Would like to learn to fly, but...

Having become dangerously addicted to MS Flight Simulator, I am
starting to develop a hankering to learn to fly for real. However I'm
having a bit of trouble reconciling this desire with my concern about
CO2 emissions and climate change. My wife and I tend to buy reasonably
fuel efficient cars and are soon to have a wind turbine installed on
our house, so to start burning aviation fuel just for fun would seem
like a bit of a step in the wrong direction.

Can anyone provide any insights to help me allay these concerns? I
don't even know how much fuel the average light aircraft consumes or
how much CO2 it puts out into the atmosphere. Is it comparable to a
car or is it a lot more? (My car gets about 50mpg, but then I spend a
lot more time driving it than I could ever afford to spend flying a
plane.)

Thanks in advance,
Colin