Today is Blog Action Day 09 - Climate Change. (Thanks for the pointer from squareCircleZ, who wrote a great post on it.)
What's that got to do with math? Well, we won't have time for the cerebral pleasures of math if we're dealing with floods and droughts, famine and war.
Here's a site that give some numbers to help you think about it. I try to live simply, but if everyone lived like I do, we'd need over 2 planet Earths.
I wanted to write more, but this is already coming out late in the day...