And those scientists have provided ample evidence that human activity is indeed linked to climate change. Just last month, the Intergovernmental Panel on Climate Change -- a body made up of the world's top climate scientists -- said it was 95% certain that we fossil-fuel-burning humans are driving global warming. The debate right now isn't whether this evidence exists (clearly, it does) but what this evidence means for us.

Simply put, I do my best to keep errors of fact off the letters page; when one does run, a correction is published. Saying "there's no sign humans have caused climate change" is not stating an opinion, it's asserting a factual inaccuracy.

So the debate shifts to what the evidence means. No wonder progress is so slow.