What do "carbon neutral" and "carbon footprint" mean?

A carbon neutral activity is one that has a zero carbon footprint.

A carbon "footprint" is a way of describing how much greenhouse gas has been added to the atmosphere as a result of some activity, measured as an equivalent amount of carbon dioxide (CO ₂ e). For example, the carbon footprint of someone who drives a petrol car to work will be greater than someone who uses a bus to travel the same distance, because the car driver is responsible for more CO emissions ₂ e as someone who commutes by bus.

A carbon neutral activity is one that has a zero carbon footprint. Some activities that produce a lot of greenhouse gases are sometimes combined with other activities that reduce the level of greenhouse gases in the atmosphere, such as converting land to grow trees. This is known as carbon offsetting and is one way that activities or products can be presented as 'carbon neutral'.

In some cases, the carbon footprint of an activity includes all emissions produced during its life cycle. This is known as life cycle analysis. (Co2AI)