But Ban says he's "aware that this is just the beginning" of a
process to craft a binding pact to rein in greenhouse gas emissions. Still, Ban says the Copenhagen Agreement "will have an immediate operational effect."
Many poor nations had bitterly protested the deal because it lacks specific targets for reducing carbon emissions.
Earlier, the conference was near collapse, but the pact was agreed on during an all-night plenary session that satisfied nations that had been blocking the accord because of the absence of the targets. Decisions are taken by unanimity in U.N. climate talks.
After a break, the conference president gaveled the decision to "take note" of the Copenhagen Accord specifying those who agreed with it in the title.
Several developing countries, including Bolivia, Cuba, Sudan and Venezuela, bitterly protested the deal and said it is unacceptable because it lacks specific targets for reducing carbon emissions. Decisions are made by consensus in U.N. climate negotiations.
After failing to resolve the impasse during an all-night session, Danish Prime Minister Lars Loekke Rasmussen announced a break for consultations with U.N. officials.
"If it fails, you have a collapse of the whole negotiating process out of Copenhagen," said Alden Meyer of the Union of Concerned Scientists. "The Copenhagen Express is in danger of derailing."
The overnight talks resulted in the ultimate agreement.
Mr. Obama appeared to have salvaged the faltering talks Friday when he declared a "breakthrough" with China, India, Brazil and South Africa. But the three-page document they agreed on ran into trouble in the plenary where some delegates denounced it because it was nonbinding and set no overall target for curbing greenhouse gas emissions.
Sudan's delegate, Lumumba Di-Aping, said it would condemn Africa to widespread deaths from global warming and compared it to Nazis sending "6 million people into furnaces" in the Holocaust. The African Union, however, backed the deal and his statement was denounced by other delegations.
British Climate Change Secretary Ed Miliband said the U.N. faced "a moment of profound crisis" if it did not approve the deal.
Mr. Obama's day of hectic diplomacy produced a document promising $30 billion in emergency aid in the next three years and a goal of channeling $100 billion a year by 2020 to developing countries with no guarantees.
The emerging outcome was a disappointment to those who had anticipated the Copenhagen Accord would be turned into a legally binding treaty. Instead, it envisions another year of negotiations and leaves myriad details yet to be decided.
It includes a method for verifying reductions of heat-trapping gases - a key demand by Washington, because China has resisted international efforts to monitor its actions.
It requires industrial countries to list their individual targets and developing countries to list the actions they will take to cut global warming pollution by specific amounts. Mr. Obama called that an "unprecedented breakthrough."
If the countries had waited to reach a full, binding agreement, "then we wouldn't make any progress," Mr. Obama said. In that case, he said, "there might be such frustration and cynicism that rather than taking one step forward, we ended up taking two steps back."
Japanese Prime Minister Yukio Hatoyama said the deal would represent "a major step forward." German Chancellor Angela Merkel, a leading proponent of strong action to confront global warming, gave the Copenhagen Accord grudging acceptance, but said she had "mixed feelings" about the outcome and called it only a first step.
Mr. Obama met twice with Chinese Premier Wen Jiabao - once privately and once with other leaders present - in hopes of sweeping aside some of the disputes that had blocked progress. The U.S. and China are the world's two largest carbon polluters.
European Commission President Jose Manuel Barroso said the deal was "clearly below" the European Union's goal.
"I will not hide my disappointment," he said.
But British Prime Minister Gordon Brown was positive, saying "a year ago nobody thought this sort of agreement was possible."
The document said carbon emissions should be reduced enough to keep the increase in average global temperatures below 2 degrees Celsius (3.6 degrees Fahrenheit) compared to pre-industrial levels.
It also is the figure that the Intergovernmental Panel on Climate Change, the U.N.-sponsored science network, recommends to head off the worst of global warming, and says would require an emissions reductions average in the 25-40 per cent range below 1990 levels.
However, some of the most vulnerable nations believe the limit should be held to no more than 1.5 degrees and environmental groups called it a meaningless aspiration.
"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, an organization that works with developing countries.
He said the agreement "barely papers over the huge differences between countries which have plagued these talks for two years."
Outside the conference hall, more than 100 protesters chanted, "You're destroying our future." Some carried signs of Mr. Obama with the words "climate shame" pasted on his face.
Mr. Obama had planned to spend only about nine hours in Copenhagen as the summit wrapped up. But, as an agreement appeared within reach, he extended his stay by more than six hours to attend a series of meetings aimed at brokering a deal. He and Secretary of State Hillary Rodham Clinton held talks with European leaders, including Merkel, Brown and French President Nicolas Sarkozy.
Mr. Obama said there was a "fundamental deadlock in perspectives" between big, industrially developed countries like the United States and poorer, though sometimes large, developing nations. Still he said this week's efforts "will help us begin to meet our responsibilities to leave our children and grandchildren a cleaner planet."
The deal as described by Mr. Obama reflects some progress helping poor nations cope with climate change and getting China to disclose its actions to address the warming problem.
He said the world will have to take more aggressive steps to combat global warming. The first step, he said, is to build trust between developed and developing countries.
In a diatribe against the U.S., Venezuelan President Hugo Chavez criticized the conference as undemocratic.
"There is a document that has been moving around, all sorts of documents that have been moving around, there is a real lack of transparency here," he said earlier Friday. "We reject any document that Mr. Obama will slip under the door."
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