Scientist "turns up the heat with new alert on warming

Age
Tuesday 8/4/2008 Page: 10

A LEADING climate scientist says the European Union and international partners must urgently rethink targets for cutting carbon dioxide in the atmosphere because of fears they have grossly, underestimated the scale of the problem. Dr James Hansen, head of the NASA Goddard Institute for Space Studies in New York, calls for a sharp reduction in carbon dioxide limits.

Dr Hansen said the EU target of 550 parts per million of carbon dioxide the most stringent in the world - should be slashed to 350 ppm. He said the cut was, if "humanity wishes to preserve a planet similar to that on which civilisation developed." A final version of the paper Dr Hansen co-wrote with eight other climate scientists has been posted on the Archive website.

Instead of using theoretical models to estimate the sensitivity of the climate, the team used evidence from Earth's history, which they contend gives a much more accurate picture. They studied cores taken from the bottom of the ocean, which indicate carbon dioxide levels millions of years ago. They show that when the world began to glaciate at the start of the ice age around 35 million years ago, the concentration of carbon dioxide was about 450 ppm.

"If you leave us at 450 ppm for long enough, it will probably melt all the ice - that's a sea rise of 75 metres," Dr Hansen said. "What we have found "is that the target we have all been aiming for is a disaster a guaranteed disaster." At levels as high as 550 ppm the world would warm by 6 degrees, the scientists' paper said. Previous estimates had suggested warming would be just 3 degrees at that point.

Dr Hansen has long been a controversial figure in climate change science. He was one of the first to bring the crisis to the world attention in testimony to the US Congress in the 1980s. His relationship with the Bush Administration has been frosty. In 2005, he accused the White House and NASA administrators of trying to censor him.

He has steadily revised his analysis of the scale of the global warming problem and was one of the architects of a 450 ppm target. But he said: "I realise that was too high." The revised target is likely to prompt criticism that he is setting the bar unrealistically high. Dr Hansen said he now regarded as implausible the view of many climate scientists that the shrinking of the ice sheets will take thousands of years.

If we follow business as usual, I can't see how west Antarctica could survive a century," he said. "We are talking about a sea-level rise of at least a couple of metres this century." Dr Hansen said his findings were not a recipe for despair. The good news, he said, was that reserves of fossil fuels. had been greatly exaggerated, so an alternative source of energy would have to be put in place rapidly in any case.

He proposed a range of measures. A moratorium on coal power stations would bring carbon dioxide levels to below 400 ppm. Reforestation coupled with innovative agricultural methods such as the use of Biochar, a form of biomass charcoal that can store carbon in the soil, could then get closer to his new 350 ppm target.

Dr Hansen's new position will pile more pressure on the British Government over plans to build a new generation of coal power stations. Last year he wrote to Prime Minister Gordon Brown urging him to block the first such power station. The London-based Royal Society made similar protestations to Britain's Business Secretary, John Hutton, last week.