Additionality means that a project goes beyond business-as-usual—that it would not have been possible without the extra revenue gained from selling offsets. The point is to ensure that any greenhouse gas reductions from the project are ‘in addition’ to what would have happened anyway. Otherwise giving money to the project doesn’t achieve any extra environmental good.
Additionality is one of the key principles of carbon offsets, and it’s a cornerstone of our carbon offset policy. Greenhouse gas reductions happen all the time, but only reductions from additional projects can be real, legitimate carbon offsets. We vet all our projects very carefully to be sure they are dependent on offset revenue.