For decades, Argentina’s Perito Moreno Glacier has stood as a symbol of resilience in a region where most glaciers have been steadily retreating. Nestled within the Southern Patagonian Icefield, this imposing river of ice has captivated scientists and tourists alike, its seemingly unwavering presence drawing nearly 800,000 visitors to Los Glaciares National Park each year. But new research published in Communications Earth & Environment has upended the glacier’s reputation for stability, revealing that Perito Moreno is now undergoing its most dramatic retreat in a century—a shift that raises urgent questions about the future of Patagonia’s ice and the global climate.
Until recently, Perito Moreno was widely regarded as an outlier. While neighboring glaciers in the Southern Patagonian Icefield—one of the world’s largest reserves of fresh water—were shrinking at alarming rates, Perito Moreno’s front barely budged. From 2000 to 2019, the glacier’s surface dropped by a modest 0.34 meters per year. But that picture has changed drastically. According to the new study, from 2019 to 2024, the rate of surface lowering surged to a staggering 5.5 meters annually. Satellite data confirm this rapid transformation, showing thinning of up to 1.2 meters per year in the glacier’s accumulation zone and as much as 5.5 meters per year near its terminus.
What’s driving this sudden shift? The research team, led by Moritz Koch, a doctoral student at Friedrich-Alexander University of Erlangen-Nuremberg, used a suite of cutting-edge tools to find out. They flew over the glacier in a helicopter, towing a ground-penetrating radar device to map the ice thickness and underlying bedrock. On the lake below, they deployed sonar to chart the bathymetry, while satellites kept watch from above. Their findings revealed a crucial change: a subglacial ridge that had long anchored the glacier in place is now losing its grip. As the glacier moves past this natural barrier, it’s becoming increasingly vulnerable to what glaciologists call “buoyancy-driven collapse”—a process where the ice, no longer held down by bedrock, floats and fractures more easily, accelerating retreat.
“We believe that the retreat that we are seeing now, and why it is so extreme in terms of values that we can observe, is because it hasn’t been climatically stable for a while now, for over a decade,” Koch explained in an interview with the Associated Press. “Now we see this very delayed response to climate change as it is slowly but surely detaching from this physical pinning point in the central part of the glacier.” The study’s authors expect Perito Moreno to retreat several more kilometers in the coming years—a scenario that would have been unthinkable just a generation ago.
Timelapse photos taken since 2020, as reported by the Associated Press, starkly illustrate the glacier’s fragile balance. Once wedged securely in its valley, Perito Moreno is now losing contact with the bedrock below, causing it to shed ice at an unprecedented pace. Bathymetric surveys have also uncovered terminal moraines—underwater ridges marking the glacier’s past advances—underscoring just how pronounced the latest retreat has been, especially along the deepest part of the glacier’s trough.
Why does this matter beyond the striking visuals? The Southern Patagonian Icefield, home to Perito Moreno, is a major contributor to global sea-level rise. The region’s glaciers are experiencing some of the highest mass loss rates anywhere on the planet. As Richard Alley, an ice scientist at Pennsylvania State University who was not involved in the study, told the Associated Press, “The basic physics of climate change and glaciers are intuitive: heat melts ice, and global warming means more and faster glacial melting.” But, he added, predicting exactly when and how glaciers will break apart is much more complicated—much like trying to guess when a dropped coffee mug will shatter.
For years, climate change skeptics have pointed to Perito Moreno’s apparent stability as evidence that global warming wasn’t as severe as scientists claimed. But the glacier’s recent reversal underscores how even the most steadfast ice can succumb to prolonged changes in climate. Erin Pettit, a glaciologist at Oregon State University, told the Associated Press that if the climate were truly stable, the accumulation of snow and ice would naturally offset melting. “We are losing these little bits of ice everywhere,” she said. “Hopefully we’re slowly gaining more respect for the ice that was here, even if it’s not always there.”
The consequences of these changes are far-reaching. Glacial melting, especially in polar and mountainous regions, is a key contributor to sea-level rise—a threat that could displace millions of people living in coastal and island communities. But the impact is also deeply local. Glaciers like Perito Moreno have shaped the landscapes of Patagonia, carved out valleys, and provided fresh water to communities. When glaciers collapse or retreat rapidly, they can unleash destructive mudslides, disrupt ecosystems, and alter the livelihoods of those who depend on glacial tourism and water resources.
The cultural significance of Perito Moreno cannot be overstated. Declared a UNESCO World Heritage Site in 1981, the glacier is famous for its spectacular calving events, where massive chunks of ice break off and crash into Lake Argentino below. These natural spectacles draw crowds from around the world, making the glacier not just a scientific marvel but also an economic lifeline for the region. The recent study warns that the glacier’s accelerated retreat could threaten both its ecological role and its status as a tourist attraction.
Despite the sobering findings, the researchers hope their work will serve as a wake-up call. By combining helicopter-borne radar, sonar mapping, and satellite imagery, they’ve set a new standard for monitoring glacial change—one that could help scientists better predict the fate of other vulnerable ice masses, including the much larger glaciers of Antarctica. As Alley put it, studies like this one are crucial for understanding “what might happen to the big guys.”
In the end, the story of Perito Moreno is a microcosm of the broader struggle against climate change. It’s a reminder that even the most resilient natural wonders are not immune to the relentless march of warming temperatures. As glaciers around the world continue to shrink, the choices made today will determine whether future generations can witness the icy giants that have shaped our planet for millennia.
