A catastrophic retreat of the Perito Moreno glacier is getting closer.

Science Editorial, Aug 7 (EFE).- The Perito Moreno Glacier in Argentina is retreating faster than previously thought. In fact, in some areas it has retreated as much as 800 meters in recent years, and new evidence shows that a catastrophic retreat is ever closer.

Located in Argentine Patagonia, the 30-kilometer Perito Moreno, a UNESCO World Heritage Site in 1981, is fed by the Southern Patagonian Ice Field and flows into Lake Argentino.

A study by Argentine and German researchers published in Communications Earth & Environment analyzes and warns about the glacier's situation.

Perito Moreno is one of the most stable glaciers in Patagonia and, unlike most of those fed by the same ice fields, it retreated only about a hundred meters between 2000 and 2019.

However, the new study shows that there has been a substantial increase in the rate of glacier retreat since then.

"Although it has not yet lost its support and is relatively stable, we know, from examples of other glaciers with similar dynamics, that when these processes begin, they are irreversible," Lucas Ruiz of the Argentine Institute of Nivology, Glaciology and Environmental Sciences (Ianigla), one of the study's signatories, told EFE.

Since 2020, a pronounced recession has been observed on the northwest shore of the Iceberg Channel lake, where the glacier retreated 800 meters in just four years, the research indicates.

Ruiz stated that "currently, information or new evidence shows that a catastrophic collapse or decline is increasingly close."

The researcher clarified that when we talk about collapse in a glacier, we are referring to a very rapid retreat of the front, at a speed of kilometers or more than a kilometer per year.

The retreat is accelerating, and something similar has already happened at Upsala and Viedma—two nearby glaciers—but "what we expect is for the front to retreat several kilometers in a few years to a new position of stability," according to Ruiz.

The team, led by Moritz Koch of Friedrich-Alexander University in Germany, used radar data to measure the glacier's ice thickness during two helicopter flights in March 2022.

They also mapped the lakebed beyond the glacier's terminus and combined these studies with satellite data to investigate changes in surface height and velocity between 2000 and 2024.

In recent years, the rate of thinning of the glacier at its terminus has increased more than sixteenfold, from 0.34 meters per year between 2000 and 2019 to an annual average of 5.5 meters between 2019 and 2024, the article indicates.

The studies also revealed the presence of a large ridge beneath the end of the glacier, on which it currently sits and which may have been the reason for its stability before 2019.

If the current rate of glacier thinning continues, it will break away from the ridge, and when it loses that support, "the retreat will accelerate so much that it's like a collapse," Ruiz said, adding that "we have increasing evidence that this moment is approaching."

Regarding the rapid retreat observed since 2019, he stated that the "trigger" was climate change, the loss of mass due to less snow accumulation and increased melting due to rising temperatures.

The available information, although not part of the current study, indicates that the glacier's mass loss began a few years earlier, Ruiz added.

On the other hand, glaciers are slow to respond to climate change, and those that end in bodies of water, in particular, retreat very rapidly.

Air temperature records measured near the glacier's terminus from the mid-1990s to 2020 reveal a decadal warming trend of 0.2 degrees Celsius.

During this period, particularly intense warming was observed in summer and spring, which contributed to increased surface melting, the study indicates. EFE