I wish to associate myself with these remarks of Jonathan Adler's, so I hope he will forgive me for the extended excerpt:
Although Christie adopted the desired policy -- withdrawing from RGGI -- some conservatives are aghast that he would acknowledge a human contribution to global warming. According to one, this makes Christie "Part RINO. Part man. Only more RINO than man." ["RINO" as in "Republican in Name Only."]
Those attacking Christie are suggesting there is only one politically acceptable position on climate science -- that one's ideological bona fides are to be determined by one's scientific beliefs, and not simply one's policy preferences. This is a problem on multiple levels. Among other things, it leads conservatives to embrace an anti-scientific know-nothingism whereby scientific claims are to be evaluated not by scientific evidence but their political implications. Thus climate science must be attacked because it provides a too ready justification for government regulation. This is the same reason some conservatives attack evolution -- they fear it undermines religious belief -- and it is just as wrong.
Writing at MichelleMalkin.com, Doug Powers warns that "if some politicians think they can swim in the waters of AGW without getting wet or soaking taxpayers, they should think again." In other words, once you accept that human activity may be contributing to global warming, embracing costly and ill-advised regulatory measures is inevitable. Yet it is actually Powers, not Christie, who is embracing a dangerous premise. As Christie's veto shows, he understands that the threat of climate change doe snot justify any and all proposed policy responses. One can believe the threat is real, and still think cap-and-trade is a bad idea. Christie's critics, on the other hand, seem to accept that once it can be shown that human activity may be having potentially negative environmental effects, this alone justifies government intervention. Yet the environmental effects of human behavior are ubiquitous. Human civilization necessarily entails remaking the world around it. So if recognizing negative environmental effects leads inevitably to governmental intervention, there is virtually no end to what government needs to do, global warming or no.
How inconvenient, then, that even the vast majority of warming "skeptics" within the scientific community would agree with Governor Christie's statement that "human activity plays a role" in rising greenhouse gas levels and resulting changes in the climate. The Cato Institute's Patrick Michaels, for instance, has written several books acknowledging human contributions to global warming. In Climate of Extremes: The Global Warming Science They Don't Want You to Know
As I've written before, it would be convenient if human activity did not contribute to global warming or otherwise create problems that are difficult to reconcile with libertarian preferences. But that's not the world we live in, and politicians should not be criticized for recognizing that fact.
I don't think that science denialism is the exclusive province of the GOP, but it's extremely disappointing whenever either side does it. As longtime readers known, I have been extremely critical of the attitude that some climate scientists seem to have developed towards dissent, and what you might call the PR aspect of their work. Nonetheless, I am quite convinced that the planet is warming, and fairly convinced that human beings play a role in this. (When you've got Reason's Ron Bailey, Cato's Patrick Michaels, and Jonathan Adler, you've convinced me). I reserve the right to be skeptical about particular claims about effects (particularly when those claims come via people who implausibly insist that every major effect will be negative) . . . and, of course, of ludicrous worries that global warming will cause aliens to destroy us. But generally, I think global warming is happening, and even that we should probably do something about that, though I'm flexible on "something."
However. Even if you disagree, it is reprehensible to have a litmus test around empirical matters of fact. (I'm not a fan of litmus tests in general, but I suppose it's fair enough to say "If you want marginal tax rates of 70% on the wealthy, you don't belong in today's GOP"). What these Republicans are doing to people like Chris Christie is no better than what Harvard did to Larry Summers when he suggested that it was possible that women had a different IQ distribution than men. Facts are not good or bad; they are correct or incorrect. And a policy based on hysterical refusal to consider all possible facts is neither good, nor correct.