3/22/2008

Global Cooling

The Australian has this interesting article today that excerpts a discussion on ABC Radio National (the Australian Broadcasting Corporation):

Duffy asked Marohasy: "Is the Earth stillwarming?"

She replied: "No, actually, there has been cooling, if you take 1998 as your point of reference. If you take 2002 as your point of reference, then temperatures have plateaued. This is certainly not what you'd expect if carbon dioxide is driving temperature because carbon dioxide levels have been increasing but temperatures have actually been coming down over the last 10 years."

Duffy: "Is this a matter of any controversy?"

Marohasy: "Actually, no. The head of the IPCC (Intergovernmental Panel on Climate Change) has actually acknowledged it. He talks about the apparent plateau in temperatures so far this century. So he recognises that in this century, over the past eight years, temperatures have plateaued ... This is not what you'd expect, as I said, because if carbon dioxide is driving temperature then you'd expect that, given carbon dioxide levels have been continuing to increase, temperatures should be going up ... So (it's) very unexpected, not something that's being discussed. It should be being discussed, though, because it's very significant."

Duffy: "It's not only that it's not discussed. We never hear it, do we? Whenever there's any sort of weather event that can be linked into the global warming orthodoxy, it's put on the front page. But a fact like that, which is that global warming stopped a decade ago, is virtually never reported, which is extraordinary."

Duffy then turned to the question of how the proponents of the greenhouse gas hypothesis deal with data that doesn't support their case. "People like Kevin Rudd and Ross Garnaut are speaking as though the Earth is still warming at an alarming rate, but what is the argument from the other side? What would people associated with the IPCC say to explain the (temperature) dip?"

Marohasy: "Well, the head of the IPCC has suggested natural factors are compensating for the increasing carbon dioxide levels and I guess, to some extent, that's what sceptics have been saying for some time: that, yes, carbon dioxide will give you some warming but there are a whole lot of other factors that may compensate or that may augment the warming from elevated levels of carbon dioxide.

"There's been a lot of talk about the impact of the sun and that maybe we're going to go through or are entering a period of less intense solar activity and this could be contributing to the current cooling."

Duffy: "Can you tell us about NASA's Aqua satellite, because I understand some of the data we're now getting is quite important in our understanding of how climate works?"

Marohasy: "That's right. The satellite was only launched in 2002 and it enabled the collection of data, not just on temperature but also on cloud formation and water vapour. What all the climate models suggest is that, when you've got warming from additional carbon dioxide, this will result in increased water vapour, so you're going to get a positive feedback. That's what the models have been indicating. What this great data from the NASA Aqua satellite ... (is) actually showing is just the opposite, that with a little bit of warming, weather processes are compensating, so they're actually limiting the greenhouse effect and you're getting a negative rather than a positive feedback." . . .

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