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Antarctica 2017

Re: Antarctica 2017

Unread postby Plantagenet » Wed 28 Jun 2017, 14:03:04

just because ice sheets have a large volume grounded below sea level you can't assume that grounding lines will not remain stable....


No one is assuming anything. In fact, NSF has just funded a large study specifically to examine this question because the grounding lines do NOT appear stable in some large Anarctic glacial systems.

...or re-stabilize.


Its highly unlikely that once a glacier starts calving into the sea it will magically "re-stabilize". We've seen examples of this over and over again here in Alaska starting with the ice retreat from Glacier Bay---once a glacier pulls back from the grounding line and starts calving it rapidly retreats from that spot because floating ice cliffs at the edge of glaciers are highly unstable.

Cheers!

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Once tidewater glaciers pull back from the grounding line, retreat occurs rapidly.
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Re: Antarctica 2017

Unread postby rockdoc123 » Wed 28 Jun 2017, 15:34:16

Its highly unlikely that once a glacier starts calving into the sea it will magically "re-stabilize".


and yet that is just what the paper I pointed to on Lambert Amery indicates will happen. The thought that glaciers can restabilize grounding lines is not something new.

Gomez, N, et al, 2010. Sea level as a stabilizing factor for marine-ice-sheet grounding lines. Nature Geoscience, 3, pp 850 – 853.

Climate change could potentially destabilize marine ice sheets, which would affect projections of future sea-level rise. Specifically, an instability mechanism has been predicted for marine ice sheets such as the West Antarctic ice sheet that rest on reversed bed slopes, whereby ice-sheet thinning or rising sea level leads to irreversible retreat of the grounding line. However, existing analyses of this instability mechanism have not accounted for deformational and gravitational effects that lead to a sea-level fall at the margin of a rapidly shrinking ice sheet. Here we present a suite of predictions of gravitationally self-consistent sea-level change following grounding-line migration. Our predictions vary the initial ice-sheet size and also consider the contribution to sea-level change from various subregions of the simulated ice sheet. Using these results, we revisit a canonical analysis of marine-ice-sheet stability and demonstrate that gravity and deformation-induced sea-level changes local to the grounding line contribute a stabilizing influence on ice sheets grounded on reversed bed slopes. We conclude that accurate treatments of sea-level change should be incorporated into analyses of past and future marine-ice-sheet dynamics.


and a later paper by Gomez along with David Pollard

Gomez, N, Pollard, D and Holland D, 2015. Sea-level feedback lowers projections of future Antarctic Ice-sheet mass loss. Nature Communications, 6. doi:10.1038/ncomms9798

The stability of marine sectors of the Antarctic Ice Sheet (AIS) in a warming climate has been identified as the largest source of uncertainty in projections of future sea-level rise. Sea-level fall near the grounding line of a retreating marine ice sheet has a stabilizing influence on the ice sheets, and previous studies have established the importance of this feedback on ice age AIS evolution. Here we use a coupled ice sheet–sea-level model to investigate the impact of the feedback mechanism on future AIS retreat over centennial and millennial timescales for a range of emission scenarios. We show that the combination of bedrock uplift and sea-surface drop associated with ice-sheet retreat significantly reduces AIS mass loss relative to a simulation without these effects included. Sensitivity analyses show that the stabilization tends to be greatest for lower emission scenarios and Earth models characterized by a thin elastic lithosphere and low-viscosity upper mantle, as is the case for West Antarctica
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Re: Antarctica 2017

Unread postby Plantagenet » Wed 28 Jun 2017, 16:09:20

Its highly unlikely that once a glacier starts calving into the sea it will magically "re-stabilize".


and yet that is just what the paper .... indicates will happen.


Actually, no.

Once again you show that your reading comprehension skills are so poor you don't understand what you are reading. Those papers you cite discuss various mechanisms that might allow a glacier to remain grounded in spite of global warming and/or sea level rise and other effects.

None of the papers you cited suggest that once a glacier backs off the grounding line and starts calving into the sea it can magically "re-stabilize." Once off the grounding line glaciers tend to calve so rapidly that the terminus retreats rapidly into deeper water. For instance in Alaska the 18th century retreat of glaciers from Glacier Bay involved retreat rates of 3-9 miles per decade.

Thats why its so critical to determine if any of the large glacier systems in Antarctica and/or Greenland is about to pull off its grounding line---once it does the calving ice front can retreat rapidly into deeper water within the main part of of the ice sheet.

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from NATURE

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Re: Antarctica 2017

Unread postby rockdoc123 » Wed 28 Jun 2017, 17:54:54

None of the papers you cited suggest that once a glacier backs off the grounding line and starts calving into the sea it can magically "re-stabilize."


did you read them and understand them? The point being made is that the grounding line is controlled by sea level and if through melt and concomitant isostatic rebound local relative sea level drops the grounding line is re-established.

Gomez et al 2010 said:

These sea-level results may be combined with the bed slope at the grounding line to compute an effective topographic slope. As an example, the grounding line of an ice sheet (Lo = 700 km) rapidly retreating on a flat bed will actually be subject to an effective topographic slope of 0.3 m km−1if the retreat reflects an ice-sheet-wide mass loss; this is as a result of the elastic uplift of the crust due to the (ice plus water) unloading and the fall of the local sea surface arising from the associated loss in gravitational attraction. Both processes act to stabilize the retreat of the grounding line.


and another reference indicating the same:

Bradley, S et al, 2014. Low post-glacial rebound rates in the Weddell Sea due to Late Holocene ice-sheet readvance. Earth and Planetary Sci Lett, V 413, pp 79-89.

Many ice-sheet reconstructions assume monotonic Holocene retreat for the West Antarctic Ice Sheet, but an increasing number of glaciological observations infer that some portions of the ice sheet may be readvancing, following retreat behind the present-day margin. A readvance in the Weddell Sea region can reconcile two outstanding problems: (i) the present-day widespread occurrence of seemingly stable ice streams grounded on beds that deepen inland; and (ii) the inability of models of glacial isostatic adjustment to match present-day uplift rates. By combining a suite of ice loading histories that include a readvance with a model of glacial isostatic adjustment we report substantial improvements to predictions of present-day uplift rates, including reconciling one problematic observation of land sinking. We suggest retreat behind present grounding lines occurred when the bed was lower, and isostatic recovery has since led to shallowing, ice sheet re-grounding and readvance. The paradoxical existence of grounding lines in apparently unstable configurations on reverse bed slopes may be resolved by invoking the process of unstable advance, in accordance with our load modelling.
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Re: Antarctica 2017

Unread postby dohboi » Wed 28 Jun 2017, 18:27:54

(Plant, keep in mind you are trying to have a rational, scientific conversation with someone who was absolutely sure that polar sea water could not be warmer below the surface than at the surface, that it was just a physical total impossibility...even though that is the normal situation with polar sea water...the guy really doesn't merit the honor of your attention, frankly...)
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Re: Antarctica 2017

Unread postby rockdoc123 » Wed 28 Jun 2017, 19:33:56

(Plant, keep in mind you are trying to have a rational, scientific conversation with someone who was absolutely sure that polar sea water could not be warmer below the surface than at the surface, that it was just a physical total impossibility...even though that is the normal situation with polar sea water...the guy really doesn't merit the honor of your attention, frankly...)


Once again I never said that and once again you add zero to a conversation in which you know actually squat about. Do you you think you understand something about isostatic response modeling? That is what the discussion is about. IF you don't then you haven't a frigging clue whether Plant has said anything that is at all relevant to the papers. Both papers referenced acknowledge the model Plant refers to, what they are saying is that model didn't take into account sea level response to ice loss which they point out has the tendency to stablize grounding lines.

I suggest you either read the papers and make an intelligent comment or just shut up as most of your appearance on this thread is a complete waste of time. One has to feel sorry for what ever school students you teach.
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Re: Antarctica 2017

Unread postby Plantagenet » Thu 29 Jun 2017, 00:28:40

The point being made is that the grounding line is controlled by sea level


Actually, the grounding line isn't controlled by sea level. The Antarctic glaciers are grounded hundreds to thousands of meters below current sea level, as shown in the illustration in my post above. If you think about it, the daily tidal cycle involving several meters of rise and fall twice a day causes much more stress then sea level and isostatic changes that take decades.


if through melt and concomitant isostatic rebound local relative sea level drops the grounding line is re-established.


Again, sea level changes aren't the issue.

]Many ice-sheet reconstructions assume monotonic Holocene retreat for the West Antarctic Ice Sheet, but an increasing number of glaciological observations infer that some portions of the ice sheet may be readvancing, following retreat behind the present-day margin.


True enough.....but this is nothing new. The process is very well understood.

It is well known that glaciers can re-advance after they retreat off the grounding line. In Glacier Bay a small amount of re-advance is occurring now about two hundred years after the retreat started. Same thing at the Taku Glacier coming off the Juneau Ice Field where I did some field research. The glacier came off the grounding line about 150 years ago, rapidly retreated, and has now started to re-advance again after pulling back 20 miles or so. More detailed research has shown that some Alaskan tidewater glaciers have retreated and then readvanced a half dozen times or so during the Holocene. This process is so well known it even has a name---it is called the TIDEWATER GLACIAL CYCLE

Tidewater_glacier_cycle

So we've already discussed what makes the glaciers retreat---it happens when they pull back from the grounding line. But what makes the glaciers start to re-advance again? In Alaska it happens when the entire tidewater portion of the glacier calves away so that the only portion of the glacier remaining is land-based. Then that land-based glacier can again readvance into the ocean.

So it takes ca. one hundred years to destroy the part of the glacier occupying the submerged troughs or valley we have here in Alaska. Only then can the remaining residual part of the glacier---which is now a normal, land based glacier, advance into the ocean. The readvance is much much slower then the calving retreat and it may take many hundreds of years for the glacier to re-advance to the original grounding line.

Some of the small outlet glaciers in small valleys from the WAIS seem to exhibit this kind of cyclic behavior. Yes, those glaciers have pulled back from the grounding line and retreated and then re advanced during the Holocene. The problem is that some of the GIANT outlet glaciers occupy enormous valleys, and calving retreat at these sites after a potential pull back from the grounding line may involve a significant portion of the WAIS.

If the Antarctic glaciers behave like other glaciers that terminate in the ocean, once they pull back from the grounding line they will begin retreating because calving rates are so rapid. Once the West Antarctic Ice Sheet is gutted and marine-based ice is basically gone, then any remaining alpine glaciers can readvance into the basin and begin to fill it again.

Cheers!
Last edited by Plantagenet on Thu 29 Jun 2017, 00:45:11, edited 1 time in total.
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Re: Antarctica 2017

Unread postby Plantagenet » Thu 29 Jun 2017, 00:40:13

dohboi wrote:Plant, keep in mind you are trying to have a rational, scientific conversation with someone who was absolutely sure that polar sea water could not be warmer below the surface than at the surface, that it was just a physical total impossibility...even though that is the normal situation with polar sea water...the guy really doesn't merit the honor of your attention, frankly...)


You are so kind, Dohboi.

I appreciate your warnings, and you're probably right that some point things will get unpleasant, but so far I am enjoying thinking about tidewater glaciers again.

Its been a while since I did my fieldwork and wrote some papers about the tidewater glaciers in SE Alaska. Its nice to think about it all again, and to remember just how amazing the scenery was.

Hope things are going well for you this summer. So far our weather here in Alaska is SPECTACULAR. My big Alaska trip this summer is a float trip down the Copper River to the Gulf of Alaska. We've had two fatal bear attacks in the backcountry this summer, so people are a bit more edgy about doing fieldwork in remote areas with large bear populations, but I've wanted to do this trip for years now.

Hope you've got some good things planned too! Take care.

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Taku Glacier, Alaska
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Re: Antarctica 2017

Unread postby rockdoc123 » Thu 29 Jun 2017, 10:40:03

Actually, the grounding line isn't controlled by sea level.


The access to the grounding line by warm circulated waters in the model you point to is what is causing melting at the terminus and subsequent retreat. If that area is now elevated it is no longer accessible. This is the premise of the papers I pointed to...read them.

Again, sea level changes aren't the issue. 


Well that is not what the literature says. The articles I pointed to indicate the relationship between isostacy, sea level and grounding line stability. Another one here:

Boer, B, et al, 2017. Current state and future perspectives on coupled ice-sheet sea-level modelling. Quaternary Sci Rev, 169, pp 13-28

The interaction between ice-sheet growth and retreat and sea-level change has been an established field of research for many years. However, recent advances in numerical modelling have shed new light on the precise interaction of marine ice sheets with the change in near-field sea level, and the related stability of the grounding line position. Studies using fully coupled ice-sheet e sea-level models have shown that accounting for gravitationally self-consistent sea-level change will act to slow down the retreat and advance of marine ice-sheet grounding lines. Moreover, by simultaneously solving the ’sea-level equation’ and modelling ice-sheet flow, coupled models provide a global field of relative sea-level change that is consistent with dynamic changes in ice-sheet extent. In this paper we present an overview of recent advances, possible caveats, methodologies and challenges involved in coupled ice-sheet e sea-level modelling. We conclude by presenting a first-order comparison between a suite of relative sea-level data and output from a coupled ice-sheet e sea-level model.


But what makes the glaciers start to re-advance again?


Glacier advance and retreat is a product of balance between additions in the accumulation zone and subtractions at the terminus. So if there is more accumulation in the headland than removal at the terminus the gravitational drive internally within the ice sheet as a consequence of an increased topographic profile (gravity induced sliding) occurs and the tendency is for the glacier to advance. As you say there is an impediment to the advance of these glaciers into deep water (greater than a few hundred m) regardless of accumulation or calving rate. But this is solved by the development of sediment accumulation at the terminus. This was described in:

Nick, F. M., C. J. van der Veen, and J. Oerlemans (2007), Controls on advance of tidewater glaciers: Results from numerical modeling applied to Columbia Glacier, J. Geophys. Res., 112, F03S24, doi:10.1029/2006JF000551

A one-dimensional numerical ice flow model is used to study the advance of a tidewater glacier into deep water. Starting with ice-free conditions, the model simulates glacier growth at higher elevations followed by advance on land to the head of the fjord. Once the terminus reaches a bed below sea level, calving is initiated. A series of simulations was carried out with various boundary conditions and parameterizations of the annual mass balance. The results suggest that irrespective of the calving criterion and accumulation rate in the catchment area, it is impossible for the glacier terminus to advance into deeper water (>300 m water depth) unless sedimentation at the glacier front is included. The advance of Columbia Glacier, Alaska, is reproduced by the model by including “conveyor belt” recycling of subglacial sediment and the formation of a sediment bank at the glacier terminus. Results indicate slow advance through the deep fjord and faster advance in shallow waters approaching the terminal moraine shoal and the mouth of the fjord


But this is largely a distraction from what the papers I pointed to propose and that is isostatic responses as a consequence of thinning and retreat result in lowered sea level and restabilization of grounding lines. If you have an argument with this then I suggest you read the papers and criticize what the authors have done.

While on the topic another recent paper that speaks to the potential for grounding lines on retrograde bed slopes to persist and reverse migration direction as a consequence of internal variations in the ice sheet mechanics.

Robel, A et al, Persistence and variability of ice stream grounding lines on retrograde bed slopes. The Cryosphere Discuss, doi:10.5194/tc-2016-18, 2016

In many ice streams, basal resistance varies in space and time due to the dynamically-evolving properties of subglacial till. These variations can cause internally-generated oscillations in ice stream flow. However, the potential for such variations in basal properties are not considered by conventional theories of grounding line stability on retrograde bed slopes, which assume that bed properties are static in time. Using a numerical flowline model, we show how internally-generated, 5 transient variations in ice stream state interact with retrograde bed slopes. In contrast to predictions from the theory of the marine ice sheet instability, our simulated grounding line is able to persist and reverse direction of migration on a retrograde bed when undergoing oscillations in the grounding line position. In turn, the presence of a retrograde bed may also suppress or reduce the amplitude of internal oscillations in ice stream state. We explore the physical mechanisms responsible for these behaviors and discuss the implications for observed grounding line migration in West Antarctica
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Re: Antarctica 2017

Unread postby Plantagenet » Thu 29 Jun 2017, 11:43:58

rockdoc123 wrote:
Actually, the grounding line isn't controlled by sea level.


The access to the grounding line by warm circulated waters in the model you point to is what is causing melting at the terminus and subsequent retreat. If that area is now elevated it is no longer accessible.


????

The grounding line under Antarctic glaciers is typically hundreds of meters below sea level. The NSF even drilled down to it at one place ----it was 740 m down under the ice (thats 2400 feet in English units).

scientists-drill-through-2-400-feet-of-antarctic-ice-for-climate-clues

How do you imagine that those areas will suddenly become so "elevated" that they are no longer accessible to warm marine currents? Are you imagining that 740 m (2400 feet) of uplift will magically occur over the next several decades?

Cheers!
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Re: Antarctica 2017

Unread postby rockdoc123 » Thu 29 Jun 2017, 12:07:25

How do you imagine that those areas will suddenly become so "elevated" that they are no longer accessible to warm marine currents? Are you imagining that 740 m (2400 feet) of uplift will magically occur over the next several decades?


Once again read the papers. The models are described fairly explicitly and methods are also described.
This isn't just one paper by the way I think I pointed to about 4 that speak to the issue.

I'm not "imagining" anything. I'm reporting what a few technical publications are proposing.
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Re: Antarctica 2017

Unread postby Plantagenet » Thu 29 Jun 2017, 12:34:28

How do you imagine that those areas will suddenly become so "elevated" that they are no longer accessible to warm marine currents? Are you imagining that 740 m (2400 feet) of uplift will magically occur over the next several decades?


I'm not "imagining" anything. I'm reporting what a few technical publications are proposing.


Actually, no. None of the papers you list say anything about "elevating" grounding lines to make the grounding lines inaccessible to warm marine currents.

That is a magical idea entirely of your devising.

Cheers!

PS: Do you have any scientific training or education? I seem to remember that at some point you said you had worked in the oil biz---is that right?

Cheers!
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Re: Antarctica 2017

Unread postby rockdoc123 » Thu 29 Jun 2017, 18:16:01

Actually, no. None of the papers you list say anything about "elevating" grounding lines to make the grounding lines inaccessible to warm marine currents.


Once again please read the papers, apparently you aren't understanding anything from reading the abstracts.

From Gomez et al, 2015

Marine-based sectors of the AIS gain most of their mass through precipitation and lose mass by ice outflux at the grounding line. Ice-sheet mass loss leads to a sea-level (that is, water depth) fall at the grounding line, both because of post- glacial rebound of the unloaded crust and a drop in sea surface height as water migrates away from the ice sheet because of reduced gravitational attraction


From Gomez et al , 2010

The departure from eustasy is due to three effects: (1) elastic deformation of the solid Earth in response to the load redistribution, including a rebound of the crust in the vicinity of the diminishing ice load; (2) load self-gravitation, which primarily involves the migration of water away from the melting ice sheet as its gravitational pull on the ocean weakens; and (3) the feedback of contemporaneous, load-induced perturbations in the orientation of the Earth’s rotation vector onto sea level


from de Boer et al, 2017

When considering the factors contributing to this process, one should note that as the grounding line retreats, marine-grounded ice at flotation will be immediately replaced by an equivalent mass of ocean water. Hence, the instantaneous net change in surface loading right at the grounding line will be negligible. However, grounding line retreat is invariably driven by regional ice loss; it is this regional decrease in ice mass that triggers solid Earth rebound and a local drop in the height of the geoid, with the net effect being a decrease in water depth at the grounding line.


and in de Boer the uplift at the grounding line and subsequent re-stabilization of the grounding line is illustrated in Figures 1 and 5

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Re: Antarctica 2017

Unread postby Plantagenet » Thu 29 Jun 2017, 19:19:40

Lets look at some math here, shall we?

Of course ice mass loss at the grounding line will cause isostatic rebound. But you don't seem to understand, even after four repetitions, that the grounding line depth in Antarctica is hundreds of meters below sea level. I linked to info on an NSF drilling program that drilled down to the grounding line---2400 feet below sea level. Thats far too deep to bring the grounding line to the surface, as your figures imply.

Lets think through this. The density of ice is about 0.9 gm/cm3, while the density of granite is ca. 2.7 gm/cm3. Rock is about three times denser then ice.

Do you understand that? DO you know what density means?

OK then, lets do a thought experiment. If we instantaneously unload the ice from a grounding line buried by 2400 feet of ice, then the ground will, after a very long time, rebound isostatically, by ca. 800 feet. Why? because that is roughly equivalent to the ice load that was removed.

OK...how long will that rebound take? It turns out the rate of rebound is a function of viscosity within the earth---- the rate of vertical surface rebound depends on deformation within the earth. We don't know the viscosity at the Antarctic grounding lines, but isostatic rebound at other sites around the earth typically takes thousands of years to fully recover. Places in Scandinavia and northern Canada are STILL rebounding 8-10,000 years after the ice disappeared from those places.

So isostatic rebound could never lift a grounding line from 2400 below sea level to an altitude above sea level, it would take thousands of years for rebound to fully occur, and sea level is actually going up anyway.

Get it now?

CHEERS!

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Boaty McBoatface is now on research patrol mapping grounding lines in Antarctica
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Re: Antarctica 2017

Unread postby Newfie » Thu 29 Jun 2017, 19:37:11

Plant,

Interesting stuff. I'm reminded of the big glacier at Disco Bay, who's name I can never even remotely spell correctly. That has been retreating at a very rapid rate.
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Re: Antarctica 2017

Unread postby rockdoc123 » Thu 29 Jun 2017, 19:55:03

Of course ice mass loss at the grounding line will cause isostatic rebound. But you don't seem to understand, even after four repetitions, that the grounding line depth in Antarctica is hundreds of meters below sea level. I linked to info on an NSF drilling program that drilled down to the grounding line---2400 feet below sea level. Thats far too deep to bring the grounding line to the surface, as your figures imply.


oh jesus wept.....read the damned papers. Why all the first principle arguments when this is all addressed in the models?
If you are too lazy to read the publications then there is really no point arguing.

And sorry you do not have to lift a grounding line any higher than from the depth at which melt is starting to occur to the depth at which it isn't occurring. Given shallower water here is colder that is not 2400 m but much much less, as suggested in the diagrams shown which came from de Boers model.

But again why am I explaining this. The models in these papers take this into account. First you claim that the papers (which you clearly haven't read) do not say that sea level has anything to due with stabilization of a grounding line (which they do) then you say the papers do not claim that isostatic uplift can restablize and even advance a grounding line (which on the contrary they clearly do). Now I suppose you are claiming that the models handle GIA incorrectly? :roll:

Rather than rambling on about how the conclusions reached by these papers can't make sense perhaps you should actually read them and critique the model inputs because according to you all of these scientists have gotten it wrong. :roll:
Once again, these aren't my ideas or my models they are those of the authors of these papers. Read them.

And what started all of this was when I said:

a major point here is that just because ice sheets have a large volume grounded below sea level you can't assume that grounding lines will not remain stable or re-stabilize. This was a point made in earlier threads where taking into account isostatic adjustments due to ice removal can result in changes to the grounding line configuration.


and you took offence to the idea that ice sheets with reversed bed slopes could ever re-stablize. This is clearly indicated as being possible in each of these papers as has been demonstrated.
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Re: Antarctica 2017

Unread postby dohboi » Thu 29 Jun 2017, 22:27:06

Plant, glad to hear you've been having good weather. We've had such steady rains here that I've hardly had to water my gardens. To our west, though, it's getting rather dry (Dakotas, Montana...).

I've noticed some pretty wild low pressure systems circulating around Antarctic lately. Not sure what effect they might have on all this or how unusual they are. If you get tired of debating pigeons, maybe we could have a reasonably intelligent conversation about something like that soon?? :) :)

Also, note that Larsen C is still ripping apart, pivoting away from the rest of the ice mass like a door on a hinge: http://forum.arctic-sea-ice.net/index.p ... #msg118702
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Re: Antarctica 2017

Unread postby Plantagenet » Fri 30 Jun 2017, 12:45:15

dohboi wrote:I've noticed some pretty wild low pressure systems circulating around Antarctic lately. Not sure what effect they might have on all this or how unusual they are. If you get tired of debating pigeons, maybe we could have a reasonably intelligent conversation about something like that soon?? :) :)

Also, note that Larsen C is still ripping apart, pivoting away from the rest of the ice mass like a door on a hinge: http://forum.arctic-sea-ice.net/index.p ... #msg118702


D--Thank you so much for posting news about Antarctica and other climate change hot spots.

I always read your intelligent and well formulated posts.

Have a great day!
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Re: Antarctica 2017

Unread postby dohboi » Mon 03 Jul 2017, 15:20:45

You, too, P.

Meanwhile,

“Antarctica is melting faster than scientists expected”

http://www.pbs.org/newshour/bb/antarcti ... -expected/
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Re: Antarctica 2017

Unread postby dohboi » Mon 03 Jul 2017, 23:05:36

More stuff on Antarctica...worth a view:

http://www.nationalgeographic.com/magaz ... te-change/
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