I'm not convinced that stepping out of air travel would really have that large an impact on any carbon footprint except yours. The flights are still going out; my assumption is that your not being on them doesn't mean much difference.

How much fuel is spent per person on a flight, and how much CO2 emission does that translate to? That would be helpful data. Without that, I can't really say if it's meaningful or not.

Edit: I already don't fly, by the way. No need to.