The melting of glaciers and ice caps as a result of the climate crisis could trigger a surge in explosive volcanic eruptions, according to a new study.
As ice is lost, the pressure on underground magma chambers is reduced, making volcanic activity more likely. This phenomenon has been observed in Iceland—an unusual location situated on a mid-ocean tectonic plate boundary—but new research from Chile provides some of the first evidence of a similar increase in volcanism on a continental landmass, following the end of the last ice age.
Rising global temperatures, driven by the burning of fossil fuels, are now causing glaciers and ice caps to melt across the globe. The researchers identified west Antarctica as the area of greatest concern, where at least 100 volcanoes lie buried beneath thick ice sheets that are expected to retreat significantly over the coming decades and centuries.
While volcanic eruptions can have a temporary cooling effect by releasing particles that reflect sunlight, sustained volcanic activity would also emit large quantities of greenhouse gases such as carbon dioxide and methane. This could intensify global warming and create a dangerous feedback loop: warming melts ice, which increases volcanic activity, further warming the planet.
Pablo Moreno-Yaeger, at the University of Wisconsin-Madison, US, who led the research, said: “As glaciers retreat due to climate change, our findings suggest these volcanoes go on to erupt more frequently and more explosively.”
The study—presented at the Goldschmidt geochemistry conference in Prague and currently undergoing peer review—involved fieldwork conducted high in the Andes, amid both active and dormant volcanoes.
One volcano in particular, Mocho-Choshuenco, was examined in detail. Researchers used radioisotope dating to determine the age of volcanic rocks formed before, during, and after the last ice age, when the region was covered by the 1,500-metre-thick Patagonian ice sheet. By analysing the minerals within these rocks, they were also able to estimate the depth and temperature at which they had formed.
The findings revealed that during the period of maximum ice cover, between 26,000 and 18,000 years ago, the volume of eruptions was suppressed—allowing a large magma reservoir to accumulate some 10 to 15 kilometres beneath the surface. When the ice began to melt around 13,000 years ago, the pressure on the magma chamber was released, gases within the molten rock expanded, and a series of explosive eruptions ensued.
“We found that following deglaciation, the volcano starts to erupt way more, and also changes composition,” said Moreno-Yaeger. The composition changed as the magma melted crustal rocks while eruptions were suppressed. This made the molten rock more viscous and more explosive on eruption.
“Our study suggests this phenomenon isn’t limited to Iceland, where increased volcanicity has been observed, but could also occur in Antarctica,” he said. “Other continental regions, like parts of North America, New Zealand and Russia, also now warrant closer scientific attention.”
Earlier studies have indicated that volcanic activity increased globally two- to six-fold following the last ice age, but this Chilean research provides some of the clearest evidence yet of the underlying mechanism. A comparable pattern was previously identified through rock analysis in eastern California in 2004.
A recent scientific review noted that little study on how the climate crisis had been affecting volcanic activity. The authors called for significantly more investigation, stressing that such research is “critically important” to better understand the potential impacts on communities and infrastructure, and to explore how volcanic-climate feedback loops could exacerbate global warming. For example, more extreme rainfall—another consequence of climate change—is also expected to increase the likelihood of violent, explosive eruptions.
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