The Republican presidential race will cast a shadow over this week’s UN climate talks as President Barack Obama pledges to take action in Paris that his would-be successors have vowed to overturn. The unexpected popularity of outsiders Donald Trump and Ben Carson has entrenched the Republican party’s image as a hotbed of climate change scepticism just as some party strategists hoped it would shift to a more reasonable stance. While all the 2016 Republicans want to repeal Mr Obama’s greenhouse gas regulations, Mr Trump and Mr Carson — who lead the primary election field — stand out for the bluntness of their denials of man-made climate change. “I consider it to be not a big problem at all,” Mr Trump, the property tycoon, has said. “I think it’s weather changes.” When a cold snap loomed recently he tweeted tartly: “Man, we could use a big fat dose of global warming.” Mr Carson, a retired neurosurgeon, has said: “I know there are a lot of people who say ‘overwhelming science’ . . . There is no overwhelming science that the things that are going on are man-caused and not naturally caused.” When a panel of scientists was asked by the Associated Press to grade the accuracy of candidates’ climate statements, the only person to score lower than Mr Carson and Mr Trump was Ted Cruz, favourite of the Republicans’ Tea Party wing.