Carbon offset

While lacking a formal definition, Carbon offset can best be described as an act of paying a third party for reducing ("offsetting") greenhouse gas emissions when one is unable or unwilling to reduce one's own emissions. A well-known example is the planting of trees to compensate for the greenhouse gas emissions from personal air travel.

The idea of paying for emissions elsewhere instead of reducing by own actions is also known from the closely related concept of emissions trading, but while emissions trading is mostly in a strict formal and legal framework, carbon offsets generally refer to voluntary acts, often arranged by a commercial carbon offset provider.

A wide variety of offset methods are in use — while tree planting has initially been a mainstay of carbon offsetting, renewable energy and energy conservation offsets have now become increasingly popular, and purchase and withdrawal of emissions trading credits is also seen.

The appeal of becoming "carbon neutral" has contributed to the increasing popularity of voluntary offsets which are often cheaper alternatives to reducing one's own fossil-fuel consumption. However, many environmentalists object to offsets in principle, and many have questioned the benefits of certain types of offsets (tree planting in particular), and numerous individual projects.