If it hadn't been for the Cold War, neither Russia nor America would have been sending people into space.

I think that we reject the evidence that our world is changing because we are still, as that wonderfully wise biologist E. O. Wilson reminded us, tribal carnivores. We are programmed by our inheritance to see other living things as mainly something to eat, and we care more about our national tribe than anything else. We will even give our lives for it and are quite ready to kill other humans in the cruellest of ways for the good of our tribe. We still find alien the concept that we and the rest of life, from bacteria to whales, are parts of the much larger and diverse entity, the living Earth.

There aren't just bad people that commit genocide; we are all capable of it. It's our evolutionary history.

If you start any large theory, such as quantum mechanics, plate tectonics, evolution, it takes about 40 years for mainstream science to come around. Gaia has been going for only 30 years or so.

Imagine a survivor of a failed civilization with only a tattered book on aromatherapy for guidance in arresting a cholera epidemic. Yet, such a book would more likely be found amid the debris than a comprehensible medical text.

The problem is we don't know what the climate is doing. We thought we knew 20 years ago. That led to some alarmist books - mine included - because it looked clear-cut, but it hasn't happened.

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