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Newly Discovered Volcanic Heat Source Under Antarctic Glacier Is Half As Hot As Iceland’s Most Active Volcano

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Several kilometers under the ice, researchers have found evidence of an active volcano spewing large amounts of heat under Antarctica's fastest melting glacier.

By accident, a team of scientists from the University of Rhode Island's School of Oceanography have discovered biochemical proof of the existence of a volcanic heat source sitting just beneath West Antarctica's Pine Island Glacier, which is already in danger of melting rapidly into the surrounding oceans because of heat from climate change.

In a new study published in the journal Nature Communications, the researchers say the heat source produces half as much heat as Grimsvotn, Iceland's most active volcano, which is roughly 25 times as much heat produced by one dormant volcano.

Helium Isotope Signifies Volcanic Activity

Led by chemical oceanographer Brice Loose, the team gleaned their findings from data collected during an expedition onboard the RRS James Clark Ross icebreaker in the Antarctic summer of 2014.

At the time, Loose and his colleagues were collecting water samples on the western coast of Antarctica with the objective of better understanding the ocean's contributing to the rapidly melting ice shelf.

They were looking for traces of noble gases, including helium and xenon, but their findings have led to a new discovery that changes the way researchers approach the study of Antarctica's fast-melting ice.

The researchers discovered helium-3, a helium isotope that is almost exclusively found in the mantle and a significant pointer of volcanic activity. At first, they thought they were mistaken, but further testing confirmed the presence of helium-3 in the waters off the coast of the Pine Island Glacier, indicating that there is some form of volcanic activity taking place underneath.

"When you find helium-3, it's like a fingerprint for volcanism," Loose says. "We found that it is relatively abundant in the seawater at the Pine Island shelf."

Volcanic Activity In Antarctica

The West Antarctic Ice Sheet lies on top of a volcanic rift called the West Antarctic Rift. The rift stretches across the expanse of Marie Byrd from the Pine Island Glacier to the Ross Ice Shelf and the Ross Sea.

As many as 138 active volcanoes have been found in Antarctica, including Mount Erebus, the most active volcano and second highest peak in the continent.

However, scientists find it challenging to find direct signs of volcanic activity because most of the volcanoes are hidden deep beneath kilometers of ice. No evidence of recent magmatic activity underneath the ice sheet has been recorded. The last dates back to 2,200 years ago, leading most experts to think that majority of the volcanic rift is dormant.

Still, new discoveries have hinted at volcanic activity under the ice. For instance, observations at the Whillans Ice stream reveal heat fluxes are hotter than expected.

Researchers have also found deformations in the thickness of the ice sheet, which suggest intense heat sources may be causing the thinning of the surface.

In 2008, scientists found a layer of ash deposited in the ice cores underneath the Executive Committee Mountains, which are by far the biggest sign of a recent volcanic eruption.

Melting Ice Sheet Is Caused By Climate Change, Not Volcano

The number of threats against Antarctica keeps growing. Pine Island Glacier is losing as much as 45 billion tons of ice every year.

However, the researchers are keen to note that the glacier's rapid melting is not caused by the heat from volcanic activity under the ice sheet. It is caused by the warming winds leading to rising temperatures in the surrounding oceans.

"Climate change is causing the bulk of glacial melt that we observe," says Loose, "and this newly discovered source of heat is having an as-yet undetermined effect, because we do not know how this heat is distributed beneath the ice sheet."

Still, the researchers say it is important to include the volcanic discovery as a factor when monitoring the stability of the ice sheet. As the glacier becomes smaller, it becomes less of a burden on the mantle, allowing more heat to rise up and warm the ocean.

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