More Explosive Volcanoes Expected As Glaciers Melt

Melting glaciers may be setting the stage for more frequent and explosive volcanic eruptions in the future.

This is the conclusion of a study of six volcanoes in the Chilean Andes, which is being presented at the Goldschmidt Conference in Prague this week.

Analysis indicates that hundreds of dormant volcanoes currently buried under glacial ice across the globe—particularly in Antarctica—could become more active as climate change accelerates glacier retreat.

The connection between retreating glaciers and increased volcanic activity has been known in Iceland since the 1970s. However, the latest study is the first one to explore the phenomenon in continental volcanic systems and helps scientists better understand and predict volcanic activity in glacier-covered regions.

Pablo Moreno-Yaeger from the University of Wisconsin-Madison, who is presenting the research at the conference, said in a statement: “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.”

In their study, researchers used argon dating and crystal analysis across six volcanoes in southern Chile, including the now dormant Mocho-Choshuenco volcano, to observe how the Patagonian Ice Sheet’s advance and retreat previously impacted volcanic behavior.

The scientists were able to track how the weight and pressure of glacial ice changes the characteristics of magma—an extremely hot liquid rock mixture found under the Earth’s surface, known as lava when it flows onto the Earth’s surface—by ascertaining the dates of previous eruptions and analyzing crystals in erupted rocks.

Their investigations showed that thick ice cover suppressed the volume of eruptions and allowed a large reservoir of silica-rich magma to accumulate around 32,800 to 49,200 feet below the surface during the height of the last ice age, which is nearly 26,000 to 18,000 years ago.

The ice sheet melted rapidly at the end of the last ice age and this sudden loss of weight caused the crust to relax and gasses in the magma to expand. The volcano was formed as a result of this pressure buildup, which caused explosive volcanic eruptions from the deep reservoir.

“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,” Moreno-Yaeger explained.

He added: “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.”

While the volcanic response to glacial melting is nearly instant in geological terms, the process of changes in the magma system is gradual, taking place over centuries, which allows some time for monitoring and early warning.

The scientists warn that heightened volcanic activity could have global climate impacts. In the short run, eruptions release tiny particles in gases, known as aerosol, that can temporarily cool the planet .

This occurred after the 1991 eruption of Mount Pinatubo in the Philippines, which dropped global temperatures by about 0.5 degrees Celsius. However, multiple eruptions can see the effects be reversed.

Moreno-Yaeger said: “Over time the cumulative effect of multiple eruptions can contribute to long-term global warming because of a buildup of greenhouse gases.

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

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