Iceland's Frozen Volcanoes Are Waking Up—And Climate Change May be to Blame

Lava fountains are pictured at the site of a fissure eruption near Iceland's Bardarbunga volcano September 2, 2014. Reuters

Frozen volcanoes in Iceland could start erupting more—especially as glaciers continue to melt.

Scientists examined volcanic ash preserved in peat deposits and lake sediments and discovered a period with less volcanic activity around 5,000 years ago. The volcanoes were much quieter during this time period, and it happened to coincide with a drop in global temperature. The study, published last week in Geology, concluded that the slowdown in volcanic activity thousands of years ago was likely due to the extensive glacier cover. Now, as Iceland's glaciers are melting due to climate change, volcanoes may start waking up.

"Climate change caused by humans is creating rapid ice melt in volcanically active regions," Graeme Swindles, lead author and earth system dynamics professor at University of Leeds, said in a statement. "In Iceland, this has put us on a path to more frequent volcanic eruptions."

Interactions between rifts in continental plates and the pressure underground from gas and magma build-up can be altered from changes above the ground—including melting glaciers. The volcanic system in Iceland has been recovering from the "Little Ice Age," which was a period of a cooler climate between 1500 and 1850. Due to a rapid increase in global temperatures over the past few decades, the decrease in glacier coverage also causes a decrease in 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," Ivan Savov, co-author and professor of geochemistry and volcanology at the University of Leeds, said in a statement. "Even small changes in surface pressure can alter the likelihood of eruptions at ice-covered volcanoes."

Icebergs covered in volcanic ash from the eruption of the Grimsvotn volcano float in a glacial lagoon below the Vatnajokull Glacier in Iceland May 27, 2011. Reuters

The volcanic activity might not come for a few hundred years, though. During the period of cooler temperatures 5,000 years ago, there was a 600-year delay before there were noticeably fewer volcanic eruptions. This suggests there could be a lag between the most recent shift to warmer temperatures and increased volcanic activity.

"The human effect on global warming makes it difficult to predict how long the time lag will be but the trends of the past show us more eruptions in Iceland can be expected in the future," Swindles said. He added that the long term consequences of human-caused climate change are why global climate change conferences like the most recent one in Bonn, Germany are crucial. "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."