It’s official: Twenty eighteen was the fourth-hottest year on record, and among the hottest in the last 120,000 years. Thanks to El Niño, 2019 will likely be still hotter—perhaps by as much as 1.5 degrees Celsius, the Paris accord boundary we were hoping not to cross until 2050. The globe is not just warming: It is warmed.

As the jet stream fails, the insects die, and the glaciers melt, the president of what is still the most powerful country on Earth has just declared a national emergency—not for this full-on planetary crisis, which he has insisted is a hoax, but for a truly imaginary one, a bad-trip jumble of official untruths, racist fantasizing and fevered, psychosexual ravings. His proposed $8 billion solution to this ginned-up nightmare is no less an absurdity. Trump’s wall represents a fundamental confusion, as if the earth could be bullied into respecting human fantasies, and nations were actual, physical entities rather than consensual hallucinations, willed into coherence by the machinery of the state.

And yet as maddeningly distant as the topics may seem from one another, border militarization is unavoidably a climate-change issue. In fact, these two crises—one manufactured, the other terrifyingly real—have been overlapping for decades, and not just in the United States. It may seem that governments have been doing little to prepare for the coming cataclysms, but they’ve been doing plenty. They’ve been building walls, fences, prisons, and camps. From Bangladesh to the Rio Grande, rendering borders lethal has become the one climate-change “adaptation strategy” that has been almost universally embraced across the globe. As the winds and seas make a mockery of transitory hominid political boundaries, governments are spending billions to try to make them real.

The convergence of climate change with weaponized xenophobia began in the 1990s, when the phenomenon that we then called the “greenhouse effect” was still a blip on the zeitgeist. Bill Clinton, spooked by the near-success of Pat Buchanan’s nativist run for the presidency, did his trademark shuffle, out-Republicaning the Republicans with a homey, aw-shucks grin. In 1994, just as his secretary of state, Madeleine Albright, was beginning to classify “environmental degradation” as a “real threat to our national security,” the Clinton administration inaugurated the modern era of border militarization—and the thousands of deaths in the desert that have accompanied it. They called it Operation Gatekeeper and, with the help of a fattened budget, began hardening enforcement near urban areas like San Diego and El Paso, and repurposing Vietnam War–era helicopter-landing pads into a 15-foot-high border wall. Then as now, Democrats preferred to call it a “fence.”

In the decade that followed, as George W. Bush’s administration was handing its climate policy over to ExxonMobil and silencing its own scientists to deny the threat of global warming, the Defense Department—in contrast—had free rein to assess potential threats, even the ones the rest of the government was pretending did not exist. In 2003, the Pentagon released a report predicting that a warming climate would slow the circulation of the oceans—it has—causing drought in major agricultural regions and resulting in what the authors termed “a significant drop in the human carrying capacity of the Earth’s environment.” A “flood of refugees,” the report predicted, might arrive as early as 2012, and cause the military to take control of the borders by 2020.

That’s more or less what happened: Ten years ahead of schedule, in 2010, just as a devastating drought was beginning to take hold in El Salvador, Guatemala, and Honduras, Barack Obama sent troops to the southern border. Already, with a fresh racist panic in sway, Obama officials had begun quietly constructing an archipelago of prisons especially for migrants. At the same time, the Pentagon, intelligence agencies, and Department of Homeland Security were producing mountains of paper documenting climate change’s role as a “threat multiplier” and an “accelerant of instability” that would displace hundreds of millions of people in Latin America, sub-Saharan Africa, and other regions already impoverished by more than a century of colonialist vampirism.

Given what followed him, Obama may go down as a climate-change saint. But the boom in hydraulic fracking occurred under his watch, as did, very quietly, the lifting of a 30-year-old ban on oil exports. Congress was happy to play along. No one wanted to risk the ire of the oil companies, and elections could always be won throwing money at the border and to the security contractors lining up beside it. When Trump inherited the controls of this machine, ICE and CBP had a budget of over $20 billion, more than all the other major domestic federal law-enforcement agencies combined.

This is not a local trend: Around the world, plans for militarized climate change prep have combined with ethno-nationalist panics to fuel a clampdown on the poor. Just a few months before Bill Clinton’s wall went up between the United States and Mexico, Spain began stretching barbed wire around its enclaves in North Africa. India has fenced nearly the entirety of its 2,000 mile-border with low-lying Bangladesh. Israel, queen of concrete and concertina wire, has fenced its southern border to keep African migrants out. And in 2015, as 5 million refugees fled Syria—where climate change–induced drought heightened tensions in the years before the war—a lush crop of razor wire bloomed in southern and eastern Europe, with hundreds of miles of fences sprouting along the borders of Hungary, Austria, Slovenia, Bulgaria, and Macedonia.

As for the rest of that privileged continent, there is little need for walls: The Mediterranean, until it fills with corpses, will do the job adequately well. Europeans are nonetheless anxious to keep their privilege to themselves: As drought and desertification push more and more Africans to risk the journey north, the European Union’s border-police force has seen its budget balloon by 6,000 percent.

If we continue on this path, a future of walls and barbed wire awaits us. This might not sound so bad if you’re certain you’ll be inside them, looking out. But can you be sure? What happens if Antarctica’s Thwaites glacier collapses and New York, Houston, and Miami go under, creating millions of refugees in weeks rather than years? Where will the walls go then? How much can a nation shrink?

As it is, even our best efforts get stuck in this poisonous, military logic. Alexandria Ocasio-Cortez’s otherwise thrilling Green New Deal legislation includes a nod to “national security” that refers to climate change’s role as a “threat multiplier”—security-speak code for impoverished foreign hordes displaced by climate-fueled instability. Even if Trump doesn’t get his wall, others live on in our heads.

Yet, the earth, if you listen, whispers the way forward. In 2011, the summer monsoons came down hard in the Sonora. Floodwaters pushed debris up against the border fence that separated Lukeville, Arizona, from the Mexican town of Sonoyta, toppling 40 feet of it. In 2014 it happened again, this time in Nogales. Sixty feet were washed away. Whether we do it or the rains do it, every wall must fall.