Some scientists say that global warming is the ultimate environmental problem - humans altering the atmosphere, raising its temperature, and thus endangering themselves and future generations.
The international agreement reached here yesterday to reduce emissions of the greenhouse gases said to cause global warming is, by almost all accounts, a meaningful first step toward averting possible environmental disaster.
But even the officials who wrapped up the deal during three nearly all-night negotiating sessions this week say that the Kyoto Protocol to the 1992 UN Framework Convention on Climate Change is only a beginning. Put another way: The hard part is over ... but now comes the hard part.
The 38 industrialized countries that have adopted binding targets for reducing emissions must put their words into action by developing ways to get along without generating so much carbon dioxide and five other gases. (For main points, see story on this page.) In many cases, including in the US, there will be political contests over whether to ratify the Kyoto protocol and turn targets into law.
The negotiating is not really over. The United States remains upset that developing nations - potentially huge emitters of greenhouse gases - are under no obligation to begin reductions. Kyoto puts off establishing a detailed framework for an international emissions-credit trading system that proponents say would allow market forces to propel the cleaning of the atmosphere.
For opponents and supporters of greenhouse-gas reductions, the debates and efforts at public education will continue. "We've got a lot of work to do to make people understand the ... impact of climate change," says Alden Meyer, director of government relations for the Cambridge, Mass.-based Union of Concerned Scientists, an advocacy group.
Tony Juniper of the Dutch-based environmental group Friends of the Earth International calls the deal "fatally compromised and riddled with loopholes." He adds: "Millions of people worldwide will remain at risk from the social and economic upheaval that will accompany progressive global warming."
Those involved in industries that generate greenhouse gases and those who say cutting emissions will cause economic turmoil will keep up criticism too.
The deal commits the US to reducing its emissions of greenhouse gases to 7 percent below US emission levels in 1990. But because the US economy has expanded in the last seven years, meeting the target effectively requires cutting greenhouse-gas emissions by about one-third over the next 15 years.
That will mean a renewed emphasis on conserving energy; a shift from fuel sources that produce lots of carbon dioxide, such as coal and oil; and efforts to promote new technologies that can help accomplish these goals. The nuclear-power industry may benefit, for example, since reactors can produce electricity without generating greenhouse gases.
Stuart Eizenstat, the chief American negotiator here, says the "single disappointment and regret" was the loss of a provision that would have allowed developing nations to undertake binding commitments. Countries such as China and India were adamant that they not be burdened with such commitments.
This omission will complicate the process of ratifying the accord in the US Senate. This summer it approved a resolution 95 to 0 insisting that developing countries also accept binding emissions-reduction targets. US negotiators had arrived in Kyoto demanding "meaningful participation" from poorer countries.
The US entered the negotiations proposing to stabilize emissions at 1990 levels, not cut them by 7 percent. It also had to cede ground in one other area: so-called emissions credit-trading. The 1990 Clean Air Act allows heavy polluters to buy rights to emit acid-rain causing chemicals from companies that are more energy efficient. The idea was to create financial incentives not to pollute and spur technological innovation. It is widely considered to have been successful.
The US wants to globalize this practice. But although the protocol adopts emissions-credit trading in principle and allows experiments, a substantive framework remains to be worked out. Mr. Meyer of the Union of Concerned Scientists says the US may be able to withhold signing the protocol - the deadline is March 1999 - as leverage.
In the end, the achievement of Kyoto may be the changes in thinking required to honor the commitment. Vice President Albert Gore, striking the most ethereal note of the conference, spoke of the consequences of "failing to act" on global warming: "More record floods and droughts. Diseases and pests spreading to new areas. Crop failures and famines. Melting glaciers, stronger storms, and rising seas."
He added: "Our fundamental challenge now is to find out whether and how we can change the behaviors that are causing the problem. To do so requires humility, because the spiritual roots of our crisis are pridefulness and a failure to understand and respect our connections to God's Earth and to each other."
Mr. Clinton hailed the accord as "environmentally strong and economically sound." But he noted that the exclusion of developing countries from any obligation to reduce greenhouse emissions would be a problem.
But in the Senate, which must ratify the protocol, Republicans reacted angrily, calling the accord a "sellout" that will be "dead on arrival." "The Senate will not ratify a flawed climate-change treaty," said majority leader Trent Lott (R) of Mississippi.
At least one Democrat agreed. "What we have here is not ratifiable in the Senate," said Sen. John Kerry (D) of Massachusetts, who served as a observer to the negotiations. But Senator Kerry and Sen. Joseph Lieberman (D) of Connecticut said they thought public support eventually would lead to ratification.
"The issue of developing-country participation is absolutely vital," said Sen. Frank Murkowski, chairman of the Energy and Natural Resources Committee, noting that the developing world's greenhouse emissions will overtake those of the industrialized world in about 15 years.
"Make no mistake about it, this deal will increase US energy prices if it goes as seen," Senator Murkowski said. "You're going to see it at your gas pump. You're going to see it on your electric bill. You're going to see it in your food prices. And the public will pay."
Business and agriculture groups added their voices to the chorus of protests. "This agreement is bad for the American economy, American workers, and American families," said Thomas Donohue, president of the US Chamber of Commerce.
The deal comes at a politically bad time for the administration. It still desperately wants Congress to restore the "fast track" trade-negotiating authority previous presidents have enjoyed. But despite the best efforts of Speaker Newt Gingrich (R) of Georgia and a minority of House Democrats, supporters of fast track have been unable to muster the votes because of growing resentment among the public to the downside of foreign trade: the highly publicized closure of manufacturing plants around the country.
Republican and Democratic senators representing agricultural and industrial states will be reluctant to vote for a treaty that could be blamed for more job losses. House Democrats also may distance themselves from measures to implement the treaty, wary of antagonizing the labor unions that have become their largest financial supporters.
"An agreement that shifts production and jobs out of the industrialized world to the developing world without environmental benefit is a trade treaty - not an environmental treaty," warned AFL-CIO Secretary-Treasurer Richard Trumka on Tuesday.
The agreement's effect on the US economy could also become a factor in the 2000 Democratic presidential nomination between Gore and House minority leader Richard Gephardt of Missouri, who has opposed the administration on several trade issues.