Argentina’s Perito Moreno glacier is losing its groove

Perito Moreno is one of the world’s most well known glaciers. Like the glaciers west of El Chaltén, it is located in Argentina’s Glacier National Park (Parque Nacional los Glaciares), whose gateway is the town of Calafate. Almost all visitors who go to Calafate—nearly one million people each year—continue the 80 km (50 miles) farther west to see the famous Perito Moreno glacier. See my last post for the location of Calafate on the south shore of Lago Argentina: https://landscapes-revealed.net/return-to-el-chalten-patagonias-premier-hiking-destination/.

I have visited this glacier three times—twice when traveling in the area in 2012 and once during our recent trip to Patagonia. After hiking around El Chaltén, we took a bus to Calafate and stayed for two nights before getting a flight to Buenos Aires. We decided to visit this glacier again because we read that it had changed a lot in the past few years.

Why is Perito Moreno glacier so famous?

This glacier has been considered one of the most stable in the world. While most glaciers around the world have receded noticeable during recent years, Perito Moreno glacier had continued to surge forward. It is one of nearly 50 glaciers that flow from the Patagonian Ice Field, but it was the only one that was not receding.

The position and behavior of Perito Moreno glacier helped to promote its fame. As shown on the Google Earth image below, the glacier was surging right to the edge of the Magellanes Peninsula, where Argentina’s national park built a vast series of walkways. The glacier has been very active, and visitors excitedly wait to see large chunks of ice calve off the front and crash into the adjacent lake.

In 2012, the glacier was right in front of us and we could easily see large chunks of ice calving off its front.

How is Perito Moreno glacier changing?

Since 2019, the glacier has started to retreat rapidly. A scientific study published in August 2025 in Nature (see references below) quantified the changing behavior. From 1999 to 2013, Perito Moreno’s ice front position fluctuated by no more than 50 m (160 feet)—mostly because of seasonal variations. But between 2019 and 2024—just a five-year period—the glacier’s ice front retreated by about 800 m (2625 feet).

Measurements also show increased thinning of the glacier’s surface. The glacier thinned about 0.34 m/yr before 2019, but recent rates have exceeded 5 m/yr near the glacier’s front. The glacier is losing mass overall—it is releasing more ice than it gains through snowfall and accumulation at its head in the Patagonian Ice Field.

The photo below shows the difference between the glacier’s position when I viewed it in 2012 (above) and how it looked in March this year.

This sudden recession of Perito Moreno glacier is clearly tied to global climate change. We talked with local people who told us how temperatures have warmed and rain/snowfall has reduced, thus causing melting to exceed accumulation. The glacier’s stability had been used by climate change deniers to support their assertion that humans were not impacting the climate, but that rationale flew in the face of abundant evidence to the contrary, and Perito Moreno is now joining the ranks of other glaciers worldwide.

The glacier’s dramatic calving

The glacier is still calving frequently, but it’s not quite as dramatic because of the distance. The three short videos below show a sequence of one large ice piece calving off the glacier front into the water. With my phone I could zoom 5X, making the glacier seem closer. Search for “calving Perito Moreno glacier” to see many more videos of this phenomenon.

Why is the glacier named Perito Moreno?

Perito Moreno, whose full name was Francisco Pascasio Moreno, was an Argentine explorer, scientist, naturalist, conservationist, politician, botanist, and geographer who was born in 1852. He is best known for his significant contributions to the exploration and mapping of Patagonia, and for his role in establishing Argentina’s national parks and defending its territorial claims. He is credited with discovering and naming significant geographical features like Lago Argentino and Cerro Fitz Roy, and contributing to the national identity of Argentina through his scientific and cultural collections. He seems like someone who deserves having his name on a famous natural feature.

Final Note

After flying from Calafate to Buenos Aires, we took a ferry to Uruguay where we stayed for two weeks. We are now headed back home, but I will return to Antarctica, as there is still much to say about that continent. I’ll also do a post about Uruguay, which turned out to be more geologically interesting than I expected.

References

The state and fate of Glaciar Perito Moreno Patagonia, by M. Koch et al., 2025: Nature Communications Earth & Environment: https://www.nature.com/articles/s43247-025-02515-7#citeas.

Perito Moreno Glacier and the climate change, by Ramiro Rodriguez 2025: https://peritomorenoglacier.com/travel-guide/el-calafate/perito-moreno-glacier-and-the-climate-change/.