气候学家谈论哥本哈根大会

TONY JONES: James Hansen, one final question: what's your estimate; how long do we have before the planet reaches one of those tipping points that you're talking about and global warming is irreversible? And if that happens, what are the consequences?

JAMES HANSEN: Well, you know, we are probably, we're already into the dangerous level of carbon dioxide and it's going to increase more. If we would phase out the coal emissions over the next 20 years, then CO2 would peak at something like 425ppm.

Doesn't look like we're starting to phase out coal though, so it may go higher than that. We're going to go well into the dangerous zone, and some things are going to happen out of our control. But that doesn't mean we should give up, because whether we get a sea level rise of one metre, or 25 metres makes a huge difference.

What we will need to do once people really see what's happening, is we're going to need to restore the planet's energy balance, or make it negative, and you do that by reducing the amount of these greenhouse gases in the atmosphere, and so the planet begins to cool off a bit.

And then, even though we're going to get some icesheet disintegration anyhow and we're going to lose some species because we're already pushing some of them, we're putting a lot of stress on many species, but we don't, that doesn't mean we should give up and decide we're willing to give up all of them.

TONY JONES: James Hansen, we're going to have to leave it there. We thank you very much for coming to join us right on the eve of the Copenhagen conference.

JAMES HANSEN: Thank you for listening. Thanks.