Once upon a time, I was a climate-change skeptic.

There is a glacier in Iceland, Solheimar, which has retreated a great deal, and every time I go back there and see what's not there any more, it does something to the heart. It makes you realise it's possible for a gigantic natural element to just disappear.

You know, we humans are programmed to think that big changes on the Earth happened a long time ago, or will happen a long time in the future. What we don't realize is that they actually can happen right now. Right here, right now, while we're alive, in our own hours and days and months and years.

Hindsight can be merciless. People of any given era often look back in time and wonder how their predecessors could have been so dimwitted.

I'm quite fond of Switzerland. I love Switzerland.

We are now beyond nature's normal variation in terms of how the atmosphere is composed. Nature did something for a million years. It actually goes back a lot further than that, but the ice core records show a million years. So, nature has this normal oscillation within this zone, and all of a sudden, we're forty percent outside that zone.