People who don’t believe that climate change is real are more likely to be old, more likely to be Republican, and more likely to be white. They are also more likely to have racist beliefs, according to a recent study published in the journal Environmental Politics. This correlation is a relatively recent phenomenon—one that occurred in the wake of Barack Obama’s election in 2008.

People who pushed Obama to take action on climate change often criticized him for being too cautious relative to the economic, environmental, and public health risks that climate change continues to pose. One example was the Keystone XL pipeline: While Obama rejected the permit to complete its northern section in 2015 (and used climate change as a justification), he approved the southern half of it back in 2012 (citing a desire to “develop as much oil and gas as we can, in a safe way”).

But the paper hypothesizes that, however moderate his actions, the mere existence of our first African American president dropping climate change into the State of the Union Address and joining the Paris climate accord correlates with a significant number of white Americans deciding that they were done believing in climate change. This correlation has also been documented with regard to health-care reform—after the Obama administration made it a priority, a subset of white Americans who had supported the issue during the Clinton administration suddenly switched their position.

“I’m not trying to make a claim in the study that race is the single most important or necessarily a massive component of all environmental attitudes” says Salil Benegal, the study’s author, who teaches political science at DePauw University. “But it’s a significant thing that we should be looking out for.”

Benegal arrived at this conclusion by looking at two collections of data: Pew data and data from the American National Election Studies (ANES), which interviews a national sample of voters before and after each presidential election. Since the 1960s, the ANES has collected information about what it calls “racial resentment” against African Americans (it does this by asking interviewees to rate, on a scale of one to five, how much they agreed or disagreed with four statements):

Irish, Italians, Jewish, and many other minorities overcame prejudice and worked their way up. Blacks should do the same without any special favors. Generations of slavery and discrimination have created conditions that make it difficult for Blacks to work their way out of the lower class. Over the past few years, Blacks have gotten less than they deserve. It's really a matter of some people not trying hard enough. If Blacks would only try harder, they could be just as well off as whites.

When Benegal looked at the Pew data, he found that the percentage of white Americans who said that they believed climate change is a very serious problem declined during the Obama administration. When he looked at the ANES data, he found that white Republicans who scored at the highest level for racial resentment were over three times as likely to disagree with the statement that climate change was real than white Republicans who tested at the lowest level of the scale. A low-resentment white Republican had a 57 percent chance of disagreeing with the statement that climate change is caused by humans, while their high-resentment equivalent was 84 percent likely to do the same thing.

Before Benegal was a political scientist, he was a chemistry major. But after he graduated, he realized that he was more interested in how scientific findings were communicated and particularly why public mistrust of scientists was so high in the United States relative to other parts of the world. Climate change seemed like a perfect way to examine this strange phenomenon.

In another paper Benegal published with his former dissertation advisor, Lyle Scruggs, both found that Gallup data showed that the belief in climate change as real and caused by humans has dropped among Republican voters just in the last year. The two saw the efforts of EPA head Scott Pruitt making climate science seem like a matter of debate, rather than something that 97.1 percent of peer-reviewed scientific research agrees on, as a probable cause. Persuading Republicans to reconsider their climate opinions required the persuasion of another Republican (preferably a powerful Republican politician), rather than a scientist—further proof, to Benegal, of how policy is splitting along partisan lines.

The gap between the two parties was once not so large. Gallup polls from the late 1990s show a small gap between Democrats and Republicans in their responses to climate change. Today Democratic voters are almost twice as likely as Republicans to agree with the scientific consensus on climate change, possibly because Republican politicians are under greater pressure from donors, and other Republicans, not to acknowledge its existence.

Political messaging with racist over- and undertones has been deployed relentlessly by some politicians because appealing to prejudice and paranoia really does motivate racist, paranoid people to show up and vote. The obsession certain Republicans have with coal miners and a “war on coal” is partly due to the efforts of donors like the Koch brothers, but “there’s a racial undertone to this kind of rhetoric,” Benegal says, “because coal mining is an industry that is overwhelmingly very white.”

This mixing of racism and politics when it comes to climate change is especially dangerous because, historically, whenever racism and government get together, some truly terrible policy is the result. Making political choices without accounting for racism is how U.S. cities across the country gutted their own downtowns, how the country became the world’s largest incarcerator in the span of a few decades, and how polluting industries were allowed to migrate into nonwhite communities rather than being forced to clean up their act or shut down entirely. In the present day, racism allows state, local, and federal programs to selectively respond to the threat posed by climate change and deem some communities more worthy of help after climate disasters than others.

“There is the tendency to just read something like this and say, 'Oh well, maybe it’s not partisanship; it’s race,'” Benegal says. “But I think the important thing is to understand that racial attitudes and partisan identity are becoming more closely aligned and go hand-in-hand for an increasing number of issues. We're noticing the interactions between these factors more frequently. It's important to understand how race and partisanship are tied together on so many issues.”