Plant a tree each time you fly, or get Treeflights to do it for you!
Firstly if you have any doubts about Global Warming and related topics you should, if you care about the Earth, watch this presentation by Al Gore
There’s no way of avoiding it, flying is inherently environmentally destructive and we shouldn’t do any more of it than we have to. Planting a tree, on the other hand, is an ecologically constructive thing to do. Trees use the sun’s energy to absorb CO2, taking it out of the atmosphere (where it’s really harmful) and turning it into this wonderful, renewable material that we call wood. Trees encourage biodiversity and are also fantastic air purifiers.