Humans Most Likely Caused Warming, Bush Report Says (Update1)

By Jim Efstathiou Jr.

May 29 (Bloomberg) -- Burning fossil fuels in power plants and automobiles is most likely responsible for global warming, according to a Bush administration report that confirms climate risks already accepted by most of the world's scientists.

Carbon dioxide, the byproduct of burning coal and oil, has contributed most to warming in the last century, the U.S. Climate Change Science Program and the White House National Science and Technology Council reported today. The assessment from President George W. Bush's top science advisers is the strongest endorsement yet of a global scientific consensus on the causes of climate change, said Jay Gulledge, senior scientist at the Pew Center on Global Climate Change, a nonprofit research group.

``This is the Bush administration saying formally and clearly in a scientific context that we have the evidence necessary to say with confidence that manmade greenhouse gases are causing global warming,'' Gulledge said in an interview. ``This is the clearest expression of that.''

Environmental groups including the Tucson, Arizona-based Center for Biological Diversity sued the Bush administration in 2006, saying it failed to assess the effects of climate change. Every four years the president must provide the report under a 1990 law.

``For almost eight years they denied and downplayed the science,'' said Kassie Siegel, climate program director for the center. ``It sounds like they've been forced to acknowledge the consensus science.''

United Nations Agrees

Today's report presents the state of climate change research with a focus on the impact in the U.S., said Sharon Hays, deputy director for science for the White House Office of Science and Technology Policy. The findings are consistent with a report last year from the United Nations Intergovernmental Panel on Climate Change, which concluded with 90 percent certainty that human activity is contributing to global warming.

Greenhouse gases, mainly from burning fossil fuels, ``are very likely the single largest cause of the recent warming,'' according to today's report. Industrialization is ``likely'' to have increased the risk of heat waves in some regions and is ``very likely'' to cause ocean temperatures to warm.

Natural forces alone can't account for warming that has led to greater extremes in heat and cold, higher sea surface temperatures and more hurricanes, according to the report.

An accompanying report examines how U.S. funding for climate research should be allocated among federal agencies. The reports are being hand-delivered today to Bush and members of Congress, Hays said.

Court-Ordered Deadline

The Center for Biological Diversity led a lawsuit in November 2006 to compel the administration to provide the climate report. In August, U.S. District Judge Saundra Brown Armstrong in the Northern District of California ordered the administration to complete the assessment before June 1.

``The court did impose some deadlines on us to get things done,'' Hays said on a conference call with reporters today. ``By delivering these reports today, we are complying with the deadline.''

The U.S. Senate is scheduled to begin debate next week on legislation that sets mandatory limits on greenhouse gases from utilities and manufacturers. Bush continues to resist government caps on carbon dioxide emissions.

The report also dispels a perception among some that rich nations including the U.S. are immune to the effects of climate change, Gulledge said. Parts of North America could warm faster this century than average global increases, according to the report.

``It's important because it unleashes the scientific authority of the United States government to make this clear to our population at home,'' Gulledge said.

To contact the reporter on this story: Jim Efstathiou Jr. in New York at jefstathiou@bloomberg.net .

Last Updated: May 29, 2008 15:52 EDT

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