One of my favorite places is the Maldives, an all-Muslim nation in the Indian Ocean with a culture that stretches back 5,000 years. But since the highest point in the archipelago is a meter or two above sea level, even the next hundred are not guaranteed. They've committed to becoming the first carbon-neutral nation on Earth by 2020, building windmills as fast as they can.

Everybody was cratered after Copenhagen. If the movie had worked the way that it should have, if it had been scripted by Holywood, the world would have come together and addressed the biggest problem it ever had faced and delegates would have embraced each other, and it all would have been a good happy scene instead of the complete farce and debacle that it turned into - maybe in certain ways, an absolute low point for human diplomacy.

We've been given a warning by science, and a wake-up call by nature; it is up to us now to heed them.

The Arctic and the Antarctic are melting quickly. We may have waited too long to get started. But this is a day for optimism because the battle is fully joined, and the idea that big oil is unbeatable is no longer true.

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.

Speaking for me, I think the odds of bankrupting Exxon are pretty small, but I think the odds of politically bankrupting them are higher. I think if we can use this as a vehicle to get out the analysis that these guys have 3-5 times as much carbon in the ground as the most conservative government thinks would be safe to burn, then that politically stigmatises them, makes them into the rogue industry that they are.

I don't spend a huge amount of time fixated on climate denial because I don't think that their objections, though sometimes couched in science, are based in science. I think they're based in ideology. And I don't think there's anything you can do.