A tree absorbs approximately 25kg of CO2 per year It's based on the estimate that a cubic metre of wood absorbs just under a ton of CO2. But really a tree absorbs anywhere between 10 and 40kg of CO2 per year on average, depending on a whole host of factors.

A reasonable estimate for aviation CO2 emissions is therefore 250 kg i.e. 1/4 tonne CO2 equivalent per passenger per hour flying, i.e. the same figure as obtained by Basis 1 above.23 Sept 2022