environmental issues

The warming effect of the Earth's atmosphere is called the greenhouse effect. Radiation from the Sun enters the atmosphere but is prevented from escaping back into space by gases such as carbon dioxide (produced for example, by the burning of fossil fuels), nitrogen oxides (from car exhausts), and CFCs (from aerosols and refrigerators). As these gases build up in the atmosphere, the Earth's average temperature is expected to rise.

Matters relating to the damaging effects of human activity on the biosphere, their causes, and the search for possible solutions. The political movement that supports protection of the environment is the green movement. Since the Industrial Revolution, the demands made by both the industrialized and developing nations on the Earth's natural resources are increasingly affecting the balance of the Earth's resources. Over a period of time, some of these resources are renewable – trees can be replanted, soil nutrients can be replenished – but many resources, such as minerals and fossil fuels (coal, oil, and natural gas), are non-renewable and in danger of eventual exhaustion. In addition, humans are creating many other problems that may endanger not only their own survival, but also that of other species. For instance, deforestation and air pollution are not only damaging and radically altering many natural environments, they are also affecting the Earth's climate by adding to the greenhouse effect and global warming, while water pollution is seriously affecting aquatic life, including fish populations, as well as human health.

Environmental pollution is normally taken to mean harm done to the natural environment by human activity. In fact, some environmental pollution can have natural sources, for example volcanic activity, which can cause major air pollution or water pollution and destroy flora and fauna. In terms of environmental issues, however, environmental pollution relates to human actions, especially in connection with energy resources. The demands of the industrialized nations for energy to power machines, provide light, heat, and so on are constantly increasing. The most versatile form of energy is electricity, which can be produced from a wide variety of other energy sources, such as the fossil fuels and nuclear power (produced from uranium). These are all non-renewable resources and, in addition, their extraction, transportation, utilization, and waste products all give rise to pollutants of one form or another. The effects of these pollutants can have consequences not only for the local environment, but also at a global level.

Widespread effects of pollution Many people think of air, water, and soil pollution as distinctly separate forms of pollution. However, each part of the global ecosystem – air, water, and soil – depends upon the others, and upon the plants and animals living within the environment. Thus, pollution that might appear to affect only one part of the environment is also likely to affect other parts. For example, the emission of vehicle exhausts or acid gases from a power plant might appear to harm only the surrounding atmosphere. But once released into the air they are carried by the prevailing winds, often for several hundred kilometres, before being deposited as acid rain. This can produce an enormous range of adverse effects across a very large area, for example: increased acidity levels in lakes and rivers are harmful to fish stocks and other aquatic life; physical damage to trees and other vegetation results in widespread destruction of forest areas; increased acidity of soils reduces the range of crops that can be grown, as well as decreasing production levels; rocks such as limestone, both in the natural landscape and in buildings, are eroded – the effect of acid rain on some of the world's most important architectural structures is having disastrous consequences. In addition, acid rain in the form of aerosols or attached to smoke particles can cause respiratory problems in humans. Pollution of the Arctic atmosphere is creating Arctic haze – the result of aerosol emissions, such as dust, soot, and sulphate particles, originating in Europe.

Desertification The destruction of fertile topsoil, and consequent soil erosion, as a result of human activity is becoming a worldwide problem. About 25% of the planet's land surface is now thought to be at risk owing to increased demand from expanding populations. This damage and destruction results not only from increased demand for food, but also as a result of changes in agricultural practices. Desertification of vast areas, such as in the Sahel in northern Africa, have resulted from the replacement of traditional farming methods in these marginal lands for the present-day cultivation of cash crops such as groundnuts and cotton. The consequence has been that the soil has lost its fertility and the land has become arid. Similarly, changes in agricultural practices produced the dust bowl in the USA in the 1930s and, more recently, the move from mixed farming to arable and the removal of hedges in order to enlarge fields for the use of modern agricultural machinery has resulted in the loss of topsoil in the large areas of the English Fenlands.

Effects of tourism Environmental problems are developing not only from demands on natural resources in order to satisfy basic needs. The greater affluence and leisure time that people in the developed nations now enjoy is giving rise to the increasing demands of tourism. Not only are the more accessible areas of scenic beauty in their own countryside at risk from overuse and tramping feet, but in the tourists' search for more exotic locations, the landscapes, lifestyles, and wildlife of some of the world's more remote regions are now being brought within the reach of – and despoilment by – an ever-expanding tourist industry.

Public awareness Concern for the environment is not just a late-20th century issue. In England, the first smoke abatement law dates from 1273, while in 1306 the burning of coal was prohibited in London because of fears of air pollution. However, the inspiration for the creation of the modern environmental movements came about from the publication in 1962 of Rachel Carson's book Silent Spring, in which she attacked the indiscriminate use of pesticides. This, combined with the increasing affluence of Western nations which allowed people to look beyond their everyday needs, triggered an awareness of environmental issues on a global scale and resulted in the formation of the Green movement. In the mid-1960s, the detection of CFCs in the atmosphere by British scientist James Lovelock led to a realization of the damaging effects of ozone depletion and added to public concern for the environment, as did his development of the Gaia hypothesis, which views the Earth as a single integrated and self-sustaining organism.

International measures In 1972, the United Nations Environment Program (UNEP) was formed to coordinate international measures for monitoring and protecting the environment, and in 1985 the Vienna Convention for the Protection of the Ozone Layer, which promised international cooperation in research, monitoring, and the exchange of information on the problem of ozone depletion, was signed by 22 nations. Discussions arising out of this convention led to the signing in 1987 of the Montréal Protocol. In 1992, representatives of 178 nations met in Rio de Janeiro for the United Nations Conference on Environment and Development. Known as the ‘Earth Summit’, this was one of the most important conferences ever held on environmental issues. UN members signed agreements on the prevention of global warming and the preservation of forests and endangered species, along with many other environmental issues.

The second Earth Summit, held in New York in 1997, tackled deforestation and agreed to work towards the preservation of the world's tropical and old-growth forests. In the same year, the United Nations Framework Convention on Climate Change (UNFCCC) adopted the Kyoto Protocol, which committed the world's industrialized countries to cutting their annual emissions of harmful gases. By July 2001 84 parties had signed and 37 ratified or acceded to the Protocol. However, US President George W Bush announced that the USA would not be ratifying the Kyoto Protocol in June 2001.