Climate change deniers are quite analogous to those who didn’t believe (and even today some still don’t believe) tobacco causes lung cancer crowd. Some of the original talking points were, 1) there are no biological data to support a mechanism, 2) why do most people who get lung cancer smoked for 20 years or more? In other words, if I start smoking today why don’t I get lung cancer today? 3) And finally, my favorite, there hasn’t been a randomized controlled trial to prove the association.