Carbon footprint

Greenhouse gases are gases that are relatively transparent to short-wave infrared radiation (such as heat from the sun). This means that they allow sunlight to enter the atmosphere and heat the Earth’s surfaces. These surfaces then re-radiate that heat as long-wave infrared radiation, which greenhouse gases tend to absorb rather than transmit.

The result is that the long-wave infrared radiation is ‘trapped’ and heat accumulates in the atmosphere causing a warming process. This process is known as the ‘greenhouse effect' because it is similar to the effect that glass has, trapping heat in greenhouses.

The four main greenhouse gases are:

Water vapour.
Carbon dioxide.
Methane.
Nitrous oxide.

The term ‘carbon footprint’ refers to the total greenhouse gas emissions associated with a particular policy, individual, event, development or product.