The Bush administration acknowledges that global warming poses serious problems, but senior officials speaking at a climate-change policy conference yesterday said numerous uncertainties remain about global warming's cause and effects. They urged caution in committing the country to long-term solutions that might hurt the economy.

The three-day, administration-sponsored conference takes place in a year marked by several global warming scares. An Antarctic ice shelf the size of Rhode Island shattered and collapsed into the sea in March, and Bolivian Andes glaciers are melting at an alarming pace.

Administration officials say the nation shouldn't panic and make unwise decisions. President Bush has called for a decade of research before the government commits to anything more than voluntary measures to stem carbon dioxide and other greenhouse gas emissions from industry and vehicles that have been closely tied to global warming.

"I don't think there's any disagreement that human activity has substantially contributed to the amount of CO2 [carbon dioxide] in the environment," said John Marburger, the White House science and technology adviser. "What we are arguing is that we need more information to have a clearly articulated regulatory policy that is practical, that's affordable and doesn't put the economy at risk."

Samuel Bodman, deputy secretary of commerce, said a primary goal of the conference is to "do our best to clear up or eliminate the uncertainties" in the mountains of existing scientific research, including a report to the president last year from the National Academy of Sciences.

More than 1,200 scientists, experts, environmentalists and others are taking part in the workshops. Commerce Secretary Donald L. Evans said the sessions were designed to "jump-start" a presidentially requested review of updated research and proposals for combating global warming.

But some environmentalists say there is more than enough scientific data from credible panels to make informed policy decisions. They questioned whether the conference was simply window dressing for an administration that has decided to oppose any mandatory limits on industrial greenhouse gas emissions, such as those contained in the Kyoto Protocol, an international global warming treaty.

"This would have been a good program if it were still 1990," said Jennifer L. Morgan, a climate change expert with the World Wildlife Fund. "Over a decade of research has been done in the United States and internationally to make the case for climate change action, so we don't need to wait for further science to take action. The U.S. is working in a time warp."

Over the past decade, the U.N.-sponsored Intergovernmental Panel on Climate Change has produced three comprehensive studies on the cause and effect of global warming, warning of the potential for large-scale and irreversible changes. They include reductions in the Greenland and West Antarctic ice sheets and a substantial slowing of the circulation of warm water in the North Atlantic.

The Clinton administration prepared a National Assessment on Climate Change that provided a region-by-region assessment of the potential impact of global warming on the United States. In June 2001, the National Academy of Sciences concluded in a review of existing data that global warming was a real problem caused, at least in part, by man-made pollution that could well have a "serious adverse" effect by the end of the century.

Within days of the report's release, Bush declared that substantial doubts remained about the causes and severity of global warming, and promised more studies as part of a voluntary approach to reducing greenhouse gas emissions. Moreover, the Competitive Enterprise Institute, a Washington think tank critical of government regulation, attacked the methodology of the Clinton national assessment and urged the Bush administration to ignore its findings.

"There are a lot of data out there," Marburger said yesterday. "But they are not always data that are useful in making the kinds of decisions that have to be made."