I think we need to think of lots of ways to communicate. And we tried some at 350. We organised what they called the largest art project in the planet's history. We do a lot with art and music and things.

Warm air holds more water vapor than cold, and so the atmosphere is about 4% wetter than it was 40 years ago. This loads the dice for flood and drought, and we're seeing both in stunning abundance.

Especially in recent years, the more and more we understand what we are doing, the more we have the science to tell us what we're doing, the fact that we continue to do it without taking steps to address it strikes me as, among many other things, irreverent in an extreme.

I've got no advice. You guys know where you are and what will work. Just know that there are people all over the place working on this and that there's a great deal of solidarity around the world and we should try to build this big, sprawling movement that looks like the kind of energy system that we want - building lots of solar panels on lots of rooftops that are all interconnected.

Alone among businesses, the fossil-fuel industry is allowed to dump its main waste, carbon dioxide, for free.

If we all used clotheslines, we could save 30 million tons of coal a year, or shut down 15 nuclear power plants. And you don't have to wait to start. Yours could be up by this afternoon. To be specific, buy 50 feet of clothesline and a $3 bag of clothespins and become a solar energy pioneer.

Certainly, packets of sea ice, in say the Arctic, which have failed to fully reform in the last couple of years.