More or less the remarks I delivered yesterday at Earthday "Climate teach in/out" at Yale University:

I study risk perception and science communication.

I’m going to tell you what I regard as the single most consequential insight you can learn from empirical research in these fields if your goal is to promote constructive public engagement with climate science in American society.

It's this:

What people “believe” about global warming doesn’t reflect what they know; it expresses who they are.

Accordingly, if you want to promote constructive public engagement with the best available evidence, you have to change the meaning of the climate change.

You have to disentangle positions on it from opposing cultural identities, so that people aren't put to a choice between freely appraising the evidence and being loyal to their defining commitments.

I’ll elaborate, but for a second just forget climate change, and consider another culturally polarizing science issue: evolution.

About every two years, a major polling organization like Gallup issues a public opinion survey showing that approximately 50% of Americans “don’t believe in evolution.”

Pollsters issue these surveys at two-year intervals because apparently that’s how long it takes people to forget that they’ve already been told this dozens of times. Or in any case, every time such a poll is released, the media and blogosphere is filled with expressions of shock, incomprehension, and dismay.

“What the hell is wrong with our society’s science education system?,” the hand-wringing, hair-pulling commentators ask.

Well, no doubt a lot.

But if you think the proportion of survey respondents who say they “believe in evolution” is an indicator of the quality of the science education that people are receiving in the U.S., you are misinformed.

Do you know what the correlation is between saying “I believe in evolution” and possessing even a basic understanding of “natural selection,” “random mutation,” and “genetic variance”—the core elements of the modern synthesis in evolutionary science?

Zero.

Those who say they “do believe” are no more likely to be able to give a high-school biology-exam-quality account of how evolution works than those who say they “don’t.”

In a controversial decision in 2010, the National Science Foundation in fact proposed removing from its standard science-literacy test the true-false question “human beings developed from an earlier species of animals.”

The reason is that giving the correct answer to that question doesn’t cohere with giving the right answer to the other questions in NSF’s science-literacy inventory.

What that tells you, if you understand test-question validity, is that the evolution item isn’t measuring the same thing as the other science-literacy items.

Answers to those other questions do cohere with one another, which is how one can be confident they are all validly and reliably measuring how much science knowledge that person has acquired.

But what the NSF “evolution” item is measuring, researchers have concluded, is test takers’ cultural identities, and in particular the significance of religiosity in their lives.

What’s more, the impact of science literacy on the likelihood that people will say they “believe in evolution” is in fact highly conditional on their identity: as their level of science comprehension increases, individuals with a highly secular identity become more likely to say “they believe” in evolution; but as those with a highly religious identity become more science literate, in contrast, they become even more likely to say they don’t.

What you “believe” about evolution, in sum, does not reflect what you know about science—in general, or in regard to the natural history of human beings.

Rather it expresses who you are.

Okay, well, exactly the same thing is true on climate change.

You’ve all seen the polls, I’m sure, showing the astonishing degree of political polarization on “belief” “human-caused” global warming.

Well, a Pew Poll last spring asked a nationally represented sample, “What gas do most scientists believe causes temperatures in the atmosphere to rise? Is it carbon dioxide, hydrogen, helium, or radon?”

Approximately 60% got the right answer to that question.

And there was zero correlation between getting it right and being a Democrat or Republican.

The percentage of Democrats who say they “believe” in global warming is substantially higher than 65%: it’s over 80%, which means that a good number of Democrats who say they “believe” in global warming don’t understand the most basic of all facts known to climate science.

The percentage of Republicans who say they don’t believe in global warming is a lot lower than 65%. Only about 25% say they believe human beings have caused global temperatures to rise in recent decades, according to Pew and other researchers.

That means that a large fraction of the Republicans who tell pollsters they “don’t believe” in human-caused global warming do in fact know the most important thing there is to understand about climate change: that adding carbon to the atmosphere causes the temperature of the earth to increase.

Do you know what the correlation is between science literacy and “belief” in human-caused global warming?

You get half credit for saying zero.

That’s the right answer for a nationally representative sample as a whole.

But it’s a mistake to answer the question without dividing the sample up along cultural or comparable lines: as their score on one or another measure of science comprehension goes up, Democrats become more likely, and Republicans less, to say they “believe” in human-caused global warming.

Like saying “I do/don’t believe in evolution,” saying I “do/don’t believe in climate change” doesn’t convey what you know about science—generally, or in relation to the climate.

It expresses who you are.

Al Gore has described the climate change debate as a “struggle for the soul of America.”

He’s right.

But that’s exactly the problem. Because in “battles for the soul” of America, the stake that culturally diverse individual have in forming beliefs consistent with their group identity dominates the stake they have in forming beliefs that fit the best available evidence.

In saying that, moreover, I’m not talking about whatever interest people have in securing comfortable accommodations in the afterlife. I’m focused entirely on the here and now.

Look: What an ordinary individual believes about the “facts” on climate change has no impact on the climate.

What he or she does as a consumer, as a voter, or as a participant in public debate is just too inconsequential to have an impact.

No mistake that individual makes about the science on climate change, then, is going to affect the risk posed by global warming for him or her or for anyone else that person cares about.

But if he or she takes the “wrong” position in relation to his or her cultural group, the result could be devastating for her, given what climate change now signifies about one’s membership in and loyalty to opposing cultural groups.

It could drive a wedge—material, emotional, and psychological—between individual the people whose support are indispensable to his or her well-being.

In these circumstances, we should expect a rational person to engage information in a manner geared to forming and persisting in positions that are dominant within their cultural groups. And the better they are at making sense of complex information—the more science comprehending they are –the better they’ll do at that.

That’s what we see in lab experiments. And it’s why we see polarization on global warming intensifying in step with science literacy in the real world.

But while that’s the rational way for people to engage information as individuals, given what climate change signifies about their cultural identities, it’s a disaster for them collectively. Because if everyone does this at the same time, members of a culturally diverse democratic society are less likely to converge on scientific evidence that is crucial to the welfare of all of them.

And yet that by itself doesn’t make it any less rational for individuals to attend to information in a manner that reliably connects them to the position that is dominant in their group.

This is a tragedy of the commons problem—a tragedy of the science communications commons.

If we want to overcome it, then we must disentangle competing positions on climate change from opposing cultural identities, so that culturally pluralistic citizens aren’t put in the position of having to choose between knowing what’s known to science and being who they are.

Only that will dissolve the conflict citizens now face between their personal incentive to form identity-consistent beliefs and the collective one they have in recognizing and giving effect to the best available evidence.

Science educators, by the way, have already figured this out about evolution. They’ve shown you can in fact teach the elements of the modern synthesis-- random mutation, genetic variance and natural selection—just as readily to students whose identities cohere with saying they “don’t believe” in evolution as you can to students whose identities cohere with saying they do. You just can’t expect the former to “I believe in evolution” after.

Indeed, you must take pains not to confuse understanding evolutionary science with the “pledge of cultural allegiance” that “I believe in evolution” has become.

You must remove from the education environment the toxic cultural meanings that make answers to that question badges of membership in and loyalty to one’s cultural group. The meanings that fuel the pathetic spectacle of hand-wringing and hair-pulling that occurs every time Gallup or another organization issues its “do you believe in evolution” survey results.

All the diverse groups that make up our pluralistic democracy are amply stocked with science knowledge.

They are amply stocked with public spirit too.

That means you, as a science communicator, can enable these citizens to converge on the best available evidence on climate change.

But to do it, you must banish from the science communication environment the culturally antagonistic meanings with which positions on that issue have become entangled—so that citizens can think and reason for themselves free of the distorting impact of identity-protective cognition.

If you want to know what that sort of science communication environment looks like, I can tell you where you can see it: in Florida, where all 7 members of the Monroe County Board of Commissioners -- 4 Democrats, 3 Republicans -- voted unanimously to join Broward County (predominantly Democratic), Monroe County (predominantly Republican), and Miami-Dade County (predominantly Republican) in approving the Southeast Climate Compact Action plan, which, I quote from the Palm Beach County Board summary, “includes 110 adaptation and mitigation strategies for addressing seal-level risk and other climate issues within the region.”

I’ll tell you another thing about what you’ll see if you make this trip: the culturally pluralistic, and effective form of science communication happening in southeast Florida doesn’t look anything like the culturally assaultive "us-vs-them" YouTube videos and prefabricated internet comments with which Climate Reality and Organizing for American are flooding national discourse.

And if you want to improve public engagement with climate science in the United States, the fact that advocates as high profile and as highly funded as that still haven’t figured out the single most important lesson to be learned from the science of science communication should make you very sad.