The tropical rain forests are a telling example. Once cut down, they rarely recover. Rainfall drops, deserts spread, the climate warms.

You never know with politicians what they are really saying. And I don't say that in a negative way-they have an appalling job.

Humans are too stupid to prevent climate change from radically impacting on our lives over the coming decades.

The big threat to the planet is people: there are too many, doing too well economically and burning too much oil.

No one who has experienced the intense involvement of computer modeling would deny that the temptation exists to use any data input that will enable one to continue playing what is perhaps the ultimate game of solitaire.

We are the intelligent elite among animal life on earth and whatever our mistakes, [Earth] needs us. This may seem an odd statement after all that I have said about the way 20th century humans became almost a planetary disease organism. But it has taken [Earth] 2.5 billion years to evolve an animal that can think and communicate its thoughts. If we become extinct she has little chance of evolving another.

I'm not a pessimist, even though I do think awful things are going to happen.