The hard-fought deal at a global climate conference in South Africa keeps talks alive but doesn't address the core problem: The world's biggest carbon polluters aren't willing to cut emissions of greenhouse gases enough to stave off dangerous levels of global warming.
With many scientists saying time is running out, a bigger part of the solution may have to come from the rise of climate-friendly technologies being developed outside the U.N. process.
"We avoided a train wreck and we got some useful incremental decisions," said Alden Meyer, of the Washington-based Union of Concerned Scientists. "The bad news is that we did very little here to affect the emissions curve which is accelerating, and the impacts of climate change which are climbing day by day."
Scientists say that if levels of greenhouse gases continue to rise, eventually the world's climate will reach a tipping point, with irreversible melting of some ice sheets and a several-foot rise in sea levels.
They cannot pinpoint exactly when that would happen, but the two-decade-long climate negotiations have been focused on preventing global temperatures from rising more than 2 degrees Fahrenheit (1.2 degrees Celsius) above current levels by the end of this century.
A report released before the Durban talks by the U.N. Environment Programme said greenhouse gas emissions need to peak before 2020 for the world to have a shot of reaching that target. It said that's doable only if nations raise their emissions pledges.
In Durban, they did not.
Sunday's deal extends by five years the Kyoto Protocol, the 1997 agreement that has binding emissions targets for some industrial countries but not the world's biggest carbon polluters, China and the United States.
The Durban agreement also envisions a new accord with binding targets for all countries to take effect in 2020. And it sets up the bodies that will collect, govern and distribute tens of billions of dollars to poor countries suffering the effects of climate change.
"But the core question of whether more than 190 nations can cooperate in order to peak and bring down emissions to the necessary level by 2020 remains open _ it is a high-risk strategy for the planet and its people," UNEP chief Achim Steiner said.
Climate talks have been bogged down by rifts between rich and poor, between fully industrialized nations and emerging economies, about how to share the burden of reducing greenhouse emissions.
Held back by a skeptical Congress, the U.S. doesn't want to commit to any binding deal unless it also imposes strict emissions targets on China and India. The latter insist their targets should be more lenient because, historically, the West has a bigger share of the blame for man-made warming.
Meanwhile, the atmosphere keeps filling up with heat-trapping gases from the burning of fossil fuels.
Figures from the U.N. weather agency show the three most powerful greenhouse gases reached record levels last year and were increasing at an ever-faster rate.
And the U.S. National Oceanic and Atmospheric Administration says the total heat-trapping force from major greenhouse gases has increased 29 percent since 1990, the benchmark year in the climate talks.
With that backdrop, some say the diplomatic effort to solve the climate issue has already failed, and that the answer lies in the development of green technologies outside the U.N. process.
"Handing the problem to diplomats was one of the first failures," Dan Sarewitz, professor of science policy at Arizona State University, said in an email.
The idea that the global energy system could be decarbonized by anything other technological developments, driven to a large extent by national polices and businesses, "was never more than a delusion," Sarewitz said.
Roger Pielke Jr. of the University of Colorado said treaties and timetables don't reduce emissions.
"Technology reduces emissions," he said. "International agreements are simply a means to stimulating technological innovation. In the climate debate we have confused ends and means."
Even in Durban, there was a growing recognition that the transition to a low-carbon economy must be underpinned by a revolution in new energy, said Nicholas Stern, who wrote a landmark 700-page report in 2006 on the effect of climate change on the global economy.
"Many inspirational examples were showcased ... in Durban, ranging from a project to develop new solar light bulbs from reused plastic bottles in the Philippines, to major water and energy conservation programs in South Africa," Stern said.
Despite technological advances, renewable energy sources like solar and wind power face big challenges, struggling to compete on cost and efficiency with fossil fuel-based energy, and still represent only a small part of the energy mix in the U.S. And in some cases it is fossil fuel production that is benefiting from technological innovation, with new techniques making it easier to drill for oil in deep water and for gas in shale beds.
U.N. officials hailed the Durban conference as a success, and judged against the low expectations for climate talks following the breakdown of the much-hyped Copenhagen talks two years ago, that's not unreasonable.
Negotiators overcame gridlock in the final hours and kept the process moving by agreeing to start talks on a new binding climate pact, though they couldn't agree on whether to call it "a protocol, another legal instrument or an agreed outcome with legal force."
Other documents in the package lay out rules for monitoring and verifying emissions reductions, protecting forests, transferring clean technologies to developing countries and scores of technical issues.
"I salute the countries who made this agreement. They have all laid aside some cherished objectives of their own to meet a common purpose _ a long-term solution to climate change," said U.N. climate chief Christiana Figueres.
The process now lives on, but the difficult part lies ahead: raising the targets for emissions cuts enough to slow the rise in temperatures. Right now, there are few signs suggesting that's going to happen.
That means efforts to reduce emissions through national and local regulations, and in the private sector through new technologies, "need to accelerate to full throttle," said Michael Oppenheimer, professor of geosciences and international affairs at Princeton University.
"If all countries pushed renewable energy and other low-carbon technologies with corresponding vigor while (simultaneously) pulling the various regulatory levers available to them," Oppenheimer said, "we might have a chance to beat the benchmark of danger."
Ritter reported from Stockholm. AP Science Writer Seth Borenstein in Washington contributed to this report.