CHANTILLY, Va. -- As a United Nations conference on global warming opened here yesterday, the United States pledged for the first time to stabilize the amount of "greenhouse" gases it emits into the air.
"America's climate-change strategy includes actions that will result in U.S. greenhouse gas emissions in the year 2000 being equal to or below 1987 levels," Michael R. Deland, chairman of the President's Council on Environmental Quality, told the first session of the 10-day U.N. conference.
As record high temperatures were reached outside the suburban Washington conference center, delegates from more than 90 nations began to negotiate a framework for an international response to the problem of global warming.
The United States' comments were an encouraging sign to environmentalists and delegates, as the United States -- unlike every other of the world's industrial nations -- never before had committed to halting growth in the amount of air-fouling chemicals from industry, autos and power plants.
A growing body of scientific evidence indicates that these chemicals -- especially carbon dioxide from burning fuel -- have begun to act as a shield in the Earth's atmosphere, keeping solar heat from escaping the Earth's atmosphere, in much the same way a greenhouse does.
The United States is the largest producer of carbon dioxide on the planet, though Canada produces more per capita, according to the Environmental Protection Agency.
The U.S. pledge garnered grudging support from scientists and environmentalists -- but they said it amounted to little more than creative accounting.
"It's really progress to recognize the reality of climate change," said Alan Miller of the University of Maryland's Center for Global Change. "But its weakness is that it doesn't mean very much. Most of the debate is about carbon dioxide, but the U.S. is not talking about any reductions in that, but offsetting an increase in carbon dioxide with reductions in other gases."
Other countries, such as Germany and Japan, have pledged to cut their carbon dioxide emissions by 20 percent or more.
The delegates hope to come up with a general agreement on what danger global warming poses and what should be done about it. A U.N.-sponsored conference in Geneva in November concluded that if present trends continue, in the next century average temperatures could rise 2 to 5 degrees, and sea levels could rise about 26 inches.