"global warming time bomb"

New warning from US climate change prophet

Andrew Revkin, Washington
June 24, 2008

TWENTY years ago yesterday, James Hansen, a climate scientist at NASA, told the world that he was "99%" certain that humans were already warming the climate.

"The greenhouse effect has been detected, and it is changing our climate now," Dr Hansen said then, referring to a string of warm years and the accumulating blanket of heat-trapping carbon dioxide and other gases emitted mainly by the burning of fossil fuels and forests.

To many observers of environmental history, that was the first time global warming moved from being a looming issue to breaking news. Dr Hansen's statement to a Senate committee helped propel the first pushes for legislation and an international treaty to cut emissions of greenhouse gases. A treaty was enacted and an addendum, the Kyoto Protocol, was added.

Even as the scientific picture of a human-heated world has solidified, emissions of the gases have continued to rise.

A series of events around Washington will commemorate Dr Hansen's appearance before the Senate committee. Dr Hansen, 67, was to appear before a House committee on global warming overnight. He planned to testify that it was almost, but not quite, too late to start defusing what he calls the "global warming time bomb".

He will offer a prescription for emissions cuts and a warning on the risks of further inaction.
"If we don't begin to reduce greenhouse gas emissions in the next several years, and really on a very different course, then we are in trouble," Dr Hansen said in New York at NASA's Goddard Institute for Space Studies, which he has directed since 1981. "Then the ice sheets are in trouble. Many species on the planet are in trouble."

In his testimony, Dr Hansen said, he will say that the next US president faces a unique opportunity to galvanise the country around the need for a transformed, non-polluting energy system.

Many climate experts say Dr Hansen, despite some faults, has been an essential prodder of the public and scientific conscience.

Jerry Mahlman, who recently retired from a long career in climatology, said he disagreed with some of Dr Hansen's characterisations of the climate problem and his ideas for solutions. "On the whole, though, he's been helpful," Dr Mahlman said. "He pushes the edge, but most of the time it's pedagogically sound."

Activists say that history will see Dr Hansen's 1988 testimony as a turning point - a moment when the word "if" started to disappear from the debate on climate change.

"Before Jim Hansen's testimony, global climate change was not on the political agenda. It was something that a few environmentalists and a few politicians … were talking about," said Jonathan Lash, president of the World Resources Institute, an environmental group.

"Hansen was clear, explicit and unequivocal," he said. "It put global climate change at the centre of the discussion."

NEW YORK TIMES, WASHINGTON POST

http://www.theage.com.au/world/new-warning-from-us-climate-change-prophet-20080623-2vjl.html?page=-1