The Heat Is Online

Glacier Melt May Trigger More Volcanic Eruptions

Warming could wake up volcanoes

Research: Where ice is thick, melt eases pressure on magma

Reuters, April 18, 2010

OSLO - A thaw of ice caps in coming decades caused by climate change may trigger more volcanic eruptions by removing a vast weight and freeing magma from deep below ground, research suggests.

While that's not the case with Iceland's Eyjafjallajokull glacier, which is too small and too light to affect local geology, other volcanoes on the island nation are seen as vulnerable.

"Our work suggests that eventually there will be either somewhat larger eruptions or more frequent eruptions in Iceland in coming decades," said Freysteinn Sigmundsson, a vulcanologist at the University of Iceland.

"Global warming melts ice and this can influence magmatic systems," he added. The end of the Ice Age 10,000 years ago coincided with a surge in volcanic activity in Iceland, apparently because huge ice caps thinned and the land rose.

From Antarctica to Alaska
Carolina Pagli, a geophysicist at the University of Leeds in England, said climate change could also trigger volcanic eruptions or earthquakes in places such as Mount Erebus in Antarctica, the Aleutian islands of Alaska or Patagonia in South America.

"The effects would be biggest with ice-capped volcanoes," she said. "If you remove a load that is big enough you will also have an effect at depths on magma production."

She and Sigmundsson wrote a 2008 paper in the scientific journal Geophysical Research Letters about possible links between global warming and Icelandic volcanoes.

That report said that about 10 percent of Iceland's biggest ice cap, Vatnajokull, has melted since 1890 and the land nearby was rising about 25 millimeters (0.98 inch) a year, bringing shifts in geological stresses.

The research paper estimated that the thaw had led to the formation of 0.3 cubic miles of magma deep below ground over the past century.
Melting ice appears to be the main way in which global warming, blamed mainly on the use of fossil fuels, could have knock-on effects on geology, Sigmundsson said.

At high pressures such as under an ice cap, they reckon that rocks cannot expand to turn into liquid magma even if they are hot enough. "As the ice melts the rock can melt because the pressure decreases," Pagli said.

Sigmundsson said that monitoring of the Vatnajokull volcano since 2008 suggested that the 2008 estimate for magma generation was "probably a minimum estimate. It can be somewhat larger."

Copyright 2010 Reuters.