What is a carbon offset?

A carbon offset unit represents the removal of one tonne of carbon dioxide equivalent (t CO2-e) from the atmosphere, or the avoidance of one tonne of emissions. The term "carbon dioxide equivalent" refers to the summation of multiple greenhouse gasses based on each gasses global warming potential (GWP). The Global Warming Potential (GWP) was developed to allow comparisons of the global warming impacts of different gases. Specifically, it is a measure of how much energy the emissions of 1 tonne of a gas will absorb over a given period of time, relative to the emissions of 1 tonne of carbon dioxide (CO2). For instance, methane has a GWP about 28 times that of CO2.