GENEVA, NOV. 7 -- The United States, spurning appeals from scientists and governments around the world, refused today to join other industrialized nations in making a firm commitment to limit emissions of gases that could sharply raise global temperatures over the next century.

Representatives from more than 130 nations concluded a United Nations conference on global warming with a declaration that emphasized the need for urgent action to cope with the climate challenge and called for negotiations to begin without delay on a worldwide treaty to control greenhouse gases. The talks are set to open in Washington in February.

The U.S. position disappointed environmental groups and many European countries which had urged the United States to embrace a pledge not to exceed current output levels of greenhouse gases, mainly carbon dioxide, by the end of the decade.

"We just don't believe in targets," said Dr. John Knauss, chief of the National Oceanic and Atmospheric Administration, who headed the U.S. delegation to the conference. "It is much more important to develop a program to reduce greenhouse gases, but we are not prepared to guarantee our projections."

Eighteen West European countries, along with Japan, Australia and other industrialized countries, have promised to stabilize or reduce greenhouse gas emissions by the year 2000. Germany has vowed to achieve a 30 percent reduction within the next 15 years, a task that will be simplified by the closing of industrial plants that were terrible polluters in the extinct state of east Germany.

Environment ministers from several European countries said they were dismayed by the U.S. refusal to set targets that could serve as disciplinary guidelines in restricting the output of greenhouse gases, which spoiled the conference's chances for success. Germany's Klaus Toepfer said the meeting achieved only "minimal compromise" and Austria's Marilies Flemming said the outcome was "definitely insufficient."

"The United States helped make this conference a failure," said Daniel F. Becker, director of the Sierra Club's global warming program. "More than 700 scientists sent out a clarion call for action now and the United States was the only wealthy country not willing to make any tangible promises."

Over the past 10 days, global warming specialists from many countries described how the rapid accumulation of greenhouse gases could cause the greatest climatic changes since the Ice Age if nothing is done to slow the process. One of the most serious environmental consequences would be rising ocean levels that could flood islands and coastal areas, displacing millions of people.

The United States is responsible for 22 percent of the world's carbon dioxide emissions, which are produced when coal, oil, gas or wood are burned. Scientists and foreign governments have insisted that a strong commitment from one of the world's biggest polluters to freeze and gradually reduce emissions of greenhouse gases was necessary to make the conference a success.

When the delegations began drafting a final declaration over the weekend, the United States resisted pressure from other nations to join in setting any fixed goals, arguing that such steps could lead to profound economic disruptions. But some scientific studies presented at the conference emphasized that cutting carbon dioxide emissions in the United States could save tens of billions of dollars without much dislocation in the economy.

Dr. Thomas Johansson, a Swedish scientist, reported that even after factoring in the costs of switching to more energy-efficient systems, the United States could save $72 billion by the year 2000 if it reduced carbon dioxide emissions by 17 percent, primarily by mandating more efficient fuel consumption in automobiles.

"The United States uses twice as much energy as Japan and Western European countries to achieve the same standards of living," said David Doniger, an attorney for the Natural Resources Defense Council. "The cuts would be easy to make and not involve much pain and sacrifice at all."

The conference declaration notes that participating nations "recognize the promotion of energy efficiency as the most cost-effective immediate measure, in many countries, for reducing energy-related emissions of greenhouse gases."

Knauss said U.S. programs were designed to accomplish goals better than promises in a final declaration. He said a new energy policy being developed by the Bush administration could lead to more efficient uses of energy, and the recently revised Clean Air Act will lead to significant reductions in greenhouse gases as well as cholofluorocarbons that are eroding the ozone layer in the upper atmosphere.

But environmental group lobbyists contested that claim, citing recent estimates by the Environmental Protection Agency that the bill may reduce carbon dioxide emissions over the next decade by 68 million tons, only 2 percent of the total U.S. output.

Besides its concerns about the economic impact of curtailing greenhouse gases, the United States argued that more research was necessary to determine the true impact of greenhouse gases. That view was adopted in the declaration's affirmation that "there is a need to strengthen national, regional and international research activities in climate, climate change and sea level rise."

But the final document also says that "where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing cost-effective measures to prevent such environmental degradation."

Knauss said the United States did not contest scientific claims that global warming would have such consequences as rising sea levels, but he stressed what remains uncertain is "by how fast and by how much."