A slow-motion disaster, but a disaster nonetheless.
At the edge of the world, a glacier that carries the weight of coastlines has offered a rare, partial reprieve. New research suggests that Thwaites Glacier — long feared as a trigger for catastrophic, self-reinforcing collapse — is less vulnerable to that particular unraveling than scientists once modeled. Yet the ice continues its retreat, driven by warming seas that do not pause for reassurance. The story of Thwaites is not one of crisis averted, but of a slower reckoning still very much in motion.
- The feared 'domino collapse' — where failing ice cliffs trigger an unstoppable chain reaction inland — now appears physically less likely than earlier models warned, offering a rare note of relief in Antarctic science.
- Thwaites is still losing ice at an accelerating rate, already responsible for roughly 4 percent of annual global sea-level rise, with enough frozen water to lift oceans more than two feet worldwide.
- Warm ocean currents infiltrating beneath the glacier's floating ice shelves remain the primary and ongoing engine of destruction — a mechanism that continues regardless of cliff collapse scenarios.
- The glacier's downward-sloping bedrock means that once retreat begins in earnest, there is no natural brake — making the question of pace critical even if the worst-case timeline has lengthened.
- What unfolds at Thwaites will determine the stability of the entire West Antarctic Ice Sheet, and the future of coastal communities on every shore — a consequence still shaped by decisions being made today.
Antarctica's Thwaites Glacier earned its nickname — the Doomsday Glacier — because of what its collapse could mean for the world's coastlines. For years, the central fear was a cascading domino effect: the glacier's floating ice shelf breaks apart, exposing a towering cliff to open water, which fails and exposes another cliff farther inland, which fails in turn, sending the glacier retreating at terrifying speed.
New research led by polar scientist Mathieu Morlighem suggests that particular nightmare may not unfold as feared. More precise modeling shows that ice cliffs don't fail catastrophically until they reach roughly 135 meters high, and even then they collapse more slowly than the original theory assumed. Running three high-resolution simulations, Morlighem's team found that even if Thwaites' ice shelf vanished entirely, the glacier would flow faster toward the ocean but also thin at its front — preventing cliffs from growing tall enough to trigger the domino effect. Through the end of this century, the models suggest, marine ice cliff instability alone would not cause rapid collapse.
This matters enormously. Thwaites drains an area larger than Florida and holds enough ice to raise global sea levels by more than half a meter. Its fate is entangled with the entire West Antarctic Ice Sheet. If the domino mechanism is less likely, the broader ice sheet may be more stable than worst-case estimates suggested.
But the reprieve is partial. The study rules out one catastrophic mechanism — not the crisis itself. Thwaites is still retreating, still losing ice, and the bedrock beneath it slopes inward, meaning deceleration becomes harder the further the glacier pulls back. The real driver of current ice loss is warm ocean water from the Antarctic Circumpolar Current, which seeps beneath the floating ice shelves, melts them from below, and removes the buttressing that slows the glaciers behind them.
Thwaites remains a slow-motion disaster — the direction unchanged, only the speed of the worst scenario revised. How much further it retreats depends on the physics of ice and ocean, and on how much carbon continues to enter the atmosphere. The glacier is not waiting for those answers.
Antarctica's Thwaites Glacier earned its grim nickname—the Doomsday Glacier—because of what it could do to the world's coastlines if it fell apart. The glacier already accounts for roughly 4 percent of the annual rise in sea levels as it sheds ice into the ocean. For years, scientists have worried about a catastrophic scenario: the glacier's ice shelf collapses, exposing a towering cliff of ice to the open sea. That cliff fails and tumbles into the water. A new, even taller cliff is exposed farther inland. That one fails too. And so on, in a cascading domino effect that could send the glacier retreating inland at terrifying speed.
But a new study suggests that worst-case scenario may not actually happen. Mathieu Morlighem, a polar scientist who led the research, explains that the physics of ice cliff collapse work differently than earlier models assumed. When scientists first proposed the domino theory a decade ago, they used rough approximations. More recent work shows that ice cliffs don't fail catastrophically until they reach about 135 meters high, and even then they collapse more slowly than the original theory predicted. Using three high-resolution computer models, Morlighem's team found that if Thwaites' ice shelf vanished tomorrow, the glacier would not rapidly retreat inland due to cliff failure alone. The ice would flow faster toward the ocean, yes, but it would also thin out at the front, keeping the cliffs from growing tall enough to trigger the domino collapse. Even if the ice shelf disappeared fifty years from now, when the glacier had already retreated farther inland, marine ice cliff instability alone would not cause a rapid collapse. The models suggest Thwaites would remain relatively stable through the end of this century.
This is genuinely good news. Thwaites drains an area of Antarctica larger than Florida—about 192,000 square kilometers. The glacier holds enough ice to raise global sea levels by more than 0.65 meters. What happens to Thwaites doesn't stay at Thwaites. Its fate ripples through the entire West Antarctic Ice Sheet, affecting sea-level rise along every coastline on Earth. If Thwaites isn't as vulnerable to the domino collapse as feared, that's a sign the entire ice sheet may be more stable than the worst-case estimates suggested.
But here's the crucial caveat: marine ice cliff instability is only one way a glacier can fail. The study doesn't mean Thwaites is stable. It means one particular doomsday mechanism is less likely than previously modeled. The glacier is still retreating at an accelerating rate. The bedrock beneath it slopes downward toward the interior of the ice sheet, which means once the glacier starts losing more ice than it gains from new snow, it becomes extremely difficult to slow down. The real culprit driving ice loss right now is something far more straightforward: warm ocean water.
Over the past few decades, the Amundsen Sea sector—where both Thwaites and its neighbor, Pine Island Glacier, sit—has experienced an intrusion of warm water from the Antarctic Circumpolar Current. This water gets underneath the ice shelves, the floating extensions that normally buttress the glaciers and slow their flow. As the water melts the ice from below, the shelves weaken. With less resistance holding them back, the ice streams accelerate toward the ocean. This ice-ocean interaction explains most of the recent ice mass loss in Antarctica. The atmosphere is warming too, but Antarctica is so cold that atmospheric warming hasn't yet become the dominant factor. The ocean is doing the work.
Thwaites remains a slow-motion disaster. The good news is that the very worst scenario—a rapid, unstoppable domino collapse—appears less likely than some scientists feared. The sobering reality is that the glacier will keep losing ice, keep raising sea levels, and keep destabilizing the ice sheet around it. The mechanism may be slower than the doomsday theory suggested, but the direction is the same. What happens next depends partly on the physics of ice and ocean, and partly on choices being made right now—how much carbon humans continue to burn, how much the planet continues to warm, how quickly the ocean currents continue to shift. The glacier isn't waiting for those answers.
Citas Notables
What we are seeing with Thwaites Glacier right now is a disaster in slow motion.— Mathieu Morlighem, polar scientist who led the study
This finding doesn't mean Thwaites is stable—marine ice cliff instability is only one mechanism of ice loss.— Mathieu Morlighem
La Conversación del Hearth Otra perspectiva de la historia
So the study is saying Thwaites won't collapse like dominoes. Does that mean we can stop worrying about it?
Not at all. It means one specific collapse mechanism—the one where ice cliffs fail in rapid succession—is less likely than the worst-case models suggested. But the glacier is still retreating, still losing ice, still raising sea levels. It's just doing it through a different process.
What process is actually melting it, then?
Warm ocean water getting underneath the ice shelves. The shelves act like a cork in a bottle, slowing the glacier's flow. When warm water thins them from below, they weaken, and the glacier accelerates toward the ocean. That's what's happening now, and it's been happening for decades.
Why does the ocean matter more than the warming air?
Antarctica is extraordinarily cold. The atmosphere is warming, but not fast enough yet to be the dominant factor. The ocean, though—warm currents are intruding into the Amundsen Sea where Thwaites sits. That's the real driver of ice loss right now.
If the domino collapse isn't the threat, what should people actually be concerned about?
The steady, relentless loss of ice through ocean melting. It's slower than a catastrophic collapse, but it's happening now and it's accelerating. And it still raises sea levels, still destabilizes neighboring glaciers, still affects coastlines everywhere.
So this study is good news, but not the kind that lets us relax?
Exactly. It's good news that one nightmare scenario is less likely. But the underlying problem—a glacier the size of Florida losing ice into the ocean—that's still very much real.