Of course the very best thing is to reduce your own carbon footprint, for example by avoiding air and car travel. But sometimes that's simply not possible. Emissions offsetting is then the second best solution and - unlike the  “selling of indulgences” in the medieval sense - has a genuine effect. It means that CO₂ is saved elsewhere. The German Federal Environment Agency also recommends a threefold approach of avoidance, reduction and offsetting. Scientists at the Universities of Kassel and Hamburg have refuted the theory that compensation trade could lead to a sell-off mentality that is misused to justify more climate-damaging consumption. People who already offset carbon emissions also tend to be climate-friendly in other areas.