WASHINGTON - Despite a strongly worded global warming report from the world's top climate scientists, the Bush administration expressed continued opposition Friday to mandatory reductions in heat-trapping "greenhouse" gases.

Energy Secretary Samuel Bodman warned against "unintended consequences" - including job losses - that he said might result if the government requires economy-wide caps on carbon dioxide from the burning of fossil fuels.

"There is a concern within this administration, which I support, that the imposition of a carbon cap in this country would - may - lead to the transfer of jobs and industry abroad (to nations) that do not have such a carbon cap," Bodman said. "You would then have the U.S. economy damaged, on the one hand, and the same emissions, potentially even worse emissions."

President Bush used the same economic reasoning when he rejected the Kyoto Protocol in 2001, an international treaty requiring 35 industrial nations to cut their global-warming gases by 5 percent on average below 1990 levels by 2012. The White House has said the treaty would have cost 5 million U.S. jobs.

"Even if we were successful in accomplishing some kind of debate and discussion about what caps might be here in the United States, we are a small contributor to the overall, when you look at the rest of the world. And so it's really got to be a global solution," Bodman said.

The United States each year contributes about a quarter of the world's greenhouse gases, though the share from China, India and other developing countries also is growing.

Bodman said he would make the same argument against carbon caps even if the U.S. share were larger. He and other administration officials at a news conference praised the report Friday by a United Nations-sponsored panel of hundreds of climate scientists from 113 governments, who said there is little doubt the earth is warming as a result of man-made emissions.

But Bodman said technology advancements that will cut the amount of carbon emissions, promote energy conservation, and hasten development of non-fossil fuels can address the problem.

"This administration's aggressive, yet practical strategy to reduce greenhouse gas emissions is delivering real results," added Stephen Johnson, administrator of the Environmental Protection Agency.

More than a half-dozen bills have been introduced, mostly by Democrats, calling for some form of mandatory carbon controls in the United States. Democrats newly in control of Congress and other critics of Bush's environmental policies pounced on the long-awaited U.N. report like fresh meat.

"This puts the final nail in denial's coffin," said Sen. Joseph Lieberman, I-Conn., head of the Senate Homeland Security and Governmental Affairs Committee.

Rep. Edward Markey, D-Mass., a senior member of House panels on energy and natural resources, said he hoped it wouldn't take until Groundhog Day two years from now, when a new president is in the White House, to alter course in the United States.

"It sounds like the Bush administration, having seen the very real shadow of scientific evidence of global warming, has chosen to go back into its hole of denial by saying that it will not support measures to reduce global warming and its disastrous affects on our economy and environment," Markey said.

The White House issued a statement less than four hours after the report's release defending Bush's six-year record on global climate change, beginning with his acknowledgment in 2001 that the increase in greenhouse gases is due largely to human activity.

It said Bush and his budget proposals have devoted $29 billion to climate-related science, technology, international assistance and incentive programs - "more money than any other country."

Bush has called for slowing the growth rate of U.S. greenhouse gas emissions, which averages 1 percent a year, but has rejected government-ordered reductions. Last week he also called for a 20 percent reduction in U.S. gasoline consumption over the next 10 years.

"This report really provides strong weight behind those saying we need much stronger action" from the United States and other nations, said Robert Watson, the World Bank's chief spokesman on global warming and former chairman of the U.N. scientific panel responsible for evaluating the threat of climate change.