WASHINGTON (AP) _ President Bush now has ``a basis of sound science on which decisions can be made'' on global warming, his spokesman said Thursday, a day after the White House got a report concluding the phenomenon is a real problem and getting worse.
``The president is committed to reducing global warming,'' spokesman Ari Fleischer told reporters.
Asked if the United States bears special responsibility as the world's largest producer of heat-trapping greenhouse gases, Fleischer said, ``The president believes that all nations have a responsibility.''
Bush, who asked for the study by the National Academy of Sciences to help the administration decide what steps to take to combat climate change, now faces mounting pressure from critics at home and abroad who want the United States to enter a global warming treaty.
The study found global warming ``is real and particularly strong within the past 20 years'' and said a leading cause is emissions of carbon dioxide from burning fossil fuels. It also said that greenhouse gases are accumulating in the Earth's atmosphere as a result of ``human activities.''
``There's no question that part of the cause is human activity,'' Fleischer said Thursday. ``The question is how much of the cause is human activity.''
The academy's report found that by the year 2100, temperatures are expected to increase between 2.5 degrees and 10.4 degrees Fahrenheit above those of 1990.
Bush assembled a Cabinet-level working group on global warming in March, about two weeks after he backed away from a campaign pledge to regulate carbon dioxide emissions from power plants. About the same time, he rejected an international pact negotiated in 1997 in Kyoto, Japan, requiring industrial nations to reduce greenhouse gases by specified amounts.
Bush has been meeting this week with Cabinet members to decide strategy on how to sell his almost-finished proposal for a global-warming agreement.
Senior administration officials say Bush, preparing for talks on the issue next week in Europe, hopes to surprise skeptical allies with a strong statement next Monday committing the United States to combatting global warming.
Fleischer previewed Bush's statements Thursday, saying ``the world has a responsibility to face up to this.''
But Bush won't carry a detailed Kyoto alternative to Europe. Administration officials, speaking on condition of anonymity, said Bush will allude to a series of mostly voluntary initiatives.
Among the likely initiatives Bush will endorse is creating a trading market where industrial polluters far exceeding emission standards could buy offsetting credits from those who pollute little, the officials said.
Such a system would effectively establish emission caps, the officials said. They didn't address how the standards would be established and enforced, but insisted that Bush's plan will have teeth.
The issue is causing Bush headaches domestically and internationally. In addition to criticism and outrage from allies, GOP polls show that doubts about his stance on global warming and other environmental issues has hurt his job approval rating.
Critics say Bush has been too slow to accept some of the science that others feel is well-established.
``The Europeans are very discouraged and frustrated with the way the Bush administration has dealt with this,'' House Minority Leader Dick Gephardt, D-Mo., said Thursday. ``My hope is that they will get back into a negotiation with the rest of the world.''
Sweden's prime minister also said Thursday he is hopeful European leaders and Bush can agree this month to ``go on with the process'' of addressing climate change despite U.S. opposition.
``We just can't sit still and see the whole process collapse,'' said Goeran Persson, whose country holds the rotating presidency of the 15-nation European Union. ``Hopefully, we will be able to have a result with the Americans that tells us that we both want to go on with the process, but we agree to disagree so far about the substance.''
Bush is scheduled to meet with 15 European Union leaders in Goteborg, Sweden, on June 14-15. He has insisted that any treaty include developing countries and assure that pollution reductions don't damage the U.S. economy.
The Senate also went on the record before the Kyoto treaty was negotiated saying that any global warming accord mandating greenhouse gas reductions for industrial countries should also require them for developing nations.