Melting glaciers could trigger volcanic eruptions - a new risk of climate change

The retreat of glaciers due to global warming could intensify volcanic activity in several regions of the world, warns a new study presented at the Goldschmidt 2025 Conference in Prague. According to the research led by Pablo Moreno Yaeger, a geologist at the University of Wisconsin-Madison, the massive ice sheet that covers volcanoes acts like a cap that suppresses eruptions. Once removed, the pressure drops and magma and underground gases can be released more easily, triggering more frequent and violent eruptions.

• Sleepy but dangerous volcanoes

The study analyzed six volcanoes in southern Chile, including Mocho-Choshuenco, to understand how they reacted to the melting of the Patagonian ice sheet, more than 18,000 years ago. The results show that: during the peak of the last ice age (26,000-18,000 years ago), the volume of eruptions was reduced. After the glaciers melted, the pressure on the magma increased significantly, triggering powerful eruptions, including the formation of the Mocho-Choshuenco volcano. The phenomenon is comparable to what happened in Iceland after the last ice age: volcanic activity increased 30-50 times after the ice retreated.

• A global danger: 245 volcanoes under glaciers

According to a 2020 study, 245 active volcanoes are currently covered by glaciers up to 5 kilometers thick. They are located mainly in: Antarctica, Russia (Kamchatka, Kuriles), North America (Alaska, British Columbia), New Zealand.

"The key is having a significant mass of ice above a magma chamber. If the ice retreats rapidly, the pressure changes and can trigger an eruption,” Moreno Yaeger explains.

How do glaciers influence volcanoes? The answer is broader: Vertical pressure: Thick ice presses down on the Earth's crust and mantle; Magma inhibition: Magma and gases are held under pressure, limiting mobility and the risk of eruption; Melting and decompression: As glaciers melt, the pressure disappears and the magma can expand and rise; Eruption: If the magma reservoir is large enough and unstable enough, the decompression can trigger an eruption.

• Implications for the future

In the context of accelerating climate change, regions with glaciers overlying magma chambers should be monitored as a priority. This phenomenon adds a geological dimension to climate risks, demonstrating that melting ice can have cascading effects, beyond sea level rise and the disappearance of biodiversity.

Climate change does not just change atmospheric temperature or precipitation patterns - it can reactivate dormant geological systems, increasing the risk of catastrophic volcanic eruptions. The study presented in Prague shows that ice acts as an agent of volcanic stability, and its loss could lead to consequences that are difficult to predict in the medium and long term. "It is vital to expand volcanic monitoring networks in melting glacial areas. This threat is real and ignoring it would be a mistake,” warned Moreno Yaeger. This new angle highlights how deep the interconnection between climate and geology is - a reality that requires rapid and responsible action.