Speaking as someone from outside the US who travels a fair bit and knows people from all over the place, it seems to me that only in America is the reality of global warming being meaningfully contested. Over here, anyone who claims that global warming isn't real is consigned to the lunatic fringe. (Not necesarily a reason to believe I know, but interesting nonetheless.) My guess is it has something to do with the crowd who seem to live in terror of left-wing politics ever since the cold war.