Once a stable wonder of nature, Argentina’s Perito Moreno Glacier is showing signs of alarming change. Local guides and glaciologists are concerned about the glacier’s recent sharp increase in the size of the icebergs breaking off from its face. The glacier is well-known for its breathtaking calving events, in which enormous chunks of ice break off and fall into the waters of Lake Argentina.
The glacier, which stands in Los Glaciares National Park in southern Patagonia, had long been a draw for tourists, many of whom gather on viewing platforms to witness the dramatic cracking sounds that signal the collapse of ice blocks up to 70 metres (230 feet) tall — equivalent to a 20-storey building. However, this natural spectacle has become increasingly worrisome in recent years as the frequency and scale of the ice calving events appear to be growing.
“In the past 20 years, ice-calving incidents of this magnitude have not occurred frequently,” stated Pablo Quinteros, the park’s official tour guide. “We have only begun to see icebergs of this size in the last four to six years.”
While Perito Moreno had been relatively stable for decades, the glacier has begun retreating in the past five years, a process which had previously been rare. Historically, the glacier’s ice face would advance and retreat in cycles, but this recent retreat has prompted concern about its future.
Lucas Ruiz, a glaciologist with Argentina’s National Scientific and Technical Research Council (CONICET), explained that the glacier had maintained a more or less steady position for 80 years, which was unusual given the trend of rapid melting in many other glaciers worldwide. But since 2020, signs of retreat have become evident, and the glacier is now losing between one and two metres of ice equivalent per year.
A 2024 report co-authored by Ruiz revealed that, although the glacier had remained stable for much of the past 50 years, it has experienced its fastest mass loss since 2015, averaging 0.85 metres per year. Globally, glaciers are disappearing at an accelerated pace, with the last three years marking the largest recorded glacial mass loss, according to a UNESCO report released in March.
Climate change’s effects are becoming increasingly noticeable. Ruiz noted that the area’s air temperature has risen by approximately 0.06 degrees Celsius per decade, while precipitation has decreased, leading to less snowfall and ice accumulation. These changes have disrupted the delicate balance between accumulation and melting at the glacier’s surface.
“Compared to other glaciers, Perito Moreno took longer to exhibit signs of climate change,” Ruiz stated. However, melting and calving at the bottom of the glacier are now outpacing the rate of ice buildup at the top. The area and thickness of the glacier are decreasing.
Despite these concerning changes, the Perito Moreno Glacier remains a significant attraction. Tourists from around the world continue to marvel at the breathtaking sight of massive ice chunks breaking off and floating in the lake. For many visitors, like Brazilian tourist Giovanna Machado, the experience is unforgettable.
“It’s insane. The most incredible thing I’ve ever seen,” Machado said while aboard one of the boats that bring visitors close to the calving ice. “Even in photos, you just can’t grasp the immensity of it. It’s perfect. It’s amazing.
As the glacier faces an uncertain future, the balance between its natural beauty and the environmental changes impacting it has never been more apparent. Scientists continue to monitor the situation, hoping for a rebound, but the growing signs of retreat serve as a stark reminder of the broader effects of global warming on the planet’s icy landscapes.