Scientists are telling us that 350 parts per million [of carbon] in the atmosphere is the upper limit. We're at 387 parts per million now, and we're up in that zone where the risk of going past irrevocable tipping points is elevated. It's no different than going to a doctor and learning your cholesterol is too high, and you're at risk for a heart attack. You have to work to lower your cholesterol and hope to get there before the heart attack comes.

Solar power seems to be truly bipartisan in its appeal.

On the top of these mile thick slabs of ice the water is percolating quickly to the base and greasing the skids, as it were, for the slide of that ice into the ocean.

I'm far less a leader than a writer.

We had other currencies that we could find work in - the currencies of movements: passion, spirit, creativity.

The irony is that one of the things people want to solve climate change is more market - more price on carbon so that markets have something to chew on when they think about climate change instead of the complete monopoly, the absurdity of allowing these guys to own the sky for free - socialise all of the costs and privatise all of the profits.

In the scientific community, the debate is over, for all intents and purposes, about whether or not the planet is heating and who is causing it. In fact, it's more or less been over since 1995.