Hillary Clinton has given US backing to proposals for a $100 billion-a-year international fund to tackle global warming in developing countries in a boost for deadlocked talks at the climate change summit in Copenhagen. The US Secretary of State said the science for climate change is now “undeniable” and the world must agree a deal in the next 48 hours. In a move that will widely be seen as a grand gesture to force developing countries to sign up to a deal, she said the US would be willing to pay into a global fund of $100 billion (£60bn) per...