By 2040, the Sahara will be moving into Europe and Berlin will be as hot as Baghdad. Atlanta will end up a kudzu jungle. Phoenix will become uninhabitable, as will parts of Beijing (desert), Miami (rising seas) and London (floods). Food shortages will drive millions of people north, raising political tensions.

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

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.

An inefficient virus kills its host. A clever virus stays with it.

Geological change usually takes thousands of years to happen but we are seeing the climate changing not just in our lifetimes but also year by year.

I've got personal views on the '60s. You can't have freedom without paying the price for it.

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.