What is the greenhouse effect?

The greenhouse effect is a naturally occurring process that helps heat the Earth's atmosphere. It results from the fact that certain atmospheric gases, such as carbon dioxide, water vapour and methane, absorb infrared radiation emitted from the Earth's surface. These greenhouse gases occur naturally in our atmosphere and without the greenhouse effect, the average temperature of the Earth would be a chilly -18°C, rather than the present 15°C. The amount of greenhouse gases in our atmosphere has increased since the Industrial Revolution.