Air pollution kills an estimated 2.7 million to 3.0 million people every year—about 6% of all deaths annually (171, 227, 261). About 9 deaths in every 10 due to air pollution take place in the developing world, where about 80% of all people live (227) (see Table 1).

About 2.5 billion people, almost all in developing countries, suffer from high levels of indoor air pollution (200). Indoor air pollution is due to burning wood, animal dung, crop residues, and coal for cooking and heating. Most of the victims of indoor pollution are women and girls, who have primary responsibility for cooking and tending the house (227).

Outdoor air pollution harms more than 1.1 billion people, mostly in cities (196). The World Health Organization (WHO) estimates that about 700,000 deaths annually could be prevented in developing countries if three major atmospheric pollutants—carbon monoxide, suspended particulate matter, and lead—were brought down to safer levels (48, 261). The direct health cost of urban air pollution in developing countries was estimated in 1995 at nearly US$100 billion a year. Chronic bronchitis alone accounted for around US$40 billion (227).

In cities that lack pollution controls, millions of people are at risk from outdoor pollution. Densely populated and rapidly growing cities such as Bangkok, Manila, Mexico City, and New Delhi are often entombed in a pall of pollution from trucks and cars and from uncontrolled industrial emissions. In 1995, for example, the average ozone concentration in Mexico City was about 0.15 parts per million, 10 times the natural atmospheric concentration and twice the maximum permitted in Japan or the US (96, 157). Ozone is a powerful secondary pollutant formed when oxides of nitrogen and unburned volatile organic hydrocarbons, mostly from vehicle exhausts, combine with oxygen under the action of sunlight. Ozone is a main component of smog.

Another powerful secondary pollutant is acid rain, formed when sulfur dioxide and oxides of nitrogen combine with water vapor and oxygen in the presence of sunlight to form a diluted "soup" of sulfuric and nitric acids. They can fall as both wet (acid rain) or dry deposition. Other harmful pollutants include sulfur dioxide, suspended particulate matter (soot, ash, and smoke from fires), carbon monoxide from vehicle exhausts, and lead, mainly from the exhaust of vehicles that burn leaded gasoline (262).

Air pollution is not only a health hazard but also reduces food production and timber harvests, because high levels of pollution impair photosynthesis. In Germany, for example, about US$4.7 billion a year in agricultural production is lost to high levels of sulfur, nitrogen oxides, and ozone (227).

Globally, 2.3 billion people suffer from diseases linked to water. Providing safe drinking water and adequate sanitation would have major health benefits. Some benefits include an estimated 2.1 million fewer deaths from diarrheal diseases, 150 million fewer cases of schistosomiasis, and 75 million fewer cases of trachoma (63, 261).

Water-borne diseases, also known as "dirty water" diseases, result from using water contaminated by human, animal, or chemical wastes. These diseases cause an estimated 12 million deaths a year, 5 million of them from diarrheal diseases. Most of the victims are children in developing countries (46, 222, 227).

In many places both surface and ground waters are fouled with industrial, agricultural, and municipal wastes. According to the World Commission on Water for the 21st Century, more than half of the world's major rivers are so depleted and polluted that they endanger human health and poison surrounding ecosystems (117). In many large cities in the developing world the drinking water supply is contaminated. Only half of Southeast Asia's 550 million people have access to safe drinking water (237).

Sara A. Holtz, Peace Corps

In rural Togo a village woman collects water for family use from a shallow well. Globally, some 2.3 billion people suffer from water-borne diseases. Providing safe drinking water and adequate sanitation would have important health benefits.

Illnesses traced to heavy metals date back to ancient Rome, where lead pots, pipes, and smelters were held responsible for loss of intelligence among children and for brain damage and abnormal behavior among adults (181). Heavy metals released into the environment today come from uncontrolled emissions by metal smelters and other industrial activities, unsafe disposal of industrial wastes, and lead in water pipes, paint, and gasoline.

The heavy metals most dangerous to health include lead, mercury, cadmium, arsenic, copper, zinc, and chromium. Such metals are found naturally in the soil in trace amounts, which pose few problems. When concentrated in particular areas, however, they present a serious danger. Arsenic and cadmium, for instance, can cause cancer. Mercury can cause mutations and genetic damage, while copper, lead, and mercury can cause brain and bone damage (262).

Lead additives in gasoline cause widespread health problems in some countries. In Thailand, for example, a 1990 study found that some 70,000 children in Bangkok risked losing four or more points of IQ (Intelligence Quotient, based on standardized tests) because they were heavily exposed to lead emissions from motor vehicles. In Latin America some 15 million children under the age of two are at risk of ill health from lead pollution (227).

In the US leaded gasoline began to be phased out after the passage of the Clean Air Act in 1970. It was not until the mid-1980s, however, that the European Community followed suit. Elsewhere, leaded gasoline continues to be used extensively (181, 227).

Human exposure to persistent organic pollutants (POPs) occurs in several ways—in foods, mostly as pesticide residues; occupationally, as among farm workers who spray pesticides on crops; and through accidents, including leaks in indoor storage areas (6, 261). POPs are organic compounds that have long lives in the environment and undergo physical, chemical, and biological changes over time.

What makes POPs especially dangerous is that they tend to accumulate in the fatty tissues of animals and humans. They climb the food chain, increasing in concentration as one organism eats a lower one, lodging eventually in human beings and such top predators as polar bears and wolves. Once in the human body, they mimic the function of steroid compounds, such as hormones, leading to the disruption of the endocrine system. Such disruption can damage reproductive health, causing sterility, birth defects, cancers, and spontaneous abortions, among other adverse effects (147).

POPs also can travel great distances in air or water. Greenlanders, for example, live thousands of miles from any known source of the pesticide hexachlorobenzene (HCB), but they have 70 times as much of this pollutant in their bodies as people from temperate areas of Canada (130, 134). The highest concentrations of one of the most potent POPs—polychlorinated biphenyls (PCBs)—have been found in Inuit people in the remote Arctic. Their levels are several hundred times higher than those reported anywhere else (134). This carcinogenic chemical has been found in elevated concentrations in the blubber of whales and seals, which are important food sources for the Inuit people.

In Denmark epidemiologists have noted a threefold increase in testicular cancer over the past 50 years, an increase that they attribute to proliferation of toxic chemicals, such as POPs, in the food chain (261). Some think that high levels of DDT may predispose women to breast cancer (28).

Global negotiations are now underway to ban or greatly limit use of 12 dangerous compounds, mostly pesticides. The first international meeting to discuss a global treaty to limit POPs took place in Montreal in July 1998. Currently, a framework treaty is being negotiated under the auspices of the United Nations Environment Program (UNEP). It is expected to be ready for signature by the end of 2000 (6). By signing the treaty, nations will commit themselves to concrete steps to phase out production and use of these chemicals by a specified date.

R. Faidutti/FAO

In Eritrea a farmer sprays pesticide on his fields. Increasingly, toxic chemicals are entering the food chain, with serious effects on human health. Global negotiations are underway to limit use of 12 dangerous chemical compounds, mostly pesticides.

In recent years scientists have become increasingly concerned about the long-term effects of deteriorating environmental conditions on the health not only of humans but also of nature itself. "We are no longer talking only of an increased exposure to specific extraneous hazards as a cause of bad health. We are also recognizing the depletion or disruption of natural biophysical processes that are the basic source of sustained good health," points out epidemiologist Tony McMichael of the London School of Hygiene and Tropical Medicine (152).

At increasing risk, according to McMichael, are the ecosystems that determine food productivity and such global systems as the hydrological cycle—in which water evaporates from bodies of water and returns to them after falling as precipitation—and the stratospheric "ozone shield" that protects against excessive solar ultraviolet radiation. Such environmental changes would have a wide variety of negative effects on human health (see Table 2).

Some ecologists use the term "environmental distress syndrome" to identify deteriorating environmental conditions and resulting threats to health. Paul Epstein of Harvard Medical School lists four symptoms of this syndrome (61):

• Re-emerging infectious diseases, including typhoid, cholera, and pneumonia, and the emergence of new diseases, such as drug-resistant tuberculosis and human reproductive disorders linked to industrial chemicals.
• Loss of biodiversity and the consequent loss of potential sources of new medicinal drugs and food crops.
• The decline in pollinators, such as bees, birds, bats, butterflies, and beetles, which are indispensable to the reproduction of flowering plants.
• Proliferation of harmful algae along the world's coastlines, leading to more deadly outbreaks of diseases such as ciguatera poisoning and paralytic shellfish poisoning.

Such symptoms raise a disturbing question: At what point might the depletion of the world's ecological and biophysical capital undermine global public health? For instance, WHO has reported that a recent epidemic of meningitis in sub-Saharan Africa could be linked to an expansion of degraded agricultural and grazing land-a result of changes in land—use patterns (less vegetative cover) and less rainfall due to regional climate change triggered by human activities (152).

One study links a marked increase in diarrheal diseases among Peruvian children to the frequent and severe El Niño weather patterns, which are characterized by heavy rainfall and result from unusual warming of the equatorial Pacific Ocean. El Niño has been linked to outbreaks of dengue fever, malaria, and cholera. Its patterns have been made worse by global climate change (33) (see side-bar, Global Warming: Worrisom Signs).

The organisms that transmit such diseases as malaria, dengue fever, and schistosomiasis are sensitive to temperature, humidity, rainfall patterns, and wind. Increases in temperature tend to accelerate the life cycles and decrease the incubation periods of the parasite or virus. These changes extend the time during which the diseases are transmitted and encourage their spread to new areas (62 , 131, 150).

Global climate change also has indirect effects upon the transmission of diseases (150). For example, global warming would increase the need for irrigation. In hot climates the prevalence of schistosomiasis already has increased due largely to the expansion of irrigation systems and dams. These systems support more water snails, an intermediate host of the schistosomiasis worm, and bring more people into closer contact with worms (131).

Will there be enough food to go around? Rapid population growth, environmental degradation, and inadequate international food distribution raise this question. About 2 billion people lack food security—defined by the UN Food and Agriculture Organization (FAO) as a "state of affairs where all people at all times have access to safe and nutritious food to maintain a healthy and active life" (75).

In many countries over the past two decades growth in the food supply has lagged behind population growth (75). Worldwide, the grain harvest increased about 1% annually between 1990 and 1997, a rate of growth substantially slower than the average population growth rate in the developing world, at 1.6% (21, 23, 53, 113).

In 64 of 105 developing countries studied by FAO between 1985 and 1995, food production lagged behind population growth (74). Among regions, Africa fared the worst during this period. Food production per person fell in 31 of 46 African countries (74, 95).

Moreover, water shortages are becoming constraints on development in general and on food production in particular (186, 201). While population tripled in the last century, water withdrawals grew sixfold (120, 233) (see Chapter 4).

Countries fall into three groups: (1) those that have the agricultural capacity to be self-sufficient in food production; (2) those that are not self-sufficient in food production but have enough other resources to import adequate supplies of food; and (3) those that are not self-sufficient in food production and do not have the financial resources needed to fill the gap with imports.

In the first group, the agriculturally self-sufficient countries, are some European countries plus Australia, Canada, and the United States. These countries have sufficient cropland to meet most of their own food needs now and probably for many decades to come. In fact, many of these countries produce substantial surpluses of food, which they export (73, 75). They probably could produce enough to meet the food needs of all food-deficit countries, if those countries could afford to buy the food. Countries in the second group, food importers, include Japan, Singapore, some European countries, and the oil-producing states of the Arabian Gulf.

The third group consists of the "low-income food-deficit countries," to use the term coined by FAO (75). The low-income food-deficit countries comprise most of the developing world, including nearly all of sub-Saharan Africa (75, 78) (see Table 3).

Marilyn Pfaltz

Around the world millions of children and adults do not get enough to eat. In 64 of 105 developing countries studied by the UN, food production has lagged behind population growth. About 2 billion people lack food security.

Today, about 3.8 billion people-nearly two-thirds of the world's population-live in low-income food-deficit countries. In these countries millions know hunger, malnutrition, and even starvation when harvests fail, unless other countries provide emergency food aid in time. Worldwide, about 825 million people are chronically malnourished, according to a recent estimate by FAO (78, 278) (see Figure 1).

Many low-income food-deficit countries have among the world's highest population growth rates. By 2050 about 6 billion people will live in countries that have food deficits today (see Table 3).

In many low-income food-deficit countries the situation is worsening. Food production capacities are deteriorating (75). These countries face a number of serious constraints to achieving food security:

Limited arable land. Most fertile land already is under cultivation. Most uncultivated land is marginal, with poor soils and either too little rainfall or too much. Without massive technological improvements or substantial investments from external sources, increases in food production in low-income food-deficit countries will soon have to come from existing agricultural land—thus putting ever more pressure on its productive capacity (49, 73).

Susanne Riveles, Lutheran World Relief

In Burkina Faso, as elsewhere in Africa, villagers often have little choice but to farm marginal land. In many developing countries pressures on arable land, freshwater supplies, and other resources have been rising because of population growth.

Shrinking family farms. In most developing countries, family farms are divided into smaller and smaller parcels for each new, larger generation of heirs. Rapid population growth has shrunk the average family farm by half over the past four decades. In 57 developing countries surveyed by FAO in the early 1990s, over half of all farms were less than one hectare in size, not enough to feed the average rural family with four to six children. In India three-fifths of all farms are less than one hectare in size (73, 192). Worldwide, an estimated 420 million people live in countries that have less than .07 hectares of cultivated land per person (59).

Gene Thiemann, Lutheran World Relief

In Bangladesh family farms are being divided into ever smaller parcels for each new generation of heirs. In developing countries as a whole, the average family farm is half the size of 40 years ago.

Land degradation. Population pressures on arable land contribute to the land's degradation, as more and more marginal land is brought into cultivation to feed more and more people (23, 49). Land degradation claims 5 million to 7 million hectares of farmland each year (73). When soils are overworked, wind and water erode them faster. Soils also can become poisoned from improper irrigation techniques and from improper use of agricultural chemicals. Moreover, in most developing countries vast amounts of agricultural land are being lost as cities expand (see sidebar, Cities at the Forefront).

Nearly 2 billion hectares of crop and grazing land are suffering from moderate to severe soil degradation—an area about the size of Canada and the US combined (14, 52, 73). In some places fertile topsoil is being depleted 300 times faster than nature can replenish it (126). In Kazakhstan, for instance, nearly half of the cropland will be lost by 2025, according to the country's Institute of Soil Management (23).

Irrigation problems. Badly planned and poorly built irrigation systems have reduced yields on one-half of all irrigated land, according to a 1995 estimate by FAO (73). Irrigation is key to agricultural production. Although only 17% of all cropland is under irrigation, irrigated croplands produce one-third of the world's food supply (178).

Roughly 70% of all water withdrawn for human use goes to irrigate crops. Yet less than half of all water withdrawn for irrigation reaches the crops. Most soaks into unlined canals, leaks out of pipes, or evaporates on its way to the fields (186). Although some of the water "lost" in inefficient irrigation systems returns to streams or aquifers, where it can be tapped again, water quality invariably is degraded by pesticides, fertilizers, and salts that run off the land (104).

I. Spanventa/FAO

In Egypt workers dredge an irrigation canal. About 70% of all water withdrawn for human use goes to irrigate crops. Yet less than half of all water withdrawn for irrigation reaches the crops.

Salt buildup in soil has severely damaged 30 million hectares of the world's 255 million hectares of irrigated land, FAO estimates. A combination of salinization and waterlogging affects another 80 million hectares (73, 186). The world's irrigated croplands may actually be shrinking at a time when they should be expanding to meet demand (23).

Achieving food security means addressing several related issues: slowing population growth, increasing food production, and safeguarding the environment. Since, of course, not every country can be self-sufficient in food production, international trade will become increasingly important in the future to achieve food security worldwide. In low-income food-deficit countries slower population growth would allow time to achieve food security.

To provide food security for all of the 8 billion people projected by 2025, the world would have to double food production over current levels (73, 75). Achieving this goal would require a second "Green Revolution" in agriculture, like the one in the 1960s that boosted food production in the face of population increases.

Recent years have brought some promising developments. These include a new strain of super rice capable of boosting yields by 25% (160, 175), improved varieties of corn that could increase yields perhaps by 40% and that could be grown on marginal land (93), and a new blight-resistant potato (174).

To achieve food security, the food-deficit countries must reverse the current course of land degradation and begin to manage soil and water resources on a sustainable basis. There are many ways to protect agricultural land. In many areas, for example, irrigated land could be managed better by using hand pumps and traditional water harvesting techniques rather than relying on large-scale automated sprinkler systems (5) (See Population Reports, Winning the Food Race, Series M, No. 13, December 1997). Specific solutions will vary from one area to another. Virtually everywhere, however, protecting the environment will help produce more food to feed more people (73, 178, 186).

Demand for freshwater is rising rapidly as population grows and becomes more urban, and as water use per capita increases. Some areas already face shortages, and more will face them in the future unless steps are taken to manage water resources better.

The supply of freshwater on earth is finite. Thus, as population grows, there is less water per capita. In 1989 there were about 9,000 cubic meters of freshwater per person available for human use (37, 135). By 2000, because of population growth, that amount dropped to about 7,800 cubic meters per person (88). If the world's population grows to over 8 billion in 2025 as expected, the amount of water per capita will be just 5,100 cubic meters (45).

Even this amount of freshwater per capita would be enough to meet human needs if it were evenly distributed. But available freshwater supplies are not distributed evenly around the globe, throughout the seasons, or from year to year. Two-thirds of the world's population—around 4 billion people—live in areas receiving only one-quarter of the world's annual rainfall (87).

Throughout much of the world the renewable supply of freshwater—the amount available year after year on a sustainable basis—comes in the form of seasonal rains that run off too quickly for efficient use (185). India, for example, gets 90% of its annual rainfall during the summer monsoon season, which lasts from June to September. For the other eight months the country gets barely a drop (37).

Lauren Goodsmith

In Morocco a girl loads water barrels onto a donkey. By 2025, about 700 million people in Africa will live in water-short countries. Worldwide, 48 countries, with about 3 billion people, are projected to face water shortages.

Water Shortages

Already, population growth and rising use per capita are creating water shortages in many countries. A country is said to experience water stress when annual water supplies drop below 1,700 cubic meters per person. When supplies drop below 1,000 cubic meters per person per year, the country faces water scarcity for all or part of the year. Swedish hydrologist Malin Falkenmark developed these concepts of stress and scarcity to gauge current and future water needs against available supplies (64, 66, 82).

In 1995 Population Action International (PAI) adapted Falkenmark's concepts to calculate water stress and scarcity in countries around the world. PAI updated this estimate in 1997, based on population projections for 2025 and 2050. The results are startling: In 1995, 31 countries—home to nearly half a billion people—regularly faced either water stress or water scarcity. In 2025, 48 countries, with about 3 billion people, are projected to face water shortages (60, 82). The 20 countries of the Near East and North Africa face the worst prospects. In fact, the Near East "ran out of water" as long ago as 1972—in the sense that since then the region has withdrawn more water from its rivers and aquifers than is being replenished by nature (154). Currently, for example, Jordan and Yemen withdraw 30% more water from groundwater supplies every year than is replenished; Israel's annual water use exceeds the renewable supply by 15% (183, 185).

Africa also faces serious water problems. Already, over 200 million Africans live in water-stressed or water-scarce countries. By 2025 the number will rise to about 700 million, of whom over half will live in countries that face severe shortages for most of the year (65, 67, 182).

If water stress and water scarcity were calculated for regions instead of countries, parts of many other countries would be considered at risk. For example, while periodic flooding afflicts the southern part of China, the northern part faces chronic water shortages (22, 82). China's freshwater supplies have been estimated to be capable of supporting 650 million people on a sustainable basis—only about half the country's current population (190).

Competing for water supplies. When water supplies become scarce, competition can become intense. In recent years withdrawals of freshwater have grown in all categories of demand—for irrigated agriculture, industrial use, and municipal (household) purposes (139, 222, 244). Freshwater demand for municipal use is expected to outpace the capacity of many cities to provide it (237). In Bangkok, Dhaka, Lagos, and other rapidly growing cities, water theft has become widespread (137, 173, 220).

Because more than 200 major river systems cross national borders, cooperation can help avoid international conflict. For example, in November 1999 Egypt, Ethiopia, and Sudan agreed in principle on a strategy for using the Nile River "for the common benefit of all the river basin states" (172). If implemented, the agreement—which covers all uses of the river, for irrigation, hydropower, drainage, drought and flood control, and pollution prevention—would be a breakthrough in cooperative use of a vital natural resource.

Competing with nature. A substantial portion of the total freshwater supply is needed to sustain marshes, rivers, coastal wetlands, and the millions of species they shelter (68). As humanity withdraws more freshwater for direct use, less is available to maintain wetland ecosystems (12, 184, 187). Over 20% of the approximately 10,000 freshwater fish species in the world are either endangered or are already going extinct because their habitats are being threatened (18, 120) (see Chapter 7.1).

Wetland ecosystems are economically valuable. Robert Costanza of the University of Maryland estimates the global value of wetlands at close to US$5 trillion a year. This amount reflects the value of wetlands as flood regulators, waste treatment plants, wildlife habitats, fisheries production, and recreation (107).

The world's 6 billion people are already appropriating just over half of all the accessible freshwater contained in rivers, lakes, and underground aquifers. By 2025 humankind's share will be at least 70%. This conservative estimate reflects the impact of population growth alone. If per capita consumption of water resources continues to rise at its current rate, humankind could be using over 90% of all available freshwater within 25 years, leaving just 10% for the rest of the world's species (106, 187).

Caught between growing demand for freshwater on one hand and limited and increasingly polluted supplies on the other, many countries face difficult choices. Finding solutions requires responses at local, national, and international levels-a "Blue Revolution" that focuses on integrated management of watersheds and shared water basins (104) (see Population Reports, Solutions for a Water-Short World, Series M, No. 14, September 1998).

Community-led initiatives to manage water resources better can help urban dwellers gain access to safe, piped water supplies, thus improving sanitation and public health (46, 119). Governments can develop national water management policies that not only improve supply but also manage demand better with appropriate pricing—for example, ending subsidies that in effect encourage overuse (221).

Over half of the world's coastlines face environmental pressures from population growth and economic development. A rising tide of pollution threatens the seas. Coastal and ocean fisheries—containing most of the world's wild food harvest—are fast being depleted.

About half of all coastal areas face moderate to severe environmental stress from population growth and development pressures, according to a 1995 review by the World Resources Institute (WRI) (26, 274). The coastlines of most developed countries—particularly Japan, Australia, the US, Europe, and the European part of Russia—suffer degradation. Developing countries fare little better.

About half the world's population occupies a coastal strip 200 kilometers wide—only 10% of the world's land surface. Two-thirds of the world's people live within 400 kilometers (240 miles) of a seacoast. Given such population density, human activities are eroding close to 70% of the world's beaches at greater than natural rates (4). Erosion is a natural process, but it can be made worse by coastal development such as construction, urban expansion, sand dredging, and harvesting coral reefs for building material (102, 230, 255).

The world's coastal wetlands are disappearing. Around the world, about 182,000 square kilometers of mangrove wetlands provide a habitat for over 2,000 species of fish, shellfish, invertebrates, and plants. In the past century over half the world's original mangrove area has been destroyed or degraded, been converted to agricultural land or fish ponds, or fallen victim to urban and industrial development (102).

Seagrass beds also are vanishing. These underwater ocean meadows support a wide variety of commercially valuable species of fish and shellfish. Although no overall estimates of damage are available, these ecosystems appear to be shrinking near virtually all inhabited coastal areas (79).

D. Hinrichsen

Coasts along the Philippine island of Negros suffer from erosion caused by rising seas and poor land-use practices. Over half of the world's coastlines face environmental degradation from population growth and development.

Development activities are destroying most of the world's coral reefs. Of the world's 600,000 square kilometers of reefs in tropical and semi-tropical seas, scientists estimate that 70% could be lost within 40 years (102, 251). Coral reefs are being buried by sediment washed off the land, poisoned by industrial and agricultural chemicals, reduced to rubble by fishermen using dynamite, damaged by boat anchors and careless divers, excavated for use as building material, and bleached white by warming ocean temperatures.

Coral reefs provide humankind with many benefits. Reefs support upwards of 1 million species. They provide feeding, breeding, and nursery areas for fish and shellfish and offer humanity a pharmacopoeia of potential medicines. They buffer waves and protect shorelines from storms. Coral reefs have been valued at US$47,000 per square foot of shoreline for their protection functions alone (40).

In 1997 a global effort to assess the status of coral resources was carried out by Reef Check, organized by Hong Kong University. The study engaged professional and recreational divers to chart the health of 300 coral reefs in 30 countries. Less than one-third of all reefs studied had healthy, living coral cover (101). According to a 1998 assessment by WRI, the world's most degraded reefs are in Southeast Asia and the Caribbean (24).

Few people recognize how important reefs are. In Indonesia, for example, less than half of respondents surveyed in 2000 viewed coral reefs as a marine resource. In urban areas less than one-third of respondents knew that coral reefs were declining. Even in coastal communities, despite widespread reliance on fish, few people connected healthy coral reefs with the supply of food from the sea (211).

Almost everywhere, coastal cities dump their untreated wastes into the sea, often creating virtual cesspools so thick with pollution that almost no marine life can survive. No place in the world's seas is immune, as ocean currents transport pollutants to the far corners of the world (269).

In the Gulf of Mexico an environmental "dead zone" now covers over 7,700 square miles and appears to be expanding. Agricultural and industrial pollution from the Mississippi River Basin is responsible (159). In Calcutta, Bombay, and other cities of developing countries, raw sewage and untreated municipal wastewater flow into coastal waters in large amounts (94). In Chile untreated effluents, mostly from copper mines, pulp and paper mills, fish processing plants, and oil refineries, flow directly into the Bays of Valparaiso and Concepcion (229).

Rapid population growth along coasts has boosted demand for fish, while mounting pollution has threatened marine habitats. Over 80% of all commercial fish are caught within 320 kilometers of land, and many within just 50 kilometers. A combination of over-fishing and pollution has contributed to lower productivity in all but 4 of the world's 15 major fishing regions (148). In the hardest-hit regions catches have fallen by more than 30% since as recently as 1989 (270). In Southeast Asia nearly all waters within 15 kilometers of land are over-fished (89).

According to FAO, 69% of the world's commercial marine fish stocks are "fully exploited, over-fished, depleted, or slowly recovering" (77). Two-thirds of commercially valuable ocean species are in decline and in urgent need of management (59). Landings of the most valuable species of fish, including cod, tuna, and haddock, have dropped by one-quarter since 1970 (149).

D. Hinrichsen

In a small fishing village near Shanghai, people sort through the day's sea catch. As in many places, China's coastal waters are becoming polluted as cities dump untreated wastes into the sea. Most of the world's coral reefs are being threatened, while pollution and over fishing have depleted many valuable ocean species.

In 1994 the Law of the Sea Convention established a foundation for sustainable ocean management. The Convention affords all states the right to manage marine resources within their 200-nautical-mile Exclusive Economic Zones (EEZs). Most developing countries do not have the means to enforce regulations over such a vast expanse of sea, however (3).

In 1998 the World Wide Fund for Nature (WWF) and the World Conservation Union (IUCN) prepared a blueprint for sustainable management. Their suggested approach involves six principles:

1. Plans for conserving marine biodiversity must take account of human needs.
2. Educating the public and raising awareness must play a role in better marine management.
3. Communities must have the opportunity to protect and manage their own coastal resources.
4. Social and economic incentives must be created for conservation and sustainable use of ocean resources.
5. Policies must reflect the fact that the world's oceans are connected.
6. Governments must take the lead in managing their own waters, while cooperating with neighboring states.

Coastal resources are not easy to manage. Around the world, 177 nations have coastlines, but only 92 have coastal management plans. While this number is nearly twice that in 1992, most countries have yet to move from planning to implementation (204, 205).

The world's forest cover is shrinking. Over the past 50 years nearly half of the world's original forest cover has been lost—some 3 billion hectares. Each year another 16 million hectares of virgin forest are cut, bulldozed, or burned (25, 76).

Between 1980 and 1995 the world lost some 180 million hectares of forest—an area the size of Indonesia. While developed countries had a net increase of 20 million hectares due to reforestation, this gain was more than offset by a net decrease of 200 million hectares in the developing world (76).

Forests have many functions of value both to humanity and to nature itself. Take away the trees, and the intricately linked ecosystem unravels (83, 162). Forests absorb carbon dioxide and produce oxygen, anchor soils, regulate the water cycle, protect against erosion, and provide a habitat for millions of species (59).

Forest products are essential to the world economy, worth about US$400 billion annually in timber, pulp, paper, and fuelwood. Forest products other than wood, such as medicines, vegetables, and fruits, provide another US$20 billion and are growing in importance (83, 162).

Healthy forests boost food production. Trees soak up and store water from season to season, slowly releasing moisture during dry periods. Without tree cover, water runs off faster during the tropical rainy season, carrying away valuable topsoil. A World Bank study found that the rate of soil loss was 10 times higher on forest lands where slash-and-burn shifting cultivation was practiced than in undisturbed forests (34). One reason that agricultural yields have fallen in sub-Saharan Africa is that vast amounts of forest cover have disappeared, hastening soil erosion and loss of soil nutrients.

Forest cover regulates climate, while destruction of forests contributes to global warming. Whereas living trees soak up and store carbon dioxide from the atmosphere, trees that are cut down and burned release carbon into the atmosphere. In the last decade tropical deforestation has released large amounts of stored carbon—accounting for roughly one-quarter of the carbon dioxide emissions to the atmosphere due to human activity (83) (see sidebar, Global Warming: Worrisome Signs).

Current demand for forest products may exceed the limits of sustainable consumption by 25% (83, 249). The developed world accounts for most of the demand for forest products. With just 16% of the world's population, North America, Europe, and Japan consume two-thirds of the world's paper and paperboard and half its industrial wood (2, 25). Demand for industrial wood products also has risen in developing countries, however, along with demand for fuelwood, the main energy source for many rural communities (76).

Throughout the 1990s many developing countries with rapid population growth had high rates of deforestation (58). Forest land was converted to agricultural use, and trees cut to provide housing and wood for fuel. Moreover, developing countries stepped up exports of forest products to meet the rising demand from developed countries.

The amount of forest area per capita fell by half between 1960 and 1995--reflecting both population growth and the disappearance of forest cover (83). In 1995 close to 1.7 billion people lived in countries with less than one-tenth of a hectare of forest cover per capita (83). By 2025, an estimated 4.6 billion people will live in such countries.

Heraldo Castro/Conservation International

In Brazil and many other developing countries, logging is an important source of revenue. Forests are essential to the world economy, but current demand for forest products may exceed the limit of sustainable consumption by 25%.

As population grows and per capita consumption of forest products increases, countries must do more to manage forest resources on a sustainable basis. The following developments offer encouragement:

Technological improvements. Technological improvements, including use of recycled paper and paperboard, have substantially reduced the amount of pulp needed to produce paper. In 1970 paper and paperboard consisted of 80% wood pulp. By 1997 more efficient production processes had reduced that figure to 56%. As a direct result, the production of pulp for paper is expected to grow by just over 1% a year over the next decade, about half the growth rate in the 1980s (76).

Forest products certification. Adopting a system that identifies forest products that come from sustainably managed forests could support efforts toward sustainability. As of 1998, about 10 million hectares of forest lands have been certified (276). Over 90% of the certified area is in northern, temperate forests, mostly in Europe and North America. Close to 60% of the entire certified area is in just two countries--Sweden and Poland--reflecting education and awareness campaigns in those countries (76). In tropical forests, where most of the destruction is taking place today, only tiny areas have been certified as providing sustainable yield.

Intergovernmental responses. In 1995 the Intergovernmental Panel on Forests (IPF) was established in response to the 1992 Earth Summit. The IPF evolved into the Intergovernmental Forum on Forests in 1997, after the UN's five-year review of the Earth Summit goals. The mission of the forum is to examine the underlying causes of deforestation and to help countries develop strategies that address them (76).

Efforts to advance an international legal convention on forests, which began in 1990, have been shelved, however. Some observers believe that advancing such a convention would only codify the standards of a weak consensus and thus would be worse than no convention at all (15, 101). Widespread opposition to a convention makes it unlikely that the issue will reach the negotiating table (6).

Instead, many organizations urge governments of countries with large forest resources to enforce existing legislation and to introduce more effective forest conservation initiatives (6, 235). Close to 130 countries have developed or updated their National Forest Programs over the past decade (76).

While such initiatives are promising, they cannot be expected to halt forest destruction completely. Millions of people rely on forest products for their livelihoods. Sustainable forest management will require not just enforcement of laws that protect forests but also alternative sources of livelihood for many rural people.

No one knows the true scope of biodiversity—how many species of plants and animals share the planet with human beings. Most estimates put the number at somewhere between 10 million and 30 million, with some consensus around the figure of 14 million (43, 56, 143, 163). In any case, only about 1.7 million species—a small share of the total—have been identified and categorized, while even fewer have been studied (162, 163).

Whatever the actual number of species, preservation of biodiversity itself is vital to humanity. Currently, over 40,000 species of plants, animals, fungi, and microbes are regularly exploited for human benefit (56). An estimated 40% of modern drugs come from the wild, worth some US$40 billion a year in over-the-counter and prescription sales (217).

Biodiversity is essential to agriculture. After 10,000 years of settled agriculture and the discovery of some 50,000 varieties of edible plants, just 15 food crops provide 90% of the world's food energy intake. Three of them—rice, wheat and corn (maize)—are the staple foods of 4 billion people (73, 75, 257).

Dependence on only a few crops can be dangerous because disease can spread rapidly through monocultures—as it did through the Irish potato harvest, starving one-fifth of the country's population in the 1840s (181). Cultivars (cultivated plants) need to be cross-bred every 5 to 15 years to give them greater resistance to diseases and insects, as well as to introduce new yield-enhancing traits, such as increased tolerance for drought or saline soils.

Without repeated infusions of new genes from the wild, geneticists cannot continue to improve staple crops. Since 1900 about three-quarters of the genetic diversity of cultivars has been lost, as well as nearly half of the wild gene pool of domestic animals (73, 217).

	Heraldo Castro/Conservation International
Endangered species. Left: Sumatra rhino. Right: Madagascar lemur. Humans share the planet with at least 10 million other animal and plant species. Biological diversity is crucial to the world's ecology, and probably to the future of humanity itself. Yet human actions and numbers are sending thousand of species into extinction—most in areas where human population density is highest.

Humankind's current patterns of resource exploitation do not bode well for the future of biodiversity. Ecologist Norman Myers recently estimated that some 600,000 species have vanished since 1950 (164). Today, two of every three species are estimated to be in decline (216).

People today use almost half the energy needed to keep all of the earth's species going. That is, human beings use about 40% of the total net primary production of the earth's green plants, which are the fundamental food source for animals. This percentage could double within a quarter century (136). Over-exploitation of plants is worrisome, as plants provide the link to all other forms of life, through photosynthesis. "All flesh is grass," biologist David Given has observed (86).

The IUCN has reported that about 5,200 species of animals currently are threatened with extinction (115), including:

• Close to 1,100 species of mammals, one-quarter of the total number of such species;
• Over 1,100 birds, 11% of the 9,600 known species of birds;
• Over 2,000 species of freshwater fish, 20% of the total number identified;
• 253 species of reptiles, 20% of the total number surveyed;
• An estimated 124 species of amphibians, 25% of the total number surveyed (216).

Nearly 40% of all freshwater fish species in the US are at risk of extinction, as are 33% of Australia's freshwater fauna, and 42% of Europe's (18). Of the 514 species of birds in Europe, 270--about two-thirds--are threatened with extinction. Of these, 200 species are migratory (100). Many migratory species are threatened because of habitat destruction at both ends of their north-south migration routes (56, 115). Two-thirds of Asia's wildlife habitats have been destroyed, many over the past five decades (233).

Plant species are not faring well, either. Of the 270,000 known species of higher plants (such vascular species as trees and flowering plants), 34,000 are endangered (116). In the US nearly 30% of the 16,000 known plant species are at risk of extinction (17). In the tropics ecosystem destruction is so severe that some 60,000 plant species, roughly one-quarter of the world's remaining total, could be lost within 25 years (112, 217, 266).

Population pressures have played a major role in the loss of biological resources (9). Human activities have accelerated the normal pace of species extinction—that is, the pace that could be expected without the influence of humanity—by some 1,000 to 10,000 times, depending on the specific species (141, 246).

In a study of 50 countries in Asia and Africa from 1980 to 1990, the United Nations Population Fund (UNFPA) found that the loss of natural habitat was greatest in areas of high population density and least in low-density areas. In the 10 countries that had lost the most habitat (averaging 85%), the average population density was close to 200 people per square kilometer. In the 10 countries that had lost the least amount of habitat (averaging 41%), the average population density was just 29 people per square kilometer (95).

Other researchers have reached similar conclusions (9, 43, 179). One estimate is that three-quarters of human-induced pressures on mammal species, and nearly two-thirds of such pressures on bird species, are the result of fragmentation and destruction of their habitats, as people use more land for agriculture, industry, roads, and other purposes (43).

Human migration and trade have posed other problems for biodiversity, as people have introduced many nonnative species to areas, such as Hawaii, whose fragile habitats cannot cope with them (19, 108). For example, the Black Sea's fauna have been nearly exterminated not only by overfishing and pollution, but also by the accidental introduction of a comb jelly fish from the North Atlantic, a species that now comprises about 95% of the Black Sea's biomass (19, 153). In the US the introduction of nonnative species has been implicated in close to 70% of all freshwater fish extinction (216).

Lauren Goodsmith

A nurse tends medicinal plants. About 40% of modern drugs come from the wild. Biodiversity also is key to agriculture, as constant infusions of new genes are crucial to improving staple food crops.

Biodiversity hotspots are areas that contain a superabundance of plant and animal species but are threatened by human activities. Norman Myers coined the term "hotspots" in 1988, initially listing 10 tropical rainforests (161). He later expanded the number of hotspots to 18, and then to 25. Collectively, hotspots contain slightly more than half of all terrestrial species on just 2% of the world's land area. Most hotspots are substantially endangered already, having lost three-quarters of their total original vegetation (155, 164).

So far, all hotspots identified are on land (270). Many hotspots remain to be assessed and identified in marine areas, especially coral reefs, which are thought to contain more than a million species living on less than 1% of the earth's surface (103, 270).

Of the world's 25 terrestrial hotspots, 9 are in tropical rainforests, 5 include both wet and dry tropical forests, and another 5 consist of temperate Mediterranean-type ecosystems. In addition, three include tropical rainforest, dry forest, and arid systems; another is a mosaic of dry forest and savannah; while another is temperate forest and steppe; and the last is an arid region. An estimated 75% of all terrestrial animal species considered endangered or threatened live within these 25 hotspots (155) (see map).

The poor state of most biodiversity hotspots results directly from population growth and migration into these areas. A study by PAI found that by 1995 around 1.1 billion people, or 20% of the global population, were living within the 25 hotspots. Moreover, the average annual population growth rate in these areas was 1.8%, substantially higher than the 1.4% global rate and even above the average for developing countries, at 1.6%. PAI concluded that "human-induced environmental changes" will continue to put pressure on hotspots and, therefore, that conserving biodiversity requires paying close attention to population trends (35, 36).

Scientists point to three actions in particular that could help protect biodiversity--and might even help ensure that human life on earth itself does not become extinct (9, 141, 163, 216) (see sidebar, Five Extinctions and Counting).

Protect hotspots. As more organizations focus on protecting hotspots, the species within them might stand a better chance of survival. In 1989 Conservation International and the MacArthur Foundation became the first organizations to adopt the concept of biodiversity hotspots as a guiding principle for investments in environmental conservation (155). As new hotspots in marine areas are identified and added to the 25 currently identified terrestrial hotspots, protection should be extended to them, as well (270).

Safeguard protected natural areas from development. Over the past two decades population pressures and a shortage of arable land have forced some 200 million landless peasants out of traditional farming areas and onto protected land rich in biodiversity. These "shifted cultivators," as Myers has termed them, have little choice but to exploit the animal and plant species in these "biological oases" (164). To protect these natural areas, more must be done to help farmers settle on productive land, while stemming the future flow of population into protected natural areas.

Implement the Convention on Biological Diversity. This Convention, which was opened for signature at the Earth Summit in Rio, took force in December 1993 and so far has been ratified by 175 countries. The Convention has three major objectives: conserving biodiversity, ensuring its sustainable use, and guaranteeing the fair and equitable sharing of its benefits.

The US has rejected this third objective, as currently worded, largely because of the influence of the pharmaceutical industry. As a result, the US has not ratified the Convention and is unlikely to help implement it until agreement can be reached on how to compensate the US pharmaceutical industry for its bio-prospecting costs (6). Nevertheless, the Convention can be a major force for conservation, and the 175 countries that have ratified can do more to achieve its goals.

Assuring a livable future requires practicing sustainable development. Enabling people around the world to meet their current needs without depriving future generations of the resources needed to meet their needs poses a challenge (259). Currently, humanity is using about one-third more of the earth's biological productivity than can be regenerated. To achieve sustainable development, people must learn, in effect, to live on the world's "ecological interest" instead of drawing down its "ecological capital" (see Measuring Population's Impact).

Debate continues about how best to accomplish sustainable development (6, 8, 91, 189). Nevertheless, in a number of areas, progress is being made. Particularly important are:

• Improving energy efficiency;
• Planning cities better;
• Ending environmentally destructive subsidies;
• Adopting water resources management;
• Saving forests;
• Accomplishing a second Green Revolution;
• Managing coastal zones and ocean fisheries;
• Curbing pollution, improving health;
• Safeguarding biodiversity; and
• Stabilizing world population

Using energy more efficiently is becoming one of the world's highest priorities and greatest challenges (50, 80). The 20% of humanity in the most affluent countries consume close to 60% of the world's commercial energy (222). Nonetheless, most industrialized countries use energy more efficiently than developing countries, which often do not have the means to invest in energy-saving technologies or pollution control measures (69, 222, 226, 261).

Since the oil crisis of 1973, developed countries have adopted energy efficient and cost-effective technologies. These technologies include more efficient heating and cooling systems, better insulation, and lighting and appliances that use far less energy per unit of output (69, 70, 248). Energy efficiencies also are rising as industrial processes become less energy-intensive and as electric utilities find that selling energy conservation—referred to in the industry as "negawatts"—pays (248). Switching to renewable energy sources, such as wind, solar, and geothermal energy, is another improvement in conservation. Renewable energy sources are increasingly competitive in price compared with fossil fuels, and they cause little or no pollution (60, 180).

The following actions also could help conserve energy:

• Encourage the design and use of low-energy buildings (69). In India, for instance, Development Alternatives, a nongovernmental organization, has designed a simple, adobe-like house that needs no air conditioning. It is made from specially designed blocks that permit airflow and a new roofing tile made from micro-concrete, free from chemicals and synthetic fibers (13).
• Eliminate government subsidies for fossil fuels. In 1991 direct subsidies for fossil fuels totaled US$220 billion worldwide. Eliminating these wasteful subsidies, paid for with public tax money, and offering tax incentives (subsidies) for wind- and solar-powered energy generation would encourage their development (70).
• Encourage energy efficiency programs in industry. Most industrialized countries have voluntary programs to encourage energy efficiency at work sites. Developing countries are starting such programs, too. China, for instance, has introduced worker bonuses for ideas that lead to more efficient energy use. Since 1990 these programs have resulted in savings of some US$6 billion through energy efficiency improvements, which have increased Chinese industrial competitiveness (69).
• Invest in public transportation. Encouraging public transportation as an alternative to individual vehicles in urban areas is difficult. But it is becoming increasingly needed as urban populations and vehicle use increase. Finding ways to get more people to use public transport would go far to reducing pollution and saving energy.
• Introduce "hypercars." Hypercars—vehicles that run 80 to 100 miles per gallon of gasoline (petrol)—already are available but have not been produced in large numbers because demand is lacking. Making such vehicles readily available would be a sound investment, perhaps promoted by offering government rebates for their purchase. They are especially needed in smog-ridden urban areas (248).

Massive migration and rising population densities have made effective city planning and urban environmental management both a necessity and an increasing challenge. Effective urban planning and management require strong local government supported by active citizen groups (257).

Curitiba, Brazil, provides an example of effective urban environmental management sustained for over two-and-a-half decades. The World Bank has supported the Curitiba effort since the 1970s (214). Early in its planning process the city set aside large tracts of land and allowed poor squatters to build low-cost housing there. The city provided sewerage and water at a price that residents could afford (32, 156).

Paraná Turismo

Curitiba, Brazil, provides an example of good urban management sustained for over two-and-a-half decades. Planning cities better in the face of rapid population growth requires strong government commitment and support from citizen groups.

The city of Curitiba also introduced public transportation to link outlying areas with the city center through five primary roadways, built like spokes on a wheel. The result was less pollution and more economic growth, since people could travel farther to work by mass transit without as many private vehicles clogging the roads (32, 156, 171). In addition, Curitiba has achieved twice the amount of green area per person recommended by the UN (32).

Citizen action groups and nongovernmental organizations (NGOs) also can do much to improve living conditions. For example, in Orangi, a slum in Karachi, Pakistan, an NGO that mobilized the community was able to provide 70,000 households with sewerage and drains at one-seventh the unit cost that municipal authorities would have charged. The NGO also helped to obtain a low-interest loan to pay for the construction materials (198).

City governments also can enforce legislation that regulates air and water pollution. Nearly every city in the world has set limits on air and water pollution, but these regulations are rarely enforced. Clamping down on major polluters would yield many health benefits. Pollution control can be phased in to allow industries to adopt pollution abatement technologies and reduce waste through recycling or reuse of resources. Cities also could offer tax inducements for avoiding and for cleaning up pollution (198).

Worldwide, governments spend between US$650 billion and US$900 billion every year to subsidize environmentally destructive practices in agriculture, energy, and transportation (47, 196). Wasteful subsidies abound. Rice growers in Southeast Asia over-irrigate their fields because subsidies cover most of the costs of water, even though the amount of water used exceeds the natural recharge rate of many aquifers. Drivers in California use congested highways because road building and repair is subsidized more than public transportation. Uneconomical and highly polluting brown coal is still mined in Germany to keep miners employed (47, 195, 196).

As an alternative to wasteful subsidies, governments can consider the following:

Environmental taxes. Taxing activities that harm the environment can promote more sustainable resource use. In Malaysia the government began to tax leaded fuel to make it more expensive than unleaded fuel. As a result, unleaded gasoline has taken more than 60% of the market. Similarly, Costa Rica has placed a 15% duty on oil products in order to pass some of the costs of road construction on to drivers (195).

Tradable permits. Introducing permits to limit exploitation of public resources can help reduce waste. For instance, Chile has auctioned off permits to regulate fisheries and water use on irrigated farms. Nearly all of New Zealand's fisheries are regulated by permit systems that, among other things, limit the number of fishing vessels allowed to fish and also limit the types of species they can harvest.

The US has become a leader in tradable permits to control emissions of sulfur dioxide, a main ingredient in acid rain. The system, which was introduced in 1990, limits sulfur emissions after 2000 to half the 1980 level. Companies that reduce pollution below industry standards can sell credits to companies that are above the limits. This initiative created a US$1.2 billion a year industry in pollution credits and has spurred companies to reduce sulfur emissions (195, 196).

Getting the price right. Phasing out subsidies that encourage waste of resources should be a goal of every government. Getting the price right is a vital step in natural resource management, as in other sectors. A study of three oil exporting countries—Algeria, Iran, and Nigeria—found that removing subsidies to domestic use and bringing the price of domestic oil up to world levels would improve the efficiency of domestic oil use, resulting in savings of 10% to 18% of current production, which could then be sold abroad (47).

Increasingly, governments and NGOs are collaborating to promote integrated water resources management (IWRM) at the watershed or river basin level. IWRM is a comprehensive approach to regional management of surface water, groundwater, and coastal and marine aquatic resources. It not only addresses water conservation issues but also permits better management of human activities and land use affecting the quantity and quality of water resources.

Examples of integrated watershed management include the Chesapeake Bay program in the US, the Rhine River Basin initiative in Europe, and the Murray-Darling River Basin Commission in Australia. These programs have in common an alliance of state and national institutions in partnership with local citizen action groups and NGOs to manage common resources on a sustainable basis (1).

The following steps can help (102):

• Countries can first try water resources management within their own borders to gain experience and public acceptance. Coordinating conservation activities among different jurisdictions and at different levels of government, while balancing the often-competing interests of various water users, is complex.
• After successes on a small scale, the initiative can be expanded. An incremental approach is best—first tackling identifiable sources of pollution before moving to more difficult issues such as controlling the runoff of agricultural chemicals and animal wastes into rivers and lakes.
• Periodic benchmarks and reviews can help maintain public interest and acceptance and can measure progress.

Community efforts to preserve forests and to manage forest resources are showing a way forward in some endangered areas. Successful efforts allow people to meet their immediate economic and household needs while safeguarding forest resources for sustainable use in the future (109, 121, 162).

For example, in Papua New Guinea, the Bainings people of New Britain have resisted commercial enterprises that want to log their forests. Instead of the usual clear-cutting approach, they practice a form of selective logging, harvesting only certain species of trees from particular forest plots. Once the most economically valuable trees have been removed, the area is left to regenerate (10).

Also, in the Talamanca Mountains on the border between Panama and Costa Rica, AMISCONDE, an NGO, helps 9,000 small-scale farmers increase yields on marginal land while preventing deforestation. AMISCONDE provides the farmers with loans and credits to improve yields on their existing farmland, rather than clearing forests to create new farmland, and to diversify their crops. The community now has a sense of ownership over forest resources that encourages conservation and stewardship (16).

At the international level, the Forest Stewardship Council, which was formed after the 1992 Earth Summit in Rio, links foresters, indigenous people, NGOs, forest products certification organizations, and timber traders in 25 countries. Its goals are to ensure that forests are managed in an environmentally appropriate manner, are socially beneficial to local communities, and are economically viable (2, 118).

D. Hinrichsen

In India a scientist examines replanted pines in the Himalayan region. Forest management works best when it allows people to meet current economic needs while encouraging sustainability.

Accomplishing a Second Green Revolution

The first Green Revolution in agriculture of the 1960s helped food production keep pace with population growth. Because population growth continued, the Green Revolution was only a "temporary success," said Norman Borlaug upon receiving the 1970 Nobel Peace Prize as one of its architects. Today, as population moves toward 8 billion in 2025, a second Green Revolution should focus on the food crops grown by the 2 billion people who lack food security (see Chapter 3). It should concentrate not only on improving the yields of the big three staples—rice, corn, and wheat—but also on such crops as sorghum, millet, and cassava (73, 75).

D. Hinrichsen

Cassava plants in Northeast Thailand. A second Green Revolution in agriculture should focus on crops grown by the world's poor.

The World Food Summit, held in Rome in 1996, also recommended the following actions to improve agriculture:

Improving yields on marginal land. Despite poor quality soil and insufficient water, many marginal lands can be farmed successfully. For instance, the International Institute of Tropical Agriculture has pioneered "alley farming" as a sustainable substitute for slash-and-burn cultivation. If crops are used in the right combination, alley farming can greatly increase yields on poor soils in hilly regions and thus reduce the need to clear forests for farmland (114). The concept is simple: leguminous crops, such as mucuna, are planted between rows of food crops, such as peas and beans. The legumes help hold the soil in place and improve nutrient content while preventing weeds from taking root.

Expanding aquaculture. Where fish farming for local or regional consumption has been tried, the results have been impressive. Unless fish farms are well managed, however, they can contribute to coastal pollution, through improper disposal of wastes and over-stocking (77, 99).

Rediscovering forgotten foods. Another way to help achieve food security is to cultivate traditional food plants that modern agriculture has neglected. Amaranth and quinoa, two grains grown by the ancient Aztecs of Mexico and Incas of Peru, are examples. Both grains are versatile and nutritious, containing more high-quality protein than most other commercial grains, including corn and rice. Moreover, both grow well under difficult conditions. Amaranth thrives in hot climates, while the quinoa plant is frost-resistant and can be grown at high elevations (257).

Increasing yields. Some countries are improving crop yields with new approaches that use low-level inputs. Examples include fertilizing with animal wastes instead of chemicals, recycling nutrients, conserving water, and selecting a variety of crops better suited to soil conditions and climate (73, 75).

Another technique is Integrated Pest Management (IPM). IPM uses several related strategies: preserving natural pest predators, using pest-resistant seed varieties, and drastically cutting amounts of pesticides. This approach has increased yields while reducing use of pesticides and fertilizers (73).

Empowering women farmers. Women grow 80% to 90% of all food consumed locally in many developing countries. Women farmers need better access to credit, agricultural extension services, and training (72, 188, 219, 241).

Better coastal management can help protect such ecosystems as mangrove forests, seagrass beds, and coral reefs; can protect coastlines from over-development; and can preserve fisheries and marine biodiversity. The following initiatives are promising:

• UNEP's Regional Seas Program needs international and regional support. It is one of the few working mechanisms in place that enables coastal states sharing the same body of water to work together on management issues.
• The International Coral Reef Initiative, launched in 1995 by eight countries, deserves high priority from NGOs, funding agencies, and the UN system. This initiative is one of the best examples of international and intergovernmental cooperation to address the decline of the world's coral resources.
• The Code of Conduct for Responsible Fisheries, which FAO launched in 1995, needs the endorsement of fishing nations and national laws to give it force. The code addresses fisheries management and operations, aquaculture and mariculture development, and integration of fisheries management into coastal area management programs, among other areas. More than 60 fishing nations have agreed to this voluntary code, but it needs legal foundation in each country (149).
• The UN Agreement on Straddling Fish Stocks and Highly Migratory Fish Stocks, which FAO put forth in 1995, prescribes a cautionary approach to fishery management, both inside and outside Exclusive Economic Zones (EEZs). As of 1999, however, only 4 of the top 20 fishing nations had ratified it. It requires 30 signatures before taking effect (149).
• The Law of the Sea Convention, which came into force in November 1994, could become a more effective mechanism for regulating coastal and near-shore activities. It permits all coastal states to manage their 200 mile EEZs. Littoral states must enact and enforce fisheries restrictions, safeguard biologically diverse areas, protect more marine areas, and enact and enforce legislation that protects coastal waters from land-based pollution (102).

Many steps that conserve natural resources and protect the environment also improve public health by curbing pollution. In particular, the following steps deserve attention:

• Provide safe water to the 1.2 billion people who lack access to this foundation of good health and well-being.
• Provide adequate sanitation to the 3 billion people who currently lack it. Breaking the water-borne disease cycle is fundamental to public health. In particular, curbing untreated sewage would help control the spread of water-related diseases.
• Prevent air pollution by reaching regional agreements that would improve air quality. Such agreements would give impetus to national and urban efforts to stem air pollution. One workable example is the Long-Range Transboundary Air Pollution Convention, endorsed by the Economic Commission of Europe (ECE), to curb acid rain and long-range pollutants.
• Adopt a globally binding treaty to eliminate POPs. Governments and NGOs can support UNEP in designing an international treaty that will phase out these dangerous chemicals as quickly as possible.

Trying to save species one at a time is a losing strategy. Instead, conservation must focus on biodiversity hotspots—the habitats in which most species live (162–164, 228, 252, 267) (see map). The fact that these habitats are highly concentrated suggests that species conservation is much less expensive and potentially more effective than previously thought (29, 155).

The Convention on Biological Diversity should be implemented as quickly as possible. It is the one global agreement in place that can help preserve biological diversity. The convention recognizes community rights to wild biodiversity. Signatory countries are to set up a system of benefit sharing to compensate communities for the use of biological resources and related knowledge by pharmaceutical, biotechnology, and agricultural companies.

The last four decades have witnessed a profound change in fertility rates and world population growth. The transition from high fertility and high mortality to low fertility and low mortality (the demographic transition) has been substantially completed in the developed world and is underway in most of the developing world. Nevertheless, in many countries of sub-Saharan Africa, the Near East, and South Asia, population continues growing at 2% a year or faster, and the average woman bears four to seven children (182).

Thus it is important that the fertility declines that have characterized the past 40 years do not stall. Even small increases in fertility rates—which could occur if commitment to providing family planning information, supplies, and services were to diminish—would mean faster population growth. "Investments in measures to slow the rate of population growth—and thereby to reach a stable population earlier, and at lower levels, than under current trends—would significantly reinforce efforts to address the environmental challenges of the century ahead, and considerably lower the cost of such efforts," according to Richard Benedick (11).

Today, most women and men want to plan their families (245). The extent to which policy-makers and reproductive health care providers offer good family planning information and services will determine whether people will be able to have the number of children they want, when they want them. In the balance is whether the world's population could eventually stabilize at 9 billion or less, or whether it will grow to 11 billion, and even beyond (58, 84, 243).

Timing matters. Largely because fertility has been high, in some countries young people just entering their reproductive years comprise as much as half of the population. The childbearing patterns of these 2 billion people now under age 24 will determine whether population continues growing rapidly or slows to a more sustainable pace in relation to development and the environment. (243).

Funding matters. Developing countries account for most spending on family planning and other reproductive health care (242). While the number of people needing services has risen, public spending on reproductive health care has dropped significantly since 1995—the peak year for investments in reproductive health.

JHU/CCP Photoshare

In Bangladesh a field worker discusses family planning with women in their community. Fertility rates have fallen in many countries, but the world's population continues to rise rapidly.

Most donor countries have not kept the commitments to population and reproductive health assistance that they made at the UN International Conference on Population and Development (ICPD) in Cairo in 1994. According to their commitments, developed countries should have invested US$5.7 billion a year in population programs by 2000 (242). Instead, the donor community has provided about US$2 billion annually. Currently, spending on global population programs amounts to less than half of the funding agreed to—around US$8 billion instead of US$17 billion.

Worries about a "population bomb" may have lessened as fertility rates have fallen, but the world's population is projected to continue expanding until the middle of the century. Just when it stabilizes and thus the level at which it stabilizes will have a powerful effect on living standards and the global environment. As population size continues to reach levels never before experienced, and per capita consumption rises, the environment hangs in the balance.