You mustn't take what I say as gospel because no one can second-guess the future.

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 climate is doing its usual tricks. There’s nothing much really happening yet. We were supposed to be halfway toward a frying world now. The world has not warmed up very much since the millennium. Twelve years is a reasonable time. The temperature has stayed almost constant, whereas it should have been rising - carbon dioxide is rising, no question about that.

There is little evidence that our individual intelligence has improved through recorded history.

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.

What we have lived through, the 20th century, has been like a great party. Adults now have had the best time humanity has ever had. Now the party is over and the Earth is reckoning up.

Science always uses metaphor.

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