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Antarctica 2020

Antarctica 2020

Unread postby Tuike » Fri 07 Feb 2020, 14:51:13

Antarctica has hottest day on record as temperatures reach 18.3°C -euronews
Temperatures in Antarctica reached a new record high on Thursday, reaching 18.3 °C. The new record was set at midday at the Esperanza research station, the Argentinian meteorological agency announced on Twitter. The research station is located at the northern-most part of the pole, some 1,100 km away from the Argentinian city of Ushuaia. It is the highest temperatures ever registered there since records began in 1961, beating the previous record of 17.5°C set in March 2015.

According to the UN's World Meteorological Organisation, the Antarctic Peninsula — defined as the northwest tip near to South America — is one of the "fastest-warming regions of the planet" with temperatures rising by almost 3°C over the past 50 years.
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Re: Antarctica 2020

Unread postby Tanada » Fri 07 Feb 2020, 21:50:02

Tuike wrote:Antarctica has hottest day on record as temperatures reach 18.3°C -euronews
Temperatures in Antarctica reached a new record high on Thursday, reaching 18.3 °C. The new record was set at midday at the Esperanza research station, the Argentinian meteorological agency announced on Twitter. The research station is located at the northern-most part of the pole, some 1,100 km away from the Argentinian city of Ushuaia. It is the highest temperatures ever registered there since records began in 1961, beating the previous record of 17.5°C set in March 2015.

According to the UN's World Meteorological Organisation, the Antarctic Peninsula — defined as the northwest tip near to South America — is one of the "fastest-warming regions of the planet" with temperatures rising by almost 3°C over the past 50 years.


Not to make too much of it but Esperanza Base is just about as far north as you can get and still be in the continent of Antarctica. Heck it is dozens of miles north of the Antarctic Circle, rather like Nome Alaska is on the other end of the planet. It is so far out on the peninsula in fact that it gets maritime climate effects for a large percentage of the year, it only trails off as the sea ice pack expands in deepest winter. Unlike the other stations in Antarctica it has a few hours of daylight even in the deepest part of winter and because it is below the Antarctic Circle it also misses out on the midnite sun effect the other bases have in mid summer.
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Re: Antarctica 2020

Unread postby yellowcanoe » Fri 07 Feb 2020, 22:51:56

Tanada wrote:
Not to make too much of it but Esperanza Base is just about as far north as you can get and still be in the continent of Antarctica. Heck it is dozens of miles north of the Antarctic Circle, rather like Nome Alaska is on the other end of the planet. It is so far out on the peninsula in fact that it gets maritime climate effects for a large percentage of the year, it only trails off as the sea ice pack expands in deepest winter. Unlike the other stations in Antarctica it has a few hours of daylight even in the deepest part of winter and because it is below the Antarctic Circle it also misses out on the midnite sun effect the other bases have in mid summer.


Yes, indeed, the weather on the polar ice cap is vastly different than at Esperanza Base. I have a friend who spent the winter at the South Pole station. The highest temperature recorded there during the entire year prior to his arrival was -19C so even during the height of the summer temperatures are well below the freezing point. Around 50 people stay at the station during the winter months and they have the opportunity to become members of the 300 degree club -- leaving a sauna heated to 200F and briefly walking outside where the temperature is at least -100F.
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Re: Antarctica 2020

Unread postby rockdoc123 » Sat 08 Feb 2020, 12:51:58

Indeed at the same time Esperanza was seeing a high Scott-Amundsen base saw a high temperature of -45 C. During the summer months the coastal stations around Antarctica usually see short time highs during the day a few degrees above zero. The peninsula is a different story as it extends quite aways north and has a climate much more like southern Argentina.
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Re: Antarctica 2020

Unread postby dohboi » Wed 12 Feb 2020, 16:02:40

Ancient Antarctic ice melt increased sea levels by 3+ meters—and it could happen again

https://phys.org/news/2020-02-ancient-a ... rsand.html

Using data gained from their fieldwork, the team ran model simulations to investigate how warming might affect the floating ice shelves. These shelves currently buttress the ice sheets and help slow the flow of ice off the continent.

The results suggest a 3.8m sea level rise during the first thousand years of a 2°C warmer ocean. Most of the modelled sea level rise occurred after the loss of the ice shelves, which collapsed within the first two hundred years of higher temperatures.

Notably, the researchers warn that this tipping point may be closer than we think...
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Re: Antarctica 2020

Unread postby rockdoc123 » Tue 05 May 2020, 15:45:12

A new paper which presents the results of NASA's ICESAT-2 over a period of 16 years has been released. In general it is in agreement with estimates of mass balance from a host of other studies, many lower, some higher. MY guess is the differences now are related to the GIA model employed and not necessarily to methodology in measuring changes in ice thickness/extent.

Smith, B et al, 2020. Pervasive ice sheet mass loss reflects competing ocean and atmosphere processes. Science, 30. DOI: 10.1126/science.aaz5845

Quantifying changes in Earth’s ice sheets, and identifying the climate drivers, is central to improving sea-level projections. We provide unified estimates of grounded and floating ice mass change from 2003 to 2019 using NASA’s ICESat and ICESat-2 satellite laser altimetry. Our data reveal patterns likely linked to competing climate processes: Ice loss from coastal Greenland (increased surface melt), Antarctic ice shelves (increased ocean melting), and Greenland and Antarctic outlet glaciers (dynamic response to ocean melting), was partially compensated by mass gains over ice sheet interiors (increased snow accumulation). Losses outpaced gains, with grounded-ice loss from Greenland (200 Gt a−1) and Antarctica (118 Gt a−1) contributing 14 mm to sea level. Mass lost from West Antarctica’s ice shelves accounted for over 30% of that region’s total.


what I found quite interesting is the map they published with the study illustrates where thinning has occurred and where thickening has occurred.

Image

and when that is compared to a map of measured crustal heat flow

Image

the correlation is pretty good especially when you think the heating at ice sheet headlands translates into increased flow at the outlet. The vast majority of losses in West Antarctica coincide pretty well with high basal heat flow and indeed the location of known volcanism. This isn't surprising to those who understand the tectonic history of Antarctica.

But papers like the NASA one tend to completely ignore any possibility of contribution to melt from elevated basal heat flow even though it has been well documented and understood that basal heat flow in excess of 80 mWm2 is all that is needed to create melt beyond that due to pressure melting.

So the -118 GT/yr of net mass balance equates to a contribution of sea level of 0.3 mm/yr or 24 mm (about 1 inch) total by 2100. And a good portion of that sea-level increase could be due to causes other than atmospheric or ocean warming.
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Re: Antarctica 2020

Unread postby Plantagenet » Tue 05 May 2020, 17:25:43

... papers like the NASA one tend to completely ignore any possibility of contribution to melt from elevated basal heat flow even though it has been well documented and understood that basal heat flow in excess of 80 mWm2 is all that is needed to create melt beyond that due to pressure melting.


Thats because if you do the math the amount of melting due to heat flow is minuscule compared to the amount of ice loss due to calving into the oceans. There is also an acceleration of surface ablation and melting on the Antarctic Peninsula and some coastal glaciers but the main effect is increased calving caused by the warming oceans.

AND the accelerated calving into the oceans has been attributed to warming oceans around Antarctica, which is clearly a product of global warming. Ditto for the increase in surface melt---thats due to warming climate as well.

pine-island-glacier-calving-warming-ocean-ice-retreat

Image
Warming oceans around Antarctica are causing increased melting at the base of tidewater calving glaciers. This also produces increased ice flow velocities, thinning at the surface, and increased calving and ice loss----all consistent with the new satellite survey data from Antarctica.

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Re: Antarctica 2020

Unread postby rockdoc123 » Tue 05 May 2020, 20:31:45

Thats because if you do the math the amount of melting due to heat flow is minuscule compared to the amount of ice loss due to calving into the oceans. There is also an acceleration of surface ablation and melting on the Antarctic Peninsula and some coastal glaciers but the main effect is increased calving caused by the warming oceans.


Well please share that math with us if you want but apparently you do not understand what it is I am saying. The increased melting at the base of the ice sheet increases the speed by which that ice sheet moves. It has nothing to do with melt loss from basal heating but all to do with increased pore fluid pressure and decreased net friction at the base of the ice sheet. At about 80 mW/m2 ice at the base of thick ice sheets changes phase and the weight of the ice sheet increases pore fluid pressure which will increase the rate of sliding. The main reason calving increases is because the speed of the ice sheet increases and that speed has been measured by satellite all the way back to headwalls for Thwaites and PIG for about a decade. If the ice sheet had not sped up there would be less there to calve. The models have all used geothermal gradients of 40 - 60 mW/m2 and recent evidence (which I've pointed to before on this threads predecessor illustrates localized heat flows in Western Antarctica well above 80 mW/m2, up to 120 mW/m2) and that will make a significant difference in speed.
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Re: Antarctica 2020

Unread postby Plantagenet » Tue 05 May 2020, 21:00:22

apparently you do not understand what it is I am saying.


Of course I do. Thats why I'm taking a moment to discuss this with you....IMHO you have erred.

The increased melting at the base of the ice sheet increases the speed by which that ice sheet moves. It has nothing to do with melt loss from basal heating but all to do with increased pore fluid pressure and decreased net friction at the base of the ice sheet. At about 80 mW/m2 ice at the base of thick ice sheets changes phase and the weight of the ice sheet increases pore fluid pressure which will increase the rate of sliding.


Thats where, IMHO, you have erred. While there are areas of Antarctic where there is higher or lower heat flow, there is no evidence of any recent changes in the heat flow that would result in increases in melt water, speed, pore pressure or changes in anything else. Regional heat flow tends to change very very slowly in response to regional tectonics.

For all intents and purposes heat flow has been constant over the time period when humans have been observing Antarctica, including the last few decades when the satellite data shows impressive increases in flow velocity and greatly increased loss of ice mass by calving has occurred. That means its far more likely the large charges we are seeing in Antarctica over the last few decades are due to global warming.

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Re: Antarctica 2020

Unread postby rockdoc123 » Wed 06 May 2020, 11:14:29

Thats where, IMHO, you have erred. While there are areas of Antarctic where there is higher or lower heat flow, there is no evidence of any recent changes in the heat flow that would result in increases in melt water, speed, pore pressure or changes in anything else. Regional heat flow tends to change very very slowly in response to regional tectonics.


Wrong on several points. First of all given actual measurements of heat flow beneath the ice sheet in Western Antarctica have only just begun (only in the last couple of years) the comment there “is no evidence of any recent changes in heat flow” is basically meaningless. That’s a bit like observing a bathtub full of water and saying “there is no evidence of any recent changes in water level”, if you didn’t observe the empty tub, of course, there isn’t. Secondly, we are not talking about ambient heat flow due to crustal rock type, the type of heat flow that has been assumed by models to this point in time. The high heat flow areas measured correspond with areas of associated volcanism in the recent past and suspected presence of magma chambers at depth. The map I showed points to the location of known sub ice and exposed volcanoes, all of which are in Western Antarctica. Heat flow around areas of magmatic activity can change abruptly. And the tectonics I referred to as it relates to this area is the West Antarctic rift which is responsible for the uplift in the transatlantic mountains and the fact that crustal thickness in West Antarctica is thinner and more susceptible to upwelling events in the asthenosphere.

For all intents and purposes, heat flow has been constant over the time period when humans have been observing Antarctica, including the last few decades when the satellite data shows impressive increases in flow velocity and greatly increased loss of ice mass by calving has occurred. That means its far more likely the large charges we are seeing in Antarctica over the last few decades are due to global warming.


Complete BS. Nobody has been actually measuring heat flow in Antarctica until very recently (2014 was the first as I remember). Please show us all the papers you imagined existed. The actual fact is that once geophysical surveys in Antarctica improved (the past half-decade) modeling allowed to indicate potential areas of higher than normal heat flow, contrary to the methodology used in the past which was to assume bedrock geology and project heat flow from that. In the past couple of years, surveys were instigated to investigate those areas of potential high heat flow, and those boreholes confirmed their existence (highest local measure at 200 mW/m2 which is higher than the central Africa rift in most places). The likely existence of sub-ice volcanism was also demonstrated through the chemistry of waters recovered.

The work on Western Antarctica heat flow is all relatively new and the authors (many of these papers I have referenced previously) point to the fact they believe understanding localized high heat flow impacts by including them in ice sheet models will be very significant. Note that the same observations have been made recently in Greenland where the area of fastest ice flow coincides with the pathway of Greenland over a mantle hot spot. This is a new area of research.

Bottom line is that the amount of melt from Antarctica in terms of equivalent sea water level rise is minuscule and if a greater portion of this is due to faster ice sheet speeds due to basal heating then the impact of climate change becomes even less than it already is in this region.
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Re: Antarctica 2020

Unread postby Plantagenet » Wed 06 May 2020, 11:22:14

the comment there “is no evidence of any recent changes in heat flow” is basically meaningless.


You're the one claiming increases in heat flow are responsible for the observed changes in Antarctic glacier dynamics.

Now you're admitting there is no evidence of such changes......which is precisely my point. :)

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Re: Antarctica 2020

Unread postby rockdoc123 » Wed 06 May 2020, 14:16:29

You're the one claiming increases in heat flow are responsible for the observed changes in Antarctic glacier dynamics.

Now you're admitting there is no evidence of such changes......which is precisely my point. :)


I was quoting you..
While there are areas of Antarctic where there is higher or lower heat flow, there is no evidence of any recent changes in the heat flow


If you had bothered to read my post you would have seen in several places I make the argument why that a suggestion there has been no change in heat flow is basically stupid. At no point to I somehow agree with your point...it is basically dumb. They just started measuring heat flow, no way of telling where, if or how it has increased, decreased remained the same or for what period.

Apparently basic reading comprehension, as well as a thorough understanding of the science, both escape you.
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Re: Antarctica 2020

Unread postby Plantagenet » Wed 06 May 2020, 14:50:11

in several places I make the argument why that a suggestion there has been no change in heat flow is basically stupid...basically dumb


Claiming the changes in glaciers dynamics are caused by changes in heat flow over huge regions of Antarctica with no evidence to support your claim is basically stupid and basically dumb.

Science is evidence based......Where is the evidence to support your claim that the observed changes in glacier dynamics in Antarctica are caused by changes in heat flow rates?

The universally accepted model posits that the changes in glacier dynamics are caused by atmospheric and oceanic changes driven by global warming, and there is plenty of evidence supporting that conclusion. The data clearly show atmospheric warming and oceanic warming is going on, and numerical models show how these observed changes drive the recent changes in Antarctic glacier dynamics.

Please provide some evidence in support of your unconventional model.

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Re: Antarctica 2020

Unread postby rockdoc123 » Wed 06 May 2020, 19:04:18

Claiming the changes in glaciers dynamics are caused by changes in heat flow over huge regions of Antarctica with no evidence to support your claim is basically stupid and basically dumb.


what is dumb is not reading or comprehending my posts. I posted a map of integrated heat flux (the source for that map is: Martos, Y et al, 2017. Heat Flux distribution of Antarctica unveiled. Geoph, Res Lett., 44, pp 11417-11426)and it is pretty clear from that map the areas of high heat flow correspond with areas of fast flow ice sheets as well as the areas of greatest ice loss as shown in the most recent publication I mentioned. There are a number of papers that reference details of the heat flux observations that I have referenced here in the past:

Schroeder, DM et al, 2014. Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet. PNAS, 111, 25, pp 9070-9072 is an example where the authors state:

show that large areas at the base of Thwaites Glacier are actively melting in response to geothermal flux consistent with rift-associated magma migration and volcanism. This supports the hypothesis that heterogeneous geothermal flux and local magmatic processes could be critical factors in determining the future behavior of the West Antarctic Ice Sheet.


Fisher, A. T. et al, 2015. High geothermal heat flux measured below the West Antarctic Ice Sheet, Science Advances, V1, 6, e1500093

The heat flux at this site is 285 ± 80 mW/m2, significantly higher than the continental and regional averages estimated for this site using regional geophysical and glaciological models. Independent temperature measurements in the ice indicate an upward heat flux through the WAIS of 105 ± 13 mW/m2. The difference between these heat flux values could contribute to basal melting and/or be advected from Subglacial Lake Whillans by flowing water. The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region.


Science is evidence based......Where is the evidence to support your claim that the observed changes in glacier dynamics in Antarctica are caused by changes in heat flow rates?


Science, which you seem to know very little about is comprised of theories based on observations. The observations made by a number of scientists are that observed locales of high heat flow correspond with areas of fast glacial ice. The theory to explain this is high fluid pressure and the decrease in basal shear stress created by sub-ice melt which allows ice streams to flow faster. That is not a new theory but something that has been understood as a mechanism that aids in glacial movement for many decades. In comparison what do you have for observations to say it all has to do with oceans. Do you have cameras photographing active melt under glacier toes? Can you prove that glacial retreat is all due to warmer oceans (it has nothing to do with atmospheric temperatures as all the data indicates that has not changed in most areas over the history of satellite measurements)? If that is the case then why are certain glaciers in East Antarctica where the oceans are much colder also retreating (while others are advancing at the same time eg: Amery)? That "observation" throws cold water on your beloved theory.

The universally accepted model posits that the changes in glacier dynamics are caused by atmospheric and oceanic changes driven by global warming, and there is plenty of evidence supporting that conclusion. The data clearly show atmospheric warming and oceanic warming is going on, and numerical models show how these observed changes drive the recent changes in Antarctic glacier dynamics.


Universally accepted in your mind perhaps...its an unproven theory and nothing more. A model is only as correct as it's assumptions; if you don't include all the variables correctly it is what we refer to as "right for the wrong reasons" or basically crap.

As to your claim of atmospheric warming, the actual data says you are completely wrong:

here are two plots amalgamating many of the AWS stations in the Pennisula and Western Antarctica

Image

Image

and the instrumental era data from satellite measurements over the continent:

Image

no warming trends there I'm afraid.
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Re: Antarctica 2020

Unread postby Plantagenet » Wed 06 May 2020, 20:53:48

what is dumb is....


What is dumb and childish is you calling other people dumb.

There are a number of papers that reference details of the heat flux observations that I have referenced here in the past...


Of course. There is a volcanic arc along the Alaska peninsula and volcanoes also occur in other areas of Antarctica. Heat flow tends to be elevated in volcanic regions and sure enough...its also elevated in the volcanic areas of Antarctica. Volcanism has been going on in these areas for millions of years, and so heat flow has been elevated in these areas for millions of years. A geophysical process that has been going on for millions of years is unlikely to be responsible for recent changes in glacier dynamics and calving rate and mass balance in diverse areas across Antarctica unless there is evidence that it has recently changed. If you have evidence the heat flow has recently increased under huge areas of the Antarctic Ice Sheet then you'd have something....but you don't have any evidence to back up your idea.

The theory to explain this is high fluid pressure and the decrease in basal shear stress created by sub-ice melt which allows ice streams to flow faster. That is not a new theory but something that has been understood as a mechanism that aids in glacial movement for many decades.


Sorry...you don't have that right. Basal shear stress is a function of the thickness and load of the ice, gravitational forces, and the slope of the ice. This means that changes in subglacial pore pressure don't don't have any effect on the basal shear stress at all, you ninny. The basal shear stress stays constant at the base of a glacier no matter what the pore pressure is. Increases in pore pressure reduce the resistance to flow at the base of the glacier and allow the ice to flow faster or even to surge but the basal shear stress is not affected by changes in pore pressure.....in fact the whole reason the flow velocity increases is the basal shear stress stays constant while the resistance to flow is reduced by increases in pore pressure so the glacier can slide faster. Sadly but characteristically, you've got this basic idea entirely backwards.

Okay...I'm going to stop there....I can't spend all day correcting your errors. You clearly don't understand how basal shear stress affects glacier flow and you can't understand the first thing about this topic if you don't understand how basal shear stress drives glacier flow. If you want to understand glacier flow you need to get this right. Count yourself lucky that you aren't a student in my class on glaciology at the University or I would now have to flunk you, since I always cover this topic thoroughly in the very first week of my glaciology class.

Image
Your homework assignment this week is to derive the equation for basal shear stress in glaciers.....and then use the equation to explain why basal shear stress doesn't change in response to pore pressure changes at the base of glaciers

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Re: Antarctica 2020

Unread postby jedrider » Wed 06 May 2020, 22:41:15

rockdoc123 wrote:the correlation is pretty good especially when you think the heating at ice sheet headlands translates into increased flow at the outlet. The vast majority of losses in West Antarctica coincide pretty well with high basal heat flow and indeed the location of known volcanism. This isn't surprising to those who understand the tectonic history of Antarctica.

But papers like the NASA one tend to completely ignore any possibility of contribution to melt from elevated basal heat flow even though it has been well documented and understood that basal heat flow in excess of 80 mWm2 is all that is needed to create melt beyond that due to pressure melting.

So the -118 GT/yr of net mass balance equates to a contribution of sea level of 0.3 mm/yr or 24 mm (about 1 inch) total by 2100. And a good portion of that sea-level increase could be due to causes other than atmospheric or ocean warming.


So, you mean, besides global atmospheric warming and warming oceans, there may also be a volcanic source of excess heat in Antarctica! You do know that melting glaciers is also believed to be stressing the earth and causing increased earthquakes and, perhaps, increased volcanism or 'basal heat' perhaps. How many ways could we be screwed!
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Re: Antarctica 2020

Unread postby rockdoc123 » Thu 07 May 2020, 16:59:44

What is dumb and childish is you calling other people dumb.

And yet you did that in your response above….whats good for the goose….people who live in glass houses…. but that seems to be your modus operandi, blame other people for the exact thing you have said previously. You must think everyone here has a very short memory.

Of course. There is a volcanic arc along the Alaska peninsula and volcanoes also occur in other areas of Antarctica. Heat flow tends to be elevated in volcanic regions and sure enough...its also elevated in the volcanic areas of Antarctica. Volcanism has been going on in these areas for millions of years, and so heat flow has been elevated in these areas for millions of years. A geophysical process that has been going on for millions of years is unlikely to be responsible for recent changes in glacier dynamics and calving rate and mass balance in diverse areas across Antarctica unless there is evidence that it has recently changed. If you have evidence the heat flow has recently increased under huge areas of the Antarctic Ice Sheet then you'd have something....but you don't have any evidence to back up your idea.


For someone who claims to have a geoscience degree you demonstrate a healthy lack of knowledge of some very simple earth processes. Surface heat flow in and around areas of volcanism fluctuate significantly due to how active magma is at depth and whether or not it is rising. As an example at Mt St Helens temperature measured at surface began to rise a few months prior to the 1980 eruption and then fell back down following eruption. When the new dome reactivated in 2004 temperatures measured at surface rose from 51 C to 300 C in the period of one month before the small eruption. And to repeat for the third time…direct measurements of heat flow below the Antarctic ice sheet have only begun to be done in the last couple of years. How exactly do you expect some to show it “has recently changed”.

But lets turn this around. In order to make your argument about warming waters reasonable you would need to demonstrate a long term increase in ocean temperatures. Well, unfortunately, there is evidence to the exact opposite in Antarctica.

Zhou, C, et a, 2019. The Characteristics of surface albedor change trends over the Antarctic Sea Ice Region during recent decades. Remote Sensing, 11,821, doi:10.3390/rs11070821

These results demonstrated that the climate of the ASIR [the entire Antarctic Sea Ice Region, the (1) Weddell Sea (WS), (2) Indian Ocean, (3) Pacific Ocean (PO), (4) Ross Sea, and (5) Bellingshausen-Amundsen Sea (BS)] exhibits a cooling trend during summer [1982-2015], except for the BS.


Consistent with the trend of SAL [surface albedo], the slope values of SIC [sea ice concentration]  were mostly positive, except for the BS (Table 4), which further demonstrated that the climate of the ASIR exhibits a cooling trend in recent decades. … The average SAL (Table 3), SIC (Table 4), and SST (Table 5) for the total ASIR were 46.75%, 65.39%, and −2.44 °C during summer.


Image
It is clear from the Zhou el 2019 ocean temperature plots from around Antarctica that from about 2000 onwards cooling not warming has been the trend.

Sorry...you don't have that right. Basal shear stress is a function of the thickness and load of the ice, gravitational forces, and the slope of the ice. This means that changes in subglacial pore pressure don't don't have any effect on the basal shear stress at all, you ninny. The basal shear stress stays constant at the base of a glacier no matter what the pore pressure is


You do not have a clue what you talking about. If pore fluid pressure rises then the ice at the point of pore fluid rise loses friction and begins to slide. This is the basis of pressure melting which is one of the main mechanisms of deformational assisted sliding in cold glaciers and indeed the whole basis of pore pressures role in deformation (a subject that King Hubbert published on extensively in the 1950s). There are literally hundreds of technical papers written on this mechanism and it is basic instruction material to first-year geology and geography students. You must have missed that week in Geology 101. But I’ll use the very good summary by Jennifer Jiskoot a glaciology professor to point out to you where you are demonstrating a healthy lack of understanding of basic ice and rock physics.

Glaciers can slide because ice melts under pressure, resulting in a film of water at the ice-bed interface. This can facilitate decoupling and enhance fast ice flow. If the glacier bed is rough, with many bumps and obstacles, this increases melting and ice flow. This process is known as regelation. If water pressures become high enough, cavities can form at the ice-bed interface, causing sliding with bed separation. This reduces basal friction and allows faster ice flow. Sliding velocity is controlled by basal shear stress and effective pressure, which is the difference between ice overburden pressure and water pressure
.

So if the basal melt is enhanced due to higher than normal geothermal heat flow then more fluid is present in a confined space hence fluid pressure increases and basal friction is lowered further resulting in sliding velocity increase. This is very, very basic ice physics which anyone with a geoscience degree should be aware of.

So, you mean, besides global atmospheric warming and warming oceans, there may also be a volcanic source of excess heat in Antarctica! You do know that melting glaciers is also believed to be stressing the earth and causing increased earthquakes and, perhaps, increased volcanism or 'basal heat' perhaps. How many ways could we be screwed!


not sure there is a need to get your knickers in a knot. The amount of net material balance in Antarctica is observable and it is quite small adding a very insignificant amount of sea-level rise at these rates projected forward to 2100. If we now assume a part of that is due to high geothermal heat flow then it only lowers the amount of contribution from ocean heating near the grounding line...it isn't something additive. As to ice melt causing earthquakes, the calculation would indicate it is a very slow response and you would have to make all sorts of assumptions about the level of stored strain along substrate pre-existing faults, their orientation with respect to relieved stresses, etc. Faults do move without causing earthquakes, sometimes continuously whereas some might store strain for many years and release it all during a small sudden movement. There are many ifs, buts, and other unknowns involved. Anyone who tells you different does not understand the science.
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