Area of Research: Technology & Human Environment

Efficiency will win

In this article, I would like to share some surprising insights into the long-term evolution of the human environment and technology that may help diverse industries to do their jobs better. Indeed, absorbing some of these insights may determine which firms survive.

My points are: Demand for many primary products, or natural resources, will drop, in the USA and other important markets. In other words, efficiency will win. Pollution will plummet. Many firms’ emissions already have. We are going to live on a green planet with abundant land for nature.

As will become evident, these developments are not discontinuities or revolutions. Rather, the wheels of history are rolling in the direction of prudent, clean use of resources. Those who understand the dynamics can make money from them, too.

Usually we hear from environmental scientists and activists about deforestation, loss of arable land, water scarcity, and exhaustion of hydrocarbon fuels. The trumpets blare that, a population grows from six to 10 billion over coming decades, humans will demand so much of everything that prices will rocket, squabbles over access to resources will turn to wars, and a bath of pollution will burn us all.

In contrast, I believe that society is a learning system – and that we have been learning to become much more efficient. Pollution and waste usually indicate inefficiency. In an economy of competing companies, inefficiency is for losers. So, over the long run, successful companies are going to be green and clean.

A tour of the major natural resources – energy, land, water, and materials – justifies my confidence. Accordingly, this article surveys the trends in the use of these resources over the last century or two, globally and in the United States.

Along the way, it is important to keep in mind three paramount facts about the economy:

• Evolution is a series of replacements. Products, performers (usually companies), and technologies substitute for one another in the market in a search for inclusive fitness.
• The struggle is bloody. Products, performers, and technologies, indeed whole systems of doing things, lose and die.
• The struggle is episodic or cyclical, in many instances. In particular, long cycles or pulses of about 50 years punctuate the evolution of the economy. We happen to be at the start of a new cycle now.

Energy

Gains in energy productivity and efficiency astonish. Consider the gains for motors and lamps, pictured in Exhibit 1 on a logarithmic scale as the fraction of the limit of efficiency they might obtain. In about 1700, the quest began to build efficient engines, starting with steam. Three-hundred years have increased the efficiency of the generators from one percent to about 50 percent of their apparent limit, the latter achieved by today’s best gas turbines, made by General Electric. Fuel cells, which will power our cars in 20 to 30 years, can advance apparent efficiency to about 70 percent.

Lamps have brightened with each decade. At the outset of the 1990s, the Photonics Lab of the 3M Company announced an advance in short-wavelength solid-state light emitters in the blue and green spectral regions using zinc-selenium lasers. These could significantly advance efficiency, penetrating the market for displays and then reaching into other commercial applications.

Analyses of the evolving efficiency of the full energy system show that the United States has averaged about one percent less energy to produce a good or service each year since about 1800. However, our modern economies still probably run at only about five-percent efficiency for the full chain from extracting primary energy to delivery of the service to the final user. Fifty-percent efficiency at each of four links in a chain, after all, produces six-percent efficiency for the chain as a whole.

For the environment, efficiency with respect to use and leaks of carbon matters greatly. Carbon darkens the environmental outlook by threatening oily beaches, smoggy air, overheated climate, and black lungs. Happily, the most important single fact to emerge from 20 years of energy analyses is the gradual “decarbonization” of the energy system, the falling number of carbon molecules used to provide a unit of energy or economic product.

In 1860, globally, about 1.1 tons of carbon went into the primary energy produced by the energy equivalent of one ton of oil then in the fuel mix; the amount has decreased monotonically to about 0.7 tons in 1990. Exhibit 2 details the shrinking carbon used for final energy to the consumer in diverse countries in the last few decades. Efficiency is much higher in the richer countries, whose firms more readily discern inefficiency as a market opportunity and can parlay the expertise and capital to reduce it.

This decarbonization partly reflects that new motors and light bulbs get more out of the fuel they use. It also reflects the substitution of fuels that are progressively lighter in carbon. I noted above that evolution is a series of replacements. In fact, we can view the process of decarbonization as the replacement of carbon with hydrogen as the source of chemical energy (see Exhibit 3). Economizing on carbon, we are on a steady trajectory toward a methane, and eventually hydrogen, economy.

A grand substitution of leading energy sources has taken place over the past century and a half for the world: from wood and hay, to coal, to oil, and now to natural gas. “Oil” companies such as Shell and Mobil affirm it in the investments they now favor. The progression of fuels has sequentially supported a higher spatial density of consumption. Effectively, each new leading fuel is superior from an environmental point of view.

Wood and hay, prevalent at the start of the 19th century, were bulky and awkward. Consider if every high-rise resident needed to keep both a half-cord of wood at hand for heat and a loft of hay for the Honda. Think of the deforestation this would cause – directly for the fuelwood, and indirectly from the land needed for hay.

Coal had a long run at the top, notwithstanding its devastating effects on miners’ lungs and lives, urban air, and the land from which it came. Then, around 1900, the advantages of a system of fluids rather than solids became evident. Coal-powered autos never had much appeal. The weight and volume of the fuel were hard problems.

Oil has a higher energy density than coal, plus the advantage of a form that allows it to flow through pipelines and into tanks. Systems of tubes and tins can deliver carefully regulated quantities from the scale of the engine of a motor car to that of the Alaska Pipeline. But transfer between tins is imperfect, and the tubes and tins puncture. The spills make headlines.

In contrast, an inconspicuous, pervasive, and efficient system of pipes distribute natural gas. Its capillaries safely reach right to the kitchen. For gas, the next decades will be a time of relative and absolute growth. Gas is the penultimate fuel, the best until hydrogen, whose combustion product is water rather than carbon dioxide. Nuclear plants remain the best long-run candidate to manufacture the hydrogen, but perhaps solar will learn to compete.

Before making “neat” hydrogen, the next step is “zero emission power plants” with supercompact, superpowerful, superfast turbines that deliver what are now combustion products in a form appropriate for injection into aquifers where they can be sequestered forever. Very high pressure CO₂ gas turbines in which combustion of the fuel with oxygen inside the gas flux provides the heat should do the trick.

Looking back, we see that growth of per capita energy consumption has been keyed to cleaner fuels (see Exhibit 4). Pulses of energy growth reach economic, social, technical, and environmental limits. In past pulses, per capita energy consumption tripled before the energy services desired outgrew the old fuels or portfolio of fuels. I postulate two new global pulses, one centered on gas and then a later one centered on hydrogen. Industrial, commercial, and residential end users have also enjoyed two neatly quantifiable pulses of penetration of electricity, and two more probably lie ahead, keyed to the information revolution and later to the electrification of travel.

The growth pulses, lasting 40 to 45 years, are followed by lulls or depressions of a decade or two in energy consumption. These years between the pulses, when demand is rather flat, matter greatly for industry organization because they especially reward producers who are the most efficient and lowest cost – in short, the most competitive. They often witness a big restructuring of the industry, as is happening today to electric utilities.

Global triplings of demand need not mean triplings in the U.S. and other rich countries, where higher efficiencies throughout the chain can effectively supply the already amply, but still sloppily, provided end-users.

To return to the environmental aspect, recall that the transport system mirrors the energy system. In personal transport, oil substituted for hay (that is, cars for horses). America had more than 20 million non-farm horses in 1910 and has about 200 million motor vehicles today. Imagine the pollution had the fleet stayed equine. So the energy story is efficiency and cleanliness to meet the demands of larger, denser markets, driven by competition, occurring in long cycles.

Land

More blood spills over land than any other resource. Yields per hectare measure the productivity of land and the efficiency of land use. During the past half century, ratios of crops to land for the world’s major grains – corn, rice, soybeans, and wheat – have climbed, fast and globally.

A cluster of innovations, including tractors, seeds, chemicals, and irrigation – joined through timely information flows and better organized markets – raised yields to feed billions more without clearing new fields.

Per hectare, world grain yields rose 2.15 percent annually between 1960-1994. The productivity gains have stabilized global cropland since mid-century, mitigating pressure for deforestation in all nations and allowing forests to spread again in many. The Green Revolution that led to high-yield crops earned a Nobel Peace Prize. The alternative – extending farming onto hundreds of millions more hectares – would surely have evoked deadly strife.

Fortunately, as Exhibit 5 shows, the agricultural production frontier remains spacious. On the same area, the average world farmer grows only about 20 percent of the corn of the top Iowa farmer, and the average Iowa farmer lags more than 30 years behind the state-of-the-art of his most productive neighbor.

Will high-yield agriculture tarnish the land? Farmers do many things on each area of land that they crop. In general, higher yields require little more clearing, tilling, and cultivating than lower yields. Protecting a plot of lush foliage from insects or disease requires only a little more pesticide than does sparse foliage. Keeping weeds from growing in deep shade beneath a bumper crop may require less herbicide per field than keeping them from growing in thin shade. The amount of water consumed is more or less the same per area whether the crop is abundant or sparse. Growing higher yields distills away only a little more water and leaves only a little more salt than lower yields.

Seed is planted per plot; choosing a higher yielding variety does not affect the surroundings. If the improved variety resists pests, it lessens the external effects of pesticides compared to a sprayed crop. By minimally changing the external effects of things that farmers do per area, lifting yields will thus lower effects per unit of yield.

On the other hand, farmers use more of some things to raise the yield of their crops. For example, farmers apply more fertilizer, especially nitrogen, per plot to raise yields. But in fact the key issue is usually the sound, complementary use of fertilizer and water. We appear to have reached the point of diminishing returns for applications of fertilizer. In America, use has been level for 15 years. Globally, use has fallen since 1985, in part because of big drops in the former Soviet bloc, where it was wastefully applied.

Globally, the future lies with precision agriculture. This approach to farming relies on technology and information to help the grower use precise amounts of inputs – fertilizer, pesticides, seed, water – exactly where they are needed. Precision agriculture includes grid soil sampling, field mapping, variable rate application, and yield monitoring, tied to global positioning systems. It helps the grower lower costs and improve yields in an environmentally responsible manner. At a soybean seminar in Dayton covered by the Associated Press on February 10, 1997, Ohio farmers reported using one-third less lime after putting fields on square-foot satellite grids detailing which areas would benefit from fertilizer.

We have had two revolutions in agriculture in this century. The first came from mechanization. The second came from agricultural chemicals. The next agricultural revolution will come from information.

If during the next 60 to 70 years, the world farmer reaches the average yield of today’s U.S. corn grower, 10 billion people will need only half of today’s cropland while being able to consume the same number of calories as Americans eat today. This will happen if we maintain the yearly 2.15% worldwide yield growth of grains achieved during 1960-1994. Even if the rate falls by half, an area the size of India, globally, will revert from agriculture to woodland or other uses. The bottom line is that farm land should become more abundant in many countries. Land prices should show it.

Water

Will water become scarce? Not if we similarly squeeze more value from each drop. Since 1975, per capita water use in the United States has fallen at an annual rate of 1.4 percent. Even absolute water withdrawals peaked about 1980.

Industry, alert to technology as well as costs, exemplifies the progress, although it consumes a small fraction of total water. Total U.S. industrial water withdrawals plateaued about 1970, and have since dropped by one-third (see Exhibit 6). Also interesting is that industrial withdrawals per unit of GNP have dropped steadily since 1940. Then, 14 gallons of water flowed into each dollar of output. Now the flow is less than three gallons per dollar.

The steep decline taps many sectors, including chemicals, paper, petroleum refining, steel, and food processing, and also reflects changes in what forms the economy. After adjusting for production levels, not only intakes but discharges per unit of production are perhaps one-fifth of what they were 50 years ago in the United States.

Technology, law, and economics have all favored frugal water use. Better management of demand reduced water use in the Boston area from 320 million gallons per day in 1978 to 240 million gallons in 1992. Incidentally, more efficient use of water and energy usually go together, through better heat-exchangers and recirculation of cooling water. And, if land used for farming shrinks, water use will also tend to fall, although the fraction that is irrigated will rise.

Despite the gains, the United States is far from the most efficient practices. Water withdrawals for all users in the OECD countries range tenfold, with the United States and Canada the highest. Allowing for national differences in the major uses (irrigation, electrical cooling, industry, and public water supply), large opportunities for reductions remain. Like enterprises supplying energy or inputs to farmers, enterprises treating and supplying water will find the emphasis in their markets on quality, not quantity.

Materials

We can reliably project more energy from less carbon, more food from less land, and less thirst with less water. What about more goods and services with less material? Let us define such a “dematerialization” as the decline over time in the weight of materials used to perform a given economic function.

Dematerialization would matter enormously for the environment. Excluding water and oxygen, in 1990 on average each American mobilized more than 50kg of materials per day (see Exhibit 7). Lower materials intensity of the economy could preserve landscapes and natural resources, lessen garbage, and reduce human exposures to hazardous materials.

Over time, new materials substitute for old. Successful new materials usually show improved properties per ton, thus leading to a lower intensity of use for a given task. The idea is as old as the epochal succession from stone to bronze to iron. In the United States, the present century has witnessed the relative decline of lumber and the traditional metals and the rise of aluminum and especially plastics (see Exhibit 8).

Modern examples of dematerialization abound. Since the early 19th century, the ratio of weight to power in industrial boilers has decreased almost 100 times. Within the steel industry, powder metallurgy, thin casting, ion beam implantation and directional solidification, as well as drop and cold forging, have allowed savings up to 50 percent of material inputs in a few decades.

In the 1970s, a mundane invention, the radial tire, directly lowered weight and material by one-quarter compared to the bias-ply tire it replaced. An unexpected and bigger gain in efficiency came from the doubling of tire life by radials – thus halving the use of material (and the piles of tire carcasses blighting landscapes and breeding mosquitoes).

Lightweight optical fibers – with 30 to 40 times the carrying capacity of conventional wiring, greater bandwidth, and invulnerability to electromagnetic interference – are ousting copper in many segments of the telecommunications infrastructure. Similarly, the development of high fructose corn syrup (HFCS) in the 1960s eliminated sugar from industrial uses in the United States. HFCS sweetens five times more than sugar on a unit weight basis, with a proportional impact on agricultural land use.

Certainly many products – for example, computers and containers – have become lighter and often smaller. A few compact discs weighing ounces and selling for less than $100 now contain 100 million phone numbers of Americans, equivalent to the content of telephone books formerly weighing tons and costing thousands. Or you can obtain the numbers from the Internet.

In containers, at mid-century, glass bottles dominated. In 1953 the first steel soft-drink can was marketed. Cans of aluminum, one-third the density of steel, entered the scene a decade later, and by 1986 garnered more than 90 percent of the beer and soft drink market. Between 1973 and 1992, the aluminum can itself lightened 25 percent. In 1976 polyethylene terephthalate (PET) resins began to win a large share of the market, especially for large containers previously made of glass. Once again, for businesses, efficiency meant opportunity, and substitutions meant life and death.

Recycling, of course, diminishes the demand for primary materials and may thus be considered a form of dematerialization. During the past 25 years, recycling and resource recovery have become generalized, albeit incipient, social practices. The basic idea is that wastes are wastes and should be eliminated.

Difficulties arise in the more complex “new materials society” in which the premium lies with sophisticated materials and their applications. Alloys and composites with attractive structural properties can be hard to separate and recycle. Popular materials can be lighter, but bulkier or more toxic. Reuse of plastics may be less economical than burning them (cleanly) for fuel or otherwise extracting their chemical energy.

Most important, economic and population growth have multiplied the volume of products and objects. Thus, total materials consumed and disposed have tended to increase, while declining per unit of economic activity.

Wood products provide an illuminating case. Does doubling the number of people or the amount of wealth double the use of products taken from the forest? We can shed light on this proportionality (or elasticity, as the economists might say) by dissecting historic growth in demand. This growth is the product of an identity: population multiplied times GDP per person multiplied times wood product per GDP.

Consider the U.S. consumption of timber products – lumber, plywood and veneer, pulp products, and fuel (Exhibit 9). Between 1900 and 1993, the national use of timber products grew 70 percent. Large features of these 93 years include the big growth of pulp – that is, paper and paperboard – while the consumption of lumber rose little. Fuel wood nearly disappeared, and then re-emerged. And plywood consumption emerged but remained small. The preeminent feature is that the consumption of timber products rose far less than the rises in population and wealth might suggest.

Near the end of the century, Americans numbered more than three and a half times as many as at the beginning, and an American’s average share of GDP had grown nearly five fold. Had a strict proportionality prevailed, Americans would have consumed 16 times as much timber in 1993 as in 1900, rather than 1.7 times.

The explanation for the difference lies in the third term of the identity mentioned above: the product consumed per unit of GDP (for example, pulp/GDP). Industrial ecologists call this parameter “intensity of use.” If intensity of use is constant, consumption will rise in unchanging proportion to the combined rise of population and wealth. If thicker paper replaces thinner paper and newspapers replace oral gossip, then intensity of use lifts consumption faster than population plus wealth. If thinner paper replaces thicker paper and television replaces newspapers, this lowers the intensity of pulp used per unit of GDP.

Five ten-year periods illustrate the power of intensity of use: the periods 1900-1909 and 1984-1993 bracket the century; in between, 1925-34 shows the decline into the Depression, 1936-45 the recovery and war, and 1973-82 the oil shock.

The segments of the bars in the upper panel of Exhibit 10 show the annual change of the components determining demand, and the unsegmented bars in the lower panel show their sum. For the timber product paper, represented by the consumption of the raw material pulp, the upper panel shows the growth of population gradually slowing from about 2% per year to less than 1% per year and the GDP per person fluctuating through business cycles. The pulp per GDP began the century rising several percent per year. The increase even continued into the Depression, countering the fall of GDP per person to maintain the national consumption of pulp unchanged. During the recovery, however, the consumption of pulp per unit of GDP fell, and it has generally fallen since. During the oil shock through the end period, falling pulp use per unit of GDP actually decreased the national pulp consumption slightly.

Mathematically, what can lower intensity of use (in this case, the ratio of timber products to GDP)? The answer: Anything that raises GDP more than timber use. Armament during the recovery from the depression ballooned production that used relatively little forest product. The war was fought more with bullets than with memos. During the period 1936-45, the divisor GDP rose faster than national consumption of pulp, lowering product per GDP at the same time national consumption went up.

Practically, what changes the amount of forest product used per unit of GDP? In the case of lumber, its replacement during the century by steel and concrete in applications from furniture and barrels to cross ties and lath lowered the intensity of use. Living in the stock of existing houses and prolonging the life of timber products by protecting them from decay and fire also lower it.

In the case of pulp, more widespread literacy and the shift to a service economy raised the intensity of use in the early 20th century. More recently, we might speculate that the onset of dematerialization, as telephones and magnetic files replace letters and manuscripts, is lowering it. Because both writing and packaging consume much pulp, both are opportunities for further improvements in intensity of use.

Overall, history shows that the extent of forests in the United States has changed little in the 20th century, and the volume of wood on American timberland has actually risen by 30% since 1950. While foresters grew more wood per hectare and millers learned to get more product from the same tree, the main reason for the lack of change in forested area is that the average American in 1993 consumed only half the timber for all uses as did a counterpart in 1900.

Overall, environmental trends with respect to materials are equivocal. Moreover, a kilogram of iron does not compare with one of arsenic. But the promise clearly exists to lessen the materials intensity of the economy, to reduce wastes, and to create “wastes” that become nutritious in new industrial food webs. Again, efficiency and substitution are toughening markets.

Conclusion

What then is the challenge for green technologists and managers? Suppose Americans wished to maintain current levels of environmental cleanliness with the 50-percent increase in population likely over the next century and with the current level and kind of economic activity now existing. In this case, emissions per unit of activity would need to drop by one-third. That is an easy target. One-and-a-half percent per year improvement reaches the target in 25 years, well before the population rises by half.

The challenge is much harder taking into account growing consumption. If per capita economic activity doubles roughly every 40 years, as it has since about 1800 in the industrialized countries, the result is a six-fold increase by 2100. Multiplied by population, the United States would have almost 10 times today’s emissions and demands on resources, other things being equal. To maintain or enhance environmental quality, this scenario requires extremely parsimonious use of inputs and micro emissions per unit of economic activity. In other words, Americans need to clean processes by an order of magnitude – to stand still. More reassuringly, the annual rate of cleaning need be only about two percent.

In Europe and Japan population is stable or even shrinking, easing the magnitude of their environmental challenges. The rest of the world, where most people live, faces the twin pressures of enlarging economies and growing populations. So in absolute terms, the performance gains must be enormous.

We have seen the outlines of how the gains can be made. In the long run, we need a smoke-free system of generating hydrogen and electricity that is highly efficient from generator to consumer, as well as food decoupled from acreage, carefully channeled water, and materials smartly designed and selected for their uses and then recycled. In short, we need a lean, dry, light economy.

In truth, I exaggerate the challenge. With respect to consumption, multiplying income will not cause an American to eat twice as much in 2040 or four times more in 2080. Moreover, with respect to production, history shows that the economy can grow from epoch to epoch only by adopting a new industrial paradigm, not by inflating the old. Hay and horses could not power Silicon Valley.

High environmental performance forms an integral part of the modern paradigm of total quality. The past 25 years signal the preferred directions: the changeover from oil to gas, the contraction of crops in favor of land for nature, diffusion of more efficient water use to farmers and residents as well as firms, and the development of a new ecology of materials use in industry.

Economists always worry about trading off benefits in one area for costs in another. Hearteningly, we have seen that, in general, efficiency in energy favors efficiency in materials; efficiency in materials favors efficiency in land; efficiency in land favors efficiency in water; and efficiency in water favors efficiency in energy. The technologies that will thrive, such as information, will concert higher resource productivity.

Some worry that the supply of a fifth major resource, ingenuity, will run short. But nowhere do averages appear near the frontier of current best practice. Simply diffusing what we know can bring gains for several decades. Overall, society hardly glimpses the theoretical limits of performance. More importantly, we forget the power of compounding our gradual technical progress, even at one or two percent per year.

Of course, societies could stop learning. Complex societies have collapsed before. To my eyes, the rejection of science would indicate the greatest danger.

If, however, learning continues as usual, the demand for natural resources will moderate, resource prices will stay low, and pollution will drop – the sustained and collective effect of innumerable actions for technical change and better practices by a multitude of competing firms operating with proper feedback.

Fluctuations, bottlenecks, and falls will make the wayside interesting. Whether they sell autos, carbon, chemicals, corn, electricity, land, paper, or zinc, companies had best take note. Though it will never be easy, the environment for future business will be green.

Bibliography

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[NOTE This is a draft of a paper that has recently appeared (slightly modified) in the journal Consequences: The Nature and Implications of Environmental Change 1(3):2-15, 1995]

A generation marks the average timespan between the birth of parents and that of their offspring. In the minds of many 1970 marked the birth of the modern environmental movement, symbolized by the first observance of “Earth Day” in April of that year. As the second green generation begins, it seems wise to measure the environmental changes since 1970.

In this paper we consider green change in three ways. First, we examine the underlying forces of economic and population growth. Second, we look at indicators of the environment per se. Third, we check changes in management and institutions. In all cases, we seek quantifiable, objective measures. 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 determine the actions on which we report. However, we limit ourselves here to phenomena that can be recognized and counted in a relatively impartial way. We intend this paper to serve those seeking a factual survey in essay form. At the conclusion we list the main sources of data.

Underlying forces of growth and development

In 1970 global population was estimated at 3.7 billion. In 1995 it is believed to have reached 5.7 billion. Some 90 percent of the growth took place in developing regions. 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 world population remained rural, by 1995 45 percent were concentrated in towns and cities. Urbanization has been fastest in developing countries, where the cities grew by almost one billion people. The continuing heavy toll from “natural” disasters is Bly associated with large and growing populations in risk-prone areas, such as flood plains and low-lying coastal regions.

Total world commercial energy consumption grew at the same rate as population, from the equivalent of a little over 5 billion tons of oil in 1970 to just under 8 annually now. Thus, global per capita commercial energy consumption has stayed level. Per capita commercial energy consumption in low-income countries more than doubled. Absolute consumption remains centered in the wealthy industrialized nations, where 15 percent of the world’s population consume over half its energy.

Not only has energy use increased, but the estimates of energy resources that might eventually be tapped have grown. Contrary to expectations that the world would begin to exhaust its so-called fossil (hydrocarbon) fuels, proven reserves of oil have increased from 600 billion barrels in 1970 to 1,000 at present, even though over 500 billion barrels of oil 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 some environmental issues would diminish because of depletion of exhaustible resources has thus become more remote.

In some respects, the global energy system has evolved in a cleaner direction. While many were predicting increased reliance on “dirty” fossil fuels such as coal and oil shale, the reverse is occurring. The share of world primary energy served by natural gas, the cleanest fossil fuel, has increased by over a quarter. Compared with coal and oil, burning natural gas releases lower quantities of carbon dioxide as well as pollutants such as sulfur dioxide and particulates.

Between the early 1970s and 1990, the energy intensity, measured in energy used per dollar of gross domestic product, decreased in 19 of 24 advanced industrialized nations belonging to the Organization for Economic Cooperation and Development (OECD). Energy efficiency has increased. The average rate of improvement that has persisted in the OECD nations doubles efficiency in about 30 years. However, overall efficiency remains extremely low, with more than 90 percent of energy lost or wasted in the complete process of conversion from the raw material such as coal to the final energy service such as the light to read a book. Further large increases in energy efficiency are clearly attainable through diffusion of existing best practices and technological progress.

Much of the expanded consumption of energy has been channeled into electrification. World production of electricity increased one and a half times 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 have nearly doubled the world rate. In contrast to the experience of industrialized countries, most electricity in Africa has come through expanded use of fossil fuels.

Generally, with electrification has also come a trend away from fossil fuels, primarily through expanded use of nuclear power, especially in industrialized countries. Although the future of nuclear power remains uncertain and national experiences with nuclear programs differ, 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. Globally, 55 nuclear plants were under construction in 1994. Chernobyl and other nuclear accidents have heightened nuclear fears that were less apparent in 1970. The shift from carbon-heavy fuels such as coal and oil to carbon-light gas and the growth of nuclear power contribute to the gradual “decarbonization” that is the central tendency of the world energy system.

With more people and more energy has come more travel. Global affluence has vastly increased mobility. The number of motor vehicles in use worldwide has more than doubled to the imposing figure of about 600 million. Automobility in countries with rapid economic growth such as Japan has increased fastest. North America had slower but substantial absolute growth, expanding its fleet from about 120 million motor vehicles in 1970 to about 220 million in the early 1990s. Car population in developing countries has increased steeply, but it remains unclear whether cars will pervade these societies as they do the North. Since the first 747 began passenger service in 1970, global air travel grew by a factor of five, much faster than car travel.

With larger and wealthier populations have also come important changes in agriculture that affect the environment. Most change has come through intensified production, as the global area of arable and permanent cropland has changed little since 1970. World fertilizer consumption nearly doubled from 1970 to the mid-1980s and has remained about level since. As with growth of energy consumption, the largest percentage increases were in low income countries. Currently, low income countries apply fertilizer at about 90 percent of the rate in high income countries; in 1970 the ratio was only 17 percent. Globally, increased mechanization, irrigation, and other changes yielded two-thirds more grain from the same hectare of land in 1994 than 1970. The use of pesticides does not appear to have expanded in industrialized nations, and in some it has decreased, while in Asia it has more than doubled. Few data exist for pesticide and herbicide trends in developing countries, but use has almost certainly increased 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, the source of raw materials out of which better crops grow, has multiplied tenfold. Yields for staple crops such as wheat and rice have grown faster than human population. Overall, food production has kept pace with population, even in sub-Saharan Africa, where many of the world’s poorest countries are located. Still, perhaps one-fifth of the world population remains hungry. Trade in agricultural products has expanded dramatically. Present cereal imports to Asia are almost double those of 1970. The direction of dietary behavior, toward higher meat consumption (including fish and poultry) with higher income, has not changed.

The reported world catch of fish has risen at one and half times the rate of world population growth. Accurate knowledge of the conditions of stocks remains inadequate, but commercial harvesting has definitely caused significant changes in the catch and species composition. The makeup of the catch has moved down the food chain as the stock of higher species, such as tuna, decrease. With wild stocks under pressure, aquaculture is beginning to play a significant role in seafood production. Fish farms produce about one- seventh of world seafood by weight and one-third by value.

More energy, travel, and food indicate some success in social facets of development. For example, since 1970 infant mortality in developing countries has dropped by 40 percent, and life expectancy at birth expanded by 5-10 years. Rates of adult literacy in the developing countries have grown substantially, especially in low income countries. Access to safe drinking water in developing countries has grown at double the rate of population.

By conventional monetary measures the absolute economic gap between rich and poor countries has widened in the last decades. The rate of growth of per capita income in the wealthier nations doubled that in the low and middle income countries between 1974 and 1991. As a result, the industrialized nations increased their share of global GDP from three quarters to almost four-fifths even as their share of global population declined.Differences in “human development,” a combination of indicators of literacy, life expectancy, and other societal measures have narrowed overall. Some developing countries with higher than average measures of economic growth have not achieved particularly high measures in other facets of development. Educational indices measured as overall school enrollments and mean years of schooling show a continuing discrepancy between the industrialized North and the developing South. While the relative incidence of poverty, illiteracy, and hunger has declined or remained constant, absolute numbers of deprived people have in almost every case increased. Moreover, in major areas of the world, notably Sub-Saharan Africa, indices of welfare have declined.

Since 1970 the composition of economic activity has continued to shift from agriculture via manufacturing to services. In some nations, the share of the workforce engaged in agriculture and in manufacturing has dropped steeply. Some service industries such as information processing, exemplified by the 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.

Environmental protection, which has been directed primarily at reducing health effects of environmental degradation, is taking place in the context of increased worldwide spending on health. This is evident in developing and industrialized countries alike. The doubling of world spending on health as share of GNP since 1970 indicates changing preferences that come with economic development. Environment and health are linked through channels ranging from irrigation waters that can harbor disease-carrying snails to the ventilating systems of office buildings and homes. Remarkably little is known in any country about actual or cumulative human exposures to environmental pollutants in air, water, soil, and food and how these may be changing.

In sum, production, consumption, and population have grown tremendously since 1970. The gross world domestic product increased to about $24 trillion in 1994, over twice the value in 1970 after accounting for inflation. Globally and on average economic and human development appears to have outpaced population growth.

Direct indicators of the environment

Indicators for environmental issues may be grouped by geographical scale, namely those associated with large areal or global issues; those primarily significant at a regional level; and those at a local level. Of course, many threads connect.

Globally, much attention has focused on projected climatic change because of the fears of the potentially far-reaching consequences of a drastic warming and associated sea level rise. To date, human-induced global climatic change is associated principally with emissions of carbon dioxide (CO2) from burning of fossil fuels in developed countries. The 1980s were an unusually warm decade, following the cool period that culminated in the early 1970s, suggesting for many that anthropogenic global warming is now evident. From 1970 to the early 1990s, fossil fuel emissions of CO2 grew 50 percent, about as much as population, so that per capita emissions have remained level. Meanwhile, atmospheric concentrations of CO2 have increased 10 percent. In some economies, including France and the United States, per capita emissions decreased due to improved energy efficiency and decarbonization. The United States remains far the largest emitter of greenhouse gases. The abundance of other greenhouse gases has also continued to rise. Atmospheric methane increased an average of 1 percent annually until 1992, when its growth slowed. Greenhouse gas emissions from developing countries have risen steeply. The developmental choices of these countries appear most fateful for the future composition of the atmosphere.

The second truly global environmental concern is depletion of the stratospheric ozone layer by chlorofluorocarbons (CFCs) which could lead to increased exposures to ultraviolet light harmful to human health and affecting the productivity of ocean plankton and land plants. Production and use of CFCs concentrate in the industrialized countries. Production grew steadily in the early 1970s and leveled later in the decade, when the United States and a few other industrial countries banned particular uses of CFCs. International protocols on substances that deplete the ozone layer, signed in 1987 and amended in 1990 and 1992, phase out fifteen CFCs by 1996. Phase out of halons, another ozone-depleting substance, was completed in 1993. Developing countries have a 10-year delay in implementing commitments. The sudden detection in the mid-1980s of a “hole” in the ozone layer in the spring over Antarctica catalyzed signature of agreements. Measurements from the past few years suggest that ozone depletion continues at a rate more rapid than predicted, spreading in area, and appearing in the Arctic and mid-latitudes as well. Documentation of increased consequent ultraviolet radiation at the surface of the Earth remains elusive.

A third global issue is preservation of biological diversity, much of which resides in tropical forests. Estimates of the total number of species range from three to more than eighty million; the number named stands at around 1.5 to 1.8 million, and cataloging new species progresses slowly. As vegetation is reduced in many parts of the world, as many as half the species may be at risk. However, data on species loss are poor; much of what is lost is unrecorded, associated with the destruction of ecosystems in areas that have been largely unstudied. The rate of worldwide species extinction may be known only within a factor of 10. Even in the United States, statistical problems are considerable, as evident in the government list of endangered and threatened species. Since 1970 the number has doubled, but inclusion is limited to well-described plants and animals. Fluctuations in the listing result partially from procedural, administrative, and political forces and do not necessarily reflect changes in the natural environment. Declines in numbers of prominent species such as the African elephant, panda bears, and sea turtles are well-documented.

Loss of habitat, particularly wetlands, is well-documented for many countries. Coastal marine regions remain under great pressure, the effect of coastal population growth and development, associated changes in water quality, increased marine debris and pollution, and destruction of habitat, including mangrove forests, sea grasses, and coral reefs. The rise of interest in biodiversity stems not only from anthropocentric concern about the potential practical value of species but from ethics that emphasize the intrinsic value of all species and ecosystems.

Integral to the issue of biological diversity is the question of deforestation, in particular in tropical regions. Globally, forest cover today appears to be about 80% of what it was 3,000 years ago, when agriculture began to expand. In the past twenty-five years, according to data reported by governments, global wooded areas have diminished slightly. In the temperate zone, forests have generally increased during recent decades, a signal development. While cutting threatens stands of older and rarer trees, the majority of tree-harvesting in this zone is done on a sustainable basis. Removal of tropical forests has progressed at rates estimated at 1 percent per year and higher, as forests are cleared for fuelwood, crops, and pastures. Asian and South American wood production since the 1970s was 70% higher than 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, human artifacts actually cover less than 1 percent.

On a regional scale, acid deposition, mainly caused by emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx), emerged in the 1970s as a major issue in North America and Europe, and to a lesser extent in East Asia. In the United States, SO2 emissions are primarily from electric power plants and have dropped a third since 1970, though pressure for reductions probably came more from concerns about the local effects of SO2 on air quality and health than from acid rain. NOx emissions, from automobiles as well as power plants, remain steady with some annual fluctuations. Decreased emissions of SO2 are evident in lower rainwater sulfate, but the acidity of rainwater has still generally increased in prone regions. Red spruce trees, among the vegetation apparently most susceptible to acid rain, show diminished growth, although the extent to which acid precipitation is the cause is uncertain.

Transboundary acid deposition also occurs in Japan from Chinese and Korean emissions, but we lack long-term records of the extent of this problem. Emission, transport, and deposition of acid-causing emissions occur elsewhere, especially where fossil fuels are heavily used, but sparse data and knowledge of regional meteorological conditions clouds assessment of the problem. The numerous other natural and anthropogenic changes pressing upon ecosystems make hard the attribution of effects to acid rain.

Another issue with regional (as well as international and local) implications is storage and disposal of nuclear wastes. With the rise of nuclear electrification, the volume of spent fuel and other wastes has risen substantially but is still small. In the United States, the volume from commercial power plants is lower than expected twenty-five years ago because the number of plants actually constructed has not reached projected levels. Defense nuclear wastes are large contributors to the total waste volume. In the United States 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 anecdotes suggest a severe problem. Earlier disposal practices, such as dumping of low-level nuclear waste at sea, have been completely stopped by formal treaty because of environment-related concerns. Improved regimes for transport, storage, and disposal of nuclear wastes have been designed but not fully tested.

On a local scale, many trends in environmental quality are well- documented, because environmental policy began by addressing such issues as urban air pollution.

In the United States, the number of persons living in areas violating the National Ambient Air Quality Standards (NAAQS) for ozone in the lower atmosphere fell by over 10 percent from 1984 to the early 1990s. National ambient concentrations of ozone, as well as carbon monoxide, have dropped by over 40 percent since 1970. The reduction was achieved through technological changes that yielded lower emissions of pollutants from transportation. The nearly complete elimination of leaded gasoline largely accounts for reduction in airborne lead levels by a factor of 20. However, with growth of vehicle fleets and accompanying gridlock, chronic pollution of urban air has not much lessened in the United States and in some areas 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 that area 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. Particulate concentrations have improved in many cases, but not by much. In France a dramatic drop occurred due to the shift from fossil fuels to nuclear power. Possible 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, particularly members of sensitive groups.

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 per year respectively. The average in New Delhi over the same period was 295 days. Since the mid 1970s, SO2 levels exceeded the standard an average of 100 days per year in Teheran. In 1991 in Mexico City air quality standards were seriously violated over 300 days. Indoor air pollution is a sometimes severe problem that has been recognized and measured only recently. Asian households using wood- and dung- fueled ovens experience indoor particulate concentrations greater than one hundred times the WHO standards.

Another problem of intense local concern is disposal of wastes. Rates of municipal waste production have increased linearly with time in the United States in the 1970s and 1980s, but have not grown as fast as GDP. In many areas the limited capacity of landfills has led to rising costs for waste disposal and attempts to export wastes to more distant locations, sometimes in other nations. Consumption of specialized materials such as aluminum and plastics continue to grow. Global steel production grew at half the rate of population and a quarter the rate of GDP. The amount 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 primary consumption. Overall, evidence of global “dematerialization” or decreasing intensity of materials use is inconclusive.

No single overall trend summarizes marine and water pollution. Since 1970 the amount of oil spilled annually has fluctuated with sporadic large departures from the mean, as in 1991 due to the Valdez oil spill in Prince William Sound. The number of tanker accidents was lower in the 1980s and early 1990s than the 1970s. The decreases probably owe 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, form the largest source of marine oil pollution and remain hard to assess. Inland water bodies, such as the Aral Sea in Central Asia, groundwaters, and many rivers in both developing and industrialized regions have continued to experience major problems as a result of combinations of imprudent irrigation, diffuse pollution sources such as urban runoff, fertilizer and pesticide use, and contamination from both active and inactive industrial sites. Some 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 twenty-five years, though much remains to achieve high levels of water quality.

The prevalence of several environmentally hazardous materials has diminished considerably. Strontium-90 has dropped sharply worldwide since the 1960s when atmospheric testing of nuclear weapons was banned. In the United States, levels of PCBs (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 being banned, their persistence in the environment has kept them a leading topic of toxicological research. Previous disposal of these and other hazardous wastes has contaminated many locations around the world, and the catalogue of these sites has grown. In the United States, documentation and remediation predominantly concern previously contaminated sites, with few new sites created.

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. Among such indicators are the number of laws and regulations governing environmental matters, the level of expenditure on environment, application of technology to environmental problems, and the creation of institutions to deal with environmental issues.

In the United States, the number of federal laws for environmental protection has more than doubled since 1970. Compliance with laws also reportedly increased, though data are sparse. The number of acts and regulations relating to environment in the United Kingdom increased from 6 in 1885, to 21 in 1945, to about 100 in 1970, and has tripled since then to about 300. The environmental directives and decisions of the European Community were initiated about 1970 and grew to almost 200 by 1990. The number of multilateral agreements on environment, which totaled about 50 in 1970, now nears 200. The point of maximum activity in the process of making rules for environment appears to have occurred about 1980.

Spending is a second indicator of response to environmental issues. In the United States, real spending on pollution abatement doubled since 1970 and currently exceeds $90 billion annually. Industry spends most. U.S federal outlays for natural resources and environment more than doubled in real term from 1970 to over $22 billion in 1994. U.S. federal environmental R&D now totals about $5 billion, likely more than doubling the comparable 1970 sum.

Pollution control commonly mandates abatement technologies, whose diffusion provides another indicator of trends in environmental protection. One example is flue gas desulfurization (FGD), which removes SO2 before release 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. Another example is catalytic converters for automobile exhausts. In the United States these were introduced in the mid-1970s and are now found on more than 90 percent of the vehicle fleet. Many countries do not yet require or enforce auto emission controls. Technological solutions can also help reduce threats to water quality. In the United States, the fraction of the population served by wastewater treatment plants has doubled since 1970 to 75 percent of the population, typical of the OECD as a whole.

To curb pollution, many government regulators, especially in the industrialized world, have recently turned to voluntary agreements that are flexible to allow for innovation by the private sector. In Japan more than forty thousand such agreements have been concluded since the early 1970s. Within firms, innovative practice is becoming more preemptive, as the trend is towards pollution prevention. Successful instances of pollution prevention must now be numerous, but non-releases are hard to quantify.

Increased governmental spending and oversight has led to the creation of institutions, governmental and non-governmental, devoted to environmental protection. Globally, the number of ministerial-level departments of environment has increased from fewer than 10 in 1970 to over 100. Green political parties have formed in many countries. In 1992 the United Nations convened an ‘Earth Summit’ on environment and development that was attended by over 100 heads of state. The summit responded to and encouraged global environmental awareness and urged individual countries to set coherent priorities through national plans which most countries prepared in advance and many are updating. Tangible products were treaties on biodiversity, climate, 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, monitoring, and coordination of national programs for environmental protection. The World Bank, UNEP, and the United Nations Development Programme created a Global Environment Facility (1991), as the main multilateral mechanism to provide funds to developing countries for complying with environmental commitments.

Non-governmental environmental organizations (NGOs) have multiplied, roughly tripling in the United States between 1970-1990. Increasingly, NGOs provide services previously reserved by governments, and distribute funds from international organizations and national governments. 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), the premiere international scientific network of environmental scientists, has published more than 40 authoritative reviews since its founding in 1969 by the International Council of Scientific Unions. New domestic institutions that bridge the public and private sectors to address particular issues such as 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 most important strategies for environmental protection has been through zoning and reservation of lands. National forests, nature parks, and similar areas represent resources set aside, with various levels of restrictions, to conserve the environment. In most countries the area of protected lands has continued to increase. Internationally, since the mid 1980s the amount of land protected rose almost 90 percent. Because of a few large acquisitions, the area of the national park system in the United States has more than tripled since 1970.

Conclusions

Our review of the past 25 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 are moving favorably as a result of applications of science and technology as well as behavioral and policy shifts in both developing and industrialized countries. For example, energy intensity, the source of major environmental problems when fuels are dirty, is decreasing, and the fuel mix is decarbonizing, signifying a shift to cleaner sources. Moreover, societies have mobilized to a remarkable extent to address environmental issues.
Keeping pace with environmental considerations may become harder. Consumption and population growth continue to offset efficiency gains so that in many cases and places environmental burdens become heavier. Humans have to be ever smarter, if we are more numerous and if each one of us on average is processing more materials. Pressure on the environment seems bound 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 issues and policy responses reflects not only changing conditions and the discovery of new problems, but also changes in what human societies define as problems and needs. On the one hand, survival requires environmental protection. On the other, with higher income preference rises for environmental amenities. Where development succeeds, the preference for environmental goods will grow. Where development fails, environmental deterioration may become worse and bear blame for impoverishment.
Environmental issues are increasingly shared and international. Pollutants cross borders, effects cross borders, and world markets link the sources and consequences of the problems. The issues are also international because key technologies are selected on a global basis, so that a nation desiring an alternative style of development can hardly maintain an island of independence from the international system. Driving forces, such as the energy system, are fundamentally global.
Developing countries are most at risk from environmental problems. Connected to industrialization and urbanization, environmental issues on the agenda in industrialized nations now manifest themselves intensely in the developing world before these countries solve earlier environmental problems associated with population growth and poverty, such as deforestation. Moreover, in some respects vulnerability of developing countries to environmental hazards may be increasing, for example, through population growth in low-lying coastal areas prone to flooding.
Knowledge of environmental issues has progressed rapidly but remains tentative, partial, and insufficiently widespread. Reliable foresight of 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.
We have prepared ourselves to solve the environmental problem. Even with the gaps in knowledge, society at all levels has articulated the environmental problem over the past twenty-five years and recognized many ways to address its sources and manifestations. The burdens humans place on the environment and the resources of knowledge and money at our disposal to modify and adjust these burdens will contest endlessly. But we can surely gain green ground over the next 25 years.

Data note

Numerous sources provided the data for this text. Several which stand out for general utility are referenced below. The biennial World Resources offers 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. For more specific information on references to these and other sources, please contact the authors.

World Resources. 1987, 1990-1, 1992-3, 1994-5. World Resources Institute. New York: Oxford University Press.

Human Development Report. 1990-4. United Nations Development Programme. New York: Oxford University Press.

World Development Report. 1992-4. World Bank. New York: Oxford University Press.

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

Statistical Abstract of the United States, 114th edition. 1994. U.S. Department of Commerce.

Environmental Quality, 23rd Annual Report. 1991-3. Council on Environmental Quality. Washington, D.C.: U.S. Government Printing Office.

Acknowledgment: We thank Peter Elias for research assistance.

Note: An antecedent of this paper by Ausubel and Victor appeared in “International Environmental Research and Assessment,” pp 55-70. New York: Carnegie Commission on Science, Technology, and Government, 1992.

Appendix

Data Sources for “The Environment Since 1970”

Data on world population by geographical region are collected by the United Nations and presented in the annual United Nations Statistical Yearbook (New York: UN), as well as World Resources Institute’s biennial World Resources (New York: Oxford University Press). Population divided along lines of economic development is reported by the World Bank in, the annual World Development Report, (New York: Oxford University Press). Urban and rural populations are disaggregated in the United Nations Development Programme’s annual editon of the Human Development Report (New York: Oxford University Press). A complete survey of world commercial energy, including data on reserves, is found in British Petroleum’s annual BP Statistical Review of World Energy (London: BP); the World Development Report conveniently aggregates energy consumption according to level of economic development. Energy intensity for the United States and other member countries of the Organisation for Economic Co-operation and Development (OECD) is reported annually in OECD: The State of the Environment (Paris: OECD). On efficiency, see R.U. Ayres, 1989, “Energy efficiency in the US economy: A new case for conservation” (Laxenburg, Austria: International Institute for Applied Systems Analysis, RR-89-12). Data on electrification (including nuclear energy) are compiled in World Resources, as well as OECD, 1994, Electricity Information 1993 (Paris: OECD). Information on the number of operating nuclear power reactors is available from the International Atomic Energy Agency, 1994, Nuclear Power Reactors in the World (Vienna: IAEA). On decarbonization see, J.H. Ausubel, 1992, “Industrial ecology: Reflections on a colloquium,” Proc. Natl. Acad. Sci. USA 89(3):879-884. Global and continental vehicle data are from the Motor Vehicle Manufacturers Association (MVMA), Motor Vehicle Facts and Figures ’93 (Detroit, MI: MVMA), and earlier editions; air travel data are from the United Nations’ Statistical Yearbook.

The annual United Nations’ Food and Agriculture Organization Production Yearbook (NY: UNFAO) compiles data from many sources on arable and permanent cropland and includes data on global fertilizer use. Data on crop yields are from B.R. Mitchell, 1988, European Historical Statistics 1750-1975 (NY: Facts on File), the UNFAO, and the U.S. Department of Agriculture’s PS&D View database; fertilizer usage and total caloric intake are from the World Bank’s World Development Report. Trends in the mechanization of agriculture are reported in the U.N. Statistical Yearbook; World Resources contains partial global data on pesticide use; comprehensive data for the U.S. are reported by the Council on Environmental Quality annual publication Environmental Quality (Washington: U.S. Government Printing Office). Trade in agricultural products is from the U.N. Food and Agriculture Organization, and selected data are printed in the U.N. Statistical Yearbook; see also U.N. Conference on Trade and Development, 1990, UNCTAD Commodity Yearbook (New York: United Nations). Growing use of gene banks is discussed in D.L. Plucknett et al., 1983, “Crop germplasm conservation and developing countries,” Science 220, 163-169. Production and yield of rice are from the International Rice Research Institute annual World Rice Statistics. Dietary data are available in the U.N. Statistical Yearbook; detail on the changing diet of the U.S. population is compiled in the U.S. Department of Commerce annual Statistical Abstract of the United States (Washington: Government Printing Office). Data on the world catch of fish and aquaculture statistics are from The State of the Environment, see also D. Pauly and V. Christensen, 1995, “Primary production required to sustain global fisheries,” Nature 374, 255-257.

Data on per capita income are taken from the World Bank’s, World Tables 93, (Baltimore: Johns Hopkins University Press). Infant mortality, life expectancy, access to safe drinking water, and adult literacy data are found in the UNDP’s Human Development Report, which also describes the “human development index”, a combination of economic and social indicators of development. Trends in the distribution of economic activity in agriculture, manufacturing, and services are from the World Development Report; data on the number of personal computers sold and in use are reported in Statistical Abstract. Spending on health as a percentage of GNP is reported in the Human Development Report. Gross World Product data are from the World Development Report.

Data on CO2 emissions from fossil fuels and cement, and methane emissions are from World Resources. Concentrations of greenhouse gases are from the Mauna Loa station (CO2) and other measuring stations and are reproduced in Environmental Quality and in World Resources. These two publications also reproduce data on production of CFCs from company reports to the Chemical Manufacturer’s Association. Methane data are in R.J. Cicerone and R.S. Oremland, 1988, “Biogeochemical aspects of atmospheric methane,” Global Biogeochemical Cycles 2:299-327. Decreases in the early 1990’s in the growth rate of atmospheric methane are reported in E.J. Dlugokencky et al., 1994, “A dramatic decrease in the growth rate of atmospheric in the northern hemisphere during 1992,” Geophysical Research Letters 21, 45-48. A summary of statistics on the loss of ozone over Antarctica and at high latitudes is found in R.T. Watson et al., 1988, Present State of Knowledge of the Upper Atmosphere 1988: An Assessment Report, NASA Ref. Publ. 1208. Worldwide ozone- loss is discussed in R.S. Stolarski et al., 1991, “Total ozone trends deduced from Nimbus 7 TOMS data,” Geophysical Research Letters 18, 1015-1018. Data on species are found in K. J. Gaston and R. M. May, 1992, “Taxonomy of taxonomists,” Nature 356, 281-282. The number of endangered and threatened species on the U.S. list is from the U.S. Department of the Interior, Fish and Wildlife Service, Office of Endangered Species and is also reported in Environmental Quality. Wetlands data for the U.S. are from Environmental Quality. Wooded areas data are from the United Nations’ Statistical Yearbook. World Resources reports information on the global wood trade; the OECD Environmental Data: Compendium 1989 (Paris: OECD) contains data on the export of wood products such as panels from all countries. Some data on changes in forest cover and resulting estimated CO2 emissions are reported in World Resources 1990-91, but these are controversial. One estimate of the increase in pastures (and decrease in forests) in Costa Rica is found in N. Myers, 1984, The Primary Source: Tropical Forests and Our Future (New York: Norton), p.132. Global land use data are in A. Gruebler, 1992, “Technology and global change: land-use, past and present” (Laxenburg, Austria: International Institute for Applied Systems Analysis).

Emissions of sulphur dioxide and nitrogen oxides in the U.S. are from Environmental Quality. Sulphate concentration and acidity of rainwater can be found in the OECD Compendium. Trends in the growth of red spruce trees are for the period 1970 to 1980 and are reported in National Research Council, 1983, Acid deposition: Long-term Trends (Washington: National Academy Press). The volume and radioactivity of nuclear wastes are from Environmental Quality; ocean dumping of nuclear wastes is discussed in OECD’s Compendium.

Data on the number of violations of the ozone standard from the National Ambient Air Quality Standards are from Environmental Quality . Emissions and average daily maximum concentrations are reported in Environmental Protection Agency, 1990, National Air Quality and Emissions Trends Report, EPA-450/4- 90- 002, as well as Environmental Quality. Similar (but less extensive) data on the Japanese environment are found in Environment Agency of the Government of Japan, 1988, Quality of the Environment in Japan. Data on particulate and SO2 levels in large cities in the developing world exceeding WHO standards are from World Resources. Municipal waste production in the U.S. is from the United States Environmental Protection Agency’s Characterization of Municipal Solid Waste in the United States: 1992 Update, Final Report. EPA Report No. 530-R-92-019. (Washington: Government Printing Office). On dematerialization, see I.K. Wernick, R. Herman, S. Govind, and J.H. Ausubel, “Materialization and dematerialization: Measures and trends,” in Technological Trajectories and the Human Environment, eds. J.H. Ausubel & H.D. Langford (Washington DC: National Academy) in press. Trends in recycling for some countries are published in the OECD Compendium. Data on global steel production broken by method of production are from the Statistical Abstract which includes world data on the volume and number of oil spills. Other marine and water data are in the OECD Compendium. Environmental Quality contains sample data on the levels of PCBs, Sr-90, and lead in the environment.

The number of environmental protection laws in the U.S. is reported by R.E. Balzhiser in J.L. Helm (ed.), 1990, Energy: Production, Consumption, and Consequences (Washington: National Academy Press). Multilateral agreements on the environment, as well as domestic spending for air and water environmental protection, are summarized in the U.S. Council on Environmental Quality’s Environmental Quality. Further information on multilateral agreements and organizations is found in L.K. Caldwell, 1990, International Environmental Policy: Emergence and Dimensions (Durham: Duke University Press), P. Brackley ed.; 1990, World Guide to Environmental Issues and Organizations (Harlow, Essex: Longman); and the 1987 European Environmental Yearbook (Washington DC: BNA). Data on U.S. expenditures on pollution abatement are from the Statistical Abstract. For a detailed account of U.S. federal environmental R&D funding see K.M. Gramp et al., 1992, “Federal funding for environmental R&D,” (Washington, DC: American Association for the Advancement of Science). Flue gas desulfurization capacity in Japan is from the Quality of the Environment in Japan report. The U.S. population served by waste water treatment plants is summarized in the U.S. Department of Commerce’s Statistical Abstract. Data on the number of environmental NGOs are from T. Princen and M. Finger, 1994, Environmental NGOs in World Politics, (London: Routledge). Data on protected areas are found in World Resources and refer to categories I-V established by the International Union for Conservation of Nature and Natural Resources (IUCN). Acreage of the U.S. national park system is from the Statistical Abstract.

Jesse Ausubel directs the Program for the Human Environment at The Rockefeller University in New York City, where Iddo Wernick is a research associate. Ausubel drafted the 1983 National Research Council report, “Toward an International Geosphere-Biosphere Program: A Study of Global Change,” the document which originated the IGBP and first employed the term “global change” in reference to environment. David Victor leads the program on compliance with international environmental commitments at the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria.