The greenhouse effect

The greenhouse effect is the warming of Earth’s surface and atmosphere by certain gases in the atmosphere. It keeps the planet warm enough to support life.

Energy from the Sun reaches Earth mainly as short-wavelength radiation. Much of this radiation passes through the atmosphere and is absorbed by Earth’s surface, warming it. The warmed surface then emits energy as longer-wavelength infrared radiation.

Greenhouse gases, including water vapour, carbon dioxide and methane, absorb some of this outgoing infrared radiation. They then re-emit radiation in different directions, including back towards Earth’s surface.

As a result, thermal energy escapes into space more slowly. The surface and atmosphere stay warmer than they would be without the greenhouse effect.