President Barack Obama declared today a "meaningful and unprecedented breakthrough" had been reached among the US, China and three other countries on a global effort to curb climate change but said much work was still be needed to reach a legally binding treaty.
"It is going to be very hard, and it's going to take some time," he said at the conclusion of a 193-nation global warming summit. "We have come a long way, but we have much further to go."
The president 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 includes the United States, China, India, South Africa and Brazil.
Earlier, a diplomatic frenzy engulfed the final day of the UN climate conference, with competing meetings, documents and agendas vying for attention.
President Barack Obama met privately twice with China's premier as world leaders pressed to salvage a global warming accord amid deep divisions between rich and poor nations.
But neither Obama nor Chinese Premier Wen Jiabao offered any new commitments to cut the greenhouse gas emissions that cause global warming as they addressed the conference. And Wen skipped a high-level meeting of nations, sending an envoy instead.
"We are ready to get this done today but there has to be movement on all sides to recognize that is better for us to act rather than talk," Obama said, insisting on a transparent way to monitor each nation's pledges to cut emissions.
Wen told delegates that China's voluntary targets of reducing its carbon intensity by 40 to 45 per cent will require "tremendous efforts."
"We will honor our word with real action," Wen said.
Abandoning any hope of reaching a comprehensive deal, a group of about 25 countries sought agreement on a two-page political statement setting out critical elements, key among them the mobilization of $30 billion in the next three years to help poor countries cope with climate change. That would scaled up to $100 billion a year in climate change aid by 2020.
As negotiations evolved, new drafts of the document, titled the Copenhagen Accord, emerged with key clauses being updated and modified. Later drafts said rich countries should cut their greenhouse emissions by at least 80 per cent by 2050.
Some drafts called for a legally binding treaty within six months or no later than December 2010.
With the climate talks in disarray, Obama and Wen met twice Friday in hopes of sweeping aside some of the disputes that have barred a final deal. Officials said the two leaders took a step forward in their first set of talks and directed negotiators to keep working, but the degree of progress was not immediately clear.
Obama also met with the leaders of wealthy nations Australia, Britain, France, Germany and Japan. Also participating in the talks were developing countries Ethiopia, Bangladesh and Colombia, among others. China and Russia, both seen as key participants in the talks, also were present.
It was the second meeting of the day for the group. Obama headed into the first meeting right after arriving. Wen skipped the high-level meeting a second time and sent another envoy instead, angering other nations.
Meanwhile, other leaders worked on a potential deal with emissions cuts that could work, said UN Environment Program Director Achim Steiner.
Diplomats and leaders had only a handful of hours left for high-level talks to find the "miracle" answer that Brazilian President Luiz Inacio Lula da Silva said was needed for more than 110 leaders to sign a deal at the conference's finale later Friday.
Frustration and discouragement outweighed hope in the addresses by leaders to the conference.
"It's a roller coaster of emotions," Steiner said. "(But) a deal is on the table, it is doable."
Many delegates had been looking toward China and the US - the world's two largest carbon polluters - to deepen their pledges to cut their emissions. But that was not to be.
China has been criticized at the two-week conference offering stronger carbon emissions targets and for resisting international monitoring of its actions. After a morning meeting with 20 leaders, including Obama, French President Nicolas Sarkozy said progress in the climate talks was being held back by China.
The US got its share of blame.
"President Obama was not very proactive. He didn't offer anything more," said delegate Thomas Negints, from Papua New Guinea. He said his country had hoped for "more on emissions, put more money on the table, take the lead."
Obama may eventually become known as "the man who killed Copenhagen," said Greenpeace US Executive Director Phil Radford.
UN Secretary-General Ban Ki-moon told negotiators that "the finishing line is in sight," reminding them that "the world is watching."
And Brazil's Silva told negotiators how frustrated he was that the job was left to heads of state after the talks ran until just before dawn Friday.
"I am not sure if such an angel or wise man will come down to this plenary and put in our minds the intelligence that we lacked," Silva said. "I believe in God. I believe in miracles."
To move the talks forward, Silva said Brazil, a developing country, would give money to help other developing countries cope with the costs of global warming.
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. "We reject any document that Obama will slip under the door."
The conference has been plagued by growing distrust between rich and poor nations. Both sides blamed the other for failing to take ambitions actions to tackle climate change. At one point, African delegates staged a partial boycott of the talks.
"It is now up to world leaders to decide," said Swedish Environment Minister Andreas Carlgren.
Carlgren, negotiating on behalf of the 27-nation European Union, blamed the Friday morning impasse on the Chinese for "blocking again and again," and on the US for coming too late with an improved offer, a long-range climate aid program announced Thursday by Secretary of State Hillary Rodham Clinton.
A leading African delegate complained bitterly about the proposed declaration.
"It's weak. There's nothing ambitious in this text," said Lumumba Di-Aping of Sudan, a leader of the developing nations bloc.
Any agreement was expected, at best, to envision emissions-cutting targets for rich nations and billions in climate aid for poor countries, but fall well short of the goal of a legally binding pact. If the political deal is done, it would still be seen by many as a setback, following two years of intense negotiations to agree on new emissions reductions and financial support for poorer nations.
China and the U.S had sought to give the negotiations a boost Thursday. Clinton said Washington would press the world to come up with a climate aid fund amounting to $100 billion a year by 2020, a move that was quickly followed by an offer from China to open its reporting on actions to reduce carbon emissions to international review.
That issue - money to help poor nations cope with climate change and shift to clean energy - seemed to be where negotiators at the 193-nation conference could claim most success.
Pollution cuts and the best way to monitor those actions remained unresolved.