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.

Countries that innovate first get the new jobs, developing an economic edge over the C-free laggards that end up having to later import the technology.

Stopping emissions growth represents the most minimal of do-something responses.

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.

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.

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.

Carbon-free energy is simply something we have to do. The time for talk is past. If we turn around net carbon emissions by 2020 rather than 2040, we get another 2° of fever rather than 3° - and that's a big difference.