Energy and Climate Secretary Chris Huhne said there was no chance of getting a legally binding deal at the summit in Cancun, Mexico. The aim, he said, should be to get “within shouting distance”.Meanwhile, the World Meteorological Organization released data showing that greenhouse gas levels continued their rise through 2009.The weather agency says concentrations of greenhouse gases in the atmosphere still increased last year despite the global economic slowdown. It said the amounts of carbon dioxide, methane and nitric oxide which caused global warming were higher than at any time since the start of the industrial age. It follows publication of a scientific paper at the weekend suggesting that without new constraints, global carbon emissions will re-commence rising at 2-3% per year, following a brief lull caused by the recession.And on Tuesday, the UN Environment Programme said pledges that countries had made on constraining emissions were not enough to keep the global temperature rise within limits that most countries say they want – either 2C or 1.5C since pre-industrial times.