Does partisan politics distort the representation of climate change expertise in U.S. policymaking? To examine this question, we classify each Congressional witness who testified on climate change between 1997 and 2016 in terms of both their expert credentials and their climate change beliefs. In contrast to prevailing wisdom, we find that Republicans are slightly more likely to call credentialed experts than Democrats. However, this pattern is largely driven by the presence of credentialed contrarians, i.e., experts who have contradicted widely accepted conclusions of their own community. Although these individuals represent less than one percent of climate change experts outside of Congress, they account for over a quarter of expert testimonies in Congress. More generally, these findings illustrate how politicians at odds with the expert community can strategically and repeatedly select the small minority of individuals who both lend credibility to their political views and meet shared standards of professionalized expertise.