If we gave up eating beef we would have roughly 20 to 30 times more land for food than we have now.

The world has not warmed up very much since the millennium. Twelve years is a reasonable time... it (the temperature) has stayed almost constant, whereas it should have been rising - carbon dioxide is rising, no question about that.

I suspect any worries about genetic engineering may be unnecessary. Genetic mutations have always happened naturally, anyway.

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.

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.

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.

Civilization in its present form hasn't got long.