The Perito-Moreno glacier in Argentina is one of the most stable in Patagonia. But climate change is now also troubled by him – and more than previously assumed. As a new study shows, the Perito Moreno now melts much faster than a few years ago. In some places, it has shrunk by 800 meters since 2019. In the near future, his glacier front could even withdraw miles or he will completely disappear. The reason for this is, among other things, that the glacier gradually dissolves from a ridge below it, which has previously served as a brake and fixed point.
The Perito Moreno is a huge glacier, the ice of which runs through Patagonia for over 30 kilometers – from the South Patagonian ice field in the Andes at 2850 meters to Lake Argentino at 190 meters, the largest lake of Argentina. The glacier, popular with tourists, has been a UNESCO World Heritage Site since 1981. In contrast to many neighboring ice fields and glaciers in Patagonia, climate change has so far seemed little to him. Between 2000 and 2019, its glacier front withdrew less than 100 meters. But since then, the melting rate of Perito Moreno has apparently increased significantly.
Perito Moreno melts 16 times faster than a few years ago
How much the glacier has really lost in ice and why, have now examined researchers around Moritz Koch from the Friedrich Alexander University Erlangen-Nuremberg. To do this, they flew over the Perito Moreno with helicopters and use the radar to measure its thickness and the topography of the rock underneath. They also map the foothills of the lake on the front of the ice stream. In addition, they evaluated satellite data from the years 2000 to 2024 to determine the development of its surface and flow speed.
The result: Between 2000 and 2019, the glacier at its lower end was only 34 centimeters a year thinner. Between 2019 and 2024, however, the ice stream lost 5.50 meters of ice thickness every year-more than 16 times as much as in the decades before. The ice melt is particularly pronounced in some places of the glacier end. The Perito Moreno has shrunk up to 800 meters on these tongue tips since 2019 and has withdrawn.
But what is behind this change? Why does the glacier now melt faster than before and what has stabilized it so far? On the one hand, the global warming increases the air temperatures in Patagonia and generally accelerate the ice melt there, as Koch and his colleagues explain. How their data unveiled also supported moraine – deposited rubble piles on the Seeboden – the glacier tongues for a long time and slowed down the mixture of the cold meltwater with the warmer sea water. However, this direct ice-rock contact has not existed for several years, as Koch and his team found out. Instead, the glacier tongue is now completely exposed to the warmer sea water, which also accelerates your melting.
Glacier melt could soon increase rapidly
Another factor that has previously been lending is a large burr under the end of the Perito Moreno. This elevation under the glacier base is a continuation of the Magallanes Peninsula in Lake Argentino. The glacier with its weight is currently still resting and has so far been unusually stable, as the team explains. However, this fixed point could soon be a passé. If the Perito Moreno melts on the same pace as currently, it could lose weight in the near future. Then the melting water collecting on the glacier base could raise the ice masses so far that they dissolve from this ridge. The glacier would then partially swim on its base and thus flow down the steep slope faster even in its upper areas, which in turn would accelerate the calves – the cancellation of ice on the glacier end.
Due to these changes, the Perito Moreno could lose several kilometers of ice within a short time after the researchers’ forecasts – similar to its neighboring glaciers in the past. “For example, the Gletscher Viedma, Upsala and O’Higgins have also passed phases reinforced retreat after they had loosened from previous fixed points,” writes the team around Koch. When exactly this will happen to the Perito Moreno and whether he will find new fixed points at his slide is still unclear.
Source: Moritz Koch (Friedrich Alexander University Erlangen-Nuremberg) et al.; Communications Earth & Environment, DOI: 10.1038/S43247-02515-7
