 a new international deal to combat global warming looked increasingly unlikely last night as the UN Climate Change Conference in Durban moves to its close.  The majority of the 194 nations assembled in the South african port city support the EU plan for a legally binding climate change pact for cutting greenhouse gas emissions to be signed by 2015 and to come into force by 2020.  Emissions need to peak by 2020 for the world to have any chance of holding global warming below the danger threshold of 2C above the pre-industrial level. Failure to achieve this target could have catastrophic consequences for millions of people.  But the "Big Three" carbon emitters - China, the US and India, who alone account for nearly half of world CO2 emissions, and without whose participation such a treaty would be meaningless - are holding out against it.  Negotiations, in which Britain's Climate Change and Energy Secretary, Chris Huhne, is playing a leading role, are likely to go down to the wire late tonight.