June 10, 2014

SCIENCE: Hidden Volcanoes Melt Antarctic Glaciers from Below.

The edge of the Thwaites glacier, shown here in an image taken during Operation Icebridge, a NASA-led study of Antarctic and Greenland glaciers. The blue along the glacier front is dense, compressed ice.
Credit: NASA photograph by Jim Yungel

Yahoo news
written by Stephanie Pappas, Live Science Contributor
Monday June 9, 2014

Antarctica is a land of ice. But dive below the West Antarctic Ice Sheet, and you'll find fire as well, in the form of subglacial volcanoes.

Now, a new study finds that these subglacial volcanoes and other geothermal "hotspots" are contributing to the melting of Thwaites Glacier, a major river of ice that flows into Antarctica's Pine Island Bay. Areas of the glacier that sit near geologic features thought to be volcanic are melting faster than regions farther away from hotspots, said Dustin Schroeder, the study's lead author and a geophysicist at the University of Texas at Austin.

This melting could significantly affect ice loss in the West Antarctic, an area that is losing ice quickly.

"It's not just the fact that there is melting water, and that water is coming out," Schroeder told Live Science. "It's how that affects the flow and stability of the ice." [Images: See an Antarctic Glacier Calve an Iceberg]

Antarctic heat

Researchers have long known that volcanoes lurk under the ice of West Antarctica. This is a seismically active region, where East and West Antarctica are rifting apart. In 2013, a team of scientists even found a new volcano beneath the West Antarctic Ice Sheet.

West Antarctica is also hemorrhaging ice due to climate change, [This is a bunch of bs. They blame everything on climate change agenda. It's called nature. (emphasis mine)] and recent studies have suggested there is no way to reverse the retreat of West Antarctic glaciers. However, the timing of this retreat is still in question, Schroeder said — it could take hundreds of years, or thousands. It's important to understand which, given that meltwater from the West Antarctic Ice Sheet contributes directly to sea level rise.

Scientists use computer models to try to predict the future of the ice sheet, but their lack of understanding of subglacial geothermal energy has been a glaring gap in these models. Measuring geothermal activity under the ice sheet is so difficult that researchers usually just enter one, uniform estimate for the contributions of geothermal heat to melting, Schroeder said.

Of course, volcanism isn't uniform. Geothermal hotspots no doubt influence melting more in some areas than in others.

"It's the most complex thermal environment you might imagine," study co-author Don Blankenship, a geophysicist at UT Austin, said in a statement. "And then, you plop the most critical dynamically unstable ice sheet on planet Earth in the middle of this thing, and then you try to model it. It's virtually impossible."

Hotspots melting

To unravel the complexity, the researchers built on a previous study they published in 2013 that mapped out the system of channels that flows beneath the Thwaites Glacier, a fast-flowing glacier that scientists say is vulnerable to global warming.

Using radar data from satellites in orbit, the researchers were able to figure out where these subglacial streams were too full to be explained by flow from upstream. The swollen streams revealed spots of unusually high melt, Schroeder said. Next, the researchers checked out the subglacial geology in the region and found that fast-melting spots were disproportionately clustered near confirmed West Antarctic volcanoes, suspected volcanoes or other presumed hotspots.

"There's a pattern of hotspots," Schroeder said. "One of them is next to Mount Takahe, which is a volcano that actually sticks out of the ice sheet."

The minimum average heat flow beneath Thwaites Glacier is 114 milliwatts per square meter (or per about 10 square feet) with some areas giving off 200 milliwatts per square meter or more, the researchers report today (June 9) in the journal Proceedings of the National Academy of Sciences. (A milliwatt is one-thousandth of a watt.) In comparison, Schroeder said, the average heat flow of the rest of the continents is 65 milliwatts per square meter.

"It's pretty hot by continental standards," he said.

The extra melt caused by subglacial volcanoes could lubricate the ice sheet from beneath, hastening its flow toward the sea, Schroeder said. To understand how much the volcanic melt contributes to this flow — and what that means for the future of the West Antarctic Ice Sheet — glaciologists and climate scientists will have to include the new, finer-grained findings in their models. Schroeder and his colleagues also plan to expand their study to other glaciers in the region.

"Anywhere in the West Antarctic Ice Sheet is going to be a candidate for high melt areas," he said. "And we have radar data covering much of it."

Dogo news
written by Allegra Staples
November 25, 2013

While above-ground active volcanoes in the Antarctica are nothing new, finding one that is buried deep inside its thick ice layer is certainly a first. The exciting discovery was revealed in the November issue of Nature Geoscience by researchers from the Washington University in St. Louis, who stumbled upon the frozen continent's well-kept secret, accidentally.

In 2010, PhD students Amanda Lough and Andrew Lloyd led a group through the frozen continent's treacherous icy terrain to place seismometers across Marie Byrd Land in West Antarctica. Their research project dubbed POLENET was not intended to seek out volcanic or earthquake activity, but to try reconstruct Antarctica's climate history, for which they needed to first research the structure of the earth's mantle - the layer that lies between the crust and the outer core.

But those plans changed when the seismometers recorded two earthquake swarms - one in January 2010 and the other in March 2011. Recorded at depths of about 15-25 miles under the earth's surface, the tremors, which measured only 0.8 and 2.1 in magnitude, were close to the boundary between the crust and mantle and therefore, much deeper than normal earthquakes. Referred to as Deep Long Period earthquakes or DLP's, they have previously been observed near active volcanic areas in Alaska and Washington.

While scientists are not completely sure of why DLP's occur, Amanda Lough theorized that they may be the result of movement of magma and other fluids which create pressure induced vibrations in cracks within the volcanic system. These register on seismometers as 'earthquakes'.

In order to verify Amanda's suspicions, the team narrowed down the area where the seismic activity had been recorded. Sure enough, both the earthquake swarms had emanated from a small area near a series of subaerial volcanic mountains known as the Executive Committee Range. What was even more interesting is that the 'earthquakes' had occurred close to the youngest mountains in the range. But given that the tremors had been weak and of very low frequency, the team knew that they were not caused by tectonic activity. This helped further solidify their suspicions of the existence of an active volcano under the ice.

In order to investigate further, they used airborne radar to create topographic maps of the bedrock. This is when they discovered a layer of ash laying in the ice at about a depth of 1.4 km, right in the vicinity where the most recent seismic swarms had been recorded. Estimated to be 8,000 years old, it helped confirm Lough's suspicion that there was indeed an active underground volcano, one that had erupted before, albeit some time ago.

Though this is the first time an active volcano has been discovered under the thick ice, Lough maintains that the volcanic complex underneath the ground has been operating and probably erupting for millions of years, without disrupting the ice layer above. Given that the ice is at least a half-mile thick, it would take an extraordinarily large eruption - one that would release a thousand times more energy than a typical volcano, to break through. Amanda believes the chances of that ever happening, are pretty slim.

What the team can envision however, is a subglacial eruption that would melt some of the ice underneath and send large amounts of water to the nearby MacAyeal Ice Stream. If that were to occur, it may hasten the ice loss mass in West Antarctica and maybe even raise sea levels slightly.

As to when an eruption will occur or even how and why these volcanoes were formed so deep underneath? For the moment, those questions must go unanswered. That's because the seismometers that recorded this volcanic system have since been moved to other locations of the continent. But the interest this discovery has spurred in the glaciological community is bound to result in further investigation - so stay tuned!

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