For decades it has been considered a rare exception: a “stable” glacier in an era in which its neighbors in Patagonia quickly retraced. Now, however, the expert Moreno – among the most famous in the world and UNESCO heritage since 1981 – has been experiencing the most substantial retreat of the last century.
View this post on Instagram
A study published in Communications Earth & Environment (Nature) reconstructed for the first time the topography of the rocky bed of the glacier, revealing the loss of that delicate balance that had so far guaranteed its stability. The data, obtained between 2022 and 2023 with helicopter radar, sonar and satellite surveys, show a clear acceleration of frontal collapse: from 2000 to 2019 the lowering of the surface in the front area was about 0.34 meters per year; Between 2019 and 2024 it risen to 5.5 meters, with peaks over 6.5 meters in the deepest areas.
The role of hidden morphology
The expert Moreno, which extends for 259 km² in the field of southern Patagonal ice, is a lake glacier: its terminal language overlooks the Argentine lake, in the Brazi Rico and Canal de los Témpanos arms. For years, a subglacial ridge and a submerged Morena have acted from natural “anchor points”, slowing down the retreat and reducing underwater fusion. But since 2020 this protection has started to yield: along the north-western bank of the Canal de los Témpanos the front has retired by about 800 meters in just four years.
The authors show that the progressive detachment from the subglacial relief eliminates the contrast tensions that stabilized the front, facilitating the basal scrolling and the increase in ice speed. The surveys indicate that between 2021 and 2023 the speeds at the forehead reached 900 meters per year, with increases over 100 m/year compared to a few years earlier.
A precarious balance and an uncertain future
The model developed by researchers projects possible withdrawal phases related to the floating push. The first stage, already in progress, is the complete detachment from the subglacial ridge. It would follow, we read in the study, an accelerated backwardness towards a more often and closer geometry area, which could offer temporary stability. Besides that point, however, a further retrograde backdrop could trigger a cycle of self -powered loss, as already observed in other Patagonical glaciers.
The analysis suggests that, if the current thinning rates were to maintain, much of the first 5 km upstream of the forehead could become floating, increasing the ice surface in contact with the water of the lake and therefore the underwater fusion.
Climate, oscillations and local variables
The average annual heating in the area, measured from 1990 to 2020, is +0.2 ° C for decade, with more marked seasonal peaks in summer and spring. Events such as El Niño and the positive phase of the Southern Annular Mode (is a model of climatic variability in the southern hemisphere) intensify winds and temperatures, reducing the surface mass balance. Despite occasional winters with snowy accumulations higher than average, more and more hot summers quickly cancel these earnings.
The authors point out that the projections remain uncertain due to the scarcity of direct data on rainfall at the highest shares of Patagonia, one of the most humid areas on the planet. However, the evidence collected indicate that the Moreno expert is no longer “insensitive” to climate change and that the delay in response – compared to less protected glaciers – is ending.
An icon at risk
Every year almost 800,000 visitors reach the glacier, attracted by the spectacular collapses of ice blocks in the lake. Its importance for the tourist economy of the city of El Calafate and for the global natural heritage makes the monitoring of its transformations even more relevant.
As Moritz Koch, the main author of the study, explained, “now we observe a very delayed response to climate change, since it is slowly but inexorably detaching from this point of physical anchor”.
The fate of the Moren expert will be a test bench to understand the vulnerability not only of the Patagonical glaciers, but also of the Antarctic and Alpine ones who share similar morphological and dynamic conditions. And the time to understand it is as well as as well as its ice.
Don’t you want to lose our news?
