WASHINGTON -- The Bush administration outlined significant environmental impacts from climate change, possibly within decades, in a new report to the United Nations.
But the administration stands firm on limiting its plans to deal with heat-trapping "greenhouse" pollution to voluntary measures and avoiding the Kyoto climate treaty.
For the first time, the administration puts most of the blame for recent warming on human actions, pointing to fossil fuel-burning that releases carbon dioxide and other heat-trapping gases into the atmosphere, according to the report released by the Environmental Protection Agency.
"The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability," the report says.
"Human-induced warming and associated sea level rises are expected to continue through the 21st century," it says. "Secondary effects ... include increases in rainfall rates and increased susceptibility of semi-arid regions to drought."
The paper, submitted to the United Nations, was first reported Monday by The New York Times.
The report also says that despite some lingering scientific uncertainties "there is general agreement that the observed warming is real and has been particularly strong within the past 20 years."
Last year, the White House described climate change as a serious issue after seeking the opinions of the National Academy of Sciences, but was undecided about how much of the problem should be blamed on human activities. President Bush favors a climate plan with voluntary measures intended to slow the rate of growth in gas emissions, but allow them to continue to rise.