One pound of uranium is worth about 3 million pounds worth of coal or oil.

Perhaps the single most important thing that we can do to undo the harm we have done is to fix firmly in our minds the thought: the earth is alive.

Those who fail to see that population growth and climate change are two sides of the same coin are either ignorant or hiding from the truth. These two huge environmental problems are inseparable and to discuss one while ignoring the other is irrational.

The world has not warmed up very much since the millennium.

I don't think we're yet evolved to the point where we're clever enough to handle a complex a situation as climate change. The inertia of humans is so huge that you can't really do anything meaningful.

One thing that being a scientist has taught me is that you can never be certain about anything. You never know the truth. You can only approach it and hope to get a bit nearer to it each time. You iterate towards the truth. You don't know it.

Climatologists are all agreed that we'd be lucky to see the end of this century without the world being a totally different place, and being 8 or 9 degrees hotter on average.