1st December 2017
Global warming could increase volcanic eruptions
A study by the University of Leeds finds that shrinking glacier cover across Iceland could lead to increased volcanism in the region, by reducing pressure on the Earth's surface.
Shrinking glacier cover could lead to increased volcanic activity in Iceland, warn scientists. A new study, led by the University of Leeds, has found that there was less volcanic activity in Iceland when glacier cover was more extensive – and as the glaciers melted, volcanic eruptions increased due to subsequent changes in surface pressure.
"Climate change caused by humans is creating rapid ice melt in volcanically active regions," Dr Graeme Swindles, from the School of Geography at Leeds, explains. "In Iceland, this has put us on a path to more frequent volcanic eruptions."
The study examined Icelandic volcanic ash preserved in peat deposits and lake sediments and identified a period of significantly reduced volcanic activity between 5,500 and 4,500 years ago. This period came after a major decrease in global temperature, which caused glacier growth in Iceland.
The findings, published in the journal Geology, found there was a time lag of roughly 600 years between the climate event and a noticeable decrease in the number of volcanic eruptions. The study suggests that perhaps a similar time lag can be expected following the more recent shift to warmer temperatures.
Iceland's volcanic system is still in the process of recovering from the 'Little Ice Age' – a recorded period of colder climate roughly between the years 1500 to 1850. Since the end of the Little Ice Age, a combination of natural and human-caused climate warming has been causing Icelandic glaciers to melt again.
"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," said Dr Swindles. "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."
Icelandic volcanism is controlled by complex interactions between rifts in continental plate boundaries, underground gas and magma build-up and pressure on the volcano's surface from glaciers and ice. Changes in surface pressure can alter the stress on shallow chambers where magma builds up.
"When glaciers retreat, there is less pressure on 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," said co-author, Dr Ivan Savov, from the School of Earth & Environment at Leeds. "Even small changes in surface pressure can alter the likelihood of eruptions at ice-covered volcanos."
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