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Evidence of Recent Volcanic Eruptions Under the Western Antarctic Ice Sheet

by David Middleton

The discovery of volcanoes under the Antarctic ice sheet may be old news, but now we have evidence that at least some of them have recently (geologically speaking) erupted…

The First Solid Evidence of Eruptions Under Antarctic Ice

By Ross Pomeroy
September 14, 2017

In August, researchers at Edinburgh University announced that frigid West Antarctica is home to at least 138 volcanoes, all concealed within an ice sheet that’s up to two kilometers thick in some places!

The finding left Robert Bingham, one of the study’s authors, with an urgent question.

“The big question is: how active are these volcanoes? That is something we need to determine as quickly as possible,” he told The Guardian.

“If one of these volcanoes were to erupt it could further destabilise west Antarctica’s ice sheets. Anything that causes the melting of ice – which an eruption certainly would – is likely to speed up the flow of ice into the sea.”

Luckily, Bingham didn’t need to wait long for an answer. A team of scientists from New Mexico Tech, Dartmouth College, and Vermont Technical College has uncovered evidence of volcanic eruptions in ice cores taken from the West Antarctic ice sheet (WAIS). A paper describing their findings has just been published in Scientific Reports.

Nels Iverson, a PhD Candidate in Geochemistry, and his team examined an ice core situated near two known volcanoes in the ice sheet, Mount Thiel and Mount Resnick. Utilizing scanning electron microscopy and electron microprobe analysis, they found thick layers in the ice core dating back 22.3 thousand years and 44.8 thousand years. These layers were filled with tephra, rock fragments and particles ejected by volcanic eruptions (see figure below).

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Real Clear Science

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Source: Nels A. Iverson, Ross Lieb-Lappen, Nelia W. Dunbar, Rachel Obbard, Ellen Kim & Ellyn Golden. The first physical evidence of subglacial volcanism under the West Antarctic Ice Sheet. Scientific Reports 7, Article number: 11457 (2017) doi:10.1038/s41598-017-11515-3

Iverson et al think that the eruptions were fairly small, with possible phreatic eruptions due to basal meltwater.  There is no evidence that the eruptions destabilized the ice sheet; but they almost certainly would have breached the surface of the ice.

Cool stuff… Or hot stuff maybe.  The full paper is available online:

Nels A. Iverson, Ross Lieb-Lappen, Nelia W. Dunbar, Rachel Obbard, Ellen Kim & Ellyn Golden. The first physical evidence of subglacial volcanism under the West Antarctic Ice Sheet. Scientific Reports 7, Article number: 11457 (2017) doi:10.1038/s41598-017-11515-3

A couple of items do seem to merit some ridicule:

The finding left Robert Bingham, one of the study’s authors, with an urgent question.

“The big question is: how active are these volcanoes? That is something we need to determine as quickly as possible,” he told The Guardian.

Why on Earth do we need to determine how active the volcanoes are… “as quickly as possible”?  It’s not like we can do anything to prevent them from erupting.  Of course, he was speaking to The Grauniad.

“Continuing ice loss from WAIS will eventually lower the ice sheet elevation and may cause a positive feedback by increasing volcanism in West Antarctic. Although there is no supporting evidence linking enhanced volcanism with collapse of WAIS in the Quaternary…

Melting of the WAIS could increase volcanism under the WAIS causing the WAIS to melt…

The eruptions didn’t occur during an interglacial stage when the WAIS may have been on the thin side.  The eruptions 22,300 and 44,800 years ago during the coldest phase of the last Pleistocene glacial stage, when the WAIS was very likely thicker, colder and less “melty” than it is today.

AntTemp

Antarctica: Pleistocene CO2 and Temperature
Ref.: https://wattsupwiththat.com/2017/09/14/evidence-of-recent-volcanic-eruptions-under-the-western-antarctic-ice-sheet/

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