Accidental pollution The accidental release of pollutants into the environment, for example, when a tanker is wrecked and leaks oil into the ocean. This may kill or harm thousands of animals or damage sensitive habitats.

Acid rain Rain containing acids that form in the atmosphere when gases emitted by factories and power stations combine with water. Acid rain harms wildlife in lakes, rivers and streams and makes soil too acidic to support plant life.

Air pollution Pollution of the air, caused by fumes and smoke from vehicles, factory chimneys and power stations. Air pollution adds to the greenhouse effect and causes respiratory illnesses, such as asthma.

Biodegradable waste Organic waste, such as food, which decomposes naturally. The decomposition of biodegradable products may release methane, a greenhouse gas.

Chemical waste Any waste made from harmful chemicals. Large areas of the Earth are now partially poisoned by chemical wastes, which harm animals and plants and can expose people to new diseases.

Chlorofluorocarbons (CFCs) Chemicals once widely used in refrigerators and aerosol sprays. When released into the atmosphere, CFCs destroy the ozone layer. Their production in recent years has been greatly reduced.

Climate change Changes to the Earth’s weather patterns. Rapid climate change in recent years has been caused by burning fossil fuels, creating excess carbon dioxide and other gases in the atmosphere. Rising temperatures and changing weather patterns may lead to violent storms, droughts and rising sea levels as the polar ice caps melt.

Conservation The management and care of the natural world, to avoid imbalances caused by habitat destruction and the extinction (dying out) of species.

Desertification The process by which forest, grassland or scrub turns to desert. Deserts may be created as a result of persistent drought, or may be manmade, for example, by farmers overgrazing animals on grassland or diverting rivers and lakes to water nearby crops. Due to desertification, there is nearly three times as much desert now as there was 100 years ago.

Eutrophication Excessive nutrients in a lake or river, often caused by chemical fertilizers leaking from the soil. Eutrophication causes a dense growth of water plants, which then decay, depleting the water of oxygen and killing fish.

Global warming The gradual rise in the temperature of the Earth. Over the past century, the average temperature has risen by more than 0.5°C (0.9°F). This is caused by the build-up of greenhouse gases through burning fossil fuels.

Greenhouse effect The warming of the Earth caused by certain gases in the atmosphere that trap some of the Sun’s heat. These gases—water vapour, carbon dioxide, methane, nitrous oxide and ozone—are called greenhouse gases. If they build up excessively, caused by burning fossil fuels like coal and oil, too much heat is trapped and the Earth becomes warmer.

Incineration Burning waste material to dispose of it. More countries are turning to this as a means of waste disposal as their landfill sites run out. The heat this causes can be used to generate electricity, but the gases given off by burning wastes can contribute to air pollution.

Landfill A place where rubbish is disposed of, usually by burying it. Landfills are the most widely used method of waste disposal.

Ozone layer The thin layer of ozone gas in the Earth’s atmosphere. It prevents harmful rays from the Sun reaching the Earth. The release of some chemicals, such as CFCs, into the air damages the ozone layer, allowing more radiation from the Sun to reach the Earth’s surface.

Pesticide drift The unintentional drift of chemical pesticides from crops into soil or water, where they poison plants and animals.

Pollution The harmful effect on the natural environment of by-products of human activity. Pollutants include chemicals, particulates, sewage, pesticides, light and noise.

Recycling The process of turning waste material, such as glass, metal, paper or plastics, into new objects. This reduces the need for landfills and incineration. Many towns have recycling collections or bins where people can take their recycling.

Soil erosion The wearing away of topsoil by the natural forces of water and wind, or through farming activities.

Sustainability If a resource's rate of recovery is balanced by the rate it is used up, that resource is described as sustainable. An example of sustainability is when the regrowth of replaced saplings in a pine forest keeps pace with the felling of trees. Sustainable development has been defined as one that "meets the needs of the present without compromising (damaging) the ability of future generations to meet their needs."

Water pollution The contamination of groundwater, rivers, streams, canals, lakes or oceans. Factories sometimes dump chemicals and other wastes in waterways and, in some places, raw sewage is poured straight into them. Water pollution is also caused by the drift of chemical fertilizers and pesticides.

Consultant: Lloyd Jenkins