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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #150 on: June 28, 2018, 10:38:06 PM »
The Thwaites outflow seems to be increasing, and to be warm! , much of the near glacier waters are shown to be ice free - see the close up below.

Given ASLR's latest post, 2 above, perhaps the focus of the research should have been on the Thwaites, not the PIG.

Per the attached image from Reply #27, the zone of low sea ice concentration that you are referring to may be associated with warm ocean water advecting from the Dotson Ice Shelf.
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steve s

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #151 on: June 28, 2018, 11:39:34 PM »
ASLR,

1) The current pattern of melting does not match the heat pattern in the computer generated image of post 27; and
2) I do not remember a similar mid-winter sea ice pattern -- maybe a polynya -- in the past.

But i'm merely an interested amateur, finding it a disturbing coincidence when the nearby land seems to be rising faster than the ice above is melting.   
« Last Edit: June 29, 2018, 12:45:33 AM by steve s »

Pmt111500

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #152 on: June 29, 2018, 04:18:38 PM »
The Thwaites outflow seems to be increasing, and to be warm! , much of the near glacier waters are shown to be ice free - see the close up below.

Given ASLR's latest post, 2 above, perhaps the focus of the research should have been on the Thwaites, not the PIG.



Isn't that the same area than last year? My guess was then it's an upwelling area for northern mid-level waters, and I see no reason to change my highly subjective opinion. Pacification of Ross Sea, or whatever antarctic loop that area was part of. The waters that might have gone Arctic producing BOE.
Amateur observations of Sea Ice since 2003.

steve s

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #153 on: June 29, 2018, 06:44:22 PM »
Pmt, I don't have a shot from last year, but I'd like to see one -- or better, a time series. The outflow seems to be more akin to a glacial belch. I've attached a June 3rd close up of the same area -- which shows a full sea ice coverage with the beginning of the melt out starting near the glacier.
 

oren

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #154 on: June 29, 2018, 06:57:00 PM »
Humanity needs to throw maximum monitoring resources at these two glaciers - buoys, boreholes, under-ice submersibles, and whatever else is physically possible. This is ground zero of abrupt sea level rise. (Apologies to ASLR for plagiarizing the username  ;))

solartim27

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #155 on: June 30, 2018, 05:15:01 PM »
I've noticed that iceberg b22a has been moving recently, sort of surprising for the middle of winter.
From the Icebergs thread
My focus is more on West-Antarctica particularly B22a (44X24 nm) which blocks Thwaites Glacier from the open sea. If this beast becomes loose all the icebergs behind can drift out as well.

Here's a recent shot from Polar View, the computer I used to make gifs crashed, and I haven't figured out a good alternate yet.
https://www.polarview.aq/images/105_S1jpgfull/S1B_IW_GRDH_1SSH_20180629T095911_82DD_S_1.final.jpg  (55 Mb)
FNORD

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #156 on: July 30, 2018, 04:44:54 AM »
While each individual needs to learn on his/her own how to accept the truth about climate change; nevertheless, presenting the truth about climate trends in Bayesian terms is the most honest way for the media to convey a truth that they only partially understand/accept themselves:

Title: "How Did the End of the World Become Old News?"

http://nymag.com/daily/intelligencer/amp/2018/07/climate-change-wildfires-heatwave-media-old-news-end-of-the-world.html

Extract: "Over the last few days, there has been a flurry of chatter among climate writers and climate scientists, and the climate-curious who follow them, about this failure. In perhaps the most widely parsed and debated Twitter exchange, MSNBC’s Chris Hayes — whose show, All In, has distinguished itself with the seriousness of its climate coverage — described the dilemma facing every well-intentioned person in his spot: the transformation of the planet and the degradation may be the biggest and most important story of our time, indeed of all time, but on television, at least, it has nevertheless proven, so far, a “palpable ratings killer.” All of which raises a very dispiriting possibility, considering the scale of the climate crisis: Has the end of the world as we know it become, already, old news?"
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VeliAlbertKallio

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #157 on: August 01, 2018, 12:03:12 AM »
I have cited sections of this thread in the UK Houses of Parliament evidence on Section "4. The John Mercer Effect: the ‘Forbidden Line’ on Sea Level Rise". Unfortunately, due to the Parliament rules, I could not represent whole text as such but had to abbreviate and leave out few points. I am also rather sad because this was thought by many at one good solution for climate change. :'(

Our Changing Climate in Action: the Risk of Global Warming and the Environmental Damage from the Rising Ocean Water Table | Sustainable Seas Enquiry | Written evidence submitted by Veli Albert Kallio, FRGS (SSI0121) | Ordered to be published 23 May 2018 by the House of Commons.

Abstract:

Recently NATURE published a discussion on construction of sills in attempt to prevent or slow melting glaciers that are discharging ice into the ice fjords. Several further papers promptly followed publication of this essentially erroneous article in a respected NATURE magazine. Here it is pointed out that there is a discrepancy of several magnitudes thus excluding a long-term viability to manage the edges of ice fjords or continental ice shelves/sheets due to a phenomenon known as the mega-erratics. These are blocks of hard rocks that are several kilometres in size that have been dislocated by a warmed and wet edges of glacier/ice sheet/ice shelf. This Parliament evidence points out the error that was not apparent to the peer-reviewers at the time and in subsequent papers that followed. The Parliament was shown evidence that large enough obstacles cannot be possibly made to prevent ice discharges due to a progression of melting, that softens and lubricates glaciers, ice caps and ice sheets. The forces unleashed by the ice front exceeds several magnitudes from the conceived objects that sills were proposed. The only, and very only effect is temporary and limited to prevention of warm water incursion where these methods will work for a while in a cold, dry, and relatively stable ice formations.

Long-term projections suggested to prevent warmed and water-infested glaciers from discharging ice into the ocean cannot be made as the forces of ice exceed many magnitudes of the sills and levies that can be made of concrete blocks, aggregates or other materials. Thus the prevention of sea level rise by this method for centuries or millennia is not functional one and thus the mitigation and prevention of rubbish gyros in ocean, the supply of housing, nuclear and food production security must be looked at as solution by the ocean littoral states. Several examples of various types of risk to the sustainability of oceans have been presented in addition to the above exposed misconception. This comes with much regret as it appears that one 'hoped-for-solution' to manage the future climate change impacts has largely foundered on the issue that the sills cannot be made strong enough to contain most important, warmed glaciers or edges of unstable ice shelves. However, for a short-term this may offer small-scale solutions provided that costs remain sufficiently small. Aggressively melting ice formations with darkened surfaces, wide spread melt water ponds, or water filled crevasses it does not offer much, if any, prolonged ice stability. (The document is best viewed as a .pdf file due to the lay-out of graph and legends.)

https://www.academia.edu/37157851/Our_Changing_Climate_in_Action_the_Risk_of_Global_Warming_and_the_Environmental_Damage_from_the_Rising_Ocean_Water_Table_Sustainable_Seas_Enquiry_Written_evidence_submitted_by_Veli_Albert_Kallio_FRGS_SSI0121_Ordered_to_be_published_23_May_2018_by_the_House_of_Commons

Stopping the Flood: Could We Use Targeted Geoengineering to Mitigate Sea Level Rise?
Michael J. Wolovick1 and John C. Moore2,3
1Atmosphere and Ocean Sciences Program, Department of Geosciences, Princeton University, GFDL, 201 Forrestal Road,
Princeton, NJ 08540, USA
2College of Global Change and Earth System Science, Beijing Normal University, Beijing, China
3Arctic Centre, University of Lapland, Finland
Correspondence: M.J. Wolovick (wolovick@princeton.edu)

Abstract. The Marine Ice Sheet Instability (MISI) is a dynamic feedback that can cause an ice sheet to enter a runaway collapse. Thwaites Glacier, West Antarctica, is the largest individual source of future sea level rise and may have already entered the MISI. Here, we use a suite of coupled ice–ocean flowband simulations to explore whether targeted geoengineering using an artificial sill or artificial ice rises could counter a collapse. Successful interventions occur when the floating ice shelf regrounds 5 on the pinning points, increasing buttressing and reducing ice flux across the grounding line. Regrounding is more likely with a continuous sill that is able to block warm water transport to the grounding line. The smallest design we consider is comparable in scale to existing civil engineering projects but has only a 30% success rate, while larger designs are more effective. There are multiple possible routes forward to improve upon the designs that we considered, and with decades or more to research designs it is plausible that the scientific community could come up with a plan that was both effective and achievable. While 10 reducing emissions remains the short-term priority for minimizing the effects of climate change, in the long run humanity may need to develop contingency plans to deal with an ice sheet collapse.

--

http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/environmental-audit-committee/sustainable-seas/written/83150.pdf

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #158 on: August 15, 2018, 06:20:03 PM »
The linked reference indicates that the projected increase (with continued global warming) of more frequent strong El Nino events combined with the projected increase in positive SAM, will significantly increase ice mass loss from the ASE, which will increase the risk of a collapse of the WAIS:

Deb, P., A. Orr, D. H. Bromwich, J. P. Nicolas, J. Turner, and J. S. Hosking, 2018: Summer drivers of atmospheric variability affecting ice shelf thinning in the Amundsen Sea Embayment, West Antarctica. Geophy. Res. Lett., 45. doi: 10.1029/2018GL077092.

http://polarmet.osu.edu/PMG_publications/deb_bromwich_grl_2018.pdf

Abstract:  "Satellite data and a 35-year hindcast of the Amundsen Sea Embayment summer climate using the Weather Research and Forecasting model are used to understand how regional and large-scale atmospheric variability affects thinning of ice shelves in this sector of West Antarctica by melting from above and below (linked to intrusions of warm water caused by anomalous westerlies over the continental shelf edge). El Niño episodes are associated with an increase in surface melt but do not have a statistically significant impact on westerly winds over the continental shelf edge. The location of the Amundsen Sea Low and the polarity of the Southern Annular Mode (SAM) have negligible impact on surface melting, although a positive SAM and eastward shift of the Amundsen Sea Low cause anomalous westerlies over the continental shelf edge. The projected future increase in El Niño episodes and positive SAM could therefore increase the risk of disintegration of West Antarctic ice shelves."

Extract: "Our study suggests that ASE ice shelves could experience an intensification of melt in the future from both above and below as a result of both regional and large-scale atmospheric changes, potentially increasing the risk of their disintegration, which in turn could potentially trigger a collapse of the West Antarctic ice sheet (DeConto & Pollard, 2016). To better understand this threat will require further detailed investigation of the impacts of ENSO, the polarity of the SAM, and the depth/location of the ASL on ASE ice shelves. Also necessary is improving the reliability of future projections, such as ENSO and its teleconnections, as well as the response of the SAM to recovery of the Antarctic ozone hole and increased greenhouse gas emissions (Polvani, Waugh, et al., 2011)."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #159 on: August 23, 2018, 03:30:27 PM »
The linked articles confirm that not only are the Earth's rotation poles wandering rapidly, but so are its magnetic poles:

Title: "Shifting Ice Caps - Magnetic Poles and Ice Caps move in Tandem"

https://planet-earth-2017.com/wandering-poles/

Extract: "“The rate of the magnetic pole’s movement has increased in the last  century compared with fairly steady movement in the previous four centuries”, said Joseph Stoner and the Oregon researchers."

See also:

Title: "Magnetic north pole drifting fast"

http://news.bbc.co.uk/2/hi/science/nature/4520982.stm

Extract: " The Earth's north magnetic pole is drifting away from North America so fast that it could end up in Siberia within 50 years, scientists have said."

The linked reference provides paleo evidence that the Earth has experienced geomagnetic pole reversals in as little as a century, and that we are overdue for our next geomagnetic pole reversal:

Yu-Min Chou, Xiuyang Jiang, Qingsong Liu, Hsun-Ming Hu, Chung-Che Wu, Jianxing Liu, Zhaoxia Jiang, Teh-Quei Lee, Chun-Chieh Wang, Yen-Fang Song, Cheng-Cheng Chiang, Liangcheng Tan, Mahjoor A. Lone, Yongxin Pan, Rixiang Zhu, Yaoqi He, Yu-Chen Chou, An-Hung Tan, Andrew P. Roberts, Xiang Zhao, and Chuan-Chou Shen (August 20, 2018), "Multidecadally resolved polarity oscillations during a geomagnetic excursion", PNAS, 201720404; https://doi.org/10.1073/pnas.1720404115

http://www.pnas.org/content/early/2018/08/14/1720404115

Abstract: "Polarity reversals of the geomagnetic field have occurred through billions of years of Earth history and were first revealed in the early 20th century. Almost a century later, details of transitional field behavior during geomagnetic reversals and excursions remain poorly known. Here, we present a multidecadally resolved geomagnetic excursion record from a radioisotopically dated Chinese stalagmite at 107–91 thousand years before present with age precision of several decades. The duration of geomagnetic directional oscillations ranged from several centuries at 106–103 thousand years before present to millennia at 98–92 thousand years before present, with one abrupt reversal transition occurring in one to two centuries when the field was weakest. These features indicate prolonged geodynamo instability. Repeated asymmetrical interhemispheric polarity drifts associated with weak dipole fields likely originated in Earth’s deep interior. If such rapid polarity changes occurred in future, they could severely affect satellites and human society."

See also:
Title: "We Have The Most Precise Reading Yet on How Fast Earth's Magnetic Poles Could Flip"

https://www.sciencealert.com/earth-geomagnetic-polarity-excursion-rapid-reversal-ancient-past

Extract: "An analysis of a stalagmite from the depths of a cave in China has unveiled clues about an event in Earth's history when its magnetic field flipped back and forth in a geological blink.

The stalagmite was cut into more than 190 samples and analysed using a high-resolution cryogenic magnetometer, providing a century-scale resolution of Earth's magnetic field direction and strength 100 thousand years ago.

Among several smaller drifts in polarity they spotted a flicker of a reversal some 98,000 years ago that stayed in place for a century or two before slipping back again.

On a geological time scale, this excursion is shockingly brief, and could suggest any significant changes to our protective shell won't come with much warning."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Tor Bejnar

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #160 on: August 23, 2018, 06:08:26 PM »
Quote
The linked reference provides paleo evidence that the Earth has experienced geomagnetic pole reversals in as little as a century, and that we are overdue for our next geomagnetic pole reversal:
The Earth may be statistically overdue for a reversal, but it is not a train-on-a-set-schedule sort of thing.  From Wikipedia
Quote
The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years[citation needed] with an average of 450,000 years. Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago, and may have happened very quickly, within a human lifetime.[1] In August 2018, researchers reported a reversal lasting only 200 years.[2]

A brief complete reversal, known as the Laschamp event, occurred only 41,000 years ago during the last glacial period. That reversal lasted only about 440 years with the actual change of polarity lasting around 250 years.
...
So that 'overdue-ness' is only if you ignore the Laschamp event.  Of course, Earth may be in the labor-pains of a reversal since about 400 years ago.  Some things just take time!

Arctic ice is healthy for children and other living things.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #161 on: August 24, 2018, 12:50:27 AM »
The Earth may be statistically overdue for a reversal, but it is not a train-on-a-set-schedule sort of thing.

Your statement is most certainly correct; however, those who might be concerned that an abrupt collapse of the WAIS (induced by following a BAU pathway for a few more decades) might trigger such a geomagnetic pole reversal might want to re-read Replies #103, #113, #115, #116 and #117.
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #162 on: August 24, 2018, 01:07:11 AM »
As I have said before, I am doubtful that icesheet collapse will trigger mag pole reversal. I am unaware of evidence that WAIS collapse in the Eemian ror in Holsteinian did any such thing.

Mechanism that generated the mag field is very poorly understood, and mechanism of pole reversal is even less understood. Present state of knowledge makes speculation of pole reversal due to WAIS collapse the equivalent of haruspicy.

sidd

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #163 on: August 24, 2018, 08:43:10 PM »
If one is looking for proof beyond a reasonable doubt (that abrupt ice mass losses could influence geomagnetic migrations), one might never that the precautions required to protect modern electronic systems from such a possibly abrupt geomagnetic flip (see the first image).

The title of the second attached image is "Approximate chronology of Heinrich events vs Dansgaard-Oeschger events and Antarctic Isotope Maxima", & it indicates that the magnetic field weakening between 105,000 and 103,000 years ago might line-up with the Heinrich event HS-10.

Title: "Earth's Magnetic Field Could Flip Much Faster Than Previously Thought"

https://www.forbes.com/sites/davidbressan/2018/08/23/earths-magnetic-field-could-flip-much-faster-than-previously-thought/#3ad0357f438c


Extract: "Modern geomagnetic measurements have shown that Earth's magnetic field is rapidly fading, by almost 16 percent since the year 1840.

… the scientists discovered two phases with a weaker magnetic field, between 105,000 and 103,000 and 98,000 to 92,000 years ago. During the more recent phase, the Magnetic North Pole "moved" from Alaska to a spot in the Antarctic Ocean. What surprised the scientist was the speed of this almost complete reversal, apparently just 144 years, with some decades as margin of error of the used radiometric dating technique. Thereafter the magnetic field switched back into the "normal", modern polarity.

… as the paper suggests, if significant magnetic disturbances really can happen in just a century, this poses new challenges to our civilization, as technology should be ready to deal with such changes."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #164 on: August 24, 2018, 08:48:26 PM »
As I have said before, I am doubtful that icesheet collapse will trigger mag pole reversal. I am unaware of evidence that WAIS collapse in the Eemian ror in Holsteinian did any such thing.

Mechanism that generated the mag field is very poorly understood, and mechanism of pole reversal is even less understood. Present state of knowledge makes speculation of pole reversal due to WAIS collapse the equivalent of haruspicy.

sidd

As I have stated previously:

Regarding correlating true polar wander (shifting of the Earth's rotational axis) and magnetic field reversals and mass redistribution around the Earth; I provide the first linked reference that provides paleo evidence that during periods of little polar wander the is reduced activity of magnetic pole flipping; while the second linked article makes it clear that polar wander is associated with all mass (ice, sea level, groundwater, isostatic rebound) redistribution.

Courtillot V & Besse J. (1987 Sep 4), "Magnetic field reversals, polar wander, and core-mantle coupling", Science vol 237, issue (4819), pp 1140-7, DOI:10.1126/science.237.4819.1140

http://science.sciencemag.org/content/237/4819/1140

Abstract: "True polar wander, the shifting of the entire mantle relative to the earth's spin axis, has been reanalyzed. Over the last 200 million years, true polar wander has been fast (approximately 5 centimeters per year) most of the time, except for a remarkable standstill from 170 to 110 million years ago. This standstill correlates with a decrease in the reversal frequency of the geomagnetic field and episodes of continental breakup. Conversely, true polar wander is high when reversal frequency increases. It is proposed that intermittent convection modulates the thickness of a thermal boundary layer at the base of the mantle and consequently the core-to-mantle heat flux. Emission of hot thermals from the boundary layer leads to increases in mantle convection and true polar wander. In conjunction, cold thermals released from a boundary layer at the top of the liquid core eventually lead to reversals. Changes in the locations of subduction zones may also affect true polar wander. Exceptional volcanism and mass extinctions at the Cretaceous-Tertiary and Permo-Triassic boundaries may be related to thermals released after two unusually long periods with no magnetic reversals. These environmental catastrophes may therefore be a consequence of thermal and chemical couplings in the earth's multilayer heat engine rather than have an extraterrestrial cause."

&

Title: "Climate Change Is Moving the North Pole"

https://news.nationalgeographic.com/2016/04/160408-climate-change-shifts-earth-poles-water-loss/

Extract: "As ice melts and aquifers are drained, Earth's distribution of mass is changing—and with it the position of the planet's spin axis."


Also, see the following reference which indicates that about 66% of the polar wander over the indicated period was due to rapid changes in ice mass loss:

Surendra Adhikari and Erik R. Ivins (08 Apr 2016), "Climate-driven polar motion: 2003–2015", Science Advances, Vol. 2, no. 4, e1501693, DOI: 10.1126/sciadv.1501693

http://advances.sciencemag.org/content/2/4/e1501693

Abstract: "Earth’s spin axis has been wandering along the Greenwich meridian since about 2000, representing a 75° eastward shift from its long-term drift direction. The past 115 years have seen unequivocal evidence for a quasi-decadal periodicity, and these motions persist throughout the recent record of pole position, in spite of the new drift direction. We analyze space geodetic and satellite gravimetric data for the period 2003–2015 to show that all of the main features of polar motion are explained by global-scale continent-ocean mass transport. The changes in terrestrial water storage (TWS) and global cryosphere together explain nearly the entire amplitude (83 ± 23%) and mean directional shift (within 5.9° ± 7.6°) of the observed motion. We also find that the TWS variability fully explains the decadal-like changes in polar motion observed during the study period, thus offering a clue to resolving the long-standing quest for determining the origins of decadal oscillations. This newly discovered link between polar motion and global-scale TWS variability has broad implications for the study of past and future climate."

Also here are some other background references:

1. Adam C. Maloof Galen P. Halverson Joseph L. Kirschvink Daniel P. Schrag Benjamin P. Weiss Paul F. Hoffman (2006), "Combined paleomagnetic, isotopic, and stratigraphic evidence for true polar wander from the Neoproterozoic Akademikerbreen Group, Svalbard, Norway",  GSA Bulletin, 118 (9-10): 1099-1124, DOI: https://doi.org/10.1130/B25892.1

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/118/9-10/1099/125331/combined-paleomagnetic-isotopic-and-stratigraphic?redirectedFrom=fulltext

Abstract: "We present new paleomagnetic data from three Middle Neoproterozoic carbonate units of East Svalbard, Norway. The paleomagnetic record is gleaned from 50 to 650 m of continuous, platformal carbonate sediment, is reproduced at three locations distributed over >100 km on a single craton, and scores a 5–6 (out of 7) on the Van der Voo (1990) reliability scale. Two >50° shifts in paleomagnetic direction are coincident with equally abrupt shifts in δ13C and transient changes in relative sea level. We explore four possible explanations for these coincidental changes: rapid plate tectonic rotation during depositional hiatus, magnetic excursions, nongeocentric axial-dipole fields, and true polar wander. We conclude that the observations are explained most readily by rapid shifts in paleogeography associated with a pair of true polar wander events. Future work in sediments of equivalent age from other basins can test directly the true polar wander hypothesis because this type of event would affect every continent in a predictable manner, depending on the continent's changing position relative to Earth's spin axis."

2. J. R. Creveling, J. X. Mitrovica, N.-H. Chan, K. Latychev & I. Matsuyama (08 November 2012), "Mechanisms for oscillatory true polar wander", Nature, volume 491, pages 244–248,
doi:10.1038/nature11571

http://www.nature.com/articles/nature11571

Abstract: "Palaeomagnetic studies of Palaeoproterozoic to Cretaceous rocks propose a suite of large and relatively rapid (tens of degrees over 10 to 100 million years) excursions of the rotation pole relative to the surface geography, or true polar wander (TPW). These excursions may be linked in an oscillatory, approximately coaxial succession about the centre of the contemporaneous supercontinent. Within the framework of a standard rotational theory, in which a delayed viscous adjustment of the rotational bulge acts to stabilize the rotation axis, geodynamic models for oscillatory TPW generally appeal to consecutive, opposite loading phases of comparable magnitude. Here we extend a nonlinear rotational stability theory to incorporate the stabilizing effect of TPW-induced elastic stresses in the lithosphere. We demonstrate that convectively driven inertia perturbations acting on a nearly prolate, non-hydrostatic Earth with an effective elastic lithospheric thickness of about 10 kilometres yield oscillatory TPW paths consistent with palaeomagnetic inferences. This estimate of elastic thickness can be reduced, even to zero, if the rotation axis is stabilized by long-term excess ellipticity in the plane of the TPW. We speculate that these sources of stabilization, acting on TPW driven by a time-varying mantle flow field, provide a mechanism for linking the distinct, oscillatory TPW events of the past few billion years."

3. To learn how much the North Pole has shifted in the recent decades due to rapid ice mass loss, see Chen, J..L., C.R. Wilson, J.C. Ries, B.D. Tapley, Rapid ice melting drives Earth's pole to the east, Geophys. Res. Lett., Vol. 40, 1-6, DOI: 10.1002/grl.50552, 2013; which can be found at the prime author's website at the University of Texas, where you can download a preprint (made available by the author):

http://www.csr.utexas.edu/personal/chen/publication.html

and here is a link directly to the preprint pdf:

ftp://ftp.csr.utexas.edu/pub/ggfc/papers/2013GL056164_preprint.pdf

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #165 on: August 27, 2018, 03:15:41 AM »
The linked reference indicates that Arctic Amplification is more sensitive to heat influx from the North Pacific than from the North Atlantic.  Here I note that a collapse of the WAIS would lead to a very large heat flux from the North Pacific into the Artic Ocean:

Summer Praetorius  et al. (2018), "Global and Arctic climate sensitivity enhanced by changes in North Pacific heat flux", Nature Communications, volume 9, Article number: 3124, DOI: https://doi.org/10.1038/s41467-018-05337-8

http://www.nature.com/articles/s41467-018-05337-8

Abstract: "Arctic amplification is a consequence of surface albedo, cloud, and temperature feedbacks, as well as poleward oceanic and atmospheric heat transport. However, the relative impact of changes in sea surface temperature (SST) patterns and ocean heat flux sourced from different regions on Arctic temperatures are not well constrained. We modify ocean-to-atmosphere heat fluxes in the North Pacific and North Atlantic in a climate model to determine the sensitivity of Arctic temperatures to zonal heterogeneities in northern hemisphere SST patterns. Both positive and negative ocean heat flux perturbations from the North Pacific result in greater global and Arctic surface air temperature anomalies than equivalent magnitude perturbations from the North Atlantic; a response we primarily attribute to greater moisture flux from the subpolar extratropics to Arctic. Enhanced poleward latent heat and moisture transport drive sea-ice retreat and low-cloud formation in the Arctic, amplifying Arctic surface warming through the ice-albedo feedback and infrared warming effect of low clouds. Our results imply that global climate sensitivity may be dependent on patterns of ocean heat flux in the northern hemisphere."
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RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #166 on: August 27, 2018, 08:03:58 PM »

On Polar wander and reversals


It seems that there is a correlation between polar wander and reversals. And it seems that rapid ice melt correlates with polar wander. Note that these correlations are on vastly different timescales.

The first paper speculates that there is a causative mechanism that is due to changes in mantle/core boundary conditions, the dynamic convection changes in the mantle altering the shape of the earth and causing polar wander, and correlating with magnetic pole reversals from thermal changes at the core mantle boundary. The paper discussing convective changes backs up the fact that you get polar reversals when the convective pattern of the mantle changes.

Perhaps Ice unloading will change the shape of the Earth and shift the axis of rotation enough to change mantle convection, but it's unlikely; there is a lot more mantle than ice, it would be analogous to a small rock hitting a car and changing it's direction (mantle mass 4×10^27g, total ice mass, 2.4x10^22g). The mantle will eventually adjust to take into account the new shape of the earth after ice melt, but it's more than likely going to be down to Asthenospheric mantle compensation as is modeled in PGR, and that alone will take 1000's of years.

My guess is the polar wander caused by ice melt is just noise in the ancient signal.


« Last Edit: August 28, 2018, 05:35:12 PM by RoxTheGeologist »

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #167 on: August 27, 2018, 08:43:45 PM »
My guess is the polar wander caused by ice melt is just noise in the ancient signal.

RoxTheGeologist,

Thank you for your thoughtful comments, and you may well be correct that ice mass redistribution from an abrupt collapse of the WAIS to the oceans of the world, might not be a sufficient trigger to accelerate the current ongoing weakening of the global geomagnetic fields.  Nevertheless, have you considered the distinctive geomagnetic field lines in the Southern Hemisphere (shown in the last image of Reply #115) and the rather unique geology beneath the WAIS as indicated by the following information which comes from the 'Antarctic Tectonics' thread with the first two images in this post coming from:

http://www.largeigneousprovinces.org/apr13

"The links between large igneous provinces, and continental break-up: evidence reviewed from Antarctica" by: Bryan C Storey,  Alan P M Vaughan and Teal R Riley; April 2013
Gateway Antarctica, Private Bag 4800, University of Canterbury, Christchurch, New Zealand; bryan.storey@canterbury.ac.nz

The first attached image shows:  Middle Jurassic Gondwana reconstruction showing three large igneous provinces (after Storey & Kyle 1997); Ferrar, Karoo and Chon Aike, and the location of the Weddell Sea Triple Junction (WSTJ) after Elliot & Fleming 2000.  DML, Dronning Maud Land; FI, Falkland Islands

The second attached image shows:  Antarctic map showing the Transantarctic Mountains as the rift shoulder of the West Antarctic Rift System (WARS), the related Cenozoic alkaline magmatic province (WARS volcanoes), the outline of the Middle Jurassic Ferrar magmatic province and the outline of the mid Cretaceous alkaline magmatism in Marie Byrd Land.

The third image shows a map of Antarctica with the relief of the crust thickness below it's ice as indicated by seismic data. Abbreviations: DML, Dronning Maud Land; GSM, Gamburtsev Subglacial Mountains.  CREDIT: Baranov, A., Morelli, A., The Moho depth map of the Antarctica region, Tectonophysics (2013).

The fourth image shows the modeled internal structure of the lithosphere in West Antarctica, showing a major source of heat from the upper mantle.

Best regards,
ASLR
« Last Edit: August 27, 2018, 10:06:46 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #168 on: August 27, 2018, 10:10:24 PM »
RoxTheGeologist,

For convenience I provide the image from Reply #115 showing the correlation between the global magnetic field lines off the coast of South Africa and off the coast of West Antarctica.

Best,
ASLR
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #169 on: August 28, 2018, 01:00:02 AM »
ASLR,

I'm not quite sure what light the magnetic field diagram is supposed to bring to the discussion. It seems to me the magnitude of the folds in the lines would be considerably less if the projection were less distorting; that the changes in the magnetic field might be an interesting note to your argument, but cannot be inferred from the diagram; and that the fold might cause the equivalent of Jupiter's Great Red Spot under different atmospheric conditions. However, I think RTG has a strong argument in the absence of a good theory -- correlations don't do much by themselves.

So, please elucidate a theoretical connection that will explain how the minor mass shift might be causal rather than coincident.
 

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #170 on: August 28, 2018, 02:17:38 AM »
ASLR,

I'm not quite sure what light the magnetic field diagram is supposed to bring to the discussion. It seems to me the magnitude of the folds in the lines would be considerably less if the projection were less distorting; that the changes in the magnetic field might be an interesting note to your argument, but cannot be inferred from the diagram; and that the fold might cause the equivalent of Jupiter's Great Red Spot under different atmospheric conditions. However, I think RTG has a strong argument in the absence of a good theory -- correlations don't do much by themselves.

So, please elucidate a theoretical connection that will explain how the minor mass shift might be causal rather than coincident.
 

The following is a copy of my Reply #113 (which suggests that the trigger for a magnetic pole reversal may be associated with the South Atlantic Anomaly):

The first image shows the southern supercontinent Gondwana about 183million year ago at the point of the initial breakup of the supercontinent.  The second image highlights the Euler geometry of hexagons and pentagons bounded by the supercontinent rupture lines that define the lines of minimum energy required to break apart the supercontinent.  These two images illustrate the origins of the area known as the South Atlantic Anomaly – an expanse of the field currently stretching from Chile to Zimbabwe, as discussed in the reference linked (and the last two images) below.  The Hare et al. (2018) linked open access reference indicates that this region is likely a key area of the Earth core-mantle boundary that is likely in the process of triggering a flip in the Earth's magnetic poles.

Vincent J. Hare et al. (15 February 2018), "New Archeomagnetic Directional Records From Iron Age Southern Africa (ca. 425–1550 CE) and Implications for the South Atlantic Anomaly", GRL, DOI: 10.1002/2017GL076007

http://onlinelibrary.wiley.com/doi/10.1002/2017GL076007/full

Abstract: "The paucity of Southern Hemisphere archeomagnetic data limits the resolution of paleosecular variation models. At the same time, important changes in the modern and historical field, including the recent dipole decay, appear to originate in this region. Here a new directional record from southern Africa is presented from analysis of Iron Age (ca. 425–1550 CE) archeological materials, which extends the regional secular variation curve back to the first millennium. Previous studies have identified a period of rapid directional change between 1225 and ∼1550 CE. The new data allow us to identify an earlier period of relatively rapid change between the sixth and seventh centuries CE. Implications for models of recurrent flux expulsion at the core-mantle boundary are discussed. In addition, we identify a possible relationship of changes recorded in these African data with archeomagnetic jerks."

See also:

Title: "A Mysterious Anomaly Under Africa Is Radically Weakening Earth's Magnetic Field"

https://www.sciencealert.com/something-mysterious-under-southern-africa-dramatically-weakening-earth-s-magnetic-field-south-atlantic-anomaly

Extract: "This could be precursor to Earth's poles swapping places.

The region that concerns scientists the most at the moment is called the South Atlantic Anomaly – a huge expanse of the field stretching from Chile to Zimbabwe. The field is so weak within the anomaly that it's hazardous for Earth's satellites to enter it, because the additional radiation it's letting through could disrupt their electronics.

… the artefacts revealed that the weakening in the South Atlantic Anomaly isn't a standalone phenomenon of history.

Similar fluctuations occurred in the years 400-450 CE, 700-750 CE, and 1225-1550 CE – and the fact that there's a pattern tells us that the position of the South Atlantic Anomaly isn't a geographic fluke.

"We're getting stronger evidence that there's something unusual about the core-mantel boundary under Africa that could be having an important impact on the global magnetic field," Tarduno says.

The current weakening in Earth's magnetic field – which has been taking place for the last 160 years or so – is thought to be caused by a vast reservoir of dense rock called the African Large Low Shear Velocity Province, which sits about 2,900 kilometres (1,800 miles) below the African continent.

"It is a profound feature that must be tens of millions of years old," the researchers explained in The Conversation last year.

"While thousands of kilometres across, its boundaries are sharp."

This dense region, existing in between the hot liquid iron of Earth's outer core and the stiffer, cooler mantle, is suggested to somehow be disturbing the iron that helps generate Earth's magnetic field.

There's a lot more research to do before we know more about what's going on here.

As the researchers explain, the conventional idea of pole reversals is that they can start anywhere in the core – but the latest findings suggest what happens in the magnetic field above us is tied to phenomena at special places in the core-mantle boundary."
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steve s

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #171 on: August 28, 2018, 06:35:06 AM »
So where does loss of Antarctic ice come into play?

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #172 on: August 28, 2018, 05:33:45 PM »
So where does loss of Antarctic ice come into play?

It would help this exchange if you would review the earlier posts in this thread; as it seems unreasonable that I should re-post all of the related information.  Nevertheless, my Replay #115 ties ice mass loss to magma flow which is related to geomagnetic fields (see the first & second images) & states:

"While glaciovolcanism (defined as “the interactions of magma with ice in all its forms, including snow, firn and any meltwater”), may still be in its infancy; nevertheless, I provide the following links to relevant information (& two images about geomagnetism), and I note that there is more information in the 'Antarctic Tectonics' thread in the Antarctic folder; for those who are interested in learning more about this topic:

J.L. Smellie (2018), "Chapter 10 – Glaciovolcanism: A 21st Century Proxy for Palaeo-Ice",
Past Glacial Environments (Second Edition), Pages 335–375, https://doi.org/10.1016/B978-0-08-100524-8.00010-5

https://www.sciencedirect.com/science/article/pii/B9780081005248000105

Abstract: "Glaciovolcanism is a young science that has undergone a major transformation during the last 15 years. It is important for a variety of reasons but it is set to play a major role in deriving critical parameters of past ice sheets and thus greatly improve the accuracy of their reconstruction. Glaciovolcanic studies can deduce a wider range of parameters than any other methodology currently existing, including: establishing the presence of ice, its age, ice thickness, ice surface elevation, and basal thermal regime. These attributes can be acquired routinely for many glaciovolcanic sequences and, uniquely, several are quantifiable. Most glaciovolcanic terrains provide punctuated rather than continuous records of the coeval ice sheet, i.e., with numerous time gaps. Despite the gaps, glaciovolcanic studies of ice sheets have been completed successfully in the three major glaciovolcanic regions of the Earth: mainly Antarctica, but also Iceland and British Columbia (Canada). Future studies in these and other glaciovolcanic regions will considerably improve our knowledge of Earth’s water inventory and contribute to a better understanding of past ice dynamics and the impact of the cryosphere on global climate."

&

Title: "Antarctic Glaciovolcanism:

https://www2.le.ac.uk/departments/geology/people/smellie-jl/personal/ant-glaciovolc
"
However glaciovolcanism is only part of the scenario as in this thread we assume the worst case WAIS collapse which produces almost 5m of average sea level rise around the world (see the third image).  This much change in mean sea level would increase both seismic and volcanic activity around the would and likely would accelerate some local continental drift.

Furthermore, the combination of sea level rise and ice mass loss is already causing polar wander (see the fourth image), which RTG acknowledges relates to magnetic pole reversals as the alignment of the Earths faults and rifts change w.r.t. rotational forces when the rotational axis shifts.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #173 on: August 28, 2018, 06:02:01 PM »
steve s,

You may (or may not) wish to also review the various posts (particularly my posts) in the thread entitled 'Earthquakes and climate change' in the Science folder at the following link.

https://forum.arctic-sea-ice.net/index.php/topic,283.msg139205.html#msg139205

My Reply #8 states:

"I like the following quote from Bill McGuire's book:

"Twenty thousand years ago, Iceland was entirely covered by a layer of ice that averaged close to a kilometer in thickness.  Around 15-16,000 year ago, planetary warming triggered rapid melting of the glaciers, reducing the load acting on the volcanoes beneath and on the underlying asthenosphere.  By 12,000 years ago unloading was sufficiently advanced to trigger a spectacular response.  Over a period of 1500 years or so, the volcanic eruption rate jumped by between 30 and 50 times, before falling back to today's level.  This volcanic rejuvenation was in part a reflection of the release of magma held ready and waiting, within and beneath the volcanoes themselves, but mainly testament to a huge increase in the supply of fresh magma from deeper within the Earth.  Such was the load reduction due to the rapid loss of ice mass, that the depressed lithosphere quickly bounced back by as much as half a kilometer, dramatically reducing the pressures in the asthenosphere and triggering a 30-fold jump in magma production."

If such behavior were to occur in the West Antarctic Ice Sheet, WAIS, (where there are numerous volcanoes and faults and a very thin crust), then the world would experience a significant increase in the rate of SLR."

My Reply #51 in that thread points out that due to the fingerprint effect a collapse of the WAIS would result in a non-uniform change in sea level around the world (see the first attached image); which would put additional differential stresses on global faults/rifts which would cause additional tectonic plate movement:

Furthermore, my Reply #62 in that thread discusses the significant amount of glacial isostatic rebound that would (& is now beginning to) occur with WAIS ice mass loss.  The second attached image indicates that with a complete WAIS collapse this rebound in several areas of the Byrd Subglacial Basin, BSB, would be several hundred meters.
« Last Edit: August 28, 2018, 10:15:47 PM by AbruptSLR »
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RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #174 on: August 28, 2018, 07:58:52 PM »
Yes, the unloading of the ice sheet in the WAIS could produce increased volcanic activity over a geologically short period of time, and I fear that there is the possibility it might have a catastrophic affect within our life times. Every km of ice depth is replaced by 300 or so M of rock from isostatic rebound and, perhaps, by thick lava flows.

Note, though, that the tectonic's are very different to Iceland. The West Antarctic rift is a very slowly growing rift, and therefore the store of magma is probably low because the lithiosphere hasn't been thinning quickly. The WAR is spreading at about 2mm a year. Iceland sits on a hotspot that's also on a MOR that's spreading at an average rate 25mm a year (the fastest measured spreading on land is probably Greece, at 70+mm a year, in the oceans the EPR, spreads at 150mm a year). We didn't see a change in magnetism due to changes in the icesheet in Iceland, despite the unloading of ice and the massive increase in volcanism. I doubt very much we will see it in the Antarctic.



« Last Edit: August 28, 2018, 10:03:54 PM by RoxTheGeologist »

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #175 on: August 28, 2018, 08:54:23 PM »
RoxTheGeologists,

Thank you for your valid comments, and I most certainty do not think that the evidence that I have presented proves beyond a reasonable doubt that there will be a change in magnetism due to a collapse of the WAIS (this century).  That said, I believe that the Earth System models used to investigate such a possible occurrence are so crude that they certainly cannot disprove such a possible change in magnetism, especially since a collapse of the WAIS would induce not only relatively local tectonic changes but would also induce global tectonic changes.

Thanks again for your comments (& I acknowledge that it would be nice if you are correct, but I am concerned that the modern electronic-based society will be caught unprepared if you are incorrect).

Best,
ASLR
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #176 on: August 28, 2018, 09:18:38 PM »
ASLR,

I understand the tectonics involved and think that the Thwaites Glacier is likely to have its melt accelerated by vulcanism, but I see no obvious case for more than a trivial direct influence of ice loss on magnetic reversal (at most). So I agree with RTG.

 

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #177 on: August 28, 2018, 10:10:46 PM »
ASLR,

I understand the tectonics involved and think that the Thwaites Glacier is likely to have its melt accelerated by vulcanism, but I see no obvious case for more than a trivial direct influence of ice loss on magnetic reversal (at most). So I agree with RTG.
steve s,

I sincerely hope that both yourself and RTG are correct.  However, if the cascade of tipping points hypothesized in this thread actually occur, we may find out as soon as 2040 whether, or not, you are both incorrect.

Regards,
ASLR
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #178 on: August 28, 2018, 11:45:16 PM »
In order to provide readers with a feel for how extreme true polar wander and change the angle of the Earth's rotational axis, I provide the following linked reference:

Bernhard Steinberger & Trond H. Torsvik (03 April 2008), "Absolute plate motions and true polar wander in the absence of hotspot tracks", Nature volume 452, pages 620–623, DOI: https://doi.org/10.1038/nature06824

http://www.nature.com/articles/nature06824

Abstract: "The motion of continents relative to the Earth’s spin axis may be due either to rotation of the entire Earth relative to its spin axis—true polar wander—or to the motion of individual plates. In order to distinguish between these over the past 320 Myr (since the formation of the Pangaea supercontinent), we present here computations of the global average of continental motion and rotation through time in a palaeomagnetic reference frame. Two components are identified: a steady northward motion and, during certain time intervals, clockwise and anticlockwise rotations, interpreted as evidence for true polar wander. We find ∼18° anticlockwise rotation about 250-220 Myr ago and the same amount of clockwise rotation about 195-145 Myr ago. In both cases the rotation axis is located at about 10-20° W, 0° N, near the site that became the North American–South American–African triple junction at the break-up of Pangaea. This was followed by ∼10° clockwise rotation about 145-135 Myr ago, followed again by the same amount of anticlockwise rotation about 110-100 Myr ago, with a rotation axis in both cases ∼25-50° E in the reconstructed area of North Africa and Arabia. These rotation axes mark the maxima of the degree-two non-hydrostatic geoid during those time intervals, and the fact that the overall net rotation since 320 Myr ago is nearly zero is an indication of long-term stability of the degree-two geoid and related mantle structure. We propose a new reference frame, based on palaeomagnetism, but corrected for the true polar wander identified in this study, appropriate for relating surface to deep mantle processes from 320 Myr ago until hotspot tracks can be used (about 130 Myr ago)."

Edit: To add more relevant data about recent changes in the Earth's rotational tilt see (& the associated image):

"Ocean circulation and climate at the Eemian and last glacial inception" by Andreas Born
Dissertation for the degree of Philosophiae Doctor (PhD), Geophysical Institute,

http://bora.uib.no/bitstream/handle/1956/4436/Dr.thesis_Andreas%20Born.pdf?sequence=1&isAllowed=y

Extract: "The tilt (obliquity) of the Earth’s rotational axis relative to the plane of rotation around the sun varies between 22.1◦and 24.5◦on a 41,000 year cycle."

Edit: For ease of reference regarding sea level rise change during the Eemian, I provide the second image.
« Last Edit: August 30, 2018, 10:27:37 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #179 on: August 30, 2018, 03:24:11 AM »
While the linked research, indicating more rapid bedrock uplift in Amundsen Sea Embayment, seems like good news, if one refers to projections from ice sheet models that do not include Pollard's & DeConto's ice cliff and hydrofacturing mechanism and which assume radiative forcing scenarios of RCP 4.5 or less.  However, if one assumes radiative forcing scenarios close to BAU for the next two decades and projections from Pollard & DeConto's recent work, then Barletta et al (2018)'s finding are actually bad news regarding the potential collapse of the WAIS this century.

V.R. Barletta el al. (22 Jun 2018), "Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability," Science,:
Vol. 360, Issue 6395, pp. 1335-1339, DOI: 10.1126/science.aao1447.

http://science.sciencemag.org/content/360/6395/1335
Because there is a volcano beneath Pine Island Glacier, and because

Evidence of an active volcanic heat source beneath the Pine Island Glacier https://www.nature.com/articles/s41467-018-04421-3 and because there was a recent eruption

A recent volcanic eruption beneath the West Antarctic ice sheet https://www.nature.com/articles/ngeo106 Ancient Antarctic eruption noted http://news.bbc.co.uk/2/hi/science/nature/7194579.stm the uplift may mean that the heat source also advances. 


Quote
The localization of mantle helium to glacial meltwater reveals that volcanic heat induces melt beneath the grounded glacier and feeds the subglacial hydrological network crossing the grounding line. The observed transport of mantle helium out of the Ice Shelf cavity indicates that volcanic heat is supplied to the grounded glacier at a rate of ~ 2500 ± 1700 MW, which is ca. half as large as the active Grimsvötn volcano on Iceland. Our finding of a substantial volcanic heat source beneath a major WAIS glacier highlights the need to understand subglacial volcanism, its hydrologic interaction with the marine margins, and its potential role in the future stability of the WAIS.

ps. can someone suggest a good open study on Marine ice cliff instability?
Here https://www.sciencedirect.com/science/article/pii/S0012821X14007961
« Last Edit: August 30, 2018, 03:40:27 AM by prokaryotes »

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #180 on: August 30, 2018, 03:41:25 AM »
ps. can someone suggest a good open study on Marine ice cliff instability?
From a Google search:

Daniel F Martin1, Brent M Minchew2, Stephen F Price3 and Esmond G Ng1, (2018), "Modeling Marine Ice Cliff Instability: Higher resolution leads to lower impact", (1)Lawrence Berkeley National Laboratory, Berkeley, CA, United States, (2)Organization Not Listed, Washington, DC, United States, (3)Los Alamos National Laboratory, Los Alamos, NM, United States

https://agu.confex.com/agu/fm18/preliminaryview.cgi/Paper435681.html

&

Jeremy N Bassis1, Doug Benn2 and Brandon Robert Berg1, (2018), "Anatomy of the Marine Ice Cliff Instability", (1)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (2)University of St Andrews, Dept. of Geography and Sustainable Development, St Andrews, United Kingdom

https://agu.confex.com/agu/fm18/preliminaryview.cgi/Paper436995.html

&

Frank Pattyn (2018), "The paradigm shift in Antarctic ice sheet modelling", Nature Communications, volume 9, Article number: 2728, DOI: https://doi.org/10.1038/s41467-018-05003-z


https://www.nature.com/articles/s41467-018-05003-z
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #181 on: August 30, 2018, 03:41:25 AM »
2500 MW melts about 1/4 Gtonne ice per year (Check my math, always)
Amundsen sea glaciers are losing about  100Gtonne/yr.

So still down in the noise.

sidd
« Last Edit: August 30, 2018, 03:56:37 AM by sidd »

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #182 on: August 30, 2018, 03:58:23 AM »
2500 MW melts about 1/2 Gtonne ice per year (Check my math, always)
Amundsen sea glaciers are losing about  100Gtonne/yr.

So still down in the noise.

sidd

Quote
All the datasets illustrate the previously documented accelerating mass loss of Antarctica (Rignot et al., 2011a, b; Velicogna, 2009). In 2005–2010, the ice sheet experienced ice mass loss driven by an increase in mass loss in the Amundsen Sea sector of West Antarctica (Mouginot et al., 2014). The following years showed a reduced increase in mass loss, as colder ocean conditions prevailed in the Amundsen Sea embayment sector of West Antarctica in 2012–2013 which reduced the melting of the ice shelves

The large interannual variability in mass balance in 2005– 2015, characteristic of Antarctica, nearly masks out the trend in mass loss, which is more apparent in the longer time series than in short time series. The longer record highlights the pronounced decadal variability in ice sheet mass balance in Antarctica, demonstrating the need for multidecadal time series in Antarctica, which have been obtained only by IOM and altimetry. The interannual variability in mass balance is driven almost entirely by surface mass balance processes. The mass loss of Antarctica, about 200 Gt yr−1 in recent years, is only about 10 % of its annual turnover of mass (2200 Gt yr−1 ), in contrast with Greenland where the mass loss has been growing rapidly to nearly 100 % of the annual turnover of mass.

The annual turnover of mass of Antarctica is about 2200 Gt yr−1 (over 6 mm yr−1 of SLE), 5 times larger than in Greenland (Wessem et al., 2017). In contrast to Greenland, ice and snow melt have a negligible influence on Antarctica’s mass balance, which is therefore completely controlled by the balance between snowfall accumulation in the drainage basins and ice discharge along the periphery.

200 Gt from entire continent, i would think most from the WAIS. https://www.earth-syst-sci-data.net/10/1551/2018/essd-10-1551-2018.pdf

prokaryotes

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #183 on: August 30, 2018, 04:01:48 AM »

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #184 on: August 30, 2018, 04:07:09 AM »
From a Google search:
Thanks.

The following link provides interactive diagrams of ice mass loss from various regions of the Antarctic thru August 16, 2016:

https://data1.geo.tu-dresden.de/ais_gmb/
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prokaryotes

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #185 on: August 30, 2018, 02:45:41 PM »
..
Is there a topic discussing Marine Ice Sheet Instability?

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #186 on: August 30, 2018, 05:01:51 PM »
..
Is there a topic discussing Marine Ice Sheet Instability?

There is currently no individual thread devoted to Marine Ice Sheet Instability.  However, the are numerous threads in the Antarctic folder (including those linked below) that contain numerous posts on this complex topic:

https://forum.arctic-sea-ice.net/index.php/topic,85.0.html
https://forum.arctic-sea-ice.net/index.php/topic,21.0.html
https://forum.arctic-sea-ice.net/index.php/topic,72.0.html
https://forum.arctic-sea-ice.net/index.php/topic,130.0.html

Part of the problem is that models of Marine Ice Sheet Instability are so immature that it is difficult to comment on them without writing a PhD Dissertation each and every time.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #187 on: August 30, 2018, 10:22:44 PM »
The linked reference indicates that the Beaufort Gyre halocline has been 'archiving' ocean heat for the past three decades.  When this warm water is eventually released, it will melt significant amounts of Arctic sea ice.

Mary-Louise Timmermans, John Toole and Richard Krishfield (29 Aug 2018), "Warming of the interior Arctic Ocean linked to sea ice losses at the basin margins", Science Advances , Vol. 4, no. 8, eaat6773, DOI: 10.1126/sciadv.aat6773

http://advances.sciencemag.org/content/4/8/eaat6773

Abstract: "Arctic Ocean measurements reveal a near doubling of ocean heat content relative to the freezing temperature in the Beaufort Gyre halocline over the past three decades (1987–2017). This warming is linked to anomalous solar heating of surface waters in the northern Chukchi Sea, a main entryway for halocline waters to join the interior Beaufort Gyre. Summer solar heat absorption by the surface waters has increased fivefold over the same time period, chiefly because of reduced sea ice coverage. It is shown that the solar heating, considered together with subduction rates of surface water in this region, is sufficient to account for the observed halocline warming. Heat absorption at the basin margins and its subsequent accumulation in the ocean interior, therefore, have consequences for Beaufort Gyre sea ice beyond the summer season."

See also:

Title: "‘Archived’ heat has reached deep into the Arctic interior, researchers say"

https://news.yale.edu/2018/08/29/archived-heat-has-reached-deep-arctic-interior-researchers-say

Extract: "“We document a striking ocean warming in one of the main basins of the interior Arctic Ocean, the Canadian Basin,” said lead author Mary-Louise Timmermans, a professor of geology and geophysics at Yale University.

The upper ocean in the Canadian Basin has seen a two-fold increase in heat content over the past 30 years, the researchers said. They traced the source to waters hundreds of miles to the south, where reduced sea ice has left the surface ocean more exposed to summer solar warming. In turn, Arctic winds are driving the warmer water north, but below the surface waters."

&

Title: "'Ticking Time Bomb' of Heated Ocean Discovered Hidden Under The Arctic"

https://www.sciencealert.com/ticking-time-bomb-hidden-heated-ocean-water-under-arctic-canada-basin-chukchi-sea

Extract: "New research has uncovered evidence of a vast reservoir of heated water building up underneath the Arctic Ocean and penetrating deep into the heart of the polar region, where it threatens to melt the ice frozen on top. And maybe a lot of it.

"We document a striking ocean warming in one of the main basins of the interior Arctic Ocean, the Canadian Basin," explains oceanographer Mary-Louise Timmermans from Yale University.
Timmermans and her team analysed temperature data on the Canada Basin taken over the last 30 years, and found that the amount of heat in the warmest part of the water had effectively doubled in the period 1987 to 2017."

Edit: See Reply #75 for other discussion about the Beaufort Gyre.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #188 on: August 30, 2018, 11:27:12 PM »

It takes 4.186x10^6 Joules to raise a cubic meter of water 1°C - so at 4.4x10^8 Joules per m2, there is enough energy to raise 100m about 1°C. Looking at their graphs, 50-150m is approximately the depth they used between the 31 and 33psu salinity boundaries.

If we have an extra 2.2x10^8 Joules per m2

That's enough heat to melt an extra ~0.6m of ice.

The density change of going from -1.3°C to 0°C at 31 psu doesn't make a huge density difference (about 0.1 g per liter), but the density difference as compared to the surface water drops by around 4% possible indicating decreased resistance to mixing; the surface waters, at 1.25°C, 28psu, are about 2.40g per liter less dense.

One can only assume that the heating will accelerate with the current state of the Arctic, and that at some point the heat loss by conduction through the surface mixed layer will be able to keep up with the extra heat input .. that or it will reach the adiabatic threshold and start mixing.



AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #189 on: August 31, 2018, 01:01:48 AM »
One can only assume that the heating will accelerate with the current state of the Arctic, and that at some point the heat loss by conduction through the surface mixed layer will be able to keep up with the extra heat input .. that or it will reach the adiabatic threshold and start mixing.

The one consideration that you are ignoring is that per the research that I reference in Reply #75, the relatively freshwater layer immediately above the deeper warm layer of water, is unstable.  So it is not that the deeper and denser warm water will magically float up through less dense cooler water, but rather that the upper cooler/fresher lay may well some day flow laterally away (into the North Atlantic) which would then leave the warm water closer to the surface.
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RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #190 on: August 31, 2018, 10:22:47 PM »

Less dense layers are, by definition, unstable when surrounded by higher density fluids. They are constantly under pressure to move laterally, just like oil spreading over water (but with mixing at the boundaries). The low density lens of fresher water in the Arctic has to be continually replenished by Arctic River drainage and/or by the freeze/melt cycle, otherwise, as you say, it will just disappear. The low density upper Arctic layer flows out of the Arctic through the Fram strait and the CAA; if it didn't then the Arctic surface would become fresher and fresher, rather like the Baltic.

I don't think that the lower layers are going to become vertically unstable and overturn, however, there will be less resistance to mixing between layers as the density difference between those layers lessens.


AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #191 on: August 31, 2018, 10:50:59 PM »
Your description of the behavior of the Beaufort Gyre, and how it accumulates and disperses relatively freshwater is overly simplified; which results in incorrect conclusions.  The first linked article (cited in Reply #75), makes it clear that in recent decades the Beaufort Gyre has been accumulating an atypically large amount of freshwater, possibly due the mechanism cited by Proshutinsky et al (2015).  If the feedback mechanism cited by Proshutinsky et al (2015) were to be disrupted some year in the future, one would expect an atypically large outflow of relatively freshwater from the Beaufort Gyre and consequently an atypically large up-flow of relatively warm deep water that is currently beneath the relatively freshwater cap in the Beaufort Gyre:

Title: "How a Wayward Arctic Current Could Cool the Climate in Europe"

http://e360.yale.edu/features/how-a-wayward-arctic-current-could-cool-the-climate-in-europe

Extract: "The Beaufort Gyre, a key Arctic Ocean current, is acting strangely. Scientists say it may be on the verge of discharging a huge amount of ice and cold freshwater that could kick off a period of lower temperatures in northern Europe.

…something is amiss with this vital plumbing system in the Arctic, a region warming faster than any other on the planet. Thanks in part to rising air temperatures, steadily disappearing sea ice, and the annual melting of 270 billion tons of ice from Greenland’s ice cap, the gyre is no longer functioning as it has predictably done for more than a half century. And now, scientists are anticipating that a sudden change in the Beaufort Gyre could set in motion events that — in a steadily warming world — would actually lead to a temporary but significant cooling of the North Atlantic region.

During the second half of the 20th century — and, most likely, earlier — the gyre adhered to a cyclical pattern in which it would shift gears every five to seven years and temporarily spin in a counter-clockwise direction, expelling ice and freshwater into the eastern Arctic Ocean and the North Atlantic. But for more than a dozen years, this carousel of ice and, increasingly, freshwater has been spinning faster in its usual clockwise direction, all the while collecting more and more freshwater from three sources: melting sea ice, huge volumes of runoff flowing into the Arctic Ocean from Russian and North American rivers, and the relatively fresh water streaming in from the Bering Sea….

The gyre’s strange behavior is likely linked, at least in part, to the profound warming of the Arctic, and it demonstrates how disruptions in one rapidly changing region of the world can affect ecosystems hundreds, even thousands, of miles away. In a recent paper, Krishfield, Proshutinsky, and other scientists suggest that frigid freshwater pouring into the north Atlantic Ocean from the rapidly melting Greenland ice sheet is forming a cap on the North Atlantic that results in stratification that prevents storm-triggering heat from the northern end of the Gulf Stream from rising to the surface. The scientists say this may be inhibiting the formation of cyclones that would cause the motion of the gyre to weaken or temporarily reverse.

If that is the case, it may mean the gyre will continue to grow and spin clockwise for years to come."

See also:

Andrey Proshutinsky, Dmitry Dukhovskoy, Mary-Louise Timmermans, Richard Krishfield, Jonathan L. Bamber (2015), "Arctic circulation regimes", Philosophical Transactions of the Royal Society A, DOI: 10.1098/rsta.2014.0160

http://rsta.royalsocietypublishing.org/content/373/2052/20140160

Abstract: "Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability."
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RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #192 on: September 01, 2018, 04:03:55 PM »
One can only assume that the heating will accelerate with the current state of the Arctic, and that at some point the heat loss by conduction through the surface mixed layer will be able to keep up with the extra heat input .. that or it will reach the adiabatic threshold and start mixing.

The one consideration that you are ignoring is that per the research that I reference in Reply #75, the relatively freshwater layer immediately above the deeper warm layer of water, is unstable.  So it is not that the deeper and denser warm water will magically float up through less dense cooler water, but rather that the upper cooler/fresher lay may well some day flow laterally away (into the North Atlantic) which would then leave the warm water closer to the surface.

I was answering your point: One of the most important fundamental driving force for freshwater drainage out of the Arctic ocean is lateral density difference. Low salinity water is continually flowing out of the Arctic. It's not something I would ignore. I attempted to simplify my answer to get the idea across. Clearly i failed.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #193 on: September 01, 2018, 04:28:48 PM »
I was answering your point: One of the most important fundamental driving force for freshwater drainage out of the Arctic ocean is lateral density difference. Low salinity water is continually flowing out of the Arctic. It's not something I would ignore. I attempted to simplify my answer to get the idea across. Clearly i failed.

While it is true that low salinity water is continually flowing out of the Arctic, the key issue to understand is that the volume of low salinity water discharging from the Beaufort Gyre fluctuates, and that since 1997 the gyre has been accumulating an atypically large volume of low salinity water, which will most likely be discharged in a future pulse rather than in a uniform flow.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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vox_mundi

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More supporting evidence that Climate Change is impacting polar drift

Scientists ID Three Causes of Earth's Spin Axis Drift
https://phys.org/news/2018-09-scientists-id-earth-axis-drift.html


The observed direction of polar motion, shown as a light blue line, compared with the sum (pink line) of the influence of Greenland ice loss (blue), postglacial rebound (yellow) and deep mantle convection (red). The contribution of mantle convection is highly uncertain.

Using observational and model-based data spanning the entire 20th century, NASA scientists have for the first time identified three broadly-categorized processes responsible for this drift—contemporary mass loss primarily in Greenland, glacial rebound, and mantle convection.

"The traditional explanation is that one process, glacial rebound, is responsible for this motion of Earth's spin axis. But recently, many researchers have speculated that other processes could have potentially large effects on it as well," said first author Surendra Adhikari of NASA's Jet Propulsion Laboratory in Pasadena, California. "We assembled models for a suite of processes that are thought to be important for driving the motion of the spin axis. We identified not one but three sets of processes that are crucial—and melting of the global cryosphere (especially Greenland) over the course of the 20th century is one of them."

While ice melt is occurring in other places (like Antarctica), Greenland's location makes it a more significant contributor to polar motion.

"There is a geometrical effect that if you have a mass that is 45 degrees from the North Pole—which Greenland is—or from the South Pole (like Patagonian glaciers), it will have a bigger impact on shifting Earth's spin axis than a mass that is right near the Pole," said coauthor Eric Ivins, also of JPL.


The results suggest that tracking polar shifts can serve as a check on current estimates of ice loss, says Erik Ivins, a geophysicist at NASA’s Jet Propulsion Laboratory in Pasadena, California. When mass is lost in one part of a spinning sphere, its spin axis will tilt directly towards the position of the loss, he says — exactly as Chen’s team observed for Greenland. “It’s a unique indicator of the point where the mass is lost,” says Ivins.

Scientists can locate the north and south poles to within 0.03 milliarcseconds by using Global Positioning System measurements to determine the angle of Earth’s spin. Knowing the motion of the poles constrains estimates of ice loss made by other methods, Chen says

With these three broad contributors identified, scientists can distinguish mass changes and polar motion caused by long-term Earth processes over which we have little control from those caused by climate change. They now know that if Greenland's ice loss accelerates, polar motion likely will, too.

JPL Interactive Polar Motion Simulator: https://vesl.jpl.nasa.gov/sea-level/polar-motion/

What drives 20th century polar motion?

https://www.sciencedirect.com/science/article/pii/S0012821X18305314

Quote
Abstract

Astrometric and geodetic measurements show that the mean position of Earth's spin axis drifted through the solid crust toward Labrador, Canada at an average speed of  cm/yr during the 20th century. Understanding the origins of this secular polar motion (SPM) has significance for modeling the global climate, as it provides a link to ice mass balance and sea-level rise. A perplexing issue, however, is that while glacial isostatic adjustment (GIA) models satisfactorily explain the direction of SPM, the associated prediction of the amplitude is insufficient. Our Bayesian GIA analysis, with constraints from relative sea-level and vertical land motion data, reveals that this process only accounts for % of the observed SPM amplitude. This shortfall motivates a more broadly scoped reassessment of SPM drivers. To address this, we assemble a complete reconstruction of Earth's surface mass transport derived from recent advancements in modeling the global 20th century cryospheric, hydrologic, oceanic, and seismogenic mass exchange. The summed signals, nonetheless, cannot fully reconcile the observed SPM, even when considering the error statistics of each driver. We investigate an additional excitation source: changes in Earth's inertia tensor caused by mantle convection. Sophisticated models have recently been advanced in tectonic plate reconstructions, in conjunction with geoid and seismic tomographic models. Here we use these models to compute new estimates of SPM. While the convection-driven SPM has considerable uncertainty, the average direction of 283 recent models aligns with the residual SPM (within 2.7 +/- 14.8 ), significantly reducing the gap between observation and prediction. We assert that one key mechanism for driving 20th century SPM is long-term mass movement due to mantle convection.
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