Delhi is locked in a complete choking smog at the moment - they've had to close schools in one of the world's biggest cities. They have their own reasons for needing to get off fossil fuels fast.

In the States, I think, the syllogism goes like this: 'free markets solve all problems. Free markets aren't solving global warming, QED global warming is not a problem'. It's not a very good syllogism but it's emotionally comforting if you're in that world.

There is no real scientific debate over what is happening; of course there is debate over exactly how it is going to play out in the decades ahead, because this is a large experiment that we haven't done before, and no one knows precisely how one can ever precisely predict what effects this heat will have. But all the science in the last few years, or almost all of it, really serves to show that the effects are larger and more rapid than we had thought even a decade ago.

We just see a sort of cascading amount of data of the damage that is being done by those increased temperatures.

But the truth is that we could win every other fight that we face and if we lose the climate fight, the other victories will be pyrrhic. I don't think even people who are worried about climate change quite understand the scale and speed with which we're now shifting the planet.

Winning slowly is another way of losing. Americans are screwing up our health care system again right now. That's going to cause grave trouble for people over the next five, 10 years. There are going to be lots of people who die, lots of people who are sick. It's going to be horrible. But 10 years from now it will not be harder to solve the problem because you ignored it for those 10 years. With climate change, that's not true. As each year passes, we move past certain physical tipping points that make it impossible to recover large parts of the world that we have known.

A voluntary simplification of life-styles is not beyond our abilities, but it is probably outside our desires.