Thursday, August 13, 2015

Study: literally looking at a single pie chart increases support for action on climate change

Ah, climate change policy. Forever frozen in a political standoff, impossible to move toward a consensus. Or is it?

Today I came across this study on PLOS via a link from the Times. As with most scientific papers, the core message is obscured by technical details and jargon (Gateway Belief Model??), but the takeaway is simple and powerful: inform people of the overwhelming scientific consensus that human-caused climate change is real, and their belief in that consensus, along with support for public action, increases. Democrats and Republicans alike. Voila!

The method of the experiment, likewise, was really basic. Step 1: ask people what their estimation of the state of the scientific consensus is around climate change (only 12% accurately put the consensus above 90% on initial questioning) along with a few other simple questions—whether they're worried about it, whether they support public action, etc. Step 2: inform them of the actual scientific consensus (via one-sentence script, pie chart, or convoluted metaphor). Step 3: repeat step 1.

I'm surprised this paper hasn't received more press, precisely because most of what you read about political opinions (not that this issue is actually political, of course!) suggests that you can't change people's mind on charged topics: people filter new information to confirm what they already believe and even harden their views in the face of conflicting evidence. I feel like I'm constantly barraged by articles in the media about the impossibility of shifting anyone's attitudes on any important, consequential topic by supplying information.

Take this recent example of an experiment about people's attitudes toward gay marriage. The study got a ton of attention because everyone was so shocked that talking to people (appeared to) succeed in shifting their attitudes on gay marriage. This American Life did a whole show about it! The study's conclusions were also really narrow: only protracted, personal and empathetic conversations were effective in changing people's views (as opposed to reading a prepared script or set of facts). Furthermore, it turned out the entire dataset was fabricated, so it's possible no one's views changed at all.

That's why this climate change study is really encouraging, and kind of shocking. Caveats: it's just one experiment and the results, while robust, are modest (4 point mean increase in people's belief, on a scale of 1-100, that humans are causing the climate to change, and 1.7 point mean increase in people's belief that people should be doing more to reduce climate change). Still, that's pretty good for one sentence, pie chart, or metaphor.

What's going on? Are people more open to new facts and shifting their views than previous research suggests, or is climate change different from other political issues associated with complete and utter intransigence like abortion, evolution in education, gun control, etc?

I'm guessing it's a little of both, but mostly the latter. Unlike abortion, evolution, or gay marriage, climate change denial isn't a result of core philosophical or theological beliefs, even loosely defined. It's not even a longstanding political divide (the first President to propose cap and trade climate legislation was George W Bush). Which suggests that elite political opposition to climate change policy, far from an inevitable result of climate change denial, may actually be a principal cause. That, at least, is the simplest explanation for people's ignorance of the scientific consensus in the first place.

So, ya know, in case you were wondering:


  1. But see also and .

  2. Hi, there, Mr. Frank Ch. Eigler! I don't know whether your motivations are innocent or nefarious, but I'm guessing you're in the "exposure to evidence only hardens views" camp based on the false and misleading information contained in the links you've shared! Nevertheless, for the skeptical and un-hardened reader, I will correct some of the most egregious falsehoods; for a complete and comprehensive rebuttal, I refer readers to a real and reputable climate science blog like skeptical science (

    First and most importantly, the "97% consensus study" authors not only rated the papers involved themselves (in phase 1), but also elicited self-reported ratings in a second phase, with the same level of consensus reached. (Readers can see the abstract at which details this process pretty clearly). Secondly, meteorologists are not climate scientists, so I'd go with Cook et. al's methods. Not that any of that really matters, since a 52% that the oceans will all be made of acid in 100 years should probably be enough to move us to action anyway.

    And while some of the commentary in the second link is reasonable regarding the effectiveness/non-effectiveness of consensus messaging, some of the other stuff in there is just plain false, for instance when claiming that the consensus-message study didn't move people's own opinions about the causes of climate change, but only moved their self-reported estimation of the scientific consensus. Again, follow the link to the research, and you'll see that that's just wrong.

  3. Hi Sam. I hadn't personally taken a close look at the Cook paper & supplementary data before tonight. But if the 97% number is really dependent on counting even the type-3 "implicit endorsement" level of support as part of the "consensus" (and it's 75% of that 97% all by itself), maybe it's not that strong a claim. AIUI, some skeptic types would agree that humans could be partly a cause, and thus could author / agree-with type-3 papers. If so, then the "consensus" as defined by Cook et al. does not discriminate between the AGW true-believers and these skeptics.

    It may also be noteworthy that the stated 97% is of -abstracts-, not -scientists-.

  4. (Plus the 97% is "amongst decided voters" only, i.e., of that 33% of papers that appeared to express an opinion on the AGW topic at all.)

  5. Okay, you're right, it's of papers, not scientists, but isn't that probably a better measure of consensus? After all, people come along with all sorts of quirky beliefs/biases, but it's much more difficult to get that biased belief—at least if it's false—represented in peer-reviewed research, at least in the "hard"-er sciences.

    Also note again that in phase 2, the self-rating phase, it was 65.5% that expressed a position on AGW, of which 97% endorsed the consensus view.

    Again, I would refer readers (and you, though sounds like you've probably been here) specifically here:

    and here: