Its been claimed that riding a bike is the worst thing you can do for the environment. The fuel for a human is the most ecologically disastrous fuel we make. Billions of acres clearcut; chemicals in the soil and air; CO2 by the gigaton. No, increasing human output has the largest impact on CO2 we could create.
I think it's a clever point, but it falls flat for me on closer inspection because:
#1: The whole point of preserving the environment is to keep it inhabitable for humans. Fueling humans is non-negotiable up to at least a baseline level of survival, and still desirable beyond that level because we like being well fed.
and
#2: Due to that whole "we like being well fed" thing, most humans in the first world -- the part of the world where people worry about things like whether biking to work is good or bad for the environment -- are already overfueled. We have a surplus of human fuel that we're consuming anyway because it feels good. Might as well burn some of it off on transportation.
