In the end, climate change is a math problem.

Katrina opened a good door and Al Gore went through it with his movie.

I think that some of it is electoral - helping candidates that are willing to take dramatic actions, not just to say a few words about how climate change might be a problem.

We spend a lot of time playing defence against bad things. So, in the US, one of the focusses has been this huge Keystone Pipeline project, another has been the coal ports on the Pacific Ocean.

At the moment, the 4 percent of us in this country produce a quarter of the world's carbon dioxide - once you look at maps of rising sea levels and spreading mosquitoes, you realize that we've probably never figured out a way to hate our neighbors around the world much more effectively.

In the end, climate change is a math problem.

Warm air holds more water vapor than cold, and so the atmosphere is about 4% wetter than it was 40 years ago. This loads the dice for flood and drought, and we're seeing both in stunning abundance.