fundamentally different approaches to the fields. Once you cut through the crap, global warming is studied by the scientific method, and conclusions are drawn based on the interpretation of available data. Reasonable scientists can come to different conclusions, but generally a majority opinion emerges. There will always be contrarians (witness the vocal minority that claim HIV has nothing to do with AIDS), but for most topics there is a consensus. Of course the bigger the problem, the more complex, the more difficult the studies, and the more open to interpretation. You have humans studying nature. Humans are ridiculous, nature isn't, so you have a 50% chance of getting it right
Politics is humans studying humans. 0% chance of getting it right. By its nature politics is designed to influence and coerce. So to try and introduce logical thinking pretty much runs against the grain of the whole enterprise.