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Melting glaciers may be silently setting the stage for more explosive and frequent volcanic eruptions in the future, according to research on six volcanoes in the Chilean Andes.

A to be presented on Tuesday, 8 July at the in Prague suggests that hundreds of dormant subglacial volcanoes worldwide—particularly in Antarctica—could become more active as climate change accelerates glacier retreat.

The link between retreating glaciers and increased volcanic activity has been known in Iceland since the 1970s, but this is one of the first studies to explore the phenomenon in continental volcanic systems. The findings could help scientists better understand and predict volcanic activity in glacier-covered regions.

Researchers from the University of Wisconsin–Madison, U.S., used argon dating and crystal analysis across six volcanoes in southern Chile, including the now dormant Mocho-Choshuenco volcano, to investigate how the Patagonian Ice Sheet's advance and retreat influenced past volcanic behavior. The work is in collaboration with researchers from Lehigh University, University of California Los Angeles, and Dickinson College.

By precisely dating previous eruptions and analyzing crystals in erupted rocks, the team tracked how the weight and pressure of glacial ice alter the characteristics of magma underground.

They found that during the peak of the last ice age (around 26,000–18,000 years ago), thick ice cover suppressed the volume of eruptions and allowed a large reservoir of silica-rich magma to accumulate 10–15 km below the surface.

As the ice sheet melted rapidly at the end of the last ice age, the sudden loss of weight caused the crust to relax and gases in the magma to expand. This buildup of pressure triggered explosive volcanic eruptions from the deep reservoir, causing the volcano to form.

Pablo Moreno-Yaeger from the University of Wisconsin-Madison, is presenting the research at the Goldschmidt Conference. He said, "Glaciers tend to suppress the volume of eruptions from the volcanoes beneath them. But as glaciers retreat due to climate change, our findings suggest these volcanoes go on to erupt more frequently and more explosively.

"The key requirement for increased explosivity is initially having a very thick glacial coverage over a magma chamber, and the trigger point is when these glaciers start to retreat, releasing pressure—which is currently happening in places like Antarctica.

"Our study suggests this phenomenon isn't limited to Iceland, where increased volcanicity has been observed, but could also occur in Antarctica. Other continental regions, like parts of North America, New Zealand and Russia, also now warrant closer scientific attention."

While the volcanic response to glacial melting is almost instant in geological terms, the process of changes in the magma system is gradual and occurs over centuries, giving some time for monitoring and early warning.

The researchers also note that increased volcanic activity could have global climate impacts. In the short term, eruptions release aerosol (tiny particles in gases) that can temporarily cool the planet. This was seen after the 1991 eruption of Mount Pinatubo in the Philippines, which reduced global temperatures by approximately 0.5°C. But with multiple eruptions, the effects reverse.

"Over time the cumulative effect of multiple eruptions can contribute to long-term global warming because of a buildup of greenhouse gases," said Moreno-Yaeger. "This creates a positive feedback loop, where melting glaciers trigger eruptions, and the eruptions in turn could contribute to further warming and melting."