What if we are? Worst case we've significantly reduced the amount of pollution we are putting into our air, land and sea, and reap those health benefits, but not actually affected the climate one way or another.
I think the evidence for climate change is pretty strong, but it's not like it's the only reason to quit burning coal and pumping the smoke into our atmosphere or producing huge amounts of plastics.
If we act and we're right we've prevented catastrophe, if we act and we're wrong we're just healthier, and kill less of the ecosystem around us.