Patrick Crusius worried that Texas — hot and dry and facing climate calamity — was being overrun by immigrants. For his entire life he’d watched as Allen, Texas, the upper-middle-class Dallas suburb where he grew up, more than doubled in size, with quick-built mansions and car-choked freeways. Crusius, 21 years old, with wavy dark brown hair, sparse stubble collecting on his round chin, was awkward and introverted. He spent eight hours a day on his computer. He learned to hate the influence of megacorporations and the culture of consuming cheap goods that he thought they fostered, and he detested the waste and pollution that came with it. He brooded over the dwindling supplies of clean water and that too many people were competing for too little of it. But more than anything he had come to hate Hispanic migrants, who had turned his overwhelmingly white town into a nearly-half ethnic one. He wanted to keep them out. “#BuildTheWall is the best way that @POTUS has worked to secure our country so far!” he tweeted in 2017. In a world of constraints and an environment under stress, why should he have to share with them?

Crusius bought a semiautomatic rifle online and 1,000 rounds of hollow-point 7.62 x 39 mm ammunition. On Aug. 3, 2019, he got into his gray Honda Civic and drove nearly 10 hours toward El Paso, Texas. Entering the city, he turned into the Cielo Vista Walmart Supercenter parking lot. By some accounts, he wanted a snack, but after briefly going into the store filled with Hispanic shoppers, he returned to his car, posted a vitriolic 2,400-word manifesto to the extremist social media site 8chan and got the gun. He shot 45 people, ultimately killing 23, eight of them Mexican citizens. “This attack is a response to the Hispanic invasion of Texas,” Crusius wrote. “I am simply defending my country from cultural and ethnic replacement brought on by an invasion.”

In his manifesto, which he titled “The Inconvenient Truth” — a seeming nod to Al Gore’s documentary about the climate crisis — he wrote that “water sheds around the country, especially in agricultural areas, are being depleted.” Americans would never change their habits of consumption, he asserted, but new immigrants would only consume more, rising to this country’s standard of living and expanding the net environmental burden on the world. “Urban sprawl creates inefficient cities which unnecessarily destroys millions of acres of land,” he continued. “If we can get rid of enough people, then our way of life can become more sustainable.”

I arrived at the Cielo Vista Walmart three weeks later to find flowers and pictures and memorials adorning a quarter-mile chain-link fence erected around the store’s perimeter and a city still in shock. I had been investigating climate change as a new driver of both large-scale migration around the world and of potential conflict. Traveling through the mountains of Guatemala, El Salvador and Mexico, I heard accounts of migrants suffering shortages of food and climate-driven despair that had forced them to move. Worldwide, the number of displaced people has been climbing alongside what appears to be the rising severity of disasters, and research suggests that by later this century as much as one-third of civilization — billions of people — could be facing the kind of heat and drought that had prohibited most human settlement for thousands of years. If humankind’s uncharted venture into the hottest and most unpredictably chaotic environment in history was to be marked by a new era of global migration, how would never-ending pressure on the U.S. border weigh on the politics and divisions of this country?

Crusius’ manifesto was striking because he considered the crushing squeeze of environmental degradation — the very changes that would be amplified by climate change — on communities, but from the opposite perspective. His fear that white Americans were being replaced by an army of invaders who must be repelled seemed to me symptoms of a reactive white supremacy, exacerbated by worries over scarcity brought on by the radically changing environment.

But there was something even more significant: For a generation, conservatives — not just the far right, which Crusius appeared to identify with — had propelled the notion that climate change was a hoax fabricated so the government could impose new restrictions on the economy and society. Yet Crusius hadn’t denied climate change at all. Instead, he seemed to claim its impacts were themselves arguments justifying his violence. I wanted to understand why and, by extension, what it said about the rise and threat of American extremism as the world warms.

After El Paso I began investigating how a border crisis, rising temperatures, disasters and the swirling political reactions to them were affecting the agendas and vigilante campaigns of the far right. I spoke with dozens of actors, militia leaders, secessionists, gun-rights advocates, immigration control activists and self-identified white nationalists. I reviewed more than 14,000 pages of letters and internal documents from the anti-immigration movement.

What I found suggested that Crusius’ grievances were neither isolated nor unique. Across the country, fear and tension about environmental threats were boiling beneath the surface. The people I spoke with largely said that climate change was real and urgent. In their hands it became a weapon to justify their agendas — or at least a useful tool to expand their movements. Some were struggling under the concussions of wildfires and drought. They believe that water and land are becoming scarcer, forcing them to hoard and defend those resources. And they hold onto a nostalgic view for the way American life was in the 1950s, when there were half as many people, and nearly 90% of them were white.

One thing stood out: The roots of their sentiments lay in concerns that the United States has become overpopulated. Almost everyone I spoke with placed the blame on immigrants, holding the view, as Crusius did, that dark-skinned people from the global south are surging northward to overwhelm white Christians, what’s become known as the “great replacement theory.” For many, this argument over population and immigration had become a battle over whether Americans want to live in a diverse society.

This fall, the great replacement theory and the immigration crisis at the border have vaulted to the top of many voters’ concerns. While violence and persecution and economic opportunity remain the primary drivers pushing migrants into the U.S., the evidence increasingly also points to climate change as a growing factor. Yet immigration is still largely seen as separate from the environmental stresses contributing to it, and scrutiny of the far right has largely missed its intertwining with the climate crisis.

The gaps hint that a critical flash point of America’s political impasse may be misunderstood. The intensifying economic and environmental pressures of the warming climate are now beginning to drive new wedges into old divisions. That flash point foretells an America becoming more polarized the hotter things get, more sharply divided between its rural and urban communities and more hateful and more dangerous. It suggests we’re entering an era of climate nationalism, where the right could be poised to reclaim climate change as an issue of its own. As Jared Taylor, the white supremacist and founder of the New Century Foundation, put it when we met this year, a new wave of “eco-supremacists” is emerging.

Crusius’ manifesto, though, wasn’t just evidence of that shift. His declarations were also eerily familiar. I realized I’d read them in the archives of one man — a man who died less than three weeks before Crusius’ crime but who, decades before, foresaw this collision of climate change and nativist fears coming and used it to set the country on its precarious course, creating the most powerful anti-immigrant organizations in the country today. It was through this history — and the story of this man, a Sierra Club environmentalist, a doctor, a father — that I suspected the clues to future strife in a hotter world might be found, because the conflicts unfolding now seemed to be the fruition of his work. The more I studied Crusius’ manifesto, the more I realized that I was also reading the imprints of a ghost, the ghost of John Tanton.

—

John Tanton grew up as an all-American farm boy in an almost mythologically quaint version of America. He was tall and brawny, with leafy brown hair. In a picture probably from the late 1940s he wears a flannel shirt tucked into trousers. He played football and baseball and was a top scorer on his district-champion basketball team and took his life lessons about the natural limits of the world from the challenges of managing crop rotations in the family fields near Saginaw Bay. Tanton gravitated to science — not to the fundamentalist Evangelical United Brethren Church of his mother — and eventually studied medicine. He met his wife, Mary Lou, in 1956, brunette and pretty, wearing bobby socks at a fraternity mixer at Michigan State.

As Tanton aged, his face would square, his dark hair turning white. He often wore wire-rimmed glasses, and his jaw jutted forward, as if clenched. It was a hint of the sternness of the ideas that became his hallmark, if not his personality, which his friends described as gentle. In one interview a videographer follows him outside the home he moved to with his wife in the tiny northern Michigan town of Petoskey, where he had begun to practice as an eye surgeon. Tanton kindles a small fire of twigs inside a metal pitcher, while expounding for the camera about ecology and overpopulation. Then he gently squeezes a bellow, pouring smoke into the hives of honeybees in his garden. He took a similarly methodical approach to dismantling the notion that the United States should continue to be a beacon for immigrants.

Tanton wasn’t just a malignant force against immigration. Virtually unknown is that Tanton also had an early and lucid understanding that climate change would exacerbate the country’s immigration conundrum, and it ultimately framed his life’s work. In 1989, when climate politics was still fledgling, he warned that the effects of warming were going to prove explosive along America’s borders — and that, left unresolved, communities could disintegrate into violence. Global warming would “put strictures on the economic growth that has been the great social salve that has kept some groups, in some measure, from each other’s throats,” he told his close friend Otis Graham, the University of California, Santa Barbara, historian. “We’re entering a time when the pie is not going to enlarge as rapidly … a time when there is going to be heightened group conflict.”

Later, he declared outright that climate change, among other reasons, would require the United States to rethink its immigration policy. Deforestation and flooding in Bangladesh, the collapse of Black Sea fisheries, the desertification of sub-Saharan Africa and “a nearly endless list” of other issues, he said, would drive human migration. He imagined a future in which “resources and livable conditions are scarce. Scarcity is the rule, and requires a degree of self-interest. Population problems are beyond solution by migration. No habitable unclaimed lands remain.”

Tanton cultivated these views as patiently as he cultivated his garden. From the time he moved to remote Michigan, he brought the world to him, amassing thousands of books and corresponding with the savants who resonated the most — Garrett Hardin, the ecologist from University of California, Santa Barbara, and Richard Lamm, the environmentalist and three-term governor of Colorado, among them. They found him intellectually engaging, admired his provocative curiosity and became his friends. Some would visit Tanton, joining him on long walks in the wooded hills above the Lake Michigan shoreline and talking for hours. He organized salons. In many ways, nature became Tanton’s religion, and the mission to protect it consumed him. He co-founded one of the state’s first conservation organizations, the Little Traverse Conservancy. His friends describe him as a charismatic orator, who spoke softly and possessed wells of energy for the issues he cared about most.

Early on, the cause was reining in the world’s population — the United States’ population, in particular. Tanton began working with the group Zero Population Growth, which posited that stabilizing the number of people on the planet was the best way to save the environment, and became its national president. (With his wife, Tanton also started a local chapter of Planned Parenthood.) In 1968, Hardin wrote his essay “The Tragedy of the Commons,” which warned that population growth will outpace the gains of conservation as people overuse the planet’s resources. The same year, the Sierra Club helped publish the bestseller “The Population Bomb” by Stanford professor Paul Ehrlich and his wife, Anne, a Stanford scientific researcher, which argued that saving the planet was a numbers game.

Much of the American environmental movement shared this sense of urgency. The Union of Concerned Scientists, the National Wildlife Federation, Earth First and The Wilderness Society, among others, all published articles or ran campaigns against runaway population growth well into the late 1990s. But it was the Sierra Club, influenced by its first executive director, David Brower, that emerged as a leading proponent of the notion that the earth had a carrying capacity — that there was an optimum number for the planet’s population to be held at. Tanton, a long-standing member of the Sierra Club’s Michigan chapter, became the head of the organization’s national population committee.

Here’s where Tanton’s personal history becomes essential to understanding America’s recent resurgence of immigrant hate. Even as he built an environmental legacy, Tanton was privately thinking more and more not just about the size of the population but about how to preserve what he described as the distinctiveness of European people. In 1975, he wrote a paper titled “The Case for Passive Eugenics” and would later, in a letter to eugenicist Robert Graham, a millionaire businessman known for starting a sperm bank for geniuses, clarify his goals. “Do we leave it to individuals to decide that they are the intelligent ones who should have more kids?” he asked. “More troublesome, what about the less intelligent, who logically should have less?”

Around this time, a fundamental demographic shift occurred: New births no longer exceeded deaths in the United States. The population should have begun to stabilize, except there was a new form of growth: immigration. The population, then at around 211 million, continued to expand, and many who at first worried for the carrying capacity of the planet became preoccupied with walling off the country and keeping the global population at bay. For Tanton, “population” became a euphemism for “immigration.” With time, “immigrant” would become a euphemism for “nonwhite.” Long before the great replacement theory became a dominant strain among mainstream conservatives — nearly 7 out of 10 Republicans have said the theory had merit — Tanton, while not using those words, began to define the term. We’ve been thinking so much about “how many” come to this country, he would write, it’s time to think about “who.”

When Tanton blended ecology with eugenics and immigration, he was digging up the two-century-old principles of Thomas Malthus, who first theorized that human population growth would lead to poverty and suffering. Tanton drew on the views of some of America’s most influential environmentalists. Sierra Club founder John Muir rhapsodized about the purity of wilderness, supporting the push to protect Yosemite’s lands from the “dirty” influence of the native tribes who inhabited it. In the early 1900s, the conservationist and anthropologist Madison Grant, who helped establish Glacier National Park and the Bronx Zoo, wrote pseudoscientific tomes about the coming extinction of white people. The Nazis used some of the same references, braiding environmental purity and racial purity. Hitler himself is said to have called Grant’s book, “The Passing of the Great Race,” about European racial superiority, “my bible.”

Tanton resurrected these sentiments and dressed them in liberal arguments about sustainability. It was an environmental appeal he crafted not just in earnest — which he certainly was — but also because he thought it was one of the strongest rationales that the United States should remain predominantly white.

All of this might have remained in the realm of intellectual exploit had Tanton not begun to formalize and evangelize his beliefs. Between 1979 and 1997, Tanton launched or helped create more than eight organizations aimed at curtailing immigration or preserving English-speaking culture, building an unparalleled modern force for shaping the debate about who should and should not be allowed into the United States. Among the most prominent is the Federation for American Immigration Reform, or FAIR, which has since become one of the nation’s largest and most influential immigration control advocacy groups. In 1982, Tanton started U.S. Inc., an umbrella nonprofit created to fundraise for his initiatives. Three years later the Center for Immigration Studies was spun off from FAIR in the hope of creating a nonpartisan immigration think tank. Tanton also published and, for many years, edited The Social Contract, a magazine that served as a clearinghouse for his ideas.

He diligently befriended Cordelia Scaife May, an heiress to Andrew Mellon’s fortunes who funded forest preservation across Pennsylvania and believed in curtailing population growth, endearing himself to her with gauzy appeals. “Dear Cordy,” he wrote to her. “We should foster diversity between nations, not within them.” She gave him hundreds of thousands of dollars, and then, after her death, her Colcom Foundation, named after the bleak and satirical novel “Cold Comfort Farm,” continued to donate to Tanton’s organizations — more than $150 million.

Tanton’s belief that mass immigration would supplant white America had one particular focus: He saw it as a threat to the country’s ecology and ultimately to the consensus among environmentalists about preserving the purity of that ecology. That’s why, he thought, the immigration fight had to be taken up inside the conservation movement itself, by what is viewed as America’s most prominent environmental organization, an organization that would have the moral authority to bring difficult messages to the public. “The Sierra Club may not want to touch the immigration issue,” he wrote in a 1986 memo. “But the immigration issue is going to touch the Sierra Club!”

—

On a spring morning in 2002, the Sierra Club’s leaders gathered at the historic Ralston White Retreat, tucked between towering redwood trees on the side of Mount Tamalpais, high above the San Francisco Bay. Carl Pope, the club’s longtime executive director, was present, as was Robert Cox, the club’s former president, who still served on the board. The board had just sworn in its newest members, including an astronomy professor from the University of California, Los Angeles, named Ben Zuckerman. With curly hair receding above his broad forehead and an energetic grin, Zuckerman was effectively Tanton’s Trojan horse.

Six years earlier, the club’s board had declared the club neutral on issues of immigration. To a sizable portion of members, the decision was an abomination, and it provoked a mutiny. A faction formed a splinter group called Sierrans for U.S. Population Stabilization, or SUSPS, and assembled a roster of notable supporters including the Harvard evolutionary biologist E.O. Wilson. Tanton offered thousands of dollars to fund the group’s efforts, but it was Zuckerman who led the charge. In 1998, he and the SUSPS members pushed an initiative that would be put to a membership vote: Should the Sierra Club formally stand against immigration, because it was a stand against population growth and environmental decline? “They wanted to be able to say, ‘This is not just a conservative cause, this is a liberal cause as well,’” Pope told me.

The Sierra Club fractured under the weight of the debate. Sixty percent of the club’s members rejected the initiative, but tens of thousands of members voted for it, demonstrating the reach of Tanton’s worldview. Brower himself soon resigned from the Sierra Club board in protest over what he saw as its refusal to consider immigration’s effect on population growth.

One afternoon shortly after the vote, members of the splinter group gathered outside of San Francisco, hiking through the chaparrals of the San Bruno hills, and plotted what to do next. They recognized that the club’s direct democratic process — and its annual elections of three members of its 15-person board — was a vulnerability, and they assembled the first stages of a plan: a hostile takeover. It would take several years of quiet, painstaking work, and it would begin with Zuckerman’s ascent.

Zuckerman maintains that Tanton was not the mastermind behind the Sierra Club effort. But he worked closely with Tanton’s protégé Roy Beck and attended national gatherings of Tanton-affiliated groups. He even visited Tanton at his Michigan home. Through these years, Zuckerman was also the vice president of a separate Tanton-aligned organization called Californians for Population Stabilization, which had received funding from the Pioneer Fund, a far-right political group known for its support of eugenics.

That morning in Mill Valley in 2002 was the moment of Zuckerman’s success. Throughout his campaign, Cox told me, Zuckerman had downplayed his anti-immigration views, and he had succeeded in quieting his opponents. But once Zuckerman was sworn in, Cox said, he began pressing the immigration question again. “He hid his agenda,” Cox told me. Just weeks later — despite a new board policy forbidding him from advocating on immigration issues — Zuckerman railed against the club’s co-directors in an interview with the Los Angeles Times Magazine, saying they can’t “save species and wetlands and so on when there are a billion Americans.” Later that summer he led a discussion about population and the border at a board retreat in Michigan, and at the next board meeting, according to the minutes, he continued to press the issue, saying that “immigration drives us to higher fertility.”

Zuckerman, like others involved with the early argument that population growth was a threat to the environment, vehemently denied prejudice against immigrants and did not advocate violence. He maintains that his work always arose from a genuine concern that more people will place an unsustainable burden on the planet. “You should not stop doing the right thing for the right reasons because somebody else is doing the right thing for the wrong reasons,” he told me. Nonetheless, he found common cause with people who prioritized race and eugenics.

The following year more board members were elected who were sympathetic to the anti-immigration cause, and the SUSPS members found themselves within reach of the votes to command the organization. The plan was for Lamm, who was chair of FAIR’s advisory board, and Frank Morris, who was on the Center for Immigration Studies board, to run for seats in 2004, along with a Cornell University environmental scientist named David Pimentel, who had written extensively for The Social Contract.

This was a period in which Tanton himself was veering in an increasingly extremist and overtly racist direction. He published an English translation of “The Camp of the Saints,” a French novel written by Jean Raspail. The plot centers on thousands of impoverished Indian farmers who commandeer a fleet and sail, dirty, uncivilized and desperate, to France, where a small resistance is all that stands in the way from their overrunning the country. It would become a treatise for the far right and help solidify the great replacement theory into popular discourse.

U.S. Inc. provided financial support for Peter Brimelow, a former Forbes journalist, to write “Alien Nation” — a book Tanton helped edit and that would go on to shape the white supremacy movement. Brimelow, who refers to himself as a civic nationalist, then launched a website devoted to discussions of racial identity, which he called VDare, after Virginia Dare, supposedly the first English baby to be born on American soil. Brimelow received a list of questions for this article but declined to comment.

Tanton was also drawing closer to Jared Taylor, whose writings about the superiority of white people had earned him a zealous following. Taylor had become a regular at Tanton’s salons, which were growing into an annual conference with dozens of prominent anti-immigration activists meeting at a Marriott hotel outside of Washington, D.C. Tanton admired Taylor’s 1992 book about the failure of affirmative action to fix race relations. When Taylor would later publish “White Identity,” warning that white people will be marginalized by other races if they do not defend themselves, Tanton would write to him: “You are saying a lot of things that need to be said.”

As the campaign for the votes of the Sierra Club’s 750,000 members grew more rancorous, Zuckerman sent board members an article from Brimelow’s VDare, about how Latinos were spreading disease and crime and that “Hispandering” politicians were encouraging it, Cox recalled. (Zuckerman acknowledged the article was from “a right-wing” site but told me he did not recall it being racist.) Cox, who had never heard of VDare, dove into the site, finding a trove of pseudoscientific articles on such subjects as measuring skull sizes and comparing Northern European and African head shapes to determine intelligence. He began recognizing connections: FAIR and the Center for Immigration Studies had links to Brimelow; Lamm chaired the advisory board of FAIR, and Morris sat on the board of the center. A letter the Sierra Club received from the Southern Poverty Law Center alerted him that they all had ties to Tanton. For the first time, Cox and Pope both saw that the internecine battle appeared coordinated. “It was like, ‘Oh my fucking God.’” Pope told me. “I mean it moved from a five-alarm fire to nuclear war.”

Old guard members of the board began to campaign against Tanton’s proxies. While the Southern Poverty Law Center publicly branded the takeover attempt as racist, news broke that a wealthy California investor, David Gelbaum, had pledged $100 million on the condition that the club never stand against immigration. The internal election spilled into public view, with an op-ed appearing in The New York Times, and 13 of the club’s past presidents wrote an open letter decrying the anti-immigrant candidates as bigots. Lamm and Pimentel are no longer alive. Morris, who is Black, called claims of racism preposterous and said it was a campaign of guilt by association. “They were trying to paint us with the Tanton stain,” he told me.

In a last-ditch effort, Tanton’s network began its own efforts to whip votes. In the fall of 2003, The Social Contract ran an ad encouraging its readers to join the Sierra Club so that they could help elect “leaders who will redirect this vital organization toward genuine environmental stewardship.” FAIR’s newsletter published the same ad. VDare encouraged its readers to “join the Sierra Club NOW and have your vote influence this debate. … The prize is enormous.”

It wasn’t enough. All three candidates lost — Lamm received just 13,000 votes — bringing an end to what Pope described as the first modern battle to bring white supremacy into mainstream America under the guise of environmentalism. It might have seemed an obscure, even parochial, battle, but America’s right wing was watching. For them, it was an epic loss, one that Ann Coulter, Tucker Carlson and others would still be mourning a decade later.

—

Having lost the backing of the Sierra Club, America’s anti-immigration movement turned more explicitly to climate change — and to one of Zuckerman’s Sierra Club colleagues, Leon Kolankiewicz, an environmental planner versed in sprawl and impact studies and a longtime proponent of the idea that the planet had a limited carrying capacity. Kolankiewicz took a job with Roy Beck, the Tanton protégé and former Washington editor of The Social Contract, who went on to found a slightly less strident “immigration reform” organization called NumbersUSA.

Kolankiewicz, for one, was fascinated by studies of the carbon legacy of families — the emerging notion that a person’s carbon footprint would multiply through generations and that the best way to reduce emissions was to have one less child. It got him thinking about the inverse: Could he quantify how much carbon increased with that extra child? If so, what was the difference between a new child born in the United States and someone arriving from abroad?

His answer helped the Tanton organizations reframe immigration squarely in global warming terms: Newcomers to the United States were making climate change worse, because as they increased their consumption here, their carbon emissions would increase, too.

It was a logical notion but shaky science. Other researchers cautioned that just because the country’s total emissions can be divided by the number of people inside its borders does not mean that each person contributes the same amount. In fact, America’s rich are responsible for an enormous proportion of the global emissions causing climate change, even as per capita emissions are rising in many other countries.

But the Tanton network pressed on anyway. In August 2008, the Center for Immigration Studies promoted Kolankiewicz’s research, publishing a joint study arguing that “immigration to the United States significantly increases world-wide CO2 emissions.” In a subsequent paper it argued that climate change was “the most important environmental challenge facing the world.” The reports began introducing the rhetoric of climate change straight into the heart of the far right’s vocabulary. Kolankiewicz told me he and Beck hoped to resurface issues of overpopulation and distinguish the fight against mass immigration from prejudice against immigrants. Both disavowed racism and violence.

But the movement seemed to be experimenting: What would happen if you took Tanton’s warnings about population and the climate and merged them with people’s fears of outsiders and paranoia about the limits of resources? What would happen if you truly turned the immigration debate into an environmental debate?

In February 2010, as Republicans gathered for the prestigious annual Conservative Political Action Conference, or CPAC, at the Marriott Wardman Park Hotel in Washington, D.C., the Center for Immigration Studies’ longtime executive director, Mark Krikorian, sat on a panel about immigration reform in front of a packed audience, along with Robert Rector from the Heritage Foundation and Steve King, the lightning-rod congressman from Iowa. Near the end of the session someone in the audience asked why the center was publishing reports about climate change if it was a hoax?

Krikorian, who declined to be interviewed for this story, offered the group a simple yet telling answer: The climate issue was a potent opportunity. He saw it as a wedge that could scare — and divide — the American left on immigration. The suggestion was that by doing so the Center for Immigration Studies would give liberals reason to support hard-line immigration controls and perhaps also offer conservatives an avenue to fold global warming into their narratives of a country under assault.

By then, the groups that Tanton had helped found had become larger than Tanton, who was in his mid-70s and diagnosed with Parkinson’s disease, and they had achieved mainstream power. FAIR created a political action committee and channeled money to up-and-coming Republicans. It hired Kellyanne Conway’s Washington firm, The Polling Company, to gauge nationwide sentiment about immigrants. NumbersUSA ran a grassroots robo-fax campaign that helped kill George W. Bush’s bipartisan immigration overhaul. FAIR’s affiliate legal organization worked to draft a bill in Arizona that gave law enforcement the right to stop people for proof of citizenship. In 2010, the Center for Immigration Studies helped torpedo the DREAM Act, forestalling the possibility that Congress might protect young people brought to the United States as children. And the groups gained a certain legitimacy — they were cited hundreds of times by six of the largest U.S. news outlets, including The New York Times.

All these efforts helped launch Tanton’s words and arguments into the flea market of American ideas. Now, politicians, newscasters, podcast hosts and white nationalists were picking up his ideas about pollution and scarcity, immigration and global warming, that fit their agendas, swirling them together with historical tropes about ecology and racist thought and conspiracy theories, not sure, necessarily, where the ideas had come from but eager to trade on their currency.

Some of those ideas could be found in the right-wing website Breitbart News, where Stephen Miller, the principal architect of President Donald Trump’s immigration policy, flooded editors with research from the Center for Immigration Studies. The site posted dozens of articles about climate-driven disasters each year, and while it often denied warming, it was full of stories about resource scarcity and food shortages and migrants, too, all published near numerous stories about the great replacement theory.

Tanton’s ideas could also be found in the proclamations of the prominent “alt-right” white nationalist leader Richard Spencer. In 2014, three years before he led the torchlight march at the Unite the Right white supremacist rally in Charlottesville, Virginia, Spencer tweeted, “Is not population control and reduction the obvious solution to the ravages of climate change?” In his Charlottesville manifesto, he wrote, “We have the potential to become nature’s steward or its destroyer.” When I spoke with Spencer recently, his views had only firmed. “If we bring everyone on the planet into an American lifestyle,” he said, “there first off might not be much planet left, and at the very least, the kind of degradation that might entail would be tremendous and horrifying.”

And Tanton’s ideas could be heard on Fox News. “The left used to care about the environment, the land, the water, the animals,” Tucker Carlson said on his show on Dec. 17, 2018. “They understood that America is beautiful because it is open and uncrowded. Not so long ago, environmentalists opposed mass immigration. They knew what the costs were. They still know. But they don’t care.” He also talked about the great replacement theory on at least 400 shows, often citing FAIR reports and hosting Center for Immigration Studies staff as guests. Ann Coulter, lamenting the Sierra Club’s rejection of immigration issues, wrote an article headlined “Your Choice — A Green America Or A Brown America” for VDare in advance of Earth Day in 2017 and then tweeted that “I’m fine with pretending to believe in global warming if we can save our language, culture & borders.” She later told Fox’s Jeanine Pirro that “you can shoot invaders.”

Half a world away, Brenton Tarrant had been absorbing similar ideas and decided to act on them. On March 15, 2019, inspired in part by a 2011 shooting in Norway and frustrated by what he described as the overtaking of white people by immigrants in New Zealand, Tarrant entered two mosques in the city of Christchurch and shot 91 people, killing 51 of them. There is no evidence that Tarrant has read or even heard of Tanton, but in his 74-page manifesto, which he titled “The Great Replacement,” he was drawing on nearly identical notions.

He pointed to “White Genocide.” He described climate change and immigration as parts of the same problem and decried “rampant urbanization and industrialization, ever expanding cities and shrinking forests, a complete removal of man from nature.” To Tarrant, conserving the purity of lands was indistinguishable from conserving white European ideals and beliefs. And he was well aware of the particular pressures at the United States border. “When the white population of the USA realizes the truth of the situation, war will erupt,” he wrote. “Soon the replacement of the whites within Texas will hit its apogee.”

Patrick Crusius read Tarrant’s words and felt similarly. His attack in El Paso unfolded four and a half months later. In his manifesto he pointed to many of those same reasons, and they were familiar. John Tanton had said them, and the reasoning had been echoed by Leon Kolankiewicz and Roy Beck and NumbersUSA and Tanton’s other organizations. They were endorsed again the week after the massacre, as if they were not shocking but the logical evolution of four decades of messaging that, until that terrible August day, had failed to land. In an interview with The Washington Post, Mark Krikorian, the Center for Immigration Studies’ executive director, denounced Crusius’ killings, but he described his manifesto as “remarkably well-written for a 21-year-old loner.”

“If you have a guy who is going to be angry about immigration, have a killer offering reasons for shooting up immigrants,” he asked, “how could he not use reasons that have already been articulated by legitimate sources?”

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In January, I drove through an affluent community of country roads, hobby farms and sprawling hilly yards outside of Fairfax, Virginia, to the home of Jared Taylor. For three decades Taylor had worked to advance eugenicist ideas. He was both an old associate of Tanton’s and a leading proponent of the great replacement theory. Several years ago, when climate change was beginning to emerge in the vernacular of the extreme right, Taylor’s publications began to reflect his own thoughts on the implications of the warming world.

He wrote the foreword to a dystopian French climate-focused analysis called “Convergence of Catastrophes,” which predicts an era of unprecedented migration and political destabilization. In 2017, his magazine, American Renaissance, under an anonymous byline, ran an article titled “What Does it Mean for Whites if Climate Change is Real?” which asked, “Are we preparing for agricultural disruption in some areas and new opportunities in others? Do we have the legal framework to deal with ‘climate refugees’?” And the magazine had conducted a survey of 578 white Americans, finding that 38% of those who identified as “racial conservatives” said there was ample scientific evidence of climate change — a leap beyond the roughly 23% of Republicans who say they believe it is a threat.

If Tanton’s efforts had shaped the present — turning concerns about overpopulation and climate change into a proxy battle for defending a white majority on an imperiled continent — I hoped that Taylor might help me understand where this battle was headed.

Taylor is 73 years old and a graduate of Yale. He is fluent in French and Japanese. He has a monkish buzz cut, a mustache and a healthy stubble. He greeted me wearing gray felt slippers, green pants and a rust-colored down vest at the door of the large brick home that he had lived in for the past 22 years. Taylor had agreed to be interviewed, but he had some conditions: I could not describe the interior of his home, the books on his shelves, the pictures on his walls. He appeared relaxed, wrapping a white scarf around his neck and reclining with legs crossed and a hot mug of coffee.

“The climate is certainly changing,” he had told me when we’d first arranged to meet, and “it will certainly drive immigration.” Now, in person, he picked up where he had left off. He framed his highest priority — the preservation of the white race — in environmental, even ecological, terms. Immigration is a battle for habitat and species. White people are an endangered breed, fighting to delay their extinction. The great replacement theory is a statistical fact, being cemented into reality. Just look at the crisis at the U.S.-Mexico border. Climate change, he added, “is just going to add to whatever pressures we already have.”

Then he offered a warning: What happened with Crusius was going to happen again and again. “I’m surprised they’re not more of these guys,” he said. Like Krikorian, Taylor described Crusius’ actions as “fantastically stupid.” But he can explain them. Crusius was like all the great preservationists “maintaining what is and what is beautiful for the benefit of future generations.” In this way, he was also like Tanton, Taylor said in a subsequent conversation, who found his own “quasi-racial consciousness” through his environmental enlightenment.

“This kind of completely unhinged, brutal and horrible reaction is inevitable in the conditions under which we live,” he said. The status quo has failed to protect Crusius’ community, and the logical response was vigilantism. That’s how Crusius must have felt. And the terrorists that came after him — like Payton Gendron, the self-declared “eco-fascist” who killed 10 Black shoppers in a Tops Friendly Market in Buffalo, New York, in 2022 and described his crime as a pursuit of “green nationalism.” And the terrorists who Taylor believes are still to come. They’re “a particularly virulent, violent form of white preservationists,” he said.

As we spoke, I thought about the surging activity I’d been seeing online. “The planet can be saved if non-Whites return to their countries, and if we can reduce their populations,” wrote Stephenm85 in 2020, on Stormfront, one of the largest and most influential global social media and publishing sites for Nazi sympathizers. “Let the savage non-Europeans die out without food and allow the intelligent non-Europeans [to] be close to each other away from us.” A 2022 study examining eco-fascist sentiments on Stormfront identified more than 10,000 similar comments across hundreds of threads, some of which had been viewed more than 4 million times. The research, published in the journal Studies in Conflict and Terrorism, found that in 70% of the posts deemed to be the most substantive, the writers “accepted or exploited climate change.”

Actual antagonistic and intimidating shows of force were increasing, too, if subtly. In July 2020, an alt-right group called the New Jersey European Heritage Association began tacking up posters in Pennsylvania warning that immigration would turn the first world into “the third”; the former was pictured as bucolic green hills, the latter as a smog-choked traffic jam. In 2023, White Lives Matter Network marched in Manlius, New York, holding pickets that read “Save the Swans, End Immigration.” This past February, the Wyoming Active Club, a white supremacist organization, plastered stickers around Campbell County in the northeast part of the state that pictured mountain forests and said, “Preserve Nature, End Immigration.” They were all part of what the Anti-Defamation League and the Southern Poverty Law Center described as a marked uptick in white supremacist activity, a small but growing portion of which is environmentally focused.

But however menacing, these were still just protests, and if Taylor was right about an approaching era of violence — something more widespread and systemic than the lone-wolf terrorism of a wayward man like Crusius — it was still unclear what the actual danger looked like. None of the academic and security experts I spoke with knew how to answer this. The rising threat is theoretical, until it isn’t.

I’d come across a guy named Mike Mahoney, a 20-something rising star in white nationalist circles who worked for Breitbart News and accompanied Milo Yiannopoulos, Breitbart’s firebrand tech editor, on his speaking tours. In 2019, going by his byline of “Mike Ma,” he self-published a novel called “Harassment Architecture,” which glorifies those lone-wolf acts of terror, picking up on strains of Ted Kaczynski, the Unabomber, who expressed fears about the future “greenhouse effect” and disavowed modernity and its consumerist culture.

The book drew a following, and Mahoney launched the “Pine Tree Party,” using the same symbol of a pine tree derived from the Christian Nationalist banner “An Appeal to Heaven” that could be seen during the Jan. 6, 2021, assault on the U.S. Capitol and would later be flown outside the vacation home of Supreme Court Justice Samuel Alito. The Pine Tree Party’s mission is environmental, broad and violent. “We will teach ourselves to respect and rely on nature,” someone who identified himself as Mahoney wrote on Telegram. “We will beat up anime kids. … We will bring the American family back to the woods, back to self-sufficiency. … We will oust illegal immigrants with zero mercy.”

The national security journal Homeland Security Today warned that the Pine Tree Party “is quickly accelerating, recruiting, and pushing the ideological bounds to promote infrastructure damage and violence now directly.” Attempts to reach Mahoney by phone and through social media were not successful. As recently as May, a Telegram account ostensibly linked to the party posted a video calling for the violent toppling of electrical towers and the destruction of power grids.

The ideas represented an evolution. They were virulent and undeniably scary. Graham Macklin, a researcher at the Center for Research on Extremism at the University of Oslo, has written that what connects these far-right groups is the view that liberals are disconnected from “wild nature” — a Kaczynski term. This is part of an emerging eco-fascist belief, he said, that the right must now take stewardship of the environment.

This is where Macklin and other counterterrorism experts warn the United States could be headed: The harsher and more challenging the environment gets and the more destructive and expensive the impacts become, the more climate change may be seized as the dominion of the right. Denialism is slowly being replaced by something more pragmatic — and a lot closer to what Taylor had described as eco-supremacy.

Put another way, Taylor explained to me, today’s acceptance of climate change on the far right — and, inevitably, he said, among conservatives writ large — is ushering in a more clear-eyed view of what lies ahead for America, one that accepts the possibility, even the necessity, of sacrifice. Consider those sacrifices a compromise in the name of self-preservation, he said. But the people most strident about protecting this version of America — the showered-with-abundance and historically white version — they will not accept sacrifices only to give away what is gained to outsiders, he told me.

In that way, the determination to keep outsiders from entering the country is, in fact, a truer and, Taylor offers, renewed form of environmentalism. That was, after all, Crusius’ original gambit. “Many people think that the fight for America is already lost,” Crusius wrote. “They couldn’t be more wrong. This is just the beginning.”