The historic U.N. climate talks ended Saturday after a 31-hour negotiating marathon, with delegates accepting a U.S.-brokered compromise that gives billions in climate aid to poor nations but does not require the world's major polluters to make deeper cuts in their greenhouse gas emissions.
Two weeks of wrangling at Copenhagen exposed sharp divisions between rich and poor nations - and even among major greenhouse-gas emitters like China and the United States - on how to fight global warming.
Yet in the end, nearly all 193 nations at the U.N. climate conference, which points toward deeper emissions cuts for rich nations but without mandatory targets that would draw sanctions.
Mr. Obama's successful 11th-hour bargaining Friday with China, India, Brazil and South Africa - the world's key developing nations - sets the stage for future cooperation between developed and developing nations. But the resulting "Copenhagen Accord" was protested by several nations that demanded deeper emissions cuts by the industrialized world and felt excluded from the major-nation bargaining process.
"The deal is a triumph of spin over substance. It recognizes the need to keep warming below 2 degrees but does not commit to do so. It kicks back the big decisions on emissions cuts and fudges the issue of climate cash," said Jeremy Hobbs, executive director of Oxfam International.
The climate conference also failed to act on one issue many thought was near success here: A plan to protect the world's rain forests, vital to a healthy climate, by paying some 40 poor tropical countries to protect their woodlands.
Deforestation for logging, cattle grazing and crops has made Indonesia and Brazil the world's third- and fourth-biggest carbon emitters, after China and the United States.
Burning trees to clear land for plantations or cattle ranches and logging forests for wood is blamed for about 20 percent of the world's emissions - or as much carbon dioxide as all the world's cars, trucks, trains, planes and ships combined.
"No treaty means that forest destruction will continue unabated, forest-dependent peoples' rights will not be protected and endangered species will continue down the path to extinction," said Stephen Leonard of the Australian Orangutan Project.
Mr. Obama's day of hectic diplomacy in the snowy Danish capital, where more than 110 presidents and premiers had gathered Friday for a rare climate summit,that rich nations would provide $30 billion in emergency climate aid to poor nations in the next three years, and set a goal of eventually channeling $100 billion a year to them by 2020.
That aid aims to help nations build seawalls, cope with unusual droughts and storms, and deal with other impacts from climate change, as well as to develop clean energy sources and reduce their own emissions.
The accord includes a method for verifying each nation's reductions of carbon dioxide and other heat-trapping gases - a key demand by Washington, because China has resisted international efforts to monitor its voluntary actions.
Under the 1997 Kyoto Protocol - rejected by the U.S. - 37 industrial nations were already modestly cutting back on their emissions of greenhouse gases. Under the new, nonbinding agreement, those richer nations, including the U.S., are to list their individual emissions targets, and developing countries must list what actions they will take to reduce the growth in their global warming pollution by specific amounts.
The overall outcome in Copenhagen was a significant disappointment to those who had hoped Mr. Obama could put new life into the flagging prospects for some kind of legally binding agreement this year. Instead, it envisions another year of negotiations and leaves myriad details yet to be decided. The next major U.N. climate conference is a year from now in Mexico City.
The Copenhagen Accord, initiated by five of the world's biggest greenhouse-gas polluters, was accepted only after it bogged down in an all-night debate early Saturday, when Bolivia, Cuba, Sudan and Venezuela traded barbs with Danish Prime Minister Lars Loekke Rasmussen, who chaired the meeting.
Lumumba Di-Aping of Sudan, a spokesman for the world's developing nations, said the deal's temperature goal would condemn Africans to widespread deaths from global warming, comparing it to Nazis sending "6 million people into furnaces" in the Holocaust.
That language drew rebukes from other delegates, however, and the African Union backed the deal.
After a break around dawn Saturday, Loekke Rasmussen was replaced with a new conference president, Philip Weech of the Bahamas, who gaveled in a compromise decision to "take note" of the agreement, instead of formally approving it. Experts said that still meant the accord could go into effect.
"This conference really has been a roller coaster ride," U.N. climate chief Yvo de Boer said in the final minutes Saturday. It's "an impressive accord, but not an accord that is legally binding."
"We have a deal in Copenhagen," said a visibly relieved U.N. Secretary-General Ban Ki-moon, who had made climate change his No. 1 priority when he took office three years ago. Ban said "this is just the beginning" of a process to craft a binding pact to reduce emissions.
The document says carbon emissions should be reduced enough to keep the increase in average global temperatures below 2 degrees Celsius (3.6 degrees Fahrenheit) since preindustrial times. But average temperatures already have risen 0.7 degrees Celsius (1.3 degrees Fahrenheit) since then.
The nations most vulnerable to climate change, including low-lying islands, believe the 2 degree Celsius figure is already too high.
Because the deal envisions emissions cuts no bigger than what countries pledged coming into Copenhagen, U.S. experts say the world's temperature is already on track to increase by 3.9 degrees Celsius (7 degrees Fahrenheit) above preindustrial levels, said team leader John Sterman of MIT.
Disputes between rich and poor countries and between the world's biggest carbon polluters - China and the U.S. - dominated the two-week conference. Tens of thousands of protesters took to the streets and staged demonstrations to demand action to cool an overheating planet.
Mr. Obama met twice with Chinese Premier Wen Jiabao - once privately and once with other leaders - in hopes of sweeping aside some of the disputes that had blocked progress.
The U.S. president argued that some kind of deal was better than none.
If the world waited to reach a binding deal, "then we wouldn't make any progress," Mr. Obama said, warning that could produce "such frustration and cynicism that rather than taking one step forward, we ended up taking two steps back."
Japanese Prime Minister Yukio Hatoyama called the deal "a major step forward," but German Chancellor Angela Merkel gave it only grudging acceptance, saying she had "mixed feelings" about it.
Annie Petsonk, international counsel for the Environmental Defense Fund, called the U.S.-led climate deal "a stepping stone on the path to a new climate treaty. The next stone must be a bill enacted by the U.S. Congress."
Legislation to impose the first caps on U.S. carbon dioxide emissions has been moving slowly through the Congress. The resulting tentativeness of the U.S. commitment - to relatively weak emissions cuts by 2020 - complicated efforts this year to negotiate a firmer global agreement on emissions.
Mr. Obama upended his schedule Friday to reach the deal, turning a 9-hour trip to Copenhagen into a 15-hour negotiating whirlwind. Besides critical meetings with the leaders of the developing world, Mr. Obama and U.S. Secretary of State Hillary Rodham Clinton held talks with European leaders, including Merkel, Britain's Gordon Brown and French President Nicolas Sarkozy.
The $100-billion-a-year climate aid goal set for 2020 falls below estimates made in some expert studies, including by the World Bank, which foresee a need for hundreds of billions of dollars each year to combat global warming as seas rise, species go extinct, farmlands go dry and storms become more severe.