Editor's note: After this story was posted, delegates at the U.N. Climate Summit resumed negotiations into the early hours of Saturday morning and the body eventually came to a consensus to recognize the deal outlined in the story below.

COPENHAGEN—The U.S., China, India and South Africa form the core of a growing group of nations that have agreed upon a commitment to combat climate change, concluding a grueling two weeks of negotiations in the Danish capital here as part of the United Nations' climate summit. The so-called "Copenhagen Accord" will not be legally binding but will list in annexed documents, for the first time, commitments from both developed and developing countries to reduce emissions of greenhouse gases.

"We're going to set a mitigation target to limit warming to no more than 2 degrees Celsius," said President Barack Obama in a press briefing. "Transparency, mitigation and finance that the U.S. and our partners embraced here in Copenhagen is a new consensus, a consensus that will serve as the foundation of global action."

A draft text of the accord—details were still be finalized as this report was filed—included goals to reduce global emissions by 50 percent below 1990 levels by 2050; developed countries will reduce their emissions by 80 percent by 2050 as well as "X" (this is the literal wording at present) percent by 2020; developing countries will take "mitigation actions" that will be "subject to international measurement, reporting and verification"; $30 billion for adaptation and mitigation between 2010 and 2012 for the most vulnerable countries, including a "Copenhagen Climate Fund"; and a review of this accord in 2016, which will "include consideration of strengthening the long-term goal to limit the increase in global average temperature to 1.5 degrees [Celsius]."

"We know [to-be-set emission targets] will not be by themselves sufficient to get to where we need to be," Obama said. "Science dictates even more needs to be done."

The accord leaves out large swaths of the world, of course, including Africa, so-called small island states, and others likely to be impacted by climate change, though prime minister Meles Zenawi of Ethiopia was part of the negotiations, Obama said. "Africa loses more than most if there is no agreement on climate change," Zenawi said Wednesday in an address to the conference. "Because we have more to lose than others, we have to be prepared to be flexible and be prepared to go the extra-mile to accommodate others."

Some of the targets likely to be listed are already clear, such as a reduction in emissions intensity by China. "We have set the new target of cutting carbon dioxide emissions per unit of GDP by 40-45 percent by 2020 from the 2005 level," said premier Wen Jiabao in an address to the conference Friday. "We have not attached any condition to the target, nor have we linked it to the target of any other country. We will honor our word with real action." And India's Prime Minister Manomhan Singh reaffirmed his country's commitment to reduce its emissions intensity by 20 percent below 2005 levels by 2020.

"The money that will be put on the table is the payment for greenhouse gas emissions that were made over two centuries because [developed countries] had the privilege of those countries that industrialized themselves first," said President Luiz Inacio Lula da Silva of Brazil in an address to the conference Friday morning. "If it is necessary for us to make more sacrifices, Brazil is willing to tap money to help other countries."

But neither the money nor the cuts are guaranteed. "I think we should still strive towards something more binding than this is but that was not achievable at this conference," Obama said. "Kyoto was legally binding and people still fell short anyway."

Nevertheless, all 193 countries will now have the opportunity to respond to the would-be "Copenhagan Accord" late Friday, the night of the last day of negotiations. Sudan's Lumumba Di-Aping, a negotiator involved with the G77 bloc of developing countries, called the accord a "gross violation" of United Nations principles and noted "two degrees Celsius will result in massive devastation for Africa and small island states." He added: "This deal remains an idea. If any single party refuses the deal, there is no deal."

Environmentalists and other activist groups also expressed skepticism. "It clearly doesn't match up to the science," says Alden Meyer, policy director at the Union of Concerned Scientists. "We don't even have the [emissions] cut numbers you need to evaluate how good it is."

Scientists have no role left to play at this point, either. "There is nothing more for us to do," says Intergovernmental Panel on Climate Change Bureau member Taka Hiraishi. "People are really exhausted. Perhaps fed up is the better phrase."

But many U.S. politicians showed support for something similar earlier in the week. "Two degrees Celsius is the proper goal for this moment in history," said U.S. Representative Edward Markey in a press conference on Thursday, although some of his colleagues in the House continued to debate the science of climate change at the summit. "There is a culture of corruption going through the scientific community," charged Rep. John Sullivan on Friday. And Senator John Kerry argued in a press conference Wednesday: "Success in Copenhagen is really critical to success next year in the U.S. Senate and Congress."

Ultimately, domestic and international politics trumped science in the drafting of this accord. "Ultimately this issue is going to be dictated by the science. The science indicates we are going to have to take more aggressive steps in future," Obama said. "We're going to meet those targets as I said before not because the science demands it but because it offers us enormous economic opportunity down the road."

"These international discussions have essentially taken place now for almost two decades, and we have very little to show for it other than an increased acceleration of the climate change phenomenon," Obama said Friday morning in his address to the conference before reaching the accord that he called "meaningful." "The time for talk is over." Yet, talks continue as Saturday begins and it remains unclear whether it's accurate to say that an agreement to combat climate change has come out of Copenhagen or not.

"You can't please everyone in the world," says Indian environmental minister Jairam Ramesh, noting that the accord will be taken to the full conference and he remained confident that the text would ultimately be approved. But, he added, some states might not think it strong enough. "For small island states, it's a matter of survival."

President Mohammed Nasheed of the Maldives would seem to agree. "Carbon concentrations higher than 350 parts-per-million and temperature rises above 1.5 degrees [Celsius] will submerge my country, dissolve our coral reefs, turn our oceans to acid, and destabilize the planet's climate," he said in an address Wednesday. "This is a matter of life and death."

But Mexico's president Felipe Calderon—Mexico City will host the next Conference of the Parties, number 16 in November 2010—announced to the press: "This conference will embrace the Copenhagen Accord…the advancements achieved here must be the basis of a future agreement."