200 miles, and signed more international fisheries agreements, but these measures have not stopped overfishing. With wild stocks under pressure, aquaculture is beginning to play a significant role in seafood production. Fish farms now produce about one-fifth of world seafood by weight and one-third in monetary value.

Social and economic indicators

Increases in energy use and travel, and changes in diet reflect other changes in social development. Since 1970 infant mortality in developing countries has dropped by 40 percent, and life expectancy at birth has been extended in most instances by five to ten years. Exceptions include Afghanistan and Russia, formerly a "second world" country, where the reported life expectancy for men dropped by a full eight years between 1970 and 1994. Adult literacy has increased substantially, especially in low income, less-developed countries, although educational attainment remains poor. Access to safe drinking water in developing countries has grown at double the rate of population. In absolute numbers, well over a billion people still lacked access to safe water supplies in 1992.

The economic gap between rich and poor countries, however, has widened in the last decades as measured by conventional indicators. Between 1974 and 1991 per capita income increased in the wealthier nations at twice the rate in low and middle income countries. As a result, the industrialized nations increased their share of global GDP from 75 to almost 80 percent even as their share of global population declined.

Differences in what the U.N. calls "human development"--a combination of indicators including literacy, life expectancy, and other societal and economic measures--have narrowed overall, although some developing countries with higher than average measures of economic growth, such as Nigeria, have not achieved particularly high measures in other facets of development. Educational indices based on school enrollments and mean years of schooling show a continuing disparity between the industrialized North and the developing South. While the relative incidence of poverty, illiteracy, and hunger has declined or remained constant, with increasing population absolute numbers of deprived people have increased. In Sub-Saharan Africa numerous indices of welfare have declined.

Since 1970 economic activity has continued to shift worldwide from agriculture by way of manufacturing to services--a trend that helps explain the reductions in energy intensity mentioned earlier. In nations from Australia to Zimbabwe the share of the work force engaged in agriculture and in manufacturing has dropped, often steeply. In much of the world, service industries, especially information processing, typified by the use of a personal computer, have reached levels unanticipated twenty-five years ago. The environmental issues of the information and services age, such as tourism and solid waste disposal, have fully joined those of manufacturing and agriculture.


The quality of the environment associates with both death and illness. Connections between environment and human health range from irrigation waters that can harbor disease-carrying snails to the ventilating systems of office buildings and homes. The fraction of all deaths in the U.S. associated with environmental conditions, such as air and water quality and natural and chemical hazards, declined from perhaps 40 percent in 1900 to below 5 percent in 1970 and has changed little since. Other countries appear to trace a similar pattern with development, which enables societies to invest in safer and more sanitary infrastructures.

Worldwide, malaria, a parasite borne by mosquitoes that breed mainly in wetlands, now damages human health more than any other environment-related illness. The incidence has greatly increased over the past two decades. One hundred million clinical cases now result in 1-2 million deaths per year. Fewer tools are available today to control malaria than twenty-five years ago, because of reluctance to drain swamps, the spread of drug and insecticide resistance, and limits on insecticides such as DDT which themselves can cause extraordinary damage to ecosystems.

As many people worry less about survival and acute and catastrophic conditions, they think more about chronic exposures and rare illnesses. Remarkably little is known in any country about actual and cumulative human exposures to environmental pollutants in air, water, soil, and food and how these may be changing. This ignorance bedevils ongoing debates about chlorinated compounds, breast and other cancers, electromagnetic fields, and a host of other concerns.

In sum, production, consumption, and population have all grown tremendously since 1970. The gross world domestic product increased to about $24 trillion in 1994, over twice the figure for 1970 after accounting for inflation. While recalling the plight of the roughly 1 billion people who remain hungry, globally and on average economic and human development appear to have outpaced population growth.

Direct Indicators of the Environment

Environmental issues may be grouped by geographical scale, namely those associated with the planet as a whole; those primarily significant at a regional level; and concerns that are chiefly local.

Global Environmental Issues

Climate change

Attention has focused throughout the world on projected climatic change because of fears of potentially far-reaching consequences of a drastic warming and associated sea level rise. This threat has been associated primarily with the developed countries' heavy use of fossil fuels whose burning releases carbon dioxide, a greenhouse gas which spreads quite evenly in the global atmosphere. The 1980s were for whatever reasons an unusually warm decade, following a cooler period that had culminated in the early 1970s, stimulating many assertions that anthropogenic global warming was now evident.

From 1970 to the early 1990s, world fossil fuel-related emissions of CO2 grew by 50 percent, about as much as population, so that per capita emissions have remained level. Meticulous measurements document a worldwide rise in atmospheric CO2 of about 10 percent in the same period, and concentrations will continue to rise even if emissions flatten, because of the time required for the land and sea to absorb carbon. In some countries, including France and the U.S., per capita emissions decreased due to improved energy efficiency and shifts to lighter fuels. Still, the U.S. remains far the largest emitter of greenhouse gases.

The abundance of other greenhouse gases has also risen. Atmospheric methane increased on average by 1 percent per year until 1992, when its growth slowed. Greenhouse gas emissions from developing countries have risen steeply, and the future composition of the atmosphere hangs heavily on the development strategies that these countries pursue, as well as the decarbonization of the energy systems of the developed countries.

Depletion of the ozone layer

A second truly global environmental concern is the depletion of the stratospheric ozone layer, traceable to the unintended lofting of a class of chemicals used primarily for refrigeration, and also for fire retardation, aerosol propulsion, and cleaning. The consequence in prospect is significantly increased penetration to the Earth's surface of ultraviolet light, harmful to human health and the functioning of ecosystems on land and in the sea. Production and use of the main culprits, chlorine- and bromine-containing halocarbons, is concentrated in the industrialized countries. Production grew steadily in the early 1970s and leveled later in the decade, when the U.S. and a few other countries banned particular industrial uses of ozone-depleting substances. The sudden detection in the mid-1980s of a springtime "hole" in the ozone layer over Antarctica catalyzed signature of formal agreements among governments. International protocols to limit the production of these chemical compounds, signed in 1987 and amended in 1990 and 1992, promise phase out of fifteen chlorofluorocarbons (CFCs), carbon tetrachloride, and methyl chloroform by 1996. Bromine-containing chemicals that also deplete ozone were phased out completely in 1993, although as in the case of CFCs, most developing countries are allowed a ten year delay in implementing their commitments.

Measurements from the past few years suggest that stratospheric ozone depletion may be continuing at a rate more rapid than foreseen in the 1980s and is spreading to the Arctic and mid-latitudes. Decisions already taken to curtail manmade ozone depletion were predicted to cause ozone destruction by industrial chemicals to peak late in the present decade. Long-term documentation of increased consequent ultraviolet radiation at the surface of the Earth remains elusive.


A third issue of global extent is the loss of diversity of plant and animal species, with particular emphasis on depletion in tropical forests and coastal marine regions where diversity is particularly rich. The care for biodiversity stems in part from practical concerns regarding the potential worth to humans of individual species and ecosystems for medicines and crop varieties, and for services Nature provides such as nutrient recycling and water purification. It also stems from ethics which intrinsically value all species and ecosystems. Estimates of the total number of plant and animal species worldwide range from three to more than eighty million, although the number that have been classified is now in the range of only 1.5 to 1.8 million. The cataloging of new species requires new public money and trained personnel and thus progresses only slowly. With reductions in wild vegetation in many parts of the world, as many as half the present number of biological species may be at risk.

Still, data on species loss are poor; much of what is lost, associated with the destruction of ecosystems in areas that have been largely unstudied, goes unrecorded. Uncertainty also makes it difficult to verify species loss. The rate of worldwide species extinction may be known only within a factor of ten. Problems of accounting are considerable, even in the U.S., as evident in the government list of endangered and threatened species. Since 1970 the number so listed has doubled, but inclusion is limited to well-described plants and animals. Moreover, additions to the list result largely from procedural, administrative, and political forces and do not necessarily correspond in a timely way to changes in the natural environment. Declines in "charismatic megafauna" such as the great cats, panda bear, and sea turtle are well documented.

A major contributor is loss of habitat, such as wetlands, a trend that is measurable in many countries. Biodiversity in coastal marine regions remains under great pressure as the result of increased population and development, associated changes in water quality, increased marine debris and pollution, and destruction of habitat, including mangrove forests, sea grasses, and coral reefs.


Integral to the issue of biological diversity is the question of deforestation, particularly in tropical regions. Globally, forest cover of all kinds today appears to be about 80 percent of what it was 3,000 years ago, when agriculture began to expand. In the past twenty-five years, according to data reported by national governments, global forest cover, overall, has diminished only slightly. These figures are hard to reconcile with widely publicized satellite images of Africa, South America, and Southeast Asia. Areas classified as forestland include thinned plots and managed tracts that harbor far fewer species of tree and animal life. In the temperate zone logging roughly balances growth of forests; where economic factors have led to the abandonment of much farmland, woodlands have generally increased during recent decades. Still, cutting threatens stands of rarer, old-growth trees.

The rate of removal of tropical forests, worldwide, was estimated for 1980-90 to be about 1 percent per year, as forests are cleared for fuel wood, crops, and pastures. Growth in wood production since the 1970s in Asia and South America was 70 percent above the global average, further suggesting deforestation.

The proportion of the world's land surface used for farms and pastures has remained constant at about 35 percent since mid-century. Though much of the land surface has been altered by human action, buildings and roads and other human artifacts actually cover less than 1 percent.

Regional Issues

Acid rain

The precipitation on forests and lakes of acid-producing residues--mainly in the form of industrially-released sulfur dioxide (SO2) and nitrogen oxides (NOx)--emerged in the 1970s as a major environmental issue in North America and Europe, and to a lesser extent in East Asia. In the United States, SO2 emissions come primarily from electric power plants and have dropped by one-third since 1970. Pressure for reductions stemmed mostly from local concerns about air quality and health and also from the downwind effects of acid rain. U.S. NOx emissions, from automobiles as well as power plants, remain steady with some annual fluctuations. Decreased emissions of SO2 are now evident in routine measurements of sulfates in rainwater, but rainwater remains more acidic in the affected regions in the U.S. than before widespread industrialization. The particularly susceptible red spruce trees of the U.S. northeast show diminished growth, although the extent to which acid precipitation is the cause is uncertain.

Acid deposition in Japan has been ascribed to transboundary emissions from China and Korea, but long-term records of the extent of this problem are lacking. Emission, transport, and deposition of acid-producing emissions occur elsewhere, especially where fossil fuels are heavily used, although again, limited data weaken assessments of the problem. Concurrent pressures on ecosystems from many other natural and anthropogenic changes make it difficult to identify, unambiguously, the effects of acid rain, which also vary with the ability of local soils to buffer imposed acidity. Political change unveiled severe environmental stress in the region of southern Poland, the Czech Republic, and eastern Germany where large amounts of low-grade coal were mined and burned.

Nuclear waste

Another issue with regional (as well as international and local) implications is the storage and disposal of radioactive wastes: both from nuclear reactors making electricity and the production of military weapons. Public concern attaches to both low- and high-level radioactive wastes; the latter, though smaller in volume is more technically problematic. With the rise of nuclear electrification, the volume of spent fuel and other wastes has risen substantially but is still small. In the U.S., the volume of high-level waste from commercial power plants now approaches 90,000 metric tons (186 million pounds), lower than what was anticipated twenty-five years ago because the number of plants constructed was less than what was projected.

Nuclear wastes from weapons production are large contributors to the total nuclear waste volume. In the U.S. the environmental problems of defense nuclear operations are now public, and considerable government resources have been allocated for site remediation. Little reliable information exists on nuclear waste in the former Soviet Union, but informal reports suggest a severe problem. Earlier disposal practices, such as dumping of nuclear waste at sea, have been completely stopped by formal treaty because of environmental concerns (and by cessation of furtive scuttling of nuclear submarines). Regimes for transport and temporary storage of civil and defense nuclear wastes now function, although sites and designs for permanent disposal have yet to be accepted.

Local Issues

Urban air pollution

In the U.S., the number of persons living in areas where ground-level ozone exceeded the National Ambient Air Quality Standards (NAAQS) fell by over 10 percent from 1984 to the early 1990s. Nationwide, ambient concentrations of ozone and of carbon monoxide have dropped by over 40 percent since 1970. The reduction was achieved through technological changes that yielded lower emissions of pollutants from automotive vehicles. The amount of lead in the atmosphere was reduced by a factor of twenty, due largely to a nearly complete elimination of leaded gasoline.

Still, because of the ever-increasing number of motor vehicles and accompanying congestion, chronic pollution of urban air in the U.S. has not appreciably diminished and in some cities has worsened. In the Los Angeles area, strategies to prevent further deterioration of air quality have roughly compensated for population growth. The serious problems of urban ozone pollution in the Los Angeles basin have not changed much since the late 1970s. In Japanese cities conditions have also roughly tracked urban population growth.

The record for other air pollutants is similarly mixed. SO2 pollution has generally lessened considerably in the cities of the industrialized world. Trends in nitrogen dioxide are mixed; in many cases concentrations have become markedly higher. The concentrations of airborne particles have fallen in many cases, but not by any significant amount. In France the shift in electric power generation from fossil fuels to nuclear power produced a dramatic drop. Concerns regarding the health effects of air pollutants provide the main basis for air quality standards. Yet, relatively little is known about the collective and cumulative effects of atmospheric pollutants on human health, and particularly to those who suffer from respiratory ailments.

In developing countries, many of the largest cities suffer acute air pollution problems. During the 1980s, major Chinese cities such as Beijing and Shanghai exceeded World Health Organization (WHO) standards for particulate levels an average of 272 and 133 days, respectively, per year. The average in New Delhi over the same period was 295 days. Since the mid 1970s, SO2 levels have exceeded the allowable standard an average of 100 days per year in Teheran. In 1991 in Mexico City air quality standards were seriously violated on over 300 days. Indoor air pollution is a sometimes severe problem that has been recognized and measured only recently. Asian and African households using wood- and dung-fueled ovens can experience indoor particulate concentrations greater than one hundred times the WHO standards.

Waste disposal and materials use

Another problem of intense local concern is the disposal of trash, garbage, and industrial wastes. Rates of municipal waste production consistently increased in the U.S. in the 1970s and 1980s (Fig. 3), although not as fast as GDP. In many areas the limited capacity of landfills has led to rising costs for waste disposal and to exportation of wastes to more distant locations, sometimes in other nations. International treaties now ban almost all shipments of hazardous waste from industrialized to developing nations.

Consumption of specialized materials such as aluminum and plastics continues to grow worldwide. Global steel production grew at half the rate of population and a quarter the rate of GDP. For the U.S., the fraction produced in electric arc furnaces, which rely almost exclusively on scrap, has more than doubled. The number of enabling technologies and markets for recycled materials continues to increase, but the gains have not fully offset growth in consumption. Overall, evidence of global "dematerialization," or decreasing intensity of materials use, is inconclusive. The high materials intensity of the richer countries appears to be flattening, while the low intensity of developing countries rises to build their infrastructure.

Marine and water pollution

There has been no simple trend in marine and freshwater pollution. Since 1970 the amount of oil spilled annually in the world's oceans and inland waters has fluctuated with sporadic large departures from the mean, as in 1989 due to the tanker spill in Prince William Sound, Alaska. The number of tanker accidents was lower in the 1980s and early 1990s than in the 1970s. The decreases, where they are found, can probably be ascribed to improved technical standards for petroleum transportation over the last two and a half decades. Although commanding less public attention than spills, "normal" operational discharges of oil into the sea, primarily from washing tanks and discharging ballast water, constitute the largest source of marine oil pollution and remain hard to assess.

Inland water bodies such as the Aral Sea in Central Asia, ground waters, and many rivers in both developing and industrialized regions have experienced serious and continuing problems as a result of combinations of imprudent irrigation; non-point-source pollution such as urban runoff, fertilizer and pesticide use; and contamination from both active and inactive industrial sites. Some estuaries and regional seas now also manifest incipient eutrophication: a reduction of dissolved oxygen, caused by an increase in deposited mineral and organic nutrients, such as those found in fertilizers. These lead to an environment where some plants choke off other aquatic life. Selected water bodies have been reclaimed. For example, on average the availability of dissolved oxygen in the rivers of the OECD nations improved over the past 25 years, though much remains to be done before high levels of water quality are achieved.

Hazardous materials

The prevalence of several environmentally hazardous materials has diminished considerably. Radioactive strontium-90 has dropped sharply worldwide since the 1960s when atmospheric testing of nuclear weapons was banned. In the U.S., levels of PCBs (the manmade polychlorinated biphenyl compounds used as coolants in power transformers) and lead (used in various forms in gasoline, cables, pipes, paint, and industrial chemical processes) have declined dramatically in the last decades as adverse health and environmental consequences have been identified and policy responses formulated and implemented. Despite bans on such materials, their persistence in the environment has kept them in the forefront of toxicological research. Previous disposal or dispersive use of these and other hazardous substances has contaminated many locations around the world, and a major activity of the past twenty-five years has been the growing catalog of hazardous sites. In the U.S. only a handful of the contaminated sites assigned priority by the government have been restored, as debate has raged about actual risk, blame, cost-sharing, and clean-up strategies.

Changes in Management and Decision Making

The source of some of the successes in decreasing environmental risks shows in indicators of environmental management and institutions. These include the number of laws and regulations governing environmental matters, the level of expenditure on the environment, the application of technology to environmental problems, and the creation of institutions to deal with environmental issues.


In the U.S., the number of federal laws for environmental protection has more than doubled since 1970. Compliance with laws has also reportedly increased, although data are sparse. The number of acts and regulations concerning the environment in the United Kingdom has grown from only 6 in 1885, to 21 in 1945, approximately 100 in 1970, and today about 300. The environmental directives and decisions of the European Economic Community were initiated about 1970 and grew in number to almost 200 by 1990. The number of multilateral agreements on the environment, which totaled about 50 in 1970, now nears 200. Activity in enacting rules for the environment appears to have peaked around the world in about 1980. In the last ten years, attempts to complement or replace "command-and-control" regulation with market-friendly means such as tradable emissions permits have grown but are too early to evaluate.


Money, and how it is spent, reveals individual and collective preferences. In the U.S., real spending on the abatement of air and water pollution has doubled since 1970 and currently exceeds $90 billion annually, with industry spending the most. U.S. federal outlays for natural resources and environment more than doubled in constant dollars since 1970 to over $22 billion in 1994. U.S. federal environmental research and development now totals about $5 billion, which is about twice that in 1970.


Pollution control has commonly mandated abatement technologies, whose diffusion provides another indicator of trends in environmental protection. One example is flue gas desulfurization (FGD), which removes SO2 before the products of coal and oil combustion are released to the atmosphere. In Japan, capacity for FGD has increased nearly thirty-fold since 1970. Germany has imposed strict FGD requirements as a result of concern over dying forests, although the link between SO2 and forest decline is still debated. Another example is catalytic converters for automobile exhausts. In the U.S. these were introduced in the mid-1970s and are now found on more than 90 percent of all vehicles on the road. Many countries, however, do not yet require or enforce auto emission controls.

Technological solutions can also help reduce threats to water quality. In the U.S., the fraction of the population served by wastewater treatment plants has doubled since 1970 to 75 percent of the population, which is typical of the OECD as a whole. As of 1992, 56 percent of the population in developing countries was estimated to have reasonable access to sanitary waste disposal, while in Sub-Saharan Africa the proportion was half this.

To curb pollution and encourage resource conservation, many governments, particularly in the industrialized world, have in recent years turned to goal-oriented, voluntary agreements with the private sector. These allow flexibility in means and encourage technical innovation. In Japan more than forty thousand such agreements have been concluded since the early 1970s. Within firms, innovative practice seeks to prevent rather than clean up pollution. Successful instances of pollution prevention must now be numerous, but non-releases are hard to quantify.


Increased governmental spending and oversight have created new institutions, governmental and non-governmental, that are devoted to environmental protection. Fewer than ten nations had high-level government departments of environment in 1970 while almost all countries do today. "Green" political parties have formed in many countries, especially in Europe. In 1992 over one hundred heads of state attended the "Earth Summit" on environment and development convened by the United Nations in Rio de Janeiro. The summit responded to and encouraged global environmental awareness and urged individual countries to set coherent priorities through national plans which most countries had prepared in advance and many are updating. Tangible products were treaties or their precursors on biodiversity, climate, high-seas fishing, and tropical deforestation as well as the establishment of an ongoing Commission on Sustainable Development to monitor progress in implementing international environmental commitments and the ideals of "sustainable development".

Formed in 1972, the United Nations Environment Programme (UNEP) has grown to be a substantial organization engaged in information exchange and coordination of national programs for environmental protection. UNEP with two partners, the World Bank and the United Nations Development Programme, created in 1991 a Global Environment Facility to serve as the principal multilateral mechanism to provide funds to developing countries for complying with environmental commitments.

Non-governmental organizations (NGOs) have multiplied and spread in space, coverage of issues, and ideologies. The number roughly tripled between 1970 and 1990 in the U.S., where recent surveys indicate that NGOs may now be in a period of consolidation. NGOs in some cases distribute funds from international organizations and national governments and increasingly provide services previously reserved by governments, for example, in wildlife protection. The NGO liaison unit with UNEP had 726 member organizations in 1993, a figure which has risen steadily since 1972.

The non-governmental Scientific Committee on Problems of the Environment (SCOPE), an international scientific network of environmental scientists, has published more than forty authoritative, book-length reviews since its founding in 1969 by its parent, the International Council of Scientific Unions. In 1988 the World Meteorological Organization and UNEP established the Intergovernmental Panel on Climate Change (IPCC), an extensive network of governmental and non-governmental experts, to advise governments on technical aspects of the greenhouse effect. The IPCC has grown to absorb thousands of person-years of effort by scientists from around the world. In 1993 UNEP formed a comparable entity to assess global biodiversity. New domestic institutions that bridge the public and private sectors to address particular issues such as the clean-up of hazardous waste sites have also been created. Numerous proposals have appeared for new international organizations, including regional networks and centers.

One of the principal strategies for environmental protection has been through the zoning and reservation of lands. National forests, nature parks, and similar areas represent resources set aside, under various restrictions, to conserve the environment. In most countries the area of protected lands has continued to increase, although protection may exist only on paper. Internationally, since the mid 1980s the amount of land so protected increased almost 90 percent. For example, between 1986-1993 all officially protected areas of Costa Rica increased from 8 percent to 12 percent of the country, though ecological destruction reportedly has continued. Because of a few large acquisitions, the area of the national park system in the U.S. has more than tripled since 1970. The numbers of visitors to national parks has climbed steeply worldwide since 1970. Globally, in 1993 official protections, both total and partial, covered about 6 percent of land area.

Our Conclusions

Our summary review of the past twenty-five years suggests the following:

  • The record of recent change in environmental quality is uneven. The common view that the environment is deteriorating in almost all respects is not justified. Several important trends show improvement. These include, for examples, energy intensity and decarbonization, investments in research and development, and reductions in fertility. These and other improvements are the result of applications of science and technology and of behavioral and policy shifts in both developing and industrialized countries. Moreover, societies have mobilized to a remarkable extent to address environmental issues.

  • Keeping pace with environmental degradation may become more difficult. Rising consumption and population growth continue to offset efficiency gains such that in many cases and places environmental burdens continue to increase. Humans will have to be more provident and smarter, if we are to be more numerous and if each of us on average processes more materials. Pressure on the environment seems certain to increase in many urban and coastal areas. The need for innovation and diffusion of environmentally more benign technology is enormous and growing.

  • People are demanding higher environmental quality. The lengthening list of environmental issues and policy responses reflects not only changing conditions and the discovery of new problems, but also changes in what society defines as problems and needs. On the one hand, survival requires environmental protection. On the other, with higher income, preference for environmental amenities rises. Where development succeeds, the preference for environmental goods will grow; where development fails, the environment will deteriorate and contribute to further cycles of impoverishment.

  • Environmental issues are increasingly shared and international. Pollutants cross borders, their effects cross borders, and world markets link the sources and consequences of the problems. Moreover, the issues are international because key technologies, whether automobile engines or industrial solvents, are mostly selected on a global basis, so that a nation desiring an alternative style of technical development can hardly maintain an island of independence from the international system. Nations now cooperate significantly more than in 1970 to understand and protect the environment.

  • Developing countries are most at risk from environmental problems. Today's wealthy nations had 100-200 years to address the environmental issues of industrialization and urbanization and face continuing difficulties. The newly-developing world faces an accelerated timetable, with generations of problems bunched together and hardened by population growth and poverty. Moreover, in some respects the vulnerability of developing countries to environmental hazards may be increasing, for example, through population growth in low-lying coastal areas that are prone to flooding.

  • Knowledge of environmental issues has increased rapidly but remains tentative, partial, and insufficiently widespread. Reliable foresight of potential environmental changes has improved, as has our ability to detect change. Yet, many environmental changes are still poorly documented, especially in developing countries. Human exposures to environmental risks are not well-documented. Surprises, such as the Antarctic ozone hole, have occurred. While our understanding of individual issues has advanced, potential interactions and cumulative effects of problems merit much more study.

  • As individuals and through the numerous ways humans associate--in governments and non-governmental organizations, in corporations, and in households and local communities--we have prepared ourselves to act strongly on the environmental problem. Even with gaps in knowledge, society at all levels has articulated the problem of how we develop in Nature over the past twenty-five years, and recognized many ways to address its sources and manifestations. The burdens that humans place on the environment will endlessly challenge our abilities and our means to modify and adjust to them. But compared to 1970 we are informed, alert, and capable of action.

For Further Reading

BP Statistical Review of World Energy. The British Petroleum Company, Employee Communications & Services. Dix Motive Press Ltd., London, 1994.

Environmental Quality, 23rd Annual Report, for 1991-1993. Council on Environmental Quality. U.S. Government Printing Office, Washington, D.C., 1993.

Human Development Report. 1990 through 1994. Annual volumes published by the United Nations Development Programme. Oxford University Press, New York.

Statistical Abstract of the United States, 114th edition. Issued by the U.S. Department of Commerce. U.S. Government Printing Office, Washington, D.C., 1994.

World Development Report. 1992 through 1994. World Bank. Oxford University Press, New York.

World Resources. 1986, 1987, 1988-9, 1990-1, 1992-3, 1994-5. Annual review volumes published by the World Resources Institute, Washington, D.C. Oxford University Press, New York.

A Note on Sources

Numerous sources provided the data that are cited here. Several which stand out for general utility are listed above. The biennial World Resources volumes offer the widest range of environment-related data with continental and global aggregates; the United Nations Development Programme's annual Human Development Report groups countries by income level and is the best source for data for social indicators; the World Bank's annual World Development Report similarly groups countries by income and is the leading source for global and national economic data; British Petroleum's annual Statistical Review of World Energy is an authoritative source on world energy consumption classified by individual countries and major energy sources; the annual Statistical Abstract of the United States and Environmental Quality report are rich sources for detailed U.S. data and include some global information as well. The authors can be contacted for more specific information on references to these and other sources, by phone (212) 327-7917 fax (212) 327-7519 or email or


Dr. Garry D. Brewer, a policy and management scientist, is both a Professor of Resource Policy and Behavior and a Professor of Business Administration at the University of Michigan in Ann Arbor. From 1991 until 1995 he was also Dean of Michigan's School of Natural Resources and Environment. His research and teaching involve the nexus between business and the environment, while his professional concern is focused on the disposal of high-level nuclear waste. To this end he serves as a member of the Presidentially appointed U.S. Nuclear Waste Technical Review Board.

Dr. Allen L. Hammond, a geophysicist, is the Director of the Resource and Environmental Information Program at the World Resources Institute, a non-partisan, non-profit policy research organization in Washington, D.C. that is committed to the objective analysis and dissemination of environmental information. He has also served in the past as an editor for scientific journals of the American Association for the Advancement of Science, and as editor of a policy journal for the National Academy of Sciences.

Scientific reviewers provide technical advice to the authors and Editor, who bear ultimate responsibility for the accuracy and balance of any opinions that are expressed.

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