Melting glaciers may awaken sleeping volcanoes

Climate change is rapidly melting glaciers. While rising seas and disappearing ice dominate the headlines, something more ominous may be stirring beneath the surface.

Dormant volcanoes – sealed under ice for millennia – could soon awaken. And when they do, the eruptions may be anything but ordinary: they could strike suddenly and with explosive force.

This isn’t just a theory. Scientists studied volcanoes in Chile’s Andes mountains. The research showed that melting glaciers can spark volcanic activity.

Antarctica hides hundreds of volcanoes under its ice. If this pattern holds, those volcanoes may start to stir too. The warning is clear. As glaciers vanish, the ground may soon roar.

Volcanoes responding to melting glaciers

Scientists in Iceland began investigating the connection between melting glaciers and increased volcanic activity as early as the 1970s.

This latest study shows that volcanoes in large continental regions may respond in the same way. The findings could reshape how we predict volcanic eruptions.

Beyond Chile, volcanoes in North America, New Zealand, and Russia may also face this hidden threat.

Many volcanoes once thought harmless may no longer stay quiet. As glaciers melt, the risk rises. Scientists are beginning to ask what else could be lying in wait.

How ice suppressed volcanoes

Researchers from the University of Wisconsin-Madison led this work. They joined forces with scientists from other U.S. universities. The team focused on six volcanoes in southern Chile.

Among these volcanoes was the now quiet Mocho-Choshuenco. Long ago, it sat beneath the thick Patagonian Ice Sheet.

The scientists collected rocks and studied them closely. They used argon dating to find the exact age of past eruptions.

The researchers also examined crystals in the rocks to see what had happened beneath the surface.

The story was clear: when glaciers were thick, they pressed down hard on the volcanoes. That pressure locked magma underground.

Melting glaciers unlock eruptions

During the last ice age, from about 26,000 to 18,000 years ago, glaciers covered the land. They acted like a giant lid, holding back eruptions.

But no glacier lasts forever. As the ice melted quickly near the end of the ice age, everything changed.

The crust beneath the volcanoes began to relax. Magma, once trapped, found space to expand. Gases inside the magma bubbled and grew. Soon, pressure built up too much. The volcanoes erupted in dramatic fashion.

These eruptions shaped the land and left scars that remain today. The cause was simple. The melting glaciers had removed the pressure that kept the magma in check.

Glacier melt raises volcano risks

Pablo Moreno-Yaeger from the University of Wisconsin-Madison presented this study. His warning was sharp and direct.

“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 Moreno-Yaeger.

“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.”

Moreno-Yaeger pointed out that this risk is not limited to Iceland. Volcanoes under thick ice in Antarctica and other parts of the world could behave the same way.

Magma shifts slowly but danger grows

Volcanoes do not react overnight. Even as ice melts fast, magma builds pressure slowly. These changes often take centuries.

However, in geological terms, this is still fast. Scientists have enough time to watch carefully. They can look for signs like moving magma or shifting gases. With close monitoring, future eruptions might be predicted before disaster strikes.

But the clock has already started ticking. Glaciers are melting now, and some volcanoes are likely already changing deep below the surface.

Eruptions also change Earth’s climate

Volcanic eruptions do more than shake the ground. They can also change the planet’s temperature.

When volcanoes erupt, they send aerosols into the atmosphere. These tiny particles block sunlight and cool Earth for a short time. After Mount Pinatubo erupted in 1991, the planet cooled by about 0.5 degrees Celsius.

Cooling the planet might sound like a good thing, but it does not last. If several volcanoes erupt within a short time, the story flips again.

Glaciers and volcanoes may fuel a loop

“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.”

This loop works like a trap. Melting glaciers cause eruptions, which release greenhouse gases. Those gases warm the planet more, causing more glaciers to melt.

This cycle could spiral out of control if left unchecked. This is no longer just about melting ice. It is about a whole chain of disasters feeding each other.

The study received funding from the National Science Foundation.

The team presented their research at the Goldschmidt Conference in Prague on July 8, 2025.

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