New research from the University of Leeds has shown that among the many dangers of climate change is one unexpected one: an increase in volcanic eruptions.

That is, an increase in volcanic eruptions in Iceland and places like it, where glaciers play a key role in preventing magma from rising to the surface.

The study found there was less volcanic activity in Iceland when glacier cover was thicker, but as the glaciers melted, volcanic eruptions increased because of changes in surface pressure.

The study examined volcanic ash preserved in Iceland’s peat deposits and lake sediments. The researchers identified a period of significantly reduced volcanic activity between 5,500 and 4,500 years ago—a period that came after a major decrease in global temperature and subsequent glacier growth in Iceland.

“Climate change caused by humans is creating rapid ice melt in volcanically active regions,” said Dr. Graeme Swindles from the School of Geography at the University of Leeds. “In Iceland, that has put us on a path to more frequent eruptions.”

There was a time lag of about 600 years between the climate event and a noticeable decrease in the number of eruptions. The researchers suggest that a similar time lag might be expected as temperatures warm.

One factor that may have slowed the increase in volcanic eruptions is that Iceland’s volcanic system is recovering from the “Little Ice Age,” a period of sharply colder climates between the years 1500 and 1850. A combination of natural and human-caused climate change is warming the globe, and the researchers suggest this may cause the time lag to be shorter than 600 years.

“The human effect on global warming makes it difficult to predict how long tie time lag will be, but the trends of the past show us more eruptions in Iceland can be expected in the future,” said Dr. Swindles. “It is vital to understand how actions today can impact future generations in ways that have not been fully realized, such as more ash clouds over Europe, more particles in the atmosphere, and problems for aviation.”

Iceland’s volcanic activity is controlled by many factors. There are interactions between rifts in continental plate boundaries, underground gas and magma buildup, and pressure on the volcanoes’ surfaces from glaciers and ice. The researchers say changes in surface pressure can alter the stress on the shallow chambers where magma builds up before erupting.

Study co-author Dr. Ivan Savov from the University of Leeds’ School of Earth & Environment said, “When glaciers retreat, there is less pressure on the Earth’s surface. This can increase the amount of mantle melt as well as affect magma flow and how much magma the crust can hold. Even small changes in surface pressure can alter the likelihood of eruptions at ice-covered volcanoes.”

Long story short: According to these researchers, it looks like the future will include more volcanic eruptions in formerly ice-covered areas. Who knew that global climate change could even affect volcanoes?

Photo: Jökulsárión, Iceland. Photo by Jeremy Bishop on Unsplash