Fire and Ice: How Glacial Retreat Could Ignite Volcanic Activity
A Reuters investigative report reveals the chilling possibility that retreating glaciers might spark a surge in volcanic eruptions globally.
Breaking the Ice:
A recent Reuters Special Report reveals how the rapid retreat of glaciers sets the stage for increased volcanic activity around the globe. Scientists are racing to determine the extent to which glacial retreat could trigger a surge in volcanic eruptions by releasing magma stored beneath the ice. The report highlights the work of Michelle Parks, a volcanologist at the Icelandic Meteorological Office, and her colleagues, who are closely monitoring Askja, an active volcano in Vatnajökull National Park, which is showing signs of significant magma buildup beneath its surface.
Researchers have observed a striking increase in Askja's inflation—the ground rising due to accumulating magma—which they believe is just the beginning. Iceland's history after the last Ice Age suggests this pattern might repeat: as glaciers melted 15,000 years ago, Iceland experienced 30 to 50 times more volcanic eruptions than during the preceding glacial period. Scientists are now studying whether ongoing glacial retreat, a direct consequence of human-induced climate change, could similarly set the stage for an upsurge in volcanic activity, not only in Iceland but also in other regions with ice-covered volcanoes, like Alaska, Russia, and Antarctica.
Quick Melt:
The link between glacial melt and volcanic activity has significant implications for nearby populations and the climate. According to the Reuters investigation, approximately 250 active volcanoes worldwide have glaciers within a 5-kilometer radius, with roughly 7 million people living within 30 kilometers of these ice-covered volcanoes, particularly in South America. The threat isn't merely theoretical—volcanoes like Iceland's Katla have historically devastated local communities and disrupted global climate patterns, even affecting monsoons in Africa and Asia.
Recent scientific findings underscore these concerns. Preliminary modeling shows that magma production beneath Iceland is already running at two to three times the rate it would be without the influence of glacial melt. This suggests a troubling feedback loop: as climate change drives glacial retreat, it could trigger more volcanic activity, which in turn could release additional greenhouse gases, further amplifying global warming. While volcanic eruptions can cause temporary cooling through aerosol emissions, their long-term CO2 contributions could exacerbate climate change.
The Thaw:
How Are Glacial Retreat and Volcanic Activity Related? Accumulation Zone Explains
At a high level, the fundamental mechanism linking glacial retreat to volcanic activity is deceptively straightforward. Glaciers and ice sheets exert enormous pressure on the Earth's crust, effectively suppressing volcanic activity. When this ice melts, the reduced pressure can allow more magma to form and alter its movement patterns, potentially leading to increased eruptions – a process known as mantle decompression.
This phenomenon has been studied extensively by Professor Charles Langmuir, Higgins Professor of Geochemistry at Harvard University. In 2022, the European Research Council awarded Professor Langmuir, in partnership with the GEOMAR Centre for Ocean Research, with a six-year grant to undertake a million-year time-series analysis of volcanic eruptions to analyze to what extent the eruptions are influenced by melting ice sheets. The researchers will use novel sampling approaches to develop the time series of hydrothermal activity that they can directly relate to past sea level changes and climate.
This research will build on Langmuir’s previous studies, which have shown volcanic activity spiked globally during the last deglaciation when ice sheets retreated rapidly. This effect is tied to mantle decompression: as the ice melts, the enormous weight lifted off the crust reduces pressure on the mantle beneath, encouraging magma production. This positive feedback cycle—where glacial melting fosters volcanic activity, which in turn releases more CO2—is a crucial element that scientists are working to better understand and more accurately predict future climate scenarios.
In Iceland, the laboratory for understanding these processes is rapidly changing. The country's glaciers, which cover just 10% of the nation but overlie more than half of its 34 active volcanic systems, have lost about 16% of their volume in the past 130 years—half of that in just the last three decades. Scientists predict another 50% will vanish by the end of the century, potentially setting the stage for increased volcanic activity. The implications extend far beyond Iceland. In Antarctica, scientists have identified over 90 previously unknown volcanoes beneath the West Antarctic Ice Sheet. The Andes present another critical zone of concern, hosting seven of the world's ten most dangerous ice-covered volcanoes.
Final Thoughts
The Reuters investigation underscores a critical reality about our changing planet: the effects of climate change extend far beyond warming temperatures and rising seas. As we continue to unravel these complex relationships between Earth's systems, the urgency of addressing climate change takes on new dimensions. The possibility that melting ice could trigger increased volcanic activity adds another layer of complexity to an already challenging global crisis, reminding us that Earth's systems are interconnected in ways we are only beginning to understand.