Ottawa Citizen: Whenever I write about the urgent need to act on climate change, I hear from folks who say there is no such need. Climate change is bunk, they say. For today only, let’s say they’re right. Who knows? They may be. Scientific conclusions are never absolutely certain. Maybe all those thousands of scientists are wrong. Maybe the national science academies of the world screwed up when they issued a joint statement declaring the problem to be real and urgent. Anything’s possible. And it …