Still, those changes - which remain uncertain and would, in any case, come about gradually - are decades and decades away.
``The politics on this issue is to run from it,'' said Kathleen McGinty, head of the President's Council on Environmental Quality. ``It's difficult to understand. It's a long-term problem. . . . There may be some economic pain in the short term.''
Nevertheless, tomorrow, President Clinton will step up and give the tar baby a hug at a White House conference on climate change that brings together top scientists and industrialists.
The White House is using the conference to help set the stage for announcing its position on strengthening the international climate change treaty - signed five years ago at the Earth Summit in Rio de Janeiro.
The treaty has failed to stem the buildup of the so-called greenhouse gases in the atmosphere, and it is slated for an overhaul at a major international meeting in Kyoto, Japan, in December.
The position of the United States - the world's leading economy, top energy user and biggest greenhouse gas generator - is considered key to the fate of the negotiations.
But the United States is in a bind. While it, like other industrialized countries, pledged to cut its greenhouse gas emissions by 5 percent, under the 1992 agreement, its generation of carbon dioxide, the prime greenhouse gas, actually has risen 5 percent since 1990, to 5.2 billion metric tons a year.
Much of the growth is the result of a booming economy. Critics warn that tampering with the emissions - mainly from burning coal, oil and gas - could jeopardize economic growth.
``This is the biggest, most complex, most difficult issue, we've ever dealt with,'' said Timothy Wirth, the deputy undersecretary of state for environmental affairs.
But the world is waiting for the United States. ``Without a strong U.S. position, negotiations won't go anywhere. . . . Everyone wants to see what the U.S. does,'' said Annie Petsonk, an attorney with the Environmental Defense Fund.
The key to improving the climate treaty, it is widely agreed, is targeting a specific cut in emissions under a set timetable. ``Without targets and timetables, you just won't get real reductions,'' Petsonk said.
The European Union has suggested a target of a 15 percent cut for industrial nations by 2010. U.S. diplomats have said that is unworkable.
The White House has been trying to craft a policy that would allow some flexibility in implementing cuts, as well as ``emissions trading'' among nations. This would enable countries that are below their target to sell the difference to others.
The White House goal is to soften the blow - both economically and politically - of reducing greenhouse gas emissions.
But while Clinton is now ready to give the tar baby a little squeeze, there are plenty of others in Congress, industry and even within his administration who still want to keep their distance.
The problem is this: Controlling greenhouse gases cuts to the heart of the nation's economic activity and lifestyle, and economists have had a field day predicting dire consequences.
One widely cited economic forecast predicts that if the United States tries to stabilize its emissions at 1990 levels (which would require about a 13 percent cut from present levels), economic growth would be reduced by 1 to 3 percent a year.
The result would be higher energy prices and the possible loss of jobs in industries such as steel, petroleum, aluminum, and, of course, coal mining.
The effects of such a policy would trickle down to consumers in higher prices for products and more expensive gasoline and electricity. A Department of Commerce study estimated that controls would raise gas prices about 26 cents a gallon.
Environmentalists counter that Americans are so wasteful and inefficient in their energy use - driving big cars and running old coal-fired power plants - that significant reductions can be made without economic dislocations.
Still, the gloomy scenarios have created a situation in which both the AFL-CIO, which fears the loss of 125,000 jobs, and the Business Roundtable, worried about global competitiveness, are lobbying side by side.
Politicians have noticed. This summer, the Senate passed by a 95-0 vote a resolution stating that the administration should not sign any treaty that doesn't require firm commitments and emission cutbacks from developing countries.
Under the current treaty, only industrial nations agreed to curb emissions. Before developing countries do so, they want industrial nations - which have created most of the problem and reaped most of the economic benefit - to show they are serious.
``The industrialized nations must take the lead,'' Wirth said. But the United States is already finding itself in economic competition with China, India and South Korea - all developing nations.
``This treaty would be a lead weight on our nation's future economic growth, killing jobs and opportunities for generations of Americans,'' said Sen. Chuck Hagel (R., Neb.), one of the resolution's sponsors.
With all the doomsaying, perhaps it isn't surprising that even within the administration there is a split over how to handle global warming.
The President's economic advisers - Treasury Secretary Robert Rubin, Deputy Secretary Lawrence Summers and Gene Sperling, head of the National Economic Council - have urged a go-slow approach on global warming.
Environmentalists, including McGinty, Wirth, EPA Administrator Carol Browner and Vice President Gore, are urging bolder action now.
``We are going to fashion a policy that is not going to please everyone,'' McGinty said. ``But it will be a serious response to what we think is a serious environmental, economic and global security problem.''
The science tends to support the environmentalists. The International Panel on Climate Change is a group of 1,500 scientists from around the world created by the United Nations to advise it on climate issues. Its broad consensus is that humans are causing an increase in greenhouse gases and that those gases appear to be trapping more heat.
The panel has said it is ``likely'' that humans are affecting the climate pattern and that global temperatures will rise.
But there the consensus ends. What that extra heat will do is unclear. Whether humans have already changed the climate is uncertain.
There are many signs that things may be changing. There has been a string of very hot years. The atmosphere is holding more moisture - which leads to torrential rains. The difference between daytime and nighttime temperatures is also narrowing.
But pronounced changes in climate have not yet occurred, and in all likelihood they will not occur until sometime in the next century - and no one can say whether those changes will be modest or disastrous.
The worst-case scenario would flood the Jersey Shore, scorch the American grain belt, permit tropical diseases like dengue fever to push into the United States, and routinely give Philadelphia 90-degree-plus summers.
Then again, it may not be that bad.
Treaty foes stress the potential of immediate economic hardships and the uncertainty of the science. ``We can't be sure that we would be doing the environment any good since science still can't identify the human fingerprint in the observed warming,'' said Senate Energy Committee Chairman Frank Murkowski (R., Alaska), at a hearing on the issue last week.
The vast majority of scientists both in the International Panel on Climate Change and in polls are worried about the trend and feel that some action should be taken. But scientific work is always filled with qualifiers, and the opponents harp on them - sometimes to the point of stretching the truth.
``The other side is extremely well-funded, extremely well-staffed lobbyists in Gucci loafers saying, `Don't worry, be happy,' '' said McGinty.