KYOTO, Japan -- Haggling over chemistry, calendars and the future of Earth's atmosphere, European and U.S. negotiators worked through the night and into early Wednesday to save a historic deal to control fuel emissions across the industrial world.
The U.S. delegation to the global warming talks in Kyoto eased its position by offering deeper gas reductions, but clung to features of the proposed agreement that the Europeans called "loopholes."
Despite their remaining differences, both sides sounded determined to succeed as the 9-day-old negotiations headed toward a deadline late Wednesday.
"We still have far to go," said Stuart E. Eizenstat, the chief U.S. negotiator. "Nevertheless, we are hopeful that ... we will be able to bridge the gaps."
"I think we are making genuine progress," Britain's environment minister, Michael Meacher, said after key talks broke up about 2:30 a.m., to resume later in the morning.
Earlier, Japanese Prime Minister Ryutaro Hashimoto telephoned the leaders of Germany, Italy and Britain to ask that their delegations take a more flexible position in the talks, Japan's Kyodo news service reported.
It said Hashimoto also planned to call President Clinton.
If the disagreement between the United States and Europe is settled, an overall deal would be presented to the 150-nation conference Wednesday for consensus approval.
The accord would wrap up two years of negotiations to strengthen the 1992 Climate Change Treaty by setting legally binding limits on 34 industrial nations' emissions of such greenhouse gases as carbon dioxide and methane.
It could help set the energy course for much of the world well into the 21st century, from how we generate electricity to what we drive.
Governments are expected to take steps such as converting coal-fired power plants to gas, encouraging development of more fuel-efficient automobiles and lifting subsidies that keep fossil fuel prices low.
The treaty had set only voluntary goals for industrial nations to roll back greenhouse gas emissions to 1990 levels by 2000. Because few countries were meeting that goal, governments decided in 1995 to negotiate mandatory cutbacks.
The gases, mostly byproducts of fossil fuel burning, trap the Earth's heat when they accumulate in the atmosphere.
An authoritative U.N. scientific assessment in 1995 found global temperatures rose slightly in the past century, apparently in part due to human activities, and would rise up to 6 degrees more by 2100 if emissions were not controlled.
Such warming would shift climate zones, disturb weather patterns and raise sea levels -- because of melted glaciers and heat expansion of the oceans -- flooding islands and low-lying coastlines.
Clinton has proposed that 1990 levels be retained as the binding goal, to be achieved between 2008 and 2012. The European Union proposed a more ambitious plan: cutting emissions by 15 percent below 1990 levels by 2010.
The trans-Atlantic argument over targets and timetables dominated the conference.
The United States contended its "zero" plan actually amounted to a 30 percent reduction from what U.S. emissions would be in 2010 if no controls were imposed.
The Europeans objected that as the world's biggest emitter of carbon dioxide -- 24 percent of the global total -- America needed to do more.
Vice President Al Gore, in a one-day visit Monday, authorized the U.S. delegation to come off its "zero" position. By Tuesday, European sources reported the U.S. team was offering reductions of more than 5 percent.
The complex, highly technical talks offered negotiators many ways to adjust the balance among parties: the chemical compounds to be covered, the year-by-year timetables, the "baseline" years for measurement.
The Europeans objected to "loopholes" in the U.S. position, especially the American idea of international trading of emissions quotas -- allowing U.S. plants, for example, to obtain the right to continue emitting by buying "rights" from countries that underutilize their quotas.
The Americans wanted to cover up to 50 percent of their emissions cuts via such "offshore" reductions. The Europeans wanted to limit traded quotas to one-third of a nation's cutback requirements.
Another U.S. demand -- that developing countries also submit to binding reductions -- met even tougher opposition.
Throughout the years of talks, developing countries have been exempted from mandatory emissions cuts. But the U.S. Senate threatened to withhold ratification of the protocol unless it extended the cutbacks to some Third World nations.
Having won few Third World concessions here, the Clinton administration is expected to try to later negotiate bilateral agreements leading to emissions limits in developing countries such as China.