"The Aborigines showed that without science and the production of carbon dioxide and global warming, they could survive for 40,000 or 50,000 years. But the world can't. The human species is likely to go the same way as many of the species that we've seen disappear.

"Homo sapiens will become extinct, perhaps within 100 years," he says. "A lot of other animals will, too. It's an irreversible situation. I think it's too late. I try not to express that because people are trying to do something, but they keep putting it off.

"Mitigation would slow things down a bit, but there are too many people here already."

It's an opinion shared by some scientists but drowned out by the row between climate change sceptics and believers.

See The Australian