Prime minister Gordon Brown today accused climate change sceptics of going "against the grain" of scientific evidence, as he launched a new group to raise billions of pounds for the fight against global warming.
Mr Brown will co-chair the United Nations High Level Advisory Group on Climate Change Financing with Ethiopian prime minister Meles Zenawi.
The group aims to raise $30bn (£19bn) over the next three years - rising to $100bn annually by 2020 – to help poor countries limit their contribution to global warming and adapt to its effects.
Cash raised from state and private sources will fund measures to halt deforestation, encourage low-carbon development and adapt to rising sea levels, extreme weather events and higher temperatures.
"66 countries have set out their plans or targets for climate change, covering 80% of global emissions," he said. "Already we can say that if promises are met, the accord will lead to a peaking of global emissions by or before 2020 and make it possible for us to hold the trajectory of global temperature increases to 2C."
Britain continues to support a legally-binding agreement at the UN conference in Cancun, Mexico, later this year, he said.
But Mr Brown brushed aside the sceptics' challenge during a UN webcast to launch the group today.
"Those people who have become global warming deniers and those people who have become climate change deniers are against the grain of all the evidence that has been assembled that global warming and climate change are indeed challenges that the world must meet and that can only be met together," he said. He has previously denounced what he described as "anti-science, flat-earth climate sceptics".
UN Secretary General Ban Ki-moon cautioned against thinking that the cold winter in the northern hemisphere – which is currently causing heavy snowfall in the New York area – disproves the global warming hypothesis.
"It may be true that you have seen some cold weather, as we have seen recently in New York, but the overall tradition of scientific evidence suggests that global warming is happening much faster than one may realise," said Mr Ban.
"That is what I have been told by the scientists and I believe that is true."
Mr Brown said that the group would take on "the task that I believe is the most important we face – combating climate change by ensuring that the poorest countries have the finance necessary to do so".
He added: "If we can resolve this problem then I believe many of the other challenges of climate change can also be solved. The task before us, while daunting, is a very important one to the future of the environment of the world."
Mr Brown said that funds for mitigation and adaptation to climate change must come on top of official development aid, and acknowledged that private sources must be found for some of the money – for instance by auctioning national emissions allowances.
"This can't all be done from taxpayer revenues so we must examine new sources of finance, both public and private," he said.
The PM pledged that Britain would contribute, saying: "Let me stress that the UK is committed to paying its share of the up to $30bn required by developing countries from 2010. We will stand by and make our commitment real to that part of the agreement at Copenhagen."
Asad Rehman, senior international climate campaigner at Friends of the Earth, said: "$10bn a year might sound like a wave of new money for poor countries to tackle climate change, but in reality it's a drop in the ocean compared to what is required. What's worse is that most of this money from rich countries will be plundered from existing aid budgets."Last month the UK government admitted that its £1.5bn contribution to the 2010-2012 funding would be taken from its existing overseas aid budget.