We run enormous risks and we know what kind of reductions of greenhouse gases are necessary to drastically reduce risks. Reducing emissions by half by 2050 is roughly in the right ballpark. It would bring us below 550 ppm.

There is still time to avoid the worst impacts of climate change, if we take strong action now.

Adaptation is a vital part of a response to the challenge of climate change

Adaptation can efficiently reduce the costs of climate change while atmospheric concentrations of greenhouse gases are being stabilised

It's very important that there should be cross-fertilisation between government and academia. Both parties can benefit from having a better understanding of how the other works.

Failing to curb the impact of climate change could damage the global economy on the scale of the Great Depression or the world wars by spawning environmental devastation that could cost 5 to 20 percent of the world's annual gross domestic product.

What we are talking about is extended world war...People would move on a massive scale. Hundreds of millions, probably billions of people would have to move.