It is strange that Americans dedicate a single month to black history. As so many have noted, black history is American history. It is impossible to understand the social, economic or political structure of the United States without also grappling with the history of African-Americans.

Martin Luther King Jr. illustrated this fact in a 1965 speech on the steps of the Alabama state capital, in which he explained how segregation shaped the broader class struggle. Toward the end of Reconstruction, King said, poor Southerners, both white and black, began to unite against the wealthy elite.

“To meet this threat, the southern aristocracy began immediately to engineer this development of a segregated society,” with the aim of dividing the working class, he said. The result was that when the white man’s “wrinkled stomach cried out for the food that his empty pockets could not provide, he ate Jim Crow, a psychological bird that told him that no matter how bad off he was, at least he was a white man, better than the black man.”

As King made clear, institutionalized racism was used to get poor white Southerners to line up behind wealthy, white elites. The study of black history illuminates a key fact about the broader class struggle in the United States. Ideologies of ignorance — racism, xenophobia, even climate change denial — are used to divide the working class.

The climate movement would do well to learn this lesson. The continued burning of coal, oil and gas will enrich fossil fuel companies, while working-class Americans will pay the rising cost of climate change. Climate denial, like racism, is a plutocratic farce, a way to hoodwink Americans into handing over their retirement to ExxonMobil. Rather than treat climate denial as a matter of science, advocates should treat it as a matter of justice, acknowledging, as Dr. King did, how ideologies of ignorance buttress the interests of the wealthy elite.

Racism was cultivated to build support for plutocratic policies.

It would be a mistake to think of racism, as we understand it today, as a natural response to observed physical differences. Racism ideologies emerged in the modern era to justify slavery. European planters targeted West Africans for their resistance to malaria, which plagued the New World, and they propagated racist myths of black pathology to win support among the white working class.

As Howard Zinn writes in A People’s History of the United States, “Only one fear was greater than the fear of black rebellion in the new American colonies. That was the fear that discontented whites would join with black slaves to overthrow the existing order.” The answer was to sow racial division. To prevent white indentured servants from joining with enslaved Africans slaveholders elevated the standing of the former group.

The poor, white Southerner should have opposed slavery, given that the abundance of free labor deprived him of work, but his place in the racial hierarchy kept him aligned with white elites and made enslaved Africans the subject of his contempt. “To these Negroes he transferred all the dislike and hatred which he had for the whole slave system,” wrote W.E.B. DuBois. “The result was that the system was held stable and intact by the poor white.”

This is not to say that working-class white Americans did not benefit materially from slavery — free labor, for example, dramatically lowered the cost of cotton, underwriting textile production in the Northeast, which created manufacturing jobs. This is only to say that racism was used to enforce the class hierarchy by dividing white and black Americans who might otherwise have common cause. Over time, racist ideas became self-animating, and racist ideology became entrenched in American life. More than 150 years after the abolition of slavery, African-Americans continue to face discrimination on the streets, in the office, and at the ballot box.

Climate denial was cultivated to build support for plutocratic policies.

Like racism, climate change denial has been deployed to win working-class support for policies and practices that benefit monied interests — namely, fossil fuel companies. Certainly, coal miners and oil drillers will benefit in the short term from our continued reliance on fossil fuels, as will Americans filling their cars with cheap gas, but over the long-term, climate change will erode the health, security and prosperity of people everywhere.

Rising temperatures threaten to weaken the girders that uphold human civilization — reliable growing seasons, stable sea levels, relatively placid weather. At the current rate, humanity is heading for a level of warming that climate scientist Kevin Anderson has called “incompatible with an organized global community.” The wealthy few will be best insulated against the coming catastrophe, while the working class will fare the worst.

This is hardly news. For decades, fossil fuel firms perpetuated climate change denial, despite their own research showing that carbon pollution was tempting an environmental cataclysm. The broader conservative movement willingly embraced climate denial, viewing climate policy as a threat to free-market ideology championed by right-wing think tanks, pundits and politicos. As Naomi Klein writes in This Changes Everything, “If the dire projections coming out of the IPCC are left unchallenged, and business as usual is indeed driving us straight toward civilization-threatening tipping points, then the implications are obvious: the ideological crusade incubated in think tanks like Heartland, Cato, and Heritage will have to come to a screeching halt.”

In recent years, many fossil companies have touted a more enlightened view. Several oil companies publicly support a carbon tax, for example. At this point, however, the damage is done. Like racism, climate denial has taken on a life of its own. Among conservatives, one’s views on climate change have become a litmus test for ideological purity. Egged on by right-wing donors, think tanks and talking heads, conservative politicians have little choice but to publicly deny climate science. This, in turn, is reinforcing climate denial among conservative voters.

“Conservative elites have made climate denialism part of conservative identity,” writes David Roberts in Vox. “Conservatives will accept the scientific facts of climate change when conservative elites signal that that’s what conservatives do — when they demonstrate trust in the institutions of climate science. When that happens, there will be no particular grassroots resistance, because there’s no particular commitment to climate denialism outside its role in the culture war.”

This is a key difference between racism and climate change denial. The former is sewn into the fabric of American life, the product of centuries of oppression, subjugation and division. The latter is a feature of political tribalism. But climate denial is becoming more deeply entrenched on the political right, as a sign of one’s tribal loyalties.

Like racism, climate denial also signals a commitment to the existing social order. Researchers have shown that both ideologies are associated with a hierarchical view of the world, of a desire to protect the interests of the powerful. Consistent with these findings, a recent study found a tentative link between racial resentment and climate change denial.

Advocates win by showing how ideologies of ignorance hurt the working class.

Many progressives have failed to engage with racism head on. Instead of responding to the racist appeals of their opponents, they focus on pocketbook issues like stagnant wages and rising healthcare costs. But recent research shows that it is more effective for progressives to talk explicitly about race, to explain how racism is used to buoy support for plutocratic policies.

In one study, researchers passed out campaign flyers to voters in Minnesota: one flyer for a conservative candidate who called for tax cuts and warned of “criminal and illegal aliens,” and one of two flyers for a progressive candidate. The first flyer for the progressive candidate described a liberal economic agenda and made no mention of race, while the second described how conservative politicians were using race to divide the working class. The second flyer earned significantly more support for the progressive candidate. As the researchers wrote in The Washington Post, “The key is to make explicit how racism oppresses people of color while serving as a weapon for a greedy few to keep the rest of us from uniting.” A second study, using a different methodology, produced similar findings.

The lessons could apply equally to climate change denial. People largely distrust fossil fuel companies. So, rather than respond to attacks on science with facts and figures, advocates should underscore the fact that climate denial is used to protect monied interests at the cost of Americans’ health and safety. They should call out fossil fuel companies for their role in spreading ignorance.

As King said, “There is little hope for us until we become tough-minded enough to break loose from the shackles of prejudice, half-truths, and downright ignorance. The shape of the world today does not permit us the luxury of soft-mindedness.”

Jeremy Deaton writes for Nexus Media, a syndicated newswire covering climate, energy, policy, art and culture. You can follow him @deaton_jeremy.