Acid rain: any form of precipitation (e.g. rainfall) with acidic parts, such as sulfuric or nitric acid. This forms when certain gases combine with water. The gases mostly come from the burning of fossil fuels.
Atmosphere: the layer of gases surrounding a planet
Biodegradable: can be broken down by bacteria or other organisms.
Biodiversity: the number and variety of plant and animal species that exist in a particular area.
Carbon dioxide: gas formed when carbon is burned, and when people or animals breathe out. A greenhouse gas.
Carbon monoxide: toxic  gas that can be formed by the burning of carbon-containing compounds or fuels.
Carcinogen: substance that causes cancer.
CFCs: Chlorofluorocarbons – gases used as refrigerants that are being phased out because they are harmful to the ozone layer in the Earth's atmosphere.
Climate: the general weather conditions that prevail in a particular place, averaged over a long period.
Climate change: change in the typical or average weather of a region, or of the Earth.
Conservation: the protection and preservation of the natural environment.
Contamination: act of making something unclean or polluted; or the state that results from this act.
Deforestation: permanent destruction of forests in order to make the land available for other uses.
Desertification: process by which land changes into desert.
Destruction: act of destroying something.
Detergents: cleaning agent that dissolves dirt and oil.
Drought: long period without rain, causing the land to dry up.
Ecosystem: the natural organisms and flora and fauna that constitute and sustain a particular area.
Endangered species: species in danger of becoming extinct.
Energy conservation: process of saving energy.
Environment: the air, water and land in or on which people, animals and plants live.
Erosion: gradual wearing away of rock or soil, sometimes due to a lack of vegetation.
Exhaust gases: gases emitted as a result of the combustion of fuels, especially from a vehicle.
Extinct: when a plant or animal species ceases to exist entirely.
Famine: severe shortage of food leading to widespread hunger.
Fertiliser/fertilizer: substance added to soil to promote plant growth.
Fossil fuels: fuel formed naturally over many years from the remains of animals and plants, for example, coal, natural gas, oil, petroleum.
Geothermal: relating to the warmth of the Earth.
Global warming: an increase in the average temperature of the Earth's atmosphere.
Greenhouse effect: the trapping of the sun's heat in the atmosphere caused by greenhouse gases.
Greenhouse gases: any gas, which contributes to the greenhouse effect. The main gases are water vapour, carbon dioxide, methane, nitrous oxide, and ozone.
Hydrocarbons: organic chemical compound containing only hydrogen and carbon atoms.
Insulation: material that stops or reduces the loss of heat.
Landfills: large areas of land where waste is buried.
Overpopulation: Too many people living in an area for the environment to be able to support.
Nitrogen dioxide: toxic gas produced especially in vehicle exhausts.
Nuclear power: energy is produced by splitting or combining atoms, and this is used to produce electricity in a nuclear power plant.
Oxygen: gas necessary for combustion (burning) and for respiration (breathing).
Ozone layer: layer of the upper atmosphere which contains a high level of ozone. This prevents sun's harmful ultraviolet rays from reaching the Earth.
Ozone: a form of oxygen. In the lower atmosphere it is a pollutant. In the upper atmosphere it forms the ozone layer.
Pollutant: a component of pollution, something that causes harm to an area of the natural environment
Pollution: process of making the environment dirty and unsafe or unsuitable to use.
Preserve: to keep something protected in its existing state.
Sewage: waste (domestic and industrial) carried away down drains.
Solar power: harnessing the Sun's energy to generate electrical power.
Stratosphere: region of the Earth’s atmosphere starting at ca. 10km above the surface.
Tidal power: power generated using the energy produced by the changes in ocean tides to generate electrical power.
Toxic: harmful to health.
Weather: short-term changes in temperature, clouds, precipitation, humidity and wind.
Wind power: power generated by using the wind.