Thousands of years ago, thick glaciers covered southern Chile, pressing down on the land and holding back the volcanoes underneath. The ice acted like a cap, trapping magma below the surface. But over time, that ice began to melt.

Now, a new study shows that this ancient geological chain reaction—ice vanishing, volcanoes erupting—could be repeating itself on a planetary scale.

“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,” said Pablo Moreno Yaeger, a geoscientist at the University of Wisconsin-Madison who led the study.

The research was presented last week at the Goldschmidt geochemistry conference in Prague and offers a sobering glimpse into a future where volcanic fire is increasingly unleashed by melting ice.

A Song of Ice and Magma

Scientists have long known that glaciers weigh heavily on the Earth’s crust. As they melt and shrink, the pressure is released. Magma rises. Gas trapped beneath the surface begins to bubble. And eruptions follow.

“When you take the load off, it’s just like opening a Coca-Cola bottle or a champagne bottle,” Brad Singer, a volcanologist and co-author of the study, told Inside Climate News. “It’s under pressure, and the dissolved gasses in the melt come out as bubbles.”

That explosive release, Singer and colleagues say, is already playing out in places like Iceland. As the last Ice Age ended some 10,000 years ago, Iceland’s volcanic activity skyrocketed, erupting up to 50 times more frequently than before the glaciers began to melt.

The researchers wondered if the same process had played out elsewhere. So they looked south.

Using radioactive argon dating and microscopic crystal analysis, the team studied six volcanoes in Chile’s Andean range. These mountains were once buried under the Patagonian Ice Sheet, which spanned much of southern South America during the last glacial maximum, between 26,000 and 18,000 years ago.

The scientists found that during this icy period, the glaciers effectively corked up magma chambers beneath the surface. But when the glaciers receded, the pressure dropped—and the volcanoes roared to life.

One of them, Mocho-Choshuenco, formed when a huge underground magma reservoir finally erupted after millennia of being compressed by glacial weight.

Researchers believe that the same process is happening right now—and could get much worse.

The Fire Below Antarctica—and Beyond

At the heart of their warning is a stark statistic: 245 active volcanoes lie within just three miles of glacial ice. Many are in regions already seeing accelerated melting—Antarctica, North America, Russia, New Zealand.

The most alarming case may be West Antarctica, where more than 100 active volcanoes lie buried beneath the ice. One glacier there—Thwaites, often dubbed the “Doomsday Glacier”—is retreating at an alarming pace.

If volcanic activity increases beneath Antarctica, it could trigger a dangerous feedback loop. The heat from eruptions would melt ice even faster. That, in turn, could lead to more eruptions. And so on.

“This creates a positive feedback loop, where melting glaciers trigger eruptions, and the eruptions in turn could contribute to further warming and melting,” Moreno Yaeger explained.

Volcano eruptions can change the global atmosphere. Sulfate aerosols released during large eruptions reflect sunlight and can cool the planet, sometimes leading to failed harvests and famines. But the long-term effect can lead to more warming.

“Over time the cumulative effect of multiple eruptions can contribute to long-term global warming because of a buildup of greenhouse gases,” Moreno Yaeger said. Volcanic CO₂ and methane released during eruptions can amplify climate change.

A Ticking Clock for Ice-Capped Peaks

The idea that volcanoes respond to melting ice isn’t new. Scientists began exploring this connection in the 1970s. But the new study offers some of the clearest evidence yet, linking real-world glacial retreat to actual eruption histories.

The work also complements earlier findings. A 2020 study in Global and Planetary Change found that glaciers near volcanoes melt 46% faster than those farther away. Rising subterranean heat, the scientists said, may be thinning glaciers from below.

The latest research suggests that many regions—North America’s Cascades, Russia’s Kamchatka, and the volcanoes of New Zealand—warrant much closer scientific attention. These are areas where thick glacial caps still sit over active magma chambers.

The findings don’t predict specific eruptions. But they do highlight a growing risk, one that spans continents and affects climate, ecosystems, and human lives.

In the short term, melting glaciers threaten sea-level rise and water scarcity. But now, scientists are warning of another, deeper danger rising from below: a planetary awakening of fire, stirred by the melting ice.