Climate change has a very high procrastination penalty that just grows with each passing year of inaction - rather like what happens if you don't pay off your credit card. But for climate, there is no such thing as a fresh start from bankruptcy.

Since Serengeti-scale savanna scenes are only one or two million years old, our earliest after-the-apes ancestors didn't move into this scene so much as they evolved with it, as the slower climate changes and uplift produced more grass and less forest.

Climate change has a very high procrastination penalty that just grows with each passing year of inaction - rather like what happens if you don't pay off your credit card. But for climate, there is no such thing as a fresh start from bankruptcy.

Perhaps we should put up posters in such places reminding people that where they stand was underwater the last time that the Earth ran a 3°F fever.

If we don't start thinking big about the CO2 problem, we may miss our opportunity to stop a climate runaway that will trash the habitable parts of the earth.

It's going to be like herding stray cats, and the political leaders who can do it will be remembered as the same kind of geniuses who pulled off the American Revolution.

Anyone who would tackle our current addiction to fossil fuels is going to have to maneuver around denial.