The Canadian Press
OTTAWA  
Friday December 8, 2000

Carbon dioxide is being over sold as the chief cause of climate change, says a top Canadian scientist who has tracked global temperatures and green house gases back 500 million years.

Natural factors such as fluctuations in the sun's intensity are more likely the prime cause of serious global warming incidents during the Earth's history, says Jan Veizer, a world-renowned geologist selected by federal science officials to study carbon dioxide.

The potential implications of Veizer's research sent shockwaves through the climate research community even before it was officially published in Thursday's issue (Thursday December 7, 2000) of the British scientific journal Nature.

Several scientists agreed the scope of the work - five years and more than $700,000 - made the findings a serious challenge to some basic assumptions in climate change.

Veizer's research identified lengthy periods in the Earth's geological past when greatly elevated levels of carbon dioxide were actually accompanied by a drop in average temperature.

"Sure we have a greenhouse effect, but it's much more complex than just carbon dioxide," said Veizer, who holds appointments both at the University of Ottawa and Ruhr University in Germany. "I don't want to jeopardize the environmental agenda. But it's better to be honest."

Veizer said his research suggests carbon dioxide and other greenhouse gases may not drive climate change, but simply amplify change set off by some other factor. "I think that could be the sun, because the amount of radiation from it changed greatly over time. But that is for the astronomers to investigate," he said.

Writing in the same issue of Nature, U.S. researcher Lee Kump feared Veizer's research "undermines the case for reducing fossil-fuel emissions."

Kump said there was an urgent need for climate researchers to sort out which was right - Veizer's reconstructed temperatures or the assumptions behind climate models.

"We're talking about high stakes," said Kump, a geological climate expert at Pennsylvania State University.

"If you're going to use the climate model predictions to justify huge expenditures and changes in our economy then we have to tackle these contradictions."

Yet one of Canada's leading climate modellers, oceanographer Andrew Weaver, said there was no contradiction between Veizer's findings and the science underlying climate predictions.

"You can have high levels of carbon dioxide and also have a cold climate. But you do it with the Earth of 400 million years ago, when all the land was concentrated around the South pole and the radiation from the sun was lower than now," said Weaver, of the University of Victoria.

Veizer's temperature reconstruction found cold and warm periods in the Earth's history did not line up with low and high levels of carbon dioxide, as predicted by current climate change theory.

The most serious discrepancy occurs during the Jurassic period, which spanned between 208 million and 145 million years ago.

While carbon dioxide levels were supposedly eight to 10 times greater than now, research found ocean temperatures at the equator were colder than the long-term average by 2.5 degrees Centigrade.

Past temperatures were calculated from the chemical composition of a primitive type of clam, a brachiopod, that has existed for almost 500 million years.