A new study of Chile’s melting glaciers has revealed that the loss of mountain ice may allow formerly-inactive volcanoes to erupt, events that could worsen the climate effects that caused the glaciers to retreat to begin with. The study warns that the same fate may await numerous glacier-capped volcanoes around the world, including more than a hundred dormant volcanoes hidden deep beneath the Antarctic ice sheet.

Examining six volcanoes in Chile’s Patagonia region, the study found evidence that a glacial retreat that occurred roughly 18,000 years ago was followed by a period of increased volcanic activity, triggered as the pressure on the magma chambers beneath the surface was alleviated as the glaciers melted.

“Glaciers tend to suppress the volume of eruptions from the volcanoes beneath them,” explained University of Wisconsin-Madison volcanologist Pablo Moreno-Yaeger, who presented his team’s findings at the Goldschmidt Conference.

“But as glaciers retreat due to climate change, our findings suggest these volcanoes go on to erupt more frequently and more explosively.”

Fortunately, it took 3,000 to 5,000 years for the region’s crust to rebound enough to allow gases in the magma chambers—followed by the magma itself—to expand and erupt to the surface, so if present-day volcanoes are affected in the same way we may have some time to prepare for the increased intensity and number of eruptions.

But since global warming is, as the name implies, global, that means this effect is extremely unlikely to be localized to a single region or continent, but rather has the potential to affect glaciated volcanoes around the world.

While previous studies in Iceland have found the same effect on the volcanoes there, Moreno-Yaeger warns that their 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.”  

Regarding Antarctica, a recent survey has brought the total number of known volcanoes hidden under the frozen continent’s ice sheets to 138, of which only two, Deception Island and Mount Erebus, are currently active. While how many of these sub-glacial mounts are capable of becoming active has yet to be determined, the global impact of the eruption of even a small portion of them could be catastrophic.

While the ash and sulfur dioxide released from volcanic eruptions can sometimes cause short-term cooling effects, those elements don’t persist nearly as long as the millions of tons of carbon dioxide that can be released into the atmosphere by an individual eruption, adding to the tens of billions of tons of CO2 already being emitted via human activity, and in turn exacerbating the already-worsening state of global warming.

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

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