Once considered a stable outlier amidst the retreating glaciers of Patagonia, Perito Moreno Glacier has recently shown signs of rapid change. Nestled in Argentina’s Southern Patagonian Icefield, this iconic glacier has long been known for its relatively stable frontal position, unlike many of its counterparts in the region. But new research is raising concerns about its future trajectory, showing alarming rates of retreat and thinning in recent years.
From 2000 to 2019, the glacier's surface lowered by just 0.34 meters per year, but from 2019 to 2024, that rate surged to 5.5 meters annually. The glacier's ice front has retreated significantly in a short time, raising questions about its stability. Using advanced helicopter-borne ground-penetrating radar (GPR) and bathymetric data, authors of a new study in the journal Communications Earth & Environment, have revealed key details about the glacier’s subglacial topography, which may explain the accelerated changes. A subglacial ridge that once helped pin the glacier in place is no longer enough to prevent retreat, leaving the glacier vulnerable to buoyancy-driven collapse once it moves past this natural barrier.
New research is raising concerns about its future trajectory, showing alarming rates of retreat and thinning in recent years
The Southern Patagonian Icefield, which houses Perito Moreno Glacier, is a major contributor to sea-level rise, with the region’s glaciers experiencing some of the highest mass loss rates globally. While the glacier had previously been an outlier in terms of stability, its recent behaviour suggests it is now following the same pattern of retreat seen in other major glaciers in Patagonia. This rapid change could have significant implications for both global sea levels and the local economy, as the glacier draws nearly 800,000 visitors annually.
The study also reveals that the glacier's subglacial bedrock configuration has changed over time. Previously, limited data had made it difficult to understand the glacier's underlying topography, but new GPR surveys have unveiled a subglacial ridge that has, until recently, acted as a barrier. With the glacier now moving past this point, the potential for large-scale retreat grows, mirroring the behaviour of other retreating glaciers in the region.
Bathymetric surveys of the glacier's proglacial lake also revealed the presence of terminal moraines, marking past glacier advances, with the most recent retreat being especially pronounced along the deepest part of the glacier’s trough. This accelerated melting and retreat is visible in satellite data as well, with surface elevation changes showing thinning of up to 1.2 meters per year in the accumulation zone and up to 5.5 meters per year near the terminus.
