Anyone paying attention these last few years will have noticed that global warming denial simply isn’t a rational phenomenon. And it’s not just that if there were any reason involved, then denial it would have decreased in prevalence—rather than increased—as climate science grew more firm and certain over the past two decades.

No: It’s much more than that. It’s that so many climate deniers are, let’s face it, angry. Try talking about the issue on the radio sometime. Get ready for them to call in, ready to argue with you.

Now there’s new scientific evidence documenting this emotional aspect of climate denial. In a new paper in Risk Analysis designed to tap into the “affective” component of the climate issue, Yale’s Nicholas Smith and Anthony Leiserowitz report on four separate studies of the public’s emotional associations related to climate change, conducted from 2002 to 2010.

In the surveys, people were asked about the first “word,” “thought,” “image,” or “phrase” that popped into mind in association with global warming. It was the analysis of these rapid fire responses that showed a steep increase in emotional climate denial. As Smith and Leiserowitz put it:

Several significant trends in Americans’ associations with “global warming” over time were identified. Perhaps most notable was the large increase in the proportion of naysayer images (e.g., “hoax”). The proportion of naysayer images rose from less than 10% in 2002 to over 20% of total responses in 2010.

And even as such denier associations increased, associations involving climate impacts like melting ice and sea level rise declined over the same period (though associations related to “disasters” also increased somewhat).  

Fascinatingly, the study also looks more closely at the various associations made by the deniers.

By the year 2010, Smith and Leiserowitz report, 23 % of all global warming associations involved naysaying or denial. And upon breaking it down, they found that the biggest proportion of the naysayers were, basically, conspiracy theorists a la Rick Santorum and James Inhofe:

Associations with conspiracy theories (e.g., “the biggest scam in the world to date”) accounted for the largest portion of 2010 naysayer images with over 40% of total responses for this category. This was followed by flat denials that global warming exists (e.g., “there really is no such problem”), belief that global warming is natural (e.g., “it is a natural occurrence”), and references to media hype (e.g., “media is taking it way too far”). Finally, several respondents doubted the reliability of climate science (e.g., “unscientific theory”).

In other words, there has been an overall “Inhofication” of climate denial—more and more deniers now associate with Inhofe’s absurd 2003 claim that global warming is the “greatest hoax ever perpetrated” against the U.S. public.

Moreover, it’s an emotional Inhofication. According to the Smith-Leiserowitz study, the conspiracy theorists were the most emotional of all the deniers:

Mean affect scores for these naysayer image categories also reveal that most of these skeptical and cynical images associated with global warming evoked negative connotations for these respondents. Associations with conspiracy theories and hype evoked the most negative affect, whereas flat denials evoked the least negative affect.

There are plenty emotions on the other side of the issue too, of course. For those who perceive global warming in an “alarmist” or catastrophic fashion, negative emotion also pervades (though to a very different effect).

Nevertheless, this study reinforces something I’ve been arguing for a long time—trying to “debate” with a global warming denier today is really a fool’s errand. This issue is affecting people emotionally, on a gut level, and probably most of all for those who believe that “big government” and “global environmentalists” are pulling the wool over our eyes.

Yes, they’ll make scientific assertions to back up their denial. But if you think it’s really about science, then at this point you’re ignoring a mountain of it.