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Diplomats have barely started arriving in Durban, South Africa for the annual UN climate talks, but their deliberations are already at an impasse. Two years after the debacle in Copenhagen, they are still fighting over a fundamental question: should their central goal be a legally binding climate treaty? Most major powers, including the US and China, appear sceptical, but most European leaders remain enthusiastic. They have been demanding that others agree at this year's talks to...