DURBAN, South Africa — For 17 years, officials from nearly 200 countries have gathered under the auspices of the United Nations to try to deal with one of the most vexing questions of our era — how to slow the heating of the planet.

　　Every year they leave a trail of disillusion and discontent, particularly among the poorest nations and those most vulnerable to rising seas and spreading deserts. Every year they fail to significantly advance their own stated goal of keeping the average global temperature from rising more than 2 degrees Celsius, or about 3.6 degrees Fahrenheit, above preindustrial levels.

　　That was the case again this year. The event, the 17th conference of the United Nations Framework Convention on Climate Change, wrapped up early Sunday morning with modest accomplishments: the promise to work toward a new global treaty in coming years and the establishment of a new climate fund.

　　The decision to move toward a new treaty — and toward replacing the 20-year-old system that requires only industrialized nations to cut emissions — was hard-won, after 72 hours of continuous wrangling. But for now it remains merely a pledge, and all details remain to be negotiated.

　　Negotiators also left for another day the precise sources of the money for the fund and how and by who it would be disbursed. Called the Green Climate Fund, it would help mobilize a promised $100 billion a year in public and private funds by 2020 to assist developing nations in adapting to climate change and converting to clean energy sources.

　　There is no denying the dedication and stamina of the environment ministers and diplomats who conduct these talks. But maybe the task is too tall. The issues on the table are far broader than atmospheric carbon levels or forestry practices or how to devise a fund to compensate those most affected by global warming.

　　What really is at play here are politics on the broadest scale, the relations among Europe, the United States, Canada, Japan and three rapidly rising economic powers, China, India and Brazil. Those relations, in turn, are driven by each country's domestic politics and the strains the global financial crisis has put on all of them. And the question of "climate equity" — the obligations of rich nations to help poor countries cope with a problem they had no part in creating — is more than an "environmental" issue.

　　Effectively addressing climate change will require over the coming decades a fundamental remaking of energy production, transportation and agriculture around the world — the sinews of modern life. It is simply too big a job for those who have gathered for these talks under the 1992 United Nations treaty that began this grinding process.

　　"There is a fundamental disconnect in having environment ministers negotiating geopolitics and macroeconomics," said Nick Robins, an energy and climate change analyst at HSBC, the London-based global bank. Mr. Robins noted that the 20-year-old framework convention and the 1997 Kyoto Protocol that amended it enshrined the two-tiered system in which so-called developed and developing countries are treated differently. China still is classified as a developing country and is thus exempt from any emissions limits, but it has a vastly larger economy than it had in 1992 and recently surpassed the United States as the world's largest emitter of greenhouse gases.

　　"They are working from a 20th-century agreement," Mr. Robins said.

　　The United States is determined to sweep away those distinctions and work toward a system where all countries are bound by the same rules. The conference here in Durban kept the tiered system alive for another few years, but it is fading. And by the time the next phase of the Kyoto Protocol expires in 2020, a good many leaders hope that it will be gone for good.

　　Todd D. Stern, the chief American climate negotiator, revealed his qualms about the inability of the United Nations climate bureaucracy to deal with the broad political and financial questions posed by climate change. "We want to see a green fund that is going to draw in a lot of capital from countries all over the world, including the United States," he said at a briefing. "And although I love climate negotiators and spend much of my time with them, they are not necessarily the most qualified people to run a multibillion-dollar fund."

　　So who is qualified to tackle these tasks? Two years ago, more than 100 heads of state and leaders of governments, including President Obama, joined the United Nations climate conference in Copenhagen hoping to write a new, legally binding treaty covering all parties. That assignment proved too much even for the leaders, and the meeting collapsed in acrimony and finger-pointing. Few top leaders have shown up at the two subsequent meetings, in Cancún, Mexico, in 2010, and in Durban this year. The agenda has narrowed and expectations have shrunk, yet the ship sails grimly on.

　　Others think that real progress will not emerge from any global forum but from action at the ground level, by entities unencumbered by the United Nations climate process.

　　Mary D. Nichols, chairwoman of the California Air Resources Board, which arguably has done more to reduce carbon pollution in the United States than any other body, was in Durban as an observer. Ms. Nichols said that given the inability of the international bureaucracy or the United States Congress to move decisively on global warming, the job would increasingly fall to the states and local governments.

　　"Instead of waiting for them to negotiate some grand bargain, we have to keep working on the ground," she said. "Progress is going to come from the bottom up, not the top down."