A poll published on the eve of the United Nations COP21 environment summit suggests the British public is increasingly sceptical of the case for man-made climate change. The Sky Data survey shows almost one in five Britons believes natural processes as opposed to man-made carbon dioxide emissions are the cause of global warming, reports Sky News. This marks a major change from a similar poll commissioned by YouGov just two years ago, which showed only one in 14 expressing a belief that human activity is not responsible for climate change. The Sky Data poll evidencing doubt in man-made climate change is badly-timed for Prime Minister David Cameron and another 150 or so world leaders due to attend the United Nations COP21 summit in Paris. One of the aims of the summit is to push for concrete commitments to big cuts in greenhouse gas emissions. In order to achieve the stated UN aim of limiting the rise in average global temperature to 2C, it is projected that worldwide emissions will have to be cut by 40-70 per cent by 2050, and by 100 per cent by the end of the century. However, the survey suggests Mr Cameron will struggle to sell any resulting climate deal to Britain, especially if it increases household bills. 54 per cent of the British public oppose so-called ‘green