The State of World Population 2001 The State of World Population 2001
Chapter 2: Environmental Trends

United Nations Population Fund

Water and Population

Water may be the resource that defines the limits of sustainable development. It has no substitute, and the balance between humanity's demands and the quantity available is already precarious.1

Only about 2.5 per cent of all water on the planet is fresh water—essential for most human purposes—and only about 0.5 per cent is accessible groundwater or surface water. Rainfall quantities vary greatly around the world. Portions of Northern Africa and Western Asia receive very small amounts of rain.


Thomas Raupach, Still Pictures
Recycling refrigerators in Germany. The world's richest countries, with 20 per cent of the global population, account for 86 per cent of private consumption.

Income is related to the availability of water between and within nations. The more developed regions have on average substantially higher rainfall than those less and least developed.2 Additionally, richer countries can better afford the investments needed to develop reservoirs, dams and other technologies to capture fresh water run-off and available groundwater.

Global population has tripled over the past 70 years and water use has grown six-fold as the result of industrial development and increased use of irrigation. More recently, per capita use of water has leveled off, so total water consumption is growing at about the same pace as population. Satisfying the water needs of 77 million additional people each year has been estimated as requiring an amount roughly equal to the flow of the Rhine. But the amount of available fresh water has not changed.

Worldwide, 54 per cent of the annual available fresh water is being used. If consumption per person remains steady, by 2025 we could be using 70 per cent of the total because of population growth alone. If per capita consumption everywhere reached the level of more developed countries we could be using 90 per cent of the available water by 2025.

Such extrapolations assume no change in the efficiency of water use. It has been estimated, however, that relatively low-cost technologies could double agricultural productivity per unit of available water.3 In the past 50 years, industrialized countries have significantly increased efficiencies in industrial and agricultural water use. Many of the same technologies—for example, drip irrigation instead of flood irrigation—are increasingly available in developing countries, but cost and cultural issues (like educational outreach to facilitate behaviour change) must be addressed.

Water Availability

Countries are characterized as water-stressed or -scarce depending on the amount of renewable water available.4 Water-stressed countries have fewer than 1,700 cubic metres of water available per person per year. In this circumstance, water is often temporarily unavailable at particular locations, and difficult choices must be made among uses of water for personal consumption, agriculture or industry. Water-scarce countries have fewer than 1,000 cubic metres per year. At this level, there may not be enough water to provide adequate food,5 economic development is hampered and severe environmental difficulties may develop.

Water Resources Per Capita, by Subregion, 2000

In the year 2000, 508 million people lived in 31 water-stressed or -scarce countries. By 2025, 3 billion people will be living in 48 such countries.6 The number of people living in conditions of scarcity will double, and those living in water stress will increase six-fold.

For some purposes, river basins are a more appropriate unit than countries for analysing water flows. Many of the world's major river basins encompass more than one country. Currently 2.3 billion people live in river basins that are at least water stressed; 1.7 billion live in basins where scarcity conditions prevail. By 2025 these numbers will be 3.5 billion and 2.4 billion, respectively.

Domestic consumption needs

"Access to safe water is a fundamental human need and, therefore, a basic human right," according to United Nations Secretary-General Kofi Annan.7

Experts have outlined a basic daily water requirement (BWR)—50 litres per capita per day for the purposes of drinking, sanitation, bathing, cooking and kitchen needs—and urged its recognition as the standard against which to measure the right to safe water.8

Countries use different methods for collecting data on domestic water use, and uniform standards for assessing quality have not been set. Available country estimates indicate that 61 countries, with combined populations of 2.1 billion people in 2000, were using less water than the BWR. By 2050, 4.2 billion people (over 45 per cent of the global total) will be living in countries below the BWR standard.

This minimal standard does not take into account other necessary uses of water—for agriculture, ecosystem protection and industry. A consumption standard of 100 litres per person per day would reflect these additional needs; in 2000 there were 3.75 billion people in 80 countries below this level. The population of these countries will increase to 6.4 billion by 2050.

Women in many parts of the world have the primary responsibility for collecting water for their families, and spend up to five times as much time on this as men do. The more distant the water source, the greater the burden on women.

Both distance and the source affect the amount of water used by individual households. For example, when the source is a public standpipe more than a kilometre from home, use is typically less than 10 litres per day; water consumption might be twice as high when the standpipe is closer, and considerably higher in households with running water connections.

Unsustainable water use

Many countries use unsustainable means to meet their water needs. If more water is withdrawn than is replenished by natural processes, the excess is essentially "mined" from reserves. These can be recent local aquifers or, in extreme cases,9 ancient sources of underground "paleo-water". The water tables under some cities in China, Latin America and South Asia are declining at over one metre per year.

Agriculture and industry divert large amounts of water with sometimes-disastrous effects. The best-known example is the Aral Sea, which has been destroyed by diverting its feeder waters for irrigation. The Yellow River in China ran dry from 600 kilometres upstream to the river's mouth every year in the 1990s. In 1997, it ran dry a record 226 days.10 The Rio Grande River on the U.S.-Mexico border developed a sandbar at its mouth recently, highlighting the loss of its flow.

The construction of large dams has slowed, particularly in more-developed countries, as their disadvantages are appreciated: environmental disruption, displacement of long-settled populations, loss of agricultural land, silting and denial of water to downstream areas, sometimes in other countries. Large dam projects continue in Turkey, China and India.

Water Quality

Quantitative estimates of water availability or consumption do not capture the full challenge of water needs. The quality of the available water is far from adequate. The World Health Organization reports that about 1.1 billion people do not have access to clean water (whatever its quantity).11 Fully 2.4-3.0 billion people lack access to sanitation.

These shortcomings are most pronounced in rural areas, where 29 per cent of residents lack access to clean water and 62 per cent to sanitation systems.

Rapid and unplanned population growth in and around urban areas is overwhelming their capacity to meet water needs. For the first time, official statistics reflect a decline in coverage compared to previous estimates: current estimates are that clean water is not available to at least 6 per cent of urban dwellers and 14 per cent lack sanitation, but this clearly understates the problem.

Water quality is closely related to availability, and to decisions about land use, industrial and agricultural production, and waste disposal. In developing countries, 90-95 per cent of sewage and 70 per cent of industrial wastes are dumped untreated into surface waters where they pollute the usable water supply.

Natural systems purify circulating water when there is enough available. When water becomes progressively scarcer, it is also generally of poorer quality. Intensive land use and industrial development also affect quality. In many industrial countries fertilizer, pesticide and manure run-off from the land and acid rain from atmospheric contamination call for expensive and energy-intensive filtration and treatment to restore acceptable quality. Restoring natural flow patterns to river systems, managing irrigation, chemical use and animal wastes, and curbing industrial air pollution are vital steps towards improving overall sustainability as well as water quality.

New Challenges

Agriculture uses two thirds of the available fresh water. Rising incomes in recent decades have led to an increase in meat consumption in many countries. This requires substantial additional inputs of grain and water.12

Competition for increasingly scarce water increases the likelihood of international conflict (both economic and military) over water quality and diversion schemes.13More than 200 river systems cross national boundaries. Thirteen major rivers and lakes are shared by 100 countries.

There are great uncertainties as to the future impacts of global warming on water availability and thus on the sustainability of human settlement patterns. Rainfall patterns, including the intensity and timing of storms and the rate of evaporation, are likely to change significantly as the climate warms.

Purely technological solutions to water scarcity are likely to have limited effect. Desalinized seawater now accounts for less than 1 per cent of the water people consume. It is likely that this will increase, but it is only feasible in countries wealthy enough to take on the costs—currently oil-producing states of west Asia—with no need to transport the water over long distances. Movement of fresh water in large plastic bags pulled by ships has been of some value in the eastern Mediterranean, but as with desalination, it is of little help to landlocked countries or in- land populations and of limited scale.

More ambitious proposals, such as transporting icebergs, have proven unfeasible to date. Collecting large amounts of rainfall that lands on the oceans may become feasible but the effects of reflected light and heat from the plastic sheets required could create problems. Transport of such water to needy populations may very well pose insurmountable problems. As in so many other areas, technology will not ride to the rescue: political and social decisions are needed, which may be difficult now but will certainly be still more difficult as populations grow and their requirements demand more from the same fixed resource.

Feeding a Future World

Environmental degradation, population growth, overstressed agriculture and inadequate international food distribution raise the question: Will there be enough food in the future?

Percentage of Population Undernourished, by Subregion, 1996-1998

Cropland Per Capita, by Subregion, 1996-1998 (hectares)

Two billion people lack food security as the Food and Agriculture Organization of the United Nations defines it, a "state of affairs where all people at all times have access to safe and nutritious food to maintain a healthy and active life".14

In many countries population growth has raced ahead of food production in recent years.15 The world grain harvest increased about 1 per cent annually between 1990 and 1997, less than the average population growth rate of 1.6 per cent in the developing world.16Between 1985 and 1995 food production lagged behind population growth in 64 of 105 developing countries studied by FAO.17 Africa fared worst among major regions. Food production per person fell in 31 of 46 African countries.18

The average amount of grain land per person dropped by almost half between 1950 and 1996—from 0.23 hectares to 0.12 hectares. By 2030, when world population is projected to be at least 8 billion, there would be just 0.08 hectares of grain land per person.19 As for developing countries, in 1992, there were about 0.2 hectares of arable land per person. By 2050, this figure could fall to about 0.1 hectare per capita.20

According to the International Food Policy Research Institute (IFPRI), the world's farmers will have to produce 40 per cent more grain in 2020 than in 1999. Most of this projected increase will have to come from yield increases on existing land, not the cultivation of new land.21

Countries are not equally affected. Australia, Europe, and North America have large surpluses of food for export.22 Their populations are growing slowly, if at all, and per capita consumption is not increasing.

These countries are probably capable of expanding food production considerably beyond current levels, though the long-term sustainability of intensive farming practices has been brought into question by recent events. The most widely publicized are outbreaks of "mad cow disease" (bovine spongiform encephalopathy) and foot-and-mouth disease; but there is also considerable concern about salmonella poisoning from eggs and chickens, and mutant, drug-resistant E. coli infections from contaminated meat and water, all of which can be traced in some way to the desire to maximize agricultural output and reduce costs.23

There is also considerable controversy over genetic modifications (GM) to food crops and animals. Though GM has not been shown to be directly harmful to humans, the practice carries risks, including social effects, which have yet to be fully evaluated. A British government report has raised fears that GM will threaten biodiversity.24

Another group of countries cannot grow enough food on their own land to feed their populations but can make up the shortfall through imports. Such countries include Japan, Singapore, Chile and the oil-producing states of the Arabian Gulf.

Over half the world's population, most of the people of the developing world—including nearly all of sub-Saharan Africa—live in "low-income, food-deficit countries", according to FAO.25

The low-income, food-deficit countries do not produce enough to feed their people and cannot import sufficient food to close the gap. In these countries just under 800 million people are chronically malnourished, according to a 1999 estimate by FAO.26

Problems of Food-Deficit Countries

In many low-income food-deficit countries, food production capacities are deteriorating in the face of soil degradation, chronic water shortages, inappropriate agricultural policies and rapid population growth.27 The gap between production and market demand for cereals in South Asia is forecast to widen from 1 million metric tons in 1990 to 24 million tons in 2020, and in sub-Saharan Africa from 9 million to 27 million metric tons. The gap between production and need in these grain-short regions will be even greater unless poverty can be significantly reduced.28

Low-income food-deficit countries face the following constraints to achieving food security:

  • Limited arable land. Increases in food production will have to come from existing agricultural land.29 Arable land could in theory be increased by 40 per cent, or 2 billion hectares, but most of the uncultivated land is marginal, with poor soils and either not enough rainfall or too much. Bringing it into production would require costly irrigation and water-management systems and large-scale measures to enrich the soil. Much of this land is now under forest, and clearing it would have unforeseeable consequences for erosion, degradation and local climate change, among others.
     
  • Shrinking size of family farms. One effect of rapid population growth is the shrinking size of family farms. In most developing countries, the size of small family farms has been cut in half over the past four decades, as plots are divided into smaller and smaller pieces for each new and larger generation of heirs. For example, in 57 developing countries surveyed by FAO in the early 1990s, over half of all farms were less than one hectare, 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.30
     
  • Land degradation. Moderate to severe soil degradation affects nearly 2 billion hectares of crop and grazing land. This is an area larger than the United States and Mexico combined.31 When soils are overworked and exposed, they are easily eroded by wind and water, the main agents of soil degradation. Faulty irrigation and drainage can make land useless through waterlogging and salinization (see below). Misuse of fertilizers, herbicides and pesticides also plays a role in soil degradation. 

Soil erosion and other forms of land degradation claim 5 million to 7 million hectares of farm land each year.32 In Kazakhstan, for instance, the Institute of Soil Management has estimated that the country will lose nearly half of its crop-land by 2025 due to soil erosion and degradation.33 Globally, land degradation threatens the livelihoods of at least 1 billion farmers and ranchers, most of them in poor countries.34

Box 3: The Pros and Cons of Fish Farming

  • Water shortages and degradation. (See section above.) Water for irrigated agriculture accounts for roughly 70 per cent of all water withdrawn for human use annually on a global basis. When water becomes short, rural farmers often find it difficult to maintain food supplies. In the Indian state of Uttar Pradesh, for instance, the number of water-short villages has soared from 17,000 to 70,000 in two decades, suppressing crop production.35 

Conflicts within countries are also of mounting concern to national governments. In China, for instance, conflicts over water seem to be escalating. In August 2000, six people were killed when officials from Luhe County, in Guangdong Province, blew up a water channel to stop a neighbouring county (Puding) from diverting water from the Yellow River, as agreed to in a court settlement. Farmers in both counties depend on river water to irrigate their crops. Within increasingly limited and polluted supplies, their yields (and incomes) are falling dramatically.36

  • Irrigation problems. Food supply is threatened not only by water shortages themselves but also by ineffective irrigation practices. Although only 17 per cent of all croplands are under irrigation, these lands produce one third of the world's total food supply.37 Less than half of all water withdrawn for irrigation purposes actually reaches the crops. The rest soaks into unlined canals, leaks out of pipes or evaporates on its way to the fields.38

Badly planned and poorly built irrigation systems have reduced yields on one half of all irrigated land, according to a 1995 estimate by FAO.39 The two main problems are salinization and waterlogging of crops. FAO estimates that salt build-up in soil has severely damaged 25-30 million hectares of the world's 255 million hectares of irrigated land.40 Another 80 million hectares are affected by a combination of salinization and waterlogging.41

Every year, on average, about 1.5 million hectares of irrigated land is taken out of production because of salt build-up alone, half of the amount of land brought into production.42 With such problems, the world's irrigated croplands may actually be shrinking at a time when they should be expanding to meet growing demand for food, according to the International Irrigation Management Institute.43

  • Waste. Tremendous amounts of food are wasted annually through the effects of rat or insect infestation, spoilage and losses that occur during the transportation process. In China, for instance, an estimated 25 per cent of grain collected is wasted; rats or other pests consume much of it. Similarly, according to the Vietnamese Government, about 13-16 per cent of rice and 20 per cent of vegetables harvested in Viet Nam are wasted because of poor preservation conditions and practices.44 

The Value of Genetic Diversity

After 10,000 years of settled agriculture and the discovery of some 50,000 varieties of edible plants, just 15 food crops provide 90 per cent of the world's food energy intake. Three of them—rice, wheat and maize (corn)—are the staple foods of 4 billion people.45 Dependence on only a few crops is dangerous because disease can spread rapidly through monocultures, as it did through the Irish potato harvest in the 1840s, starving to death a fifth of the country's population.46

Since 1900 about three quarters of the genetic diversity of domestic agricultural crops has been lost, FAO estimates.47 Without constant infusions of new genes from the wild, geneticists cannot continue to improve staple crops. Cultivars (cultivated plants) need to be reinvigorated every 5 to 15 years in order to give them greater resistance against diseases and insects, as well as to introduce new yield-enhancing traits, such as increased tolerance for drought or saline soils. The most effective way to do this is to interbreed domestic varieties with wild ones.

Plant breeders are alarmed at the continuing genetic erosion of the earth's wild strains of cereals and other cultivars. Tropical deforestation, rapid urbanization, the destruction of vital wetlands and the over-cultivation of dry lands has destroyed countless habitats for wild progenitors of domestic crops.48 Unless the rate of plant genetic loss is halted or slowed substantially, as many as 60,000 plant species—roughly one quarter of the world's total—could be lost by 2025, according to the International Center for Agricultural Research in Dry Areas.49

The Meat Consumption Revolution

For many food deficit low-income countries, feeding a growing population means coaxing more food out of the same amount of land. Canadian geographer Vaclav Smil estimated that the minimum amount of land needed to supply a vegetarian diet for one person without any use of artificial chemical inputs is 0.07 hectare, or slightly less than a quarter of an acre. Based on this, Population Action International estimated that currently some 420 million people live in land-scarce developing countries. If fertility and population growth in developing countries continue to fall, there could be 560 million by 2025. If not, there could be 1.04 billion such people.50

According to IFPRI, a "demand-driven livestock revolution is under way in the developing world with profound implications for global agriculture, health, livelihoods and the environment".51 IFPRI projects that meat demand in the developing world will double between 1995 and 2020 to 190 million metric tons. Demand for meat in the developing world is expected to grow much faster than for cereals—by close to 3 per cent per year for meat compared with 1.8 per cent for cereals. In per capita terms, demand for meat will increase 40 per cent between 1995 and 2020.

What this means is that demand for cereals to feed livestock will double in developing countries over the next generation. By 2020, feed grain demand is projected to reach just under 450 million metric tons. Given this trend, well under way in much of Asia, demand for maize (corn) will increase much faster than any other cereal, growing by 2.35 per cent per year over the next 20 years. Nearly two thirds of this increased demand will go towards feeding livestock.

In China, rising incomes and changing diets have resulted in a tremendous demand for meat, particularly poultry and pigs. Over the next two decades total demand for meat will double, increasing pressure on grain producers. It takes 4-5 kilograms of feed to produce 1 kilogram of meat.52

Moving Towards Food Security

Achieving food security—assuring that everyone has access to enough food to be healthy—requires action to increase food production, and at the same time protect the environment. Slower population growth in poor countries would allow more time to achieve sustainable food production. Actions that promote slower population growth, especially the empowerment of women, also work towards protecting the natural resource base on which increased food production depends.

Increasing food production. To accommodate the nearly 8 billion people expected on earth by 2025 and improve their diets, the world will have to double food production over current levels.53 In recent years, there have been some promising developments. These include a new strain of super rice capable of boosting yields by 25 per cent,54 improved varieties of maize that could increase yields by up to 40 per cent and could be grown on marginal land,55 and a new blight-resistant potato.56

Experience with the Green Revolution of the 1960s indicates that technological advances and market forces can dramatically increase food production, but do not necessarily solve food security problems. New high-yielding varieties, for example, call for specialized fertilizers and pesticides. These inputs increase yields but there is increasing evidence that they disturb the ecological balance, creating new disease and pest problems, which call for further inputs. In low-income areas, these inputs represent a considerable expense, which biases success towards large holdings with considerable cash reserves to invest. Smaller farmers may be less successful and may even be forced to give up their land, becoming casual labourers with an uncertain income.

As Amartya Sen and others have pointed out, the problems of food shortage are often not absolute but related to income. During famines, poor people have often starved while food was plentiful, but beyond their reach. Social mechanisms such as overall responsible governance, local control over food production and supply, and emergency stocks to ensure fair prices are needed to avoid hunger.

Protecting the environment. Protecting the environment enhances a country's food production potential.57To achieve food security, countries must reverse the current course of land and water resource degradation. Specific actions include local management, including land ownership reform, and a careful review of land use, especially for cash crops calling for intensive fertilizer application and irrigation. Trade-offs may be sought between different forms of land use, for example, between building dams to increase water supply and losing arable land to reservoirs, or between higher yields and environmental costs. Finding the correct balance calls for careful and responsible discussion among all the parties involved.

One frequent problem is where alternative uses are proposed for land and water resources among remote and scattered communities with little political power. The interests of such communities need protection. In many cases, they represent more than local interests and should be carefully weighed. Such remote areas may be important upland watersheds, or they may be forests that harbour genetic diversity. The simple prospect of increasing food production in the short term may be less important than a more complex long-term calculus taking these factors into account.

Local voices should often be those of women, who have most of the responsibility for finding food, water and fuel for the family. In most of the food deficit countries, women's power to manage local land and water resources does not match their responsibility. Actions to empower women in this area include health care and education, which also give women control over other areas of their lives, including fertility and family size.

Even the poorest countries can safeguard their resource base—particularly topsoil and freshwater sources—improve the productive capacity of land, increase agricultural yields and hope to achieve food security in the future. To do this successfully, however, calls for responsible governance balancing many interests, a commitment to food security, considered action and the cooperation of the international community.

Greenhouse Gas Emissions and Climate Change

Carbon dioxide and other "greenhouse gases" trap heat in the atmosphere and raise average global surface temperatures. Emissions of carbon dioxide grew 12-fold between 1900 and 2000, from 534 million metric tons per year in 1900 to 6.59 billion metric tons in 1997.58

In the same period, human population nearly quadrupled, from 1.6 billion to 6.1 billion, progressively consuming greater quantities of fossil fuels—oil, gas and coal. Expanded agriculture, destruction of forests and increased production of certain chemicals also increase greenhouse gases in the atmosphere.

It is unlikely that the human population could ever have reached its present size without the energy provided by fossil fuels. Conversely, the needs of the growing population have provided an ever-expanding market for exploration and production.59

Global CO2 Emissions, 1950-1997

Projected CO2 Emissions Under Different Population and Technology Assumptions, 1990-2100

Climate change will have a serious impact. The Intergovernmental Panel on Climate Change (IPCC) estimates that the earth's atmosphere will warm by as much as 5.8 degrees Celsius over the coming century, a rate unmatched over the past 10,000 years.60 The IPCC's "best estimate" scenario projects a sea-level rise of about half a metre by 2100 (with a range of 15 to 95 centimetres), substantially greater than the increase over the last century.61

The human and ecological impacts of rising oceans include increased flooding, coastal erosion, salinization of aquifers, and loss of coastal cropland, wetlands and living space. The intensity and frequency of hurricanes and other hazardous weather may also increase, endangering the growing human population in coastal areas.62

Rising global surface temperatures and changes in precipitation magnitude, intensity and geographical distribution may well redraw the world renewable resources map. Whether or not these climatic changes affect net global agricultural production, they are almost certain to shift productivity among regions and countries, and within nations.63

For example, recent projections suggest that while total U.S. agriculture production may not diminish, certain regions of the country are likely to suffer substantially relative to others, as a result of changes in precipitation and temperature.64 Climate change policy will have to address changing regional and national fortunes, as well as the global economic and biological impact.65

A warming climate also poses a significant public health threat. The redistribution of precipitation would markedly increase the number of people living in regions under extreme water stress—a problem compounded by increasing population.66 The geographical range of temperature-sensitive tropical diseases, such as malaria and dengue fever, would also expand.67 Higher average temperatures mean longer and more-intense heat waves, with a corresponding rise in heat-related health problems.

The combined effects of population growth and climate change could produce regional resource shortages, which in turn could result in the exploitation of environmentally sensitive areas such as hillsides, flood plains, coastal areas and wetlands.68 These conditions may also increase environmental refugees, international economic migration and associated socio-political challenges.69 Climate and environmental policy should address the geographical distribution and movement of people in the 21st century, as well as their absolute numbers.70

Box 4: Equity and Environmental Intervention

Box 5: Melting Ice Confirms Warming is Under Way

Population and Climate Policy

Since 1970, average carbon dioxide emissions per capita have been relatively stable, so that on a worldwide scale the rise in industrial emissions over the last three decades correlates closely with population growth.71 Population trends and policy have therefore played a major part in the trajectory of emissions in the past, and they could have an even greater role in the future.72

The 1997 Kyoto Protocol to the Framework Convention on Climate Change, if ratified, would commit 38 "Annex B" countries (broadly, the industrial countries) to cut their national emissions of greenhouse gases by an average of 5.2 per cent between 1990 and 2008-2012 (herein after referred to as 2010).73Developing (non-Annex B) nations face no specific emissions limitation obligations in the protocol, on the principle that industrialized nations have contributed the most to the problem and thus have an obligation to take the first steps.74

The Kyoto Protocol does not refer to population, but population factors will play a major role in its success or failure, and in future climate policy. The protocol is based on national caps on emissions; these will not be adjusted for increases or decreases in population due to either fertility or migration between 1990 and 2010.75 Since population increases, especially in more-developed economies, result in more houses, cars and other consumption, countries with rising populations and growing economies are at a comparative disadvantage under the national cap formula used in Kyoto.76

Box 6: Kyoto Protocol Faces Uncertain Fate

Demographic divergences among the major Annex B countries are projected to continue or become sharper after 2012. The population of the United States, for instance, is projected to rise from 255 million in 1990 to 397 million in 2050 (middle scenario), a 56 per cent increase.77 Germany, meanwhile, is projected to experience a population decline from 79 million to 71 million over the same period, a 10 per cent decrease, while the Russian Federation is projected to fall from 148 million to 104 million people, a 30 per cent decrease.

Population projections for the developing world (non-Annex B countries) vary even more dramatically. For example, Pakistan's population is projected to rise from 119 million to 344 million between 1990 and 2050 (a 189 per cent rise), while South Korea's is projected to grow only from 43 million to 51.6 million (a 20 per cent increase) over the same period.

For the developed (Annex B) countries as a whole, per capita emissions have been relatively flat since 1970, fluctuating in a range above 3 metric tons per person. In 1950, the developing (non-Annex B) country per capita average emission was only 0.1 metric tons, but it increased six-fold to 0.59 metric tons by 1996 and continues to rise (see Figure 5).78 Per capita developing country emissions are still far lower than those of developed countries, but the gap declined from 1:17 to 1:5 from 1950 to 1996,79 and this trend is expected to continue.

Box 7: Population and International Environmental Agreements

One reason the gap is closing is that as family size drops in developing countries, as it already has in the United States and other developed countries, households are getting smaller and significant economies of scale in energy use are being lost. In 1990, average household size in developed and developing countries was 2.7 and 4.8 persons, respectively. By 2050, one analysis projects the ratio may be only 2.6 to 3.4.80 Population ageing also has significant implications for household and per capita greenhouse gas emissions.81

In 1995, the 20 per cent of the world's population living in countries with the highest per capita fossil-fuel carbon dioxide emissions contributed 63 per cent of the world's total emissions. The 20 per cent with the lowest per capita emissions contributed just 2 per cent of all carbon dioxide emissions.82

Almost all additional significant population growth is projected to occur in developing countries (the notable exception being the United States).83 Developing country emissions will become the major factor early in the 21st century, and a future global climate change treaty will need to respond to this coming demographic reality.84 Per capita emissions must be reduced, in the developed countries but also in major developing nations such as China and Mexico.

Forests, Habitat and Biodiversity

People now use or appropriate an estimated 39-50 per cent or more of the earth's biological production, through agriculture, forestry and other activities.85 Half of the world's forests have disappeared since the end of the last Ice Age, and only 22 per cent of the original forest cover remains in large, unbroken areas without substantial human influence.86 Deforestation rates in the last few decades have reached the highest levels in history, as glo- bal population growth has also peaked.

In the last 40 years, per capita forest area worldwide has fallen by more than 50 per cent, from a global average of 1.2 hectares to less than 0.6 hectares per person. This is due to both decreasing forest area and increasing population, and it threatens the well-being of both people and the forests they depend on. The proportional loss of forests (the amount lost relative to the amount remaining) has been greatest in Asia, followed by Africa and Latin America. These ongoing losses have been partially offset (by about 10 per cent) by a relatively small increase in forest plantations and re-growth in some developed countries.87

Tropical forests contain an estimated 50 per cent of the world's remaining biodiversity (plant and animal species).88 At current rapid deforestation rates, and in the absence of any intervention, the last significant primary tropical forest could be harvested within 50 years.89 Because habitat destruction is the leading cause of species extinction, the loss of tropical forests is likely to lead to a substantial and irreversible decline in global biodiversity.90

Biomass (both above and below-ground) in tropical forests amounts to a substantial carbon sink within the global ecosystem. After fossil fuel combustion, tropical deforestation is the second most important source of carbon dioxide, the primary greenhouse gas. Only 8 per cent of the remaining tropical forests are legally well-protected, and often protected status does not confer actual protection.91

International development and conservation organizations have promoted "integrated conservation and development projects" as a strategy for developing countries where people depend on land and biotic resources within reserves.92Tropical parks have been somewhat effective in reducing land clearing (deforestation) relative to surrounding unmanaged areas.93 However, their success in slowing tropical deforestation has been mixed or poor, in part because such projects may attract people to the remaining forests.94

Box 8: Protecting 'Biodiversity Hotspots'

Human population growth, density and other demographic variables, and their effect on deforestation, are critically important but under-studied factors in this context.95 Many of the countries that contain the largest blocks of remaining tropical forest are also those with the highest population growth rates (2-4 per cent per year).96 Ongoing human migration, both national and international, is another critical factor that affects forests, habitat and biodiversity.

Recent research in Central America has shown that human population density and loss of forest cover are closely correlated at local, district, and national levels and over time, both outside and within protected and managed reserves.97

Box 9: 'Eco-tourism': Boon or Boom?

Evidence to date suggests that reserves with essentially unbroken forest cover may be successful only where very low human population densities (1-2 persons per square kilometre) can be maintained.98Unfortunately, population growth and fertility rates are often very high in and near developing country forest reserves, while access to reproductive health care and contraceptive prevalence rates are low in these rural and frequently isolated areas.99

Sustainable forestry and other sustainable development approaches hold some promise for reducing habitat destruction and species loss. However, the projected increases in human population over the next few decades, particularly in the tropics, will inevitably continue to present very difficult choices between the use of land for forests, habitat and biodiversity preservation, and human uses such as the production of food and fuel.

Regional Environmental Trends

The following are highlights of major environmental trends in Asia, Africa, and Latin America, as reported in the United Nations Environment Programme's Global Environment Outlook 2000 (GEO-2000) report.100

Asia and the Pacific

Asia, with 29.5 per cent of the world's land area, supports 60 per cent of its population. High population densities and widespread poverty are putting enormous stress on the environment. Major challenges include101:

Land degradation: At least 1.3 billion people (39 per cent of the region's population) live in areas prone to drought and desertification. More than 350 million hectares are already desertified. About 20 per cent (around 550 million hectares) of Asia's vegetated land is affected by soil degradation. In India, Iran and Pakistan, water and wind erosion are major contributors to soil degradation. In India, as much as 27 per cent of the soil has been affected by severe ero-sion. China, India and Pakistan all suffer from land salinization resulting from excessive groundwater irrigation. Excessive agrochemical inputs are also responsible for land degradation in many countries of this region.

Deforestation: Forest cover has been receding rapidly across Asia, largely due to the unsustainable exploitation of timber reserves and unchecked agricultural expansion. Six countries (China, Indonesia, Malaysia, Myanmar, the Philippines, and Thailand) account for three quarters of recent deforestation in the region. Many forests, such as those in the Mekong Basin, have been logged to the point that they are of critically low quality. Illegal logging amplifies the pressure on forest resources in several Asian countries. Fuelwood harvesting, irrigation schemes, hydroelectric power projects, urbanization, infrastructure development, natural disasters and fires also contribute to deforestation. Wars denuded forest cover in Viet Nam and Laos, while forest fires were a significant factor in Indonesia. The adoption of sustainable forest and agricultural management policies has slowed forest depletion in Thailand, Viet Nam and Cambodia.

Water resource depletion: Agriculture accounts for a larger percentage of freshwater usage in Asia than in any other part of the world and freshwater will be the major limiting factor to producing more food in the future. Dams and groundwater irrigation have disrupted the natural hydrological cycle, reducing river levels, depleting wetlands and aquifers, and salinizing agricultural lands. Dirty water and poor sanitation claim more than 500,000 infant deaths a year. Asia's rivers contain three times as many bacteria from human waste as the world average. One in three Asians has no access to safe drinking water, often as a result of contamination of groundwater and surface water reserves by sewage and industrial waste. A study of 15 Japanese cities, for example, showed that chlorinated solvents from industry contaminate 30 per cent of all groundwater supplies. Agrochemical inputs are a growing source of water contamination as nitrates leach into freshwater bodies. Salt-water intrusion also threatens the water supply in many areas; in Madras, India, for instance, salt water has rendered many irrigation wells useless as far as 10 kilometres inland.

Biodiversity depletion: Indonesia, India, and China are among the countries with the most threatened species of mammals and birds, according to the World Conservation Union (IUCN).102 Indonesia has the highest number of threatened mammals (135 species), followed by India (80) and China (72). The Philippines has more critically endangered birds than any other country in the world.

Air quality and carbon emissions: Air pollution is now becoming a part of the region's environment, causing deaths. In China, for instance, smoke and small particles from burning coal cause more than 50,000 premature deaths and 400,000 new cases of chronic bronchitis a year. Led by China and Japan, emissions of carbon dioxide increased at twice the average world rate of 2.6 per cent per year during 1975-1995.

Urbanization: Asia has 160 of the world's 369 cities with more than 750,000 residents. Growing populations have frequently outpaced the development of urban infrastructures, and slums and shanty towns are growing in many cities. In Colombo, for example, some 50 per cent of the urban population resides in slums and squatter areas. The urban population of the region, now about 35 per cent of the total population, grew by 3.2 per cent a year between 1990 and 1995, compared with 0.8 per cent a year for the rural population. In most countries, the urban population is likely to grow threefold in the next 40 years. China alone is expected to have 832 million urban residents by 2025.

GEO-2000 reports that "some governments are now taking action to reconcile trade and environmental interests through special policies, agreements on products standards, enforcement of the Polluter Pays Principle, and the enforcement of health and sanitary standards for food exports."

Africa

Africa's population density of 249 people per 1,000 hectares is well below the world average of 442. However, a great deal of the total destruction of the natural environment is occurring in the region. Poverty is a major cause and consequence. Natural disasters such as storms, floods and droughts are common and highly destructive. Global warming may make Africa even dryer in the future; this could seriously disrupt natural ecosystems and make food security a major problem. Widespread poverty, HIV/AIDS and diseases spread by water and insects remain critical challenges for the region. Major environmental issues include103:

Land degradation: Soil degradation is a major concern in Africa, where 500 million hectares have been affected, including 65 per cent of the agricultural land. Crop yields could be cut in half in 40 years if degradation continues at the current rate. In Southern Africa, over-grazing of livestock is a major contributor to soil degradation. Large portions of Northern Africa are facing desertification caused by a combination of over-grazing, rainfall variability and drought conditions. In Western and Central Africa, rising populations and shifting agriculture have damaged large swathes of land.

Deforestation: Although Africa still accounts for 17 per cent of global forest cover, forests are being steadily degraded by population growth, drought, agricultural expansion, fuelwood extraction, commercial exploitation, bush fires, civil wars and political instability. During 1990-1995, Africa lost its forest cover at an annual rate of 0.7 per cent. Unsustainable agricultural practices such as shifting cultivation and slash-and-burn techniques in Southern and Central Africa contributed, as did commercial logging, oil-exploration and mining activities. Ninety per cent of the population depends on firewood and other biomass for energy. Production and consumption of firewood and charcoal doubled between 1970 and 1994 and is expected to rise by another 5 per cent by 2010.

Water resource depletion: While Africa uses only about 4 per cent of its renewable freshwater resources and some countries have abundant lakes and rivers, countries in arid regions depend on limited groundwater reserves. Already, 14 countries in Africa are facing water stress. By 2025, another 11 countries can be expected to face the same conditions. The prospects are particularly bad in northern Africa. The demand for water is expected to grow by at least 3 per cent annually until 2020 as populations increase and economies develop. Surface water contamination is a growing problem with serious implications for public health.

Urbanization: Africa's annual urban growth is now the highest in the world, at more than 4 per cent. In the 1960s about 20 per cent of the population lived in urban areas; the figure rose to 35 per cent in 1995. Urban infrastructure is poorly developed, and peri-urban areas are expanding, often without planned services and amenities. Much of the urban population lives in medium-sized cities that lack the economic dynamism of larger cities.

Biodiversity depletion: Africa is home to more than 50,000 known plant species, 1,000 mammal species, and 1,500 bird species. This diverse biological heritage is at risk in all subregions.

Carbon emissions: Africa's emissions of greenhouse gases are still low. The region contributes only 3.5 per cent of the world's total carbon dioxide emissions and this figure is expected to increase to only 3.8 per cent by 2010.

Latin America and the Caribbean

Major environmental challenges in Latin America and the Caribbean include104:

Land degradation: An estimated 300 million hectares of land have been affected by soil degradation, mostly the result of soil erosion and chemical use. Approximately 100 million hectares are estimated to have been degraded through deforestation and 70 million hectares were overgrazed.

Deforestation: Endowed with the world's most luxuriant tropical forest cover, Latin America is the focus of the global effort to achieve sustainability. Nearly half the region is still covered by natural forest, but 3 per cent of the forest cover was lost during 1990-95. Brazil lost some 15 million hectares of forest area in 1988-97, according to the GEO-2000 report. Agricultural expansion through traditional slash-and-burn practices is considered the prime cause of deforestation. Modern agriculture, logging, mining, infrastructure development, fires and urbanization also contribute.

Water resource depletion: Although Latin America has extensive freshwater systems, nearly two thirds of the region is classified as arid or semi-arid. In some areas, aquifers are being exploited at unsustainable rates as demand for water from domestic, industrial and agricultural users increases. Pollution and sanitation continue to be major issues. The region is also vulnerable to toxic chemical discharge into its water systems from extensive mining and industrial activities.

Urbanization: Nearly 75 per cent of the region's population is already urbanized, many in megacities such as Mexico City (16.5 million people), São Paulo (16 million), Buenos Aires (12 million) and Rio de Janeiro (10 million). Large numbers of city dwellers live in squatter settlements and shantytowns, including 4 million of Rio de Janeiro's 10.6 million residents.

Air pollution and carbon emissions: Air quality in most major cities threatens human health. In São Paulo and Rio de Janeiro, air pollution is estimated to cause 4,000 premature deaths a year. The average ozone concentration in 1995 in Mexico City was about 0.15 parts per million, 10 times the natural atmospheric concentration. The main source of carbon dioxide emissions is deforestation. The region is responsible for 4.3 per cent of the world's total carbon dioxide emissions from industrial processes and 48.3 per cent from land-use changes.

Depletion of biodiversity: The loss of forest cover threatens the region's biological diversity. Already, more than 1,000 vertebrate species are now threatened with extinction. Brazil has the second largest number of threatened bird species (103 species) in the world, and Peru and Colombia occupy fifth place with 64 species each. More than half of the Argentinean mammals and birds are threatened.

Western Asia

Western Asia's population density is well below the world average. However, the scarcity and degradation of water and land resources pose an increasing challenge. Exploitation of the region's oil resources has conferred great benefits to some countries but has also exacted significant costs. Pollution and inadequate waste management are causing degradation of the marine and coastal environment. Major environmental issues include105:


Hartmut Swarzbach, Still Pictures
Construction boom in Shanghai. China will have more than 832 million urban residents by 2025.

Land degradation: Soil degradation has long been a serious problem, increasingly so in the past few decades. Nearly 96 per cent of the land is vulnerable to desertification; nearly four fifths is desert or desertified. Increasing food demand due to population growth has resulted in overgrazing and the extension of cereals onto rangelands in fragile ecosystems; laws and decrees to protect rangeland have not produced significant results. Poor irrigation techniques have also led to soil salinization and nutrient depletion.

Deforestation: Much of the natural forests that once covered much of the north of the region was long ago cleared for settlements, agriculture, grazing and charcoal production. Reforestation programmes have kept forest areas at their current levels over the past two decades, but the high cost of imported timber could increase pressures for further clearing. Clearing of mountain slopes for agriculture has led to severe soil erosion in Jordan, Lebanon, Syria and Yemen.

Water resource depletion: Water is a precious and limited resource in the region, and a potential trigger for serious national conflicts; rainfall is low and erratic and evaporation high. Rapid population growth, relative to water resource development, is reducing per capita use. The Mashriq subregion106 has rivers that originate outside and short seasonal or perennial rivers.

The Arabian Peninsula is poor in surface water but has larger groundwater reserves than the Mashriq; those reserves are being withdrawn faster than natural recharge rates, however. Conflicts and disputes over water allocations have impeded improvements in the use of surface water. Seawater intrusion and contamination by human and industrial waste and pesticides are affecting water quality. Surface water contamination is a growing problem with serious implications for public health. Costly desalination and wastewater treatment alleviate but do not solve the problems.

Global warming is not expected to reduce, and may worsen, water constraints. Small projected increases in rainfall may be offset by higher temperatures and evaporation.

Urbanization: Urban growth in some countries has been proceeding at twice the rate of overall population growth. More than two thirds of the people live in urban areas (even higher levels obtain in the Gulf countries). Much growth has been concentrated in a small number of cities where opportunities and infrastructure are concentrated. Though land use planning has been attempted, chaotic physical growth and encroachment on agricultural land are common. Peri-urban areas are expanding, often without planned services and amenities.

Biodiversity depletion: The diverse ecosystems of the region are home to many endangered species. Marine ecosystems (mudflats, mangrove swamps, sea grass and coral reefs) are under particular stress. Marine biodiversity has been harmed by over-fishing, pollution and habitat destruction. Protected areas have been established in all parts of the region but depletion of water resources, soil salinization and plant pests are having a large impact on many endemic plant and animal species. Oil and waste spillage into the Persian Gulf is also having a growing impact.

Carbon emissions: The development of the oil industry and rapid industrial and population growth have led some countries to become high energy consumers. Atmospheric emissions of hydrocarbons, carbon dioxide and other pollutants have reached alarming levels, particularly in larger cities. Year-round sunshine and high temperatures help convert primary pollutants to ozone and sulphates, which can be more hazardous to health and the environment.

Box 10: Living Planet Index

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