Scientists warn glacier melt could trigger increased volcanic eruptions in Iceland

In recent months, scientists have observed significant activity at Iceland's Askja volcano, raising concerns that melting glaciers may be triggering increased volcanic eruptions. Since 2021, Askja has uplifted by approximately 80 centimeters (32 inches), a result of 44 million cubic meters (1.6 billion cubic feet) of magma flowing into the existing reservoir around three kilometers (two miles) beneath the surface. Michelle Parks, a volcanologist with the Icelandic Meteorological Office, has been closely monitoring Askja, including submerging a temperature probe in Viti's crater lake, which measured 26.4 degrees Celsius (79.5 degrees Fahrenheit), consistent with recent readings.

"The time scale can be quite short. Hours, maybe... You would want to have a plan if something happens to quickly evacuate the caldera," explained Freysteinn Sigmundsson, a geophysicist at the University of Iceland and co-head with Michelle Parks of the government-funded project studying this phenomenon.

The research project aims to determine whether the rapid retreat of glaciers due to human-caused climate change will trigger increased volcanic activity, which could put many lives at risk around the world. Glaciers now cover just 10% of Iceland, but that ice still weighs on more than half of the nation's 34 active volcanic systems, and it is melting rapidly as global temperatures rise. Scientists predict roughly half of the remaining glacier volume will be gone by this century's end.

As glaciers retreat, the downward pressure on the Earth's thin outer crust eases, allowing the ground to rebound and the Earth's surface to rise. This can affect stress fields in the Earth, creating new fractures underneath a volcano, which may lead to eruptions when the pressure is high enough. The immense weight of glaciers and ice sheets can suppress volcanoes, but as the ice melts, magma can move more freely beneath the surface.

Historical evidence supports this theory. After the melting of ice 10,000 to 15,000 years ago, the frequency of volcanic eruptions on the island increased 30 to 50 times. Scientists found that eruption rates surged an estimated 30 to 50 times during and shortly after the ice loss compared to the preceding Ice Age and recent times. Michelle Parks said it was likely a cataclysmic scenario, with a "ridiculous amount of eruptions," as rivers of lava reshaped the island and ash rained into surrounding seas.

There are about 245 active or potentially active volcanoes around the world that are under ice or within five kilometers (three miles) of it. About 160 million people live within 100 kilometers (62 miles) of at least one of those volcanoes, and 20,000 people live within the immediate vicinity. Numbers like that underscore the threat if glacial melt were to push more volcanoes to erupt, unleashing deadly floods and mudflows and spewing vast clouds of ash and deadly gases into the atmosphere.

Increased volcanic activity could also exacerbate global warming. Eruptions rich in carbon dioxide, a greenhouse gas, could contribute to climate change, outlasting the sulphur aerosols that can cause initial periods of cooling. Volcanoes now known to sit under the West Antarctic Ice Sheet could help speed ice melt into the ocean, raising sea levels.

Askja is of particular interest because, although it has been free of ice for 10,000 years, it is rebounding due to pressure changes from glacial retreat affecting large parts of the Earth's crust and mantle. Michelle Parks remarked, "More magma is coming in underneath Iceland, and we just don't need it. We've got enough."

Another volcano of concern is Katla, located near the southern coast under a small ice cap. Katla has racked up more than 20 eruptions since the Middle Ages, averaging one every 60 years. Katla is past due for another eruption, having last erupted in 1918. During the 1918 eruption, heat pouring from Katla's caldera rapidly melted the ice atop the volcano, releasing a torrent of water greater than the combined discharges of the Amazon, Mississippi, and Yangtze rivers at its peak.

The Icelandic government has emergency plans in place for a Katla-style eruption and works with local police districts to create near-term risk assessments for other volcanoes. The government has also used its volcanic foundation to its benefit, using geothermal energy to heat homes and businesses and draw tourists to rejuvenating geothermal baths.

As glaciers continue to melt, the interplay between volcanoes and ice will remain a chief worry among volcanologists. The potential for increased volcanic activity due to glacial retreat is a global concern, with scientists closely monitoring volcanoes under ice in regions like Antarctica and the Andes. In 2017, scientists reported detecting another 91 possible volcanoes hidden under the West Antarctic Ice Sheet.

"At the end of the day, what we're aiming for with this project is a much bigger picture. It's the future of volcanic eruptions. How large can they be? ... And what's in store for us in the future, not only in Iceland but for the rest of Europe and potentially farther afield," said Michelle Parks.

Scientists are continuing to collect data on ice retreat and magma generation to feed into complex computer models. Their goal is to determine whether climate change may be playing a part in increased volcanic activity, which could have profound implications for populations living near volcanoes and for the global climate.

Sources: Reuters, Tuoi Tre News, Izvestia.ru, The Indian Express, Alghad

This article was written in collaboration with generative AI company Alchemiq