Representatives of the world's 17 biggest and most polluting nations gather Sunday to search for a breakthrough on financing efforts to contain climate change and reduce gas emissions causing global warming. Pressure has been mounting for the United States to finalize its position before a decisive December conference in Denmark meant to cap two years of negotiations on a global climate change treaty. “With only 50 more days to go before the final talks at Copenhagen, we have to up our game. Britain is determined to throw everything at this because the stakes are so high,” British Environment Minister Ed Miliband said in a statement released Sunday. Earlier Miliband had said it was “important that the US makes as much progress as possible” at the two-day meeting of the Major Economies Forum. The Obama administration said it was tied to action by US Congress, where climate bills were making their slow way toward legislation – an argument which cut little ice with other negotiators. “The rich countries of the Major Economies Forum must urgently put new money on the table to ensure the developing world can grow cleanly and adapt to the effects of climate change, which are already putting millions of lives at risk,” said Asad Rehman of Friends of the Earth. Miliband said there had been some progress. “We have seen countries moving toward each other: India, Japan, China and Indonesia have all made significant shifts in the past few weeks,” Miliband said. “As the deadline races toward us, it becomes more important to narrow the gaps between countries as fast as we can,” he said. One further negotiating session is set for November in Barcelona, Spain. But pessimism was mounting that a deal can be struck without policy changes at the highest level. “In recent months, the prospects that states will actually agree to anything in Copenhagen are starting to look worse and worse,” Rajendra Pachauri, head of the UN scientific panel studying climate change, wrote on the Newsweek Web site posted Friday. President Barack Obama initiated the Major Economies Forum earlier this year as an informal caucus to quietly deal with the toughest problems. Participants agree to keep the talks confidential. A key issue is helping poor countries adapt to changes in the earth's climate that threaten to flood coastal regions, make farming unpredictable and spread diseases. They also need funds and technologies to develop their economies without overly increasing pollution. Estimates range in the hundreds of billions of dollars needed every year, but a formula for raising, administering and distributing the funds has proved elusive. “Only bold pledges by rich countries to slash their emissions by at least 40 percent by 2020 without carbon offsetting and a commitment to provide at least $200 billion of new money will break the current logjam,” Rehman said. Rapidly growing nations like India, China, Brazil and Mexico have agreed to draw up national strategies for slowing the growth of greenhouse gas emissions, but resist making those limits binding and subject to international monitoring in a treaty.