By Deborah Zabarenko, Environment CorrespondentWASHINGTON, Feb 2 (Reuters) - The Bush administration played down the U.S. contribution to world climate change on Friday and called for a "global discussion" after a U.N. report blamed humans for much of the warming over the past 50 years."We are a small contributor when you look at the rest of the world," U.S. Energy Secretary Sam Bodman said of greenhouse gas emissions. "It's really got to be a global discussion."The United States is responsible for one-quarter of the world's emissions of carbon dioxide and uses one-quarter of the world's crude oil.A unilateral U.S. program to cut emissions might hurt the economy and send business overseas, Bodman said.In measured tones that accepted the reality of global climate change but stopped short of urging specific limits on the emission of greenhouse gases that contribute to it, Bodman hailed the report by the Intergovernmental Panel on Climate Change, released in Paris."We're very pleased with it. We're embracing it. We agree with it," Bodman told a news conference. "Human activity is contributing to changes in our Earth's climate and that issue is no longer up for debate."He reiterated the administration's opposition to mandatory caps on the emission of carbon dioxide, a greenhouse gas produced naturally and by coal-fired power plants and petroleum-fueled vehicles, among other sources.A SOURCE FOR POLICYMAKERSAt the White House, spokesman Tony Fratto called the report valuable and significant and said the United States was an important participant its framing.A White House statement released in Paris quoted the head of the U.S. delegation, Sharon Hays, as saying the report "will serve as a valuable source of information for policymakers."President George W. Bush's stance on global warming has evolved over his presidency, from open skepticism to acceptance that human activities accelerate change. He briefly mentioned the issue in last week's State of the Union address, saying solutions to the problem lie in technological advances and the use of renewable fuels like ethanol.This is at odds with environmentalists who have urged mandatory limits on the carbon emissions. Last month, a panel of top corporate leaders, including those from electric companies, urged this same kind of federal regulation.John Holdren, president of the American Association for the Advancement of Science, said the report's significance lies in the solidity of its science and the unequivocal link it makes between the global warming and its human cause."It is a much more powerful report than the last version (from 2001) ... There really has been a torrent of new scientific evidence over the last five or six years, evidence that bears on the magnitude and the human origins and the growing impacts of the climate changes that are already under way," Holdren said in a telephone interview.
