Climate change: Expect more volcanic eruptions, warn scientists

As the effects of global warming worsen, shrinking glacier cover could lead to increased volcanic activity, according to a new study conducted in Iceland.

Researchers from the University of Leeds found that as glaciers have melted on the island, changes in surface pressure have led to more volcanic eruptions.

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

The researchers identified a period of significantly reduced volcanic activity between 5,500 and 4,500 years ago after examining volcanic ash in peat deposits and lake sediments. This period came after a major decrease in global temperatures which resulted in glacier growth in Iceland.

They also found that there was a time lag of around 600 years between this decrease in global temperatures and the reduction in the number of eruptions. The research suggests that perhaps a similar time lag can be expected before we feel the effects of recent warming trends.

Currently, Iceland's climate is recovering from the 'Little Ice Age' – an era of colder temperatures between the years 1500 to 1850. Following this period, Iceland's glaciers have begun to melt again as a result of natural and man-made global warming.

"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.

"These long-term consequences of human effect on the climate is why summits like COP are so important. It is vital to understand how actions today can impact future generations in ways that have not been fully realised, such as more ash clouds over Europe, more particles in the atmosphere and problems for aviation."

Volcanic activity is controlled by a number of complex interactions between the rifts in continental plate boundaries, underground gas and magma build-ups and pressure on the surface of volcanos caused by glaciers and ice. Any changes to pressure on the surface can alter stress forces in the shallow chambers where magma builds up.

"When glaciers retreat there is less pressure on the Earth's surface," said Ivan Savov from the School of Earth & Environment at Leeds. 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 volcanos."

The team's findings were published in the journal Geology.