Most of us have to take a flight now and then – for professional or recreational reasons. But massive price decline has created a frequent flyer culture that is extravagating. Though in comparison to cars the CO2 emission caused by planes is rather small, CO2 and water vapour emitted in such heights contribute considerably to the green house effect and are degraded much slower than on ground level.
In order to address people using planes directly, fields adjacent to airports can be used to deliver a message: Does it make sense? People will be surprised by this giant natural "billboard". A two-sided ad campaign in magazines and newspapers (usually distributed during the flight anyway) will explain what the the question means: Did I really have to take the plane? Wouldn't it have been even easier to take the train or use the web instead?
The sensation of seeing the text in such an extraordinary setting can be amplified by accompanying measures on city light posters and real billboards on the way to/from the airport. Thus the magazine or billboard campaigns can stand for themselves, too.
Mind it: It is not about making every air passenger a scapegoat. It is about making people realise that it is their responsibility and their choice. Making them aware of the problem during take-off will empower them to make a change next time, it will free them from this fatalistic "What can I do?"