Saturday, October 11, 2014

New paper finds West Antarctic glacier likely melting from geothermal heat below

A paper published today in Earth and Planetary Science Letters finds evidence that one of the largest glaciers in West Antarctica, the Thwaites Glacier, is primarily melting from below due to geothermal heat flux from volcanoes located along the West Antarctic Volcanic Rift System, i.e. not due to man-made CO2.

CAGW proponents have alleged that West Antarctic glaciers such as such as the Thwaites Glacier and the neighboring Pine Island Glacier are rapidly melting due to man-made greenhouse gases and/or ocean heating, despite observations showing the air temperature in the Antarctic hasn’t risen since 1979, Antarctic sea surface temperatures have fallen since 2006, and ARGO ocean heat content of the Southern Ocean shows no increase at any level of the top 2000 meters since the system was put in place in 2004. The authors find the neighboring Pine Island Glacier also overlies the same volcanic rift system and thus may also be melting from geothermal heat below. 

The West Antarctic Volcanic Rift System is illustrated by JoNova below, and just so happens to correspond to the areas of notable glacier melt and alleged warming. In contrast, East Antarctica, which holds > 80% of Antarctic ice mass and does not have any known underlying volcanoes, is significantly increasing in ice mass. 

The paper joins several others finding geothermal heat largely if not entirely responsible for glacier melt in multiple regions in both Antarctica and Greenland, i.e. not anthropogenic. 




Excerpts from post "The "pause" of global sea ice. Up by ~76% in 2013 & 2014 from the 2007-2012 minima":


The air temperature in the Antarctic hasn’t risen since 1979:

And Antarctic sea surface temperature has fallen since 2006, which would explain the extra sea ice:


And if we look at ARGO OHC measurements in the Antarctic we see there is no warming at any level in the ocean:

The Byrd Subglacial Basin beneath Thwaites Glacier is part of Mesozoic widespread rifting.
Thin crust (18–24 km) exists in eastern Marie Byrd Land and beneath Thwaites Glacier.
Gravity evidence supports hypothesis of warm mantle beneath Marie Byrd Land.
Supports the use of thin crust and higher heat flux values in Western Antarctica.

Abstract

Thwaites Glacier has one of the largest glacial catchments in West Antarctica. The future stability of Thwaites Glacier's catchment is of great concern, as this part of the West Antarctic Ice Sheet has recently been hypothesized to already be en route towards collapse. Although an oceanic trigger is thought to be responsible for current change at the grounding line of Thwaites Glacier, in order to determine the effects of this coastal change further in the interior of the West Antarctic Ice Sheet it is essential to also better constrain basal conditions that control the dynamics of fast glacial flow within the catchment itself. One major contributor to fast glacial flow is the presence of subglacial water, the production of which is a result of both glaciological shear heating and geothermal heat flux. The primary goal of our study is to investigate the crustal thickness beneath Thwaites Glacier, which is an important contributor to regional-scale geothermal heat flux patterns. Crustal structure is an indicator of past tectonic events and hence provides a geophysical proxy for the thermal status of the crust and mantle. Terrain-corrected Bouguer gravity disturbances are used here to estimate depths to the Moho and mid-crustal boundary. The thin continental crust we reveal beneath Thwaites Glacier supports the hypothesis that the West Antarctic Rift System underlies the region and is expressed topographically as the Byrd Subglacial Basin. This rifted crust is of similar thickness to that calculated from airborne gravity data beneath neighboring Pine Island Glacier, and is more extended than crust in the adjacent Siple Coast sector of the Ross Sea Embayment. A zone of thinner crust is also identified near the area's subaerial volcanoes lending support to a recent interpretation predicting that this part of Marie Byrd Land is a major volcanic dome, likely within the West Antarctic Rift System itself. Near-zero Bouguer gravity disturbances for the subglacial highlands and subaerial volcanoes indicate the absence of supporting crustal roots, suggesting either (1) thermal support from a warm lithosphere or alternatively, and arguably less likely; (2) flexural support of the topography by a cool and rigid lithosphere, or (3) Pratt-like compensation. Although forward modeling of gravity data is non-unique in respect to these alternative possibilities, we prefer the hypothesis that Marie Byrd Land volcanoes are thermally-supported by warmer upper mantle. The presence of such inferred warm upper mantle also suggests regionally elevated geothermal heat flux in this sector of the West Antarctic Rift System and consequently the potential for enhanced meltwater production beneath parts of Thwaites Glacier itself. Our new crustal thickness estimates and geothermal heat flux inferences in the Thwaites Glacier region are significant both for studies of the structure of the broader West Antarctic Rift System and for assessments of geological influences on West Antarctic Ice Sheet dynamics and glacial isostatic adjustment models.
Fig 1 from the paper illustrating West Antarctic region studied in red box
Fig 2. Geothermal heat flux within box in Fig 1.

Related:

13 comments:

  1. Andrew, there was a recent paper on a gravity anomaly also in West Antarctica. That also a sign of volcanoes. Have you seen it?...Latitude

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    1. Yes, it's been all over the alarmist media that climate change is now "affecting gravity" too. For example,

      http://www.techtimes.com/articles/16973/20141005/dwindling-antarctic-ice-messing-with-earths-gravity-blame-climate-change.htm

      Yes that paper is discussing the exact same W Antarctic glaciers as this paper, the Pine Island and Thwaites glaciers.

      Thus, the silly claim that this gravity change is man-made is debunked, it is due to geothermal heat from volcanoes.

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    2. This new paper, BTW, is also based upon an analysis of gravity changes due to geothermal heat melting glaciers from below.

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  2. see also:

    http://okulaer.wordpress.com/2014/09/13/a-case-to-prove-a-point-the-claims-of-major-ongoing-antarctic-peninsula-warming/

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  3. http://notalotofpeopleknowthat.wordpress.com/2014/10/12/pine-island-glacier-melting-has-little-to-with-global-warming-been-going-on-for-1000-years/

    Pine Island Glacier Melting “Has Little To With Global Warming” – Been Going On For 10000 Years.

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  4. While ever you can produce no explanation for the net inflow of thermal energy required to raise the temperature of the Venus surface by 5 degrees during its sunlit hours (as per Hans Jelbring's paper) then you have no understanding of planetary atmospheric and surface temperatures and the complete picture of all energy flows. I have explained what physics tells us in "Why It's Not Carbon Dioxide After All." You have not.

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  5. "You have not."

    Au contraire, Hans Jelbring's paper was posted here a long time ago:

    http://hockeyschtick.blogspot.com/2010/09/shattering-greenhouse-effect.html

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  6. I actually pointed this out to Johnathan Shanklin head of meteorology and ozone moitoring unit for the UK Antarctic Survey Team about 6years ago. His team had observed the string of volcanic vents 6 months earlier during flyovers. He knew nothing of it. There was no info as to the relative importance.

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    1. Not important to the CAGW narrative

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  7. Set up parallel mirrors and shine a torch through a small hole in one. Does the light get brighter and brighter as it bounces back and forth? No. And neither does the radiative flux that enters Earth's atmosphere get stronger and stronger as it bounces back and forth between the surface and the atmosphere, supposedly delivering more flux out of the base of the troposphere and into the surface than the flux which entered the atmosphere in the first place. But that's what the fancy K-T cum IPCC back radiation diagrams show and the IPCC authors brainwash gullible people into believing, just like they want you to believe water vapour warms dry regions with 1% WV by about 10 or 12 degrees and moist regions with 4% WV by about 40 or 50 degrees. Actually, real world data shows it cools. But if you do realise that these diagrams are false, how then do you explain the surface temperature?

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  8. Can you expand on the use of the term 'primarily' as in 'primarily melting from below'? I didn't see this word used, but it adds an interpretation that may not be justified from the context. In fact the paper uses the word 'potential': 'elevated geothermal heat flux in this sector of the West Antarctic Rift System and consequently the potential for enhanced meltwater production beneath parts of Thwaites Glacier'.

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    1. Fig 2 shows highly localized crustal thinning characteristic of a localized geothermal source over land, not the ocean and not diffuse as would be expected if AGW warming of either the atmosphere or the oceans was responsible for the melt.

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