 A weak U.N. climate deal, agreed on Saturday after two weeks of talks pulled back from near collapse, underscored the vulnerability of a process depending on global consensus. The U.N.'s top climate official Yvo de Boer said it was exactly the job of a multilateral process such as the United Nations to forge a solution to a global problem which may impact the least politically powerful first. But the principal negotiations took place among about 30 countries and the biggest breakthrough involved just five -- the United States, China, Brazil, South Africa and India. The final deal was not legally binding and left it for countries to choose to participate, marking a departure from its umbrella U.N. climate convention. "Heads of state came in and crafted a deal a bit independently of the U.N. process," said Jennifer Morgan, director of the World Resource Institute's climate and energy program. "I don't think it's the end of the U.N.'s climate role but it's a new model inside of it," she said. The "new model" was bitterly criticised by a number of nations, however, who felt the deal had been imposed by a handful of powers on others. De Boer points out that part of the reason for the U.N. "is to ensure that we address global issues like climate change equitably, taking the concerns of all into account." "You could argue that it would be far more effective to just address climate change in the G20," whose members account for most carbon emissions, he said. "(But) it's not correct from an equity or from an environmental point of view" because that would exclude many countries "already on the front lines of impacts of climate change." STAND OFF U.N. decisions have to be made by unanimity, between countries as different as the United States and the tiny Pacific island of Tuvalu with a population of just over 12,000. That rule threatened to derail the December 7-18 Copenhagen conference, as developing nations insisted any text be reviewed in a plenary session of 193 countries. Sources said that the Danish hosts were reluctant to do that, fearing that it would take too long for the whole group to draft one text, leading to days of lost negotiation in a tense stand-off. On the last night, a plenary meeting illustrated exactly that problem of reaching unanimity on a final text. The countdown to a final deal on Friday involved 28 nations, sources told Reuters, including developed countries such as the United States and Europe, big emerging economies, India and China, and small island states Grenada and the Maldives. That grouping whittled down to the largest economies, a climate negotiating group reminiscent of the Major Economies Forum originally convened by former U.S. President George W. Bush as a parallel track to the U.N. talks, that some critics said undermined them. Saturday's decision supported a "goal" for a $100 billion annual fund by 2020 to help poor countries fight climate change, and recognized the scientific view of the importance of limiting warming to 2 degrees Celsius. There were no emissions cuts targets, however, and no commitment that all countries would one day sign up to a successor treaty to the Kyoto protocol. UN CHIEF RESCUES DEAL It needed the direct intervention of the U.N. Secretary-General Ban Ki-moon to rescue the flimsy Copenhagen Accord. Ban mediated with reluctant countries including Venezuela and Bolivia. The flawed Copenhagen outcome demonstrated the "underlying weakness" in the United Nations climate process, said Andrew Light, coordinator of international climate policy at the Center for American Progress. "We need to start investigating other options, or at a minimum start using some alternative forums," he said, suggesting the G20 and the Major Economies Forum. But several developing countries vehemently supported the role of the United Nations, exactly because it preserved their voice. "You won't get an agreement involving only a limited number of countries," said Brazil's climate change ambassador Sergio Serra. "Perhaps on some occasions they can be a driving force to mobilize the others, but they will never close a deal by themselves, because this deal will lack legitimacy. So the U.N. will certainly remain at the heart of it." "The U.N. process is secure," said Dessima Williams, head of the 43-member alliance of Small Island States (AOSIS). "I think there may have been confidences jolted but the process is not going to be derailed. What is necessary now is some fence mending and yes some confidence building around the outcome of the conference."