There is nothing at all inherently political about climate science. For instance, the infrared energy absorption and emission characteristics of carbon dioxide are not affected by the political affiliation of whomever emits it. Unforunately though we seem to be entering a frightening period where one of the major political parties in this country, the Republicans, are making a litmus test out of the refusal to address the threat wrought by human activities that are altering the climate.
The Wonk Room reported during the election season on the detachment from reality of GOP candidates for the US House of Representatives, the US Senate, and governorships.
The only big tent these days in the GOP is in the variety of denial and excuses to do nothing about climate change. One can claim that there is no warming, that there is warming but it is due to some unexplained natural cycle, that there is warming but it is due to some cause that scientists have already conclusively ruled out, that climate change is simply not understood, that climate science is some sort of conspiracy to push a political agenda, etc. So there are a lot of accepted ways to get there, but the end result must be to parrot the accepted rhetoric like "cap-and-tax" and "job-killing regulations" and to oppose action to reduce greenhouse gas emissions.
A prominent example of the devolution of the Republican party into anti-science ideology when it comes to climate is Senator John McCain. Despite claims to the contrary, the science has steadily solidified and confirmed our understanding of how human activities are altering climate. Yet in the last several years McCain has gone from "unequivocally" holding that global warming is real and pushing for cap-and-trade legislation to reduce greenhouse gas emissions to questioning the science and dismissing serious action to maintain a livable climate.
To reiterate, climate science is not a political issue. Being a Democrat does not make one right on the issue. One need look no further than do-nothing local outgoing Representative Earl Pomeroy and West Virginia Governor and Senator-elect Joe Manchin. But the Democratic party has at least not systematically bought into and become a mouthpiece for the misinformation and contrived controversy driven by polluting industries, political thinktanks, and simply ignorant individuals and groups.
Why has the Republican party abandoned not only the environmental legacy of Theodore Roosevelt but also the more recent accomplishments on environmental issues of Richard Nixon? There is no one simple answer. But important factors from the last few decades are a growing canonization of free market ideology and demonization of government action to address societal problems. An inflection point within the last few years is likely An Inconvenient Truth, the documentary that centers on the climate science slideshow of Al Gore, a figure widely loathed by the political right.
On a general and more visceral level, there seems to be a paranoia about a 'taking away what is mine.' This permeates many other issues from taxes ("spread the wealth") to immigration (fear of illegal aliens taking jobs and benefits). When it comes to addressing climate change the protests include things like that environmentalists want to make everyone live in caves and that shifting away from fossil fuel use or putting a price on carbon pollution is only a reach into people's pocketbooks.
I plan to explore the psychology of it further in the future, but to close out for now I will restate the main point. A major political party is disregarding an entire field of science. What if various food industries challenged long-established science and refuted connection between diet and health, then politicians across the board in a major party started pushing the same misinformation? Eat, baby, eat! Gorging yourself mean more demand and thus more jobs! There may be short-term political gain in divorcing from physical reality like that, but the negative impacts will cost everyone as time goes by.