气候学家谈论哥本哈根大会

TONY JONES: Okay well one of the published emails we're talking about goes to the key part of the sceptics argument that since 1998, the hottest year on record, carbon dioxide in the atmosphere kept going up, but the temperature didn't keep going up with it.

Now you've been bombarded, I understand, with scores of messages along those lines from people who want you to repent and admit that global warming is a hoax. So how do you respond to them?

JAMES HANSEN: You know, if you look at this global temperature curve and smooth it over a few years you'll see that it's continued to increase over the last decade. And in fact, it's not true that 1998 was the warmest year. 2005 was the warmest year.

The British analysis shows 1998 as the warmest year because they exclude polar regions, because there are no weather stations there or very few. But there are other ways to estimate the temperature in the polar regions and in fact, because of the decreased sea ice in the Arctic it has been warmer and warmer in the Arctic.

And when you include these polar regions, it turns out that 2005 was the warmest year. And when you average over a few years you'll find that the temperature curve has continued up. And besides, you don't expect the temperature to go up every year.

There's a lot of natural variability in the system primarily due to the tropical El Nino/La Nina cycle. And now we are moving into the El Nino phase, so it's a pretty good bet that, first of all, this year is going to be one of the warmest years, 2009, and 2010 will probably be the warmest year on the record.

TONY JONES: Is there already evidence for that? I mean are you seeing early data from your global temperature recordings?

JAMES HANSEN: Yeah, we see the data up to now, and we know that the global temperature tends to lag a few months behind the tropical temperature. So it's because the El Nino started a few months ago, it's likely to have its greatest effect on 2010, but it's already having an effect this year making this year some place between the second and the fifth warmest, it depends on the November and December data, which we don't have yet.