THE HAGUE, Netherlands - As some 10,000 people open a major U.N. conference to draft rules on slowing global warming, differences remain vast on greenhouse gas emissions and there are concerns that everything the parties have agreed to so far could unravel.
The problem some 100 participants will tackle when the two-week meeting begins Monday is stark: Most scientists now agree that our cars, factories and power plants are pumping so much heat-trapping gas into the air that we are changing the world's climate, causing severe storms and droughts. New weather patterns threaten to extinguish animal species, submerge coastal areas and low islands and cause dramatic changes in the way we live.
The 1990s were the warmest 10 years in a millennium, and 1998 was the warmest year on record. Researchers say winters in the northern hemisphere are 18 days shorter than they were 150 years ago. Glaciers from Montana to the Himalayas are melting. Some animals are migrating uphill to cooler altitudes.
Yet despite three years of quiet negotiations to address the problem of emissions, countries disagree on crucial issues. Among them is whether nations falling short of their own emission reduction targets can strike deals with those able to reduce more than is required. The United States - the world's largest polluter - is arguing against the European Union for unrestricted trading of ''credits.''
The conference brings together government ministers, bureaucrats, environmentalists, lobbyists, student activists and a new breed of businessman - pollution traders. Demonstrators are also expected to converge on the Dutch city.
The road to The Hague began at the Earth Summit in Rio de Janeiro in 1992 when world leaders, alarmed by predictions of a climatic apocalypse, pledged to combat global warming.
Five years later, negotiators met in Kyoto, Japan, and agreed the total amount of greenhouse gases released each year into the atmosphere should fall to 5.2 percent less than it was in 1990. The target date was set for 2012.
To meet that goal, though, the Kyoto Protocol needs to come into force by 2002. ''That's why this is a make-it-or-break-it conference,'' said Jennifer Morgan of the World Wildlife Fund for Nature.
The agreement is yet to be ratified by any industrial nation.
''The Hague is about making sure the Kyoto agreements are not reopened for debate. It's about putting them into practice,'' said Jan Pronk, the conference chairman and Dutch environment minister.
At Kyoto, negotiators agreed the European Union would slash greenhouse gas emissions by 8 percent of 1990 levels, the United States by 7 percent and Japan by 6 percent. In all, 38 countries accepted binding commitments, but developing countries like India and China, with huge economies, did not.
The Kyoto delegates failed to agree on how to go about meeting those reductions.
Rather than shrinking since 1990, emissions have grown by 20 percent, making the targets even tougher to meet, said Pronk.
The Kyoto negotiators agreed that countries falling short of their own targets can strike deals with nations that are able to reduce more than required, trading in ''credits'' from the excess. Countries with large ''emission deficits'' could sell their shortfall for cash.
Some companies have already begun to trade, anticipating that the emissions credits they buy now will count for them once their governments enforce emissions reductions.
Countries also can earn ''credits'' by helping other countries control emissions. That means if the United States helps India to develop clean energy or to plant forests that soak up carbon dioxide from the air, it will get credit against its own emissions reductions.
''It's cheaper to lock up 1,000 tons of carbon dioxide in a forest somewhere than to reduce 1,000 tons of emissions at a coal plant in the United States,'' said Phil Kosnett, of the Global Issues section of the U.S. Embassy in The Hague.
''We won't get anything through Congress that will cost too much money,'' he said.
Trading in credits is one of the hottest issues at The Hague conference.
The European Union, fearing the United States will use the credit ''loophole'' to avoid or delay real reductions, wants to put a 50 percent ceiling on the tonnage any country can purchase rather than reduce itself.
The U.S. delegation will argue for unrestricted trading. Limiting credits is ''a wrongheaded idea that doesn't make sense,'' said the chief U.S. delegate, Frank Loy. ''It's anti-environment.''
Among other contentious issues are how to monitor compliance and how to punish those who fail to meet their obligations.
Australia, for one, objects to the proposal to establish an inspection body to police greenhouse gas emissions. Andrew Thomson, head of the parliament's treaty committee, called the idea was ''outrageous,'' and said the Kyoto agreement was so flawed that Australia should shelve it for 20 years before looking at it again.
