Study finds surprisingly high geothermal heating beneath West Antarctic Ice Sheet

Study finds surprisingly high geothermal heating beneath West Antarctic Ice Sheet
UCSC researchers lowered a geothermal probe through a borehole in the West Antarctic ice sheet to measure temperatures in the sediments beneath half a mile of ice. Credit: WISSARD/UCSC

The amount of heat flowing toward the base of the West Antarctic ice sheet from geothermal sources deep within the Earth is surprisingly high, according to a new study led by UC Santa Cruz researchers. The results, published July 10 in Science Advances, provide important data for researchers trying to predict the fate of the ice sheet, which has experienced rapid melting over the past decade.

Lead author Andrew Fisher, professor of Earth and planetary sciences at UC Santa Cruz, emphasized that the geothermal heating reported in this study does not explain the alarming loss of ice from West Antarctica that has been documented by other researchers. "The developed and evolved with the geothermal coming up from below—it's part of the system. But this could help explain why the ice sheet is so unstable. When you add the effects of global warming, things can start to change quickly," he said.

High heat flow below the West Antarctic ice sheet may also help explain the presence of lakes beneath it and why parts of the ice sheet flow rapidly as ice streams. Water at the base of the ice streams is thought to provide the lubrication that speeds their motion, carrying large volumes of ice out onto the floating at the edges of the ice sheet. Fisher noted that the geothermal measurement was from only one location, and heat flux is likely to vary from place to place beneath the ice sheet.

"This is the first geothermal heat flux measurement made below the West Antarctic ice sheet, so we don't know how localized these warm geothermal conditions might be. This is a region where there is volcanic activity, so this measurement may be due to a local heat source in the crust," Fisher said.

The study was part of a large Antarctic drilling project funded by the National Science Foundation called WISSARD (Whillans Ice Stream Subglacial Access Research Drilling), for which UC Santa Cruz is one of three lead institutions. The research team used a special thermal probe, designed and built at UC Santa Cruz, to measure temperatures in sediments below Subglacial Lake Whillans, which lies beneath half a mile of ice. After boring through the ice sheet with a special hot-water drill, researchers lowered the probe through the borehole until it buried itself in the sediments below the subglacial lake. The probe measured temperatures at different depths in the sediments, revealing a rate of change in temperature with depth about five times higher than that typically found on continents. The results indicate a relatively rapid flow of heat towards the bottom of the ice sheet.

This geothermal heating contributes to melting of basal ice, which supplies water to a network of subglacial lakes and wetlands that scientists have discovered underlies a large region of the ice sheet. In a separate study published last year in Nature, the WISSARD microbiology team reported an abundant and diverse microbial ecosystem in the same lake. Warm geothermal conditions may help to make subglacial habitats more supportive of microbial life, and could also drive fluid flow that delivers heat, carbon, and nutrients to these communities.

According to coauthor Slawek Tulaczyk, professor of Earth and planetary sciences at UC Santa Cruz and one of the WISSARD project leaders, the geothermal heat flux is an important value for the computer models scientists are using to understand why and how quickly the West Antarctic ice sheet is shrinking.

"It is important that we get this number right if we are going to make accurate predictions of how the West Antarctic ice sheet will behave in the future, how much it is melting, how quickly ice streams flow, and what the impact might be on sea level rise," Tulaczyk said. "I waited for many years to see a directly measured value of geothermal flux from beneath this ice sheet."

Antarctica's huge ice sheets are fed by snow falling in the interior of the continent. The ice gradually flows out toward the edges. The West Antarctic ice sheet is considered less stable than the larger East Antarctic ice sheet because much of it rests on land that is below sea level, and the ice shelves at its outer edges are floating on the sea. Recent studies by other research teams have found that the ice shelves are melting due to warm ocean currents now circulating under the ice, and the rate at which the ice shelves are shrinking is accelerating. These findings have heightened concerns about the overall stability of the West Antarctic ice sheet.

The geothermal heat flux measured in the new study was about 285 milliwatts per square meter, which is like the heat from one small LED Christmas-tree light per square meter, Fisher said. The researchers also measured the upward heat flux through the ice sheet (about 105 milliwatts per square meter) using an instrument developed by coauthor Scott Tyler at the University of Nevada, Reno. That instrument was left behind in the WISSARD borehole as it refroze, and the measurements, based on laser light scattering in a fiber-optic cable, were taken a year later. Combining the measurements both below and within the ice enabled calculation of the rate at which melt water is produced at the base of the ice sheet at the drill site, yielding a rate of about half an inch per year.


Explore further

Sediment wedges not stabilizing West Antarctic Ice Sheet

More information: High geothermal heat flux measured below the West Antarctic Ice Sheet, Science Advances, , advances.sciencemag.org/content/1/6/e1500093
Journal information: Science Advances , Nature

Citation: Study finds surprisingly high geothermal heating beneath West Antarctic Ice Sheet (2015, July 10) retrieved 24 August 2019 from https://phys.org/news/2015-07-surprisingly-high-geothermal-beneath-west.html
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Jul 10, 2015
Note that on other planets & moons like Enceladus, we see hot spots at the poles. On Enceladus in particular, planetary scientists can observe that the activity of the Enceladus plume is correlated with Saturn's aurora. While planetary scientists admit that they did not expect a polar hotspot on Enceladus, they nevertheless ignore the observable electrical connection between Enceladus and Saturn as a potential cause for the hot spot.

It may ultimately turn out that a similar, yet more disguised, situation is happening here on Earth. NASA appears to think, to the tune of $1 million so far, that the sudden stratospheric warming events are caused by electrical currents traveling over the solar wind medium, which of course is highly conductive. And they are betting on the predictive power of new electrical weather & climate models. They aren't even the only group.

Jul 10, 2015
Vendicar,

Weren't we talking about this a year, or so, ago? What a surprise! A higher than expected geothermal flux, and in a region where there is volcanic activity. Hmmm, that sounds familiar.

Jul 10, 2015
Its good to see climate science maturing. I am very hopeful that one day, we'll be able to understand climate variability to the point where societal policies won't be insane.

Jul 10, 2015
I wouldn't hold my breath waiting for NASA's adoption of electrical currents heating the earth. Until they find an alternate source of funding Co2 remediation will be their only focus.

Jul 10, 2015
x


Jul 10, 2015
Now isn't this the sheet that they claim was shrinking due to warm ocean currents caused by high Co2 levels?

Jul 10, 2015
"The ice sheet developed and evolved with the geothermal heat flux coming up from below—it's part of the system. But this could help explain why the ice sheet is so unstable. When you add the effects of global warming, things can start to change quickly," he said.

"Recent studies by other research teams have found that the ice shelves are melting due to warm ocean currents now circulating under the ice, and the rate at which the ice shelves are shrinking is accelerating. These findings have heightened concerns about the overall stability of the West Antarctic ice sheet."

Read more at: http://phys.org/n...html#jCp

Jul 11, 2015
Hi MR166. :)

I know you're intelligent and somewhat reasonable; but, as we all know, those aren't always active enough to prevent reading/comprehension confirmation bias in one's approach to the facts actually presented. I have long explained to others before you that the volcanic heat inputs have always been there. No news. They are just now finding out what that pre-existing level of input there was, that's all. And no matter what heat inputs to the global system from volcanoes, burning fossil fuels/nuclear or Solar there is, or what variations there are in those, if the output away from Earth to space is increasingly 'lagged' by effect of increasing atmospheric CO2 content, then THAT is what counts in the net-net. And that is what is happening, irrespective of inputs from all sources. It is the CO2-lagged output to space that is the problem, not the inputs per se.

So no more excuses for reading confirmation bias on your part now you know what's what, hey mate? Cheers. :)

Jul 11, 2015
"The geothermal heat flux measured in the new study was about 285 milliwatts per square meter, which is like the heat from one small LED Christmas-tree light per square meter, Fisher said."

285 milliwatts would be the total output of about a dozen regular small LEDs and not just the heat.

Jul 11, 2015
285 milliwatts is not as trivial as it may seem. In light of the latest ARGO ocean temperature measurements. The total global warming ocean heating is 330 milliwatts in the upper 700 meters and only 420 milliwatts including the whole upper 2000 meters. Since the northern hemisphere seems not to be heating, the southern hemisphere containing much more of the ocean water apparently is heating more than this but less than twice this rate. (all power numbers are per square meter).

Jul 11, 2015
Re: "Is there a relationship between temperature and solar storm events (or large changes in the magnetic field)."

The lower stratosphere temp anomalies generally track sunspot numbers when you subtract out things like volcanic activity. The correlation does not hold for some parts of the solar cycle, but the problem is fixed when you take into account the solar wind from coronal holes.

A number of researchers are looking at the role of sudden stratospheric warming events right now. It should be easy to understand that under particular conditions, plasma can flood into the polar regions. If this occurs, one expected consequence would be a sudden warming. Researchers increasingly believe that they can predict the weather many weeks in advance with this technique.

And it has nothing at all to do with CO2.

Jul 11, 2015
Reality Check:

"No matter what heat inputs to the global system from volcanoes, burning fossil fuels/nuclear or Solar there is, or what variations there are in those, if the output away from Earth to space is increasingly 'lagged' by effect of increasing atmospheric CO2 content, then THAT is what counts in the net-net. And that is what is happening, irrespective of inputs from all sources. It is the CO2-lagged output to space that is the problem, not the inputs per se."


Here's how I see "reality":

Admittedly, the 'heat flow' from volcanoes has always been there; but, has it been constant? Of course not. And, if this flow increases, then ice will melt, and ocean temperatures will rise, and more water vapor will be in the air, and this will lead to some net rise in temperature, ever so slight. It is unthinkable that the heat below an ice shelf "feels" the effect of the ionosphere more than the cold from the ice shelf above. This is simple logic.

Jul 11, 2015
Re: "It is unthinkable that the heat below an ice shelf "feels" the effect of the ionosphere more than the cold from the ice shelf above."

The fact of the matter is that there is some sort of coupling happening between the stratospheric polar vortex and the ocean's currents. See http://phys.org/n...per.html

"Reichler and colleagues used weather observations and 4,000 years worth of supercomputer simulations of weather to show a surprising association between decade-scale, periodic changes in stratospheric wind patterns known as the polar vortex, and similar rhythmic changes in deep-sea circulation patterns."

Honestly, this really should surprise nobody, because the oceans and the solar wind are clearly conductive. There is only 50 miles of non-conductive atmosphere separating the two for most of the planet -- except of course at the poles, where the magnetic field permits the plasma to make its closest approach to the Earth's surface.

Jul 11, 2015
Hi Lino235. :)
"No matter what heat inputs to the global system from volcanoes, burning fossil fuels/nuclear or Solar there is, or what variations there are in those, if the output away from Earth to space is increasingly 'lagged' by effect of increasing atmospheric CO2 content, then THAT is what counts in the net-net. And that is what is happening, irrespective of inputs from all sources. It is the CO2-lagged output to space that is the problem, not the inputs per se."
Here's how I see "reality": Admittedly, the 'heat flow' from volcanoes has always been there; but, has it been constant? Of course not. And, if this flow increases, then ice will melt, and ocean temperatures will rise, and more water vapor will be in the air, and this will lead to some net rise in temperature, ever so slight.
Local variations in heat loads from volcanoes average out over decades/centuries, and within a certain range. Transient variability is already reflected/involved. :)

Jul 11, 2015
RealityCheck:

Winter and summer average out over a year; hence, annual global temperatures. This doesn't mean that it doesn't snow in winter, and get hot in summer. If, over the last 150 to 200 years, volcanic activity around the entire globe (and, hence, even on the ocean bottom where little of this is seen) has increased, then, ever so slightly, will this cause the ocean to warm; with, as I already mentioned, the concomitant increase in water vapor. Let's remember that CO2 heats 'indirectly', via its effects (reflected radiation) on the seas. IOW, it's not CO2 that increases temperatures, but the increased level of water vapor in the air.

Jul 11, 2015
Hi Lino235. :)
Winter and summer average out over a year; hence, annual global temperatures. This doesn't mean that it doesn't snow in winter, and get hot in summer.
That's right. I never implied otherwise. But if heat normally escaping to space is lagged by atmos CO2 then overall heat in system rises, creates more severe swings/extreme events as this heat is shuffled around between hot/cold regions before finally escaping.

Re volcanism/water vapor etc heat/transport mechanisms, these are well understood, and drive transient events. Geophysics/plate-techtonics knows undersea heat from plate spreading away from 'ring of fire' seabed/landmass subduction/spreading fissures in the Earth's crust; plus other more isolated volcanoes/hot vents on land and undersea. The heat from these escapes quickly upwards from ocean bottom to surface, atmosphere and thence space. When increasing atmos CO2 lags escape to space too much it creates extreme weather and trending climate change. :)

Jul 11, 2015
HannesAlfven:

The fact of the matter is that there is some sort of coupling happening between the stratospheric polar vortex and the ocean's currents.


And how does the 'polar vortex' have anything to do with CO2 emissions? It seems to me this last winter, as Canada and the East Coast was freezing to death, all we heard about was the "polar vortex," the latest fancy word weather reporters like to use.

There is no logical connection anywhere here. Please point it out.

Jul 11, 2015
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Jul 11, 2015
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Jul 11, 2015
Study finds surprisingly high geothermal heating beneath West Antarctic Ice Sheet
Umm, umm... Does the geothermal theory of global warming still look implausible? BTW I expected this report in 2010 already http://www.nasa.g....html...

Yes. The heat coming from the earth is still much less than the heat from greenhouse gases and there's no evidence that the heat from the earth has increased - something that would be necessary to explain the sudden increase in warming that occurred in the 70s. There's also the problem that the signature of the current warming can't be explained by geothermal warming, but matches warming caused by greenhouse gases very well.

You wouldn't also go by the name of Doug Cotton, would you?

Jul 11, 2015
This comment has been removed by a moderator.

Jul 11, 2015
This comment has been removed by a moderator.

Jul 11, 2015
This comment has been removed by a moderator.

Jul 11, 2015
This comment has been removed by a moderator.

Jul 12, 2015
Re: "Is there a relationship between temperature and solar storm events (or large changes in the magnetic field)."

The lower stratosphere temp anomalies generally track sunspot numbers when you subtract out things like volcanic activity. The correlation does not hold for some parts of the solar cycle, but the problem is fixed when you take into account the solar wind from coronal holes.

A number of researchers are looking at the role of sudden stratospheric warming events right now. It should be easy to understand that under particular conditions, plasma can flood into the polar regions. If this occurs, one expected consequence would be a sudden warming. Researchers increasingly believe that they can predict the weather many weeks in advance with this technique.

And it has nothing at all to do with CO2.

Nor has it anything to do with reality.

Jul 12, 2015
Hi docile. :)
Umm, umm... Does the geothermal theory of global warming still look implausible? BTW I expected this report in 2010 already http://www.nasa.g....html...
It's many factors, some pre-existing (internal heat), some new (CO2 warming effect and stronger air/ocean currents/vortices). Any internal heat is dissipated to ice and air/ocean as usual. So it was always there. But if warmer air/ocean and stronger winds/currents due to CO2-associated global warming, the heat from interior is not dissipated as quickly, so ice melts faster. Then the increased air/ocean currents bring more heat from water/atmos to base/bays which further shrinks the 'thermal gradient' which previously existed in balance between prior interior temp and outside ambient. So interior heat 'dwells' longer and melts more than before. Elsewhere, volcanism heat in ocean goes upwards quickly as usual, but if atmos CO2 lagging increased, it builds in atmos. :)

Jul 15, 2015
It would seem that there is an overlooked reason for some warming of the sea due the the atmosphere being cleaned up in the past decade. Felicity Aston & Dr Jim McQuad suspect that the lack of dirt particals to help clouds form maybe causing more of the suns energy to get to the earths surface rather than being reflected by clouds producing more violent weather, ie, hurricanes. Who has a good firt hand memory of the weather before 1800 AD?

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