气候学家谈论哥本哈根大会

TONY JONES: Okay, can you tell us how the Goddard Institute takes and adjusts these global temperatures because sceptics claim that urban heat centres make a huge difference; that they distort global temperatures and they make it appear hotter that it really is.

So do you adjust, in your figures, for the urban heat zone effects?

JAMES HANSEN: We get data from three different sources and we now, in order to avoid criticisms from contrarians, we no longer make an adjustment. Even if we see there are eight stations in Alaska and seven of them have temperatures in the minus 30s and one of them says plus 35, which pretty obvious what happens, someone didn't put the minus sign there, we just, we don't correct that.

Instead we send an email or letter or a letter to the organisation that produces the data and say, you'd better check the Alaska temperatures, because we don't want to be blamed for changing anything. But as far as adjusting for urban effects, we have a very simple procedure.

We exclude urban locations, use rural locations to establish a trend, and that does eliminate - though urban stations do have more warming than the rural stations, and so we eliminate that effect simply by eliminating those stations, but it's very clear that the warming that we see is not urban, it's largest in Siberia, and in the Arctic and the Antarctic, and there aren't any cities there, and there's warming over the oceans, there are no cities there. So it's not urban warming that's just nonsense.