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Melting moment ... Ian Plimer says processes which end in ice caps crashing down start as long as 800 years ago

Mankind is naive to think it can influence climate change, according to a prize-winning Australian geologist.

Solar activity is a greater driver of climate change than man-made carbon dioxide, argues Ian Plimer, Professor of Mining Geology at the University of Adelaide and winner of several notable science prizes.

"When meteorologists can change the weather then we can start to think about humans changing climate," Prof Plimer said.

"I think we really are a little bit naive to think we can change astronomical and solar processes."

Speaking last night after presenting his theory for the first time, to the Australasian Institute of Mining and Metallurgy in Sydney, Prof Plimer said he had researched the history of the sun, solar and supernovae activity and had been able to correlate global climates with solar activity.

"But correlations don't mean anything, you really need a causation," Prof Plimer said.

So he then examined how cosmic radiation builds up clouds.

A very active sun blows away the cosmic radiation, while a less active sun allows radiation to build up, he said.

"So you can very much tie in temperature, cloud formation, cosmic radiation and the sun," he said.

The next part of Prof Plimer's research was to examine the sources of carbon dioxide.

He said he found that about 0.1 per cent of the atmospheric carbon dioxide was due to human activity and much of the rest due to little-understood geological phenomena.

Prof Plimer also argued El Nino and La Nina were caused by major processes of earthquake activity and volcanic activity in the mid-ocean ridges, rather than any increase in greenhouse gases.

Nor does the melting of polar ice have anything to do with man-made carbon dioxide, he said.

"Great icebergs come off, not due to temperature change but due to the physics of ice and the flow of ice," Prof Plimer said.

"There's a lag, so that if temperature rises, carbon dioxide rises 800 years later.

"If ice falls into the ocean in icebergs that's due to processes thousands of years ago."

On the same basis, changes to sea level and temperature are also unrelated to anything happening today, he said.

"It is extraordinarily difficult to argue that human-induced carbon dioxide has any effect at all," he said.

Prof Plimer added that as the planet was already at the maximum absorbance of energy of carbon dioxide, any more would have no greater effect.

There had even been periods in history with hundreds of times more atmospheric carbon dioxide than now with "no problem", he said.

The professor, a member of the Australian Skeptics, an organisation devoted to debunking pseudo-scientific claims, denied his was a minority view.

"You'd be very hard pushed to find a geologist that would differ from my view," he said.

He said bad news was more fashionable now than good and that people had an innate tendency to want to be a little frightened.

But Prof Plimer conceded the politics of greenhouse gas emissions meant that attention was being given to energy efficiency, which he supported.

The professor, who is writing a book on the subject, said he only used validated scientific data, published in reputable peer-reviewed refereed journals, as the basis of his theories.