Dan Farber (here) directs our attention to a study by Brad Johnson at The Wonk Room (here), which examines where all Republican candidates for the House and Senate stand on climate science and policy. All but one of the dozens of Republic candidates in the current election cycle believe that climate science is insufficient to support the adoption of any national policy to deal with climate change. That number includes some, such as John McCain, who used to believe climate science and favor a national climate policy, but have been virtually forced to recant for fear of losing primary elections. The one outlier, incumbent congressman Republican Mike Castle of Delaware, was just defeated in the Delaware primary by a "Tea Party" candidate endorsed by Sarah Palin.
Just to be clear about this: virtually all (that is, way over 90% of) climate scientists and economists agree that the science unambiguously points to the need for some immediate action to reduce greenhouse gas emissions, for instance by raising prices of fossil fuels (either through taxes or quantity-based regulations). But the hyper-partisan politics that currently reigns in the US has led 100% of (surviving) Republican candidates to deny the need for sensible climate policies and, either expressly or by implication, climate science.
Upton Sinclair was surely right when he wrote, “It’s hard to get a man to understand something when his income depends on him not understanding it.” In the case of Republican candidates, it's clear that their political futures depend on not understanding the clear implications of climate science.