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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #100 on: February 08, 2018, 05:15:30 PM »
Here is another repost regarding possible increased risks of flipping the Earth's magnetic poles


": sidd  Today at 02:26:20 AM

"In my opinion, a collapse of the WAIS this century would likely accelerate schedule for the long overdue flipping of the Earth's magnetic poles. "

Interesting. What leads you to this opinion ? Do tell.

sidd




Here is some 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 #101 on: February 08, 2018, 05:18:39 PM »
Here is my last repost from the 'Adapting to the Anthropocene' thread about increased risk of flipping the Earth's magnetic pole due to abrupt sea level rise associated with abrupt ice mass loss this century:


": sidd  Today at 06:55:23 AM

Do you mean magnetic pole or rotational pole ? both the papers you cite talk about the rotational pole.

sidd




sidd,

I will move this line of discussion to the 'Ice Apocalypse' thread (see the link below) in the Antarctic folder as this topic was meant to be just a word of warning here.  However, my general point is that a some portion of the changes in the magnetic pole can be associated with changes in the rotational pole (the attached image illustrates how fast this is currently changing), due to changes in the magma flow associated with ice mass redistribution.  Furthermore, my point is that due to the current exceptionally high rate of anthropogenic forcing and the bipolar seesaw mechanism that possible abrupt changes in ice mass loss can make faster changes in tectonic behavior than observed in the paleorecord.

https://forum.arctic-sea-ice.net/index.php/topic,2205.50.html

ASLR"
“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 #102 on: February 08, 2018, 06:12:17 PM »
As a follow on to my last series of re-posts about 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.  Also, Hansen's ice-climate feedback results in changes in precipitation patterns that will affect polar wander.

I recommend that scientists with the appropriate Earth models that include Earth's interior core-mantle-lithosphere mechanisms should assume some up-bound scenarios for possible future abrupt mass redistributions around the Earth (including: a WAIS ice mass collapse and associated isostatic rebound, increased rainfall at both poles; changes in groundwater distributions, etc.) and then see what happens to tectonic activity (including magnetic fields, volcanism and seismic activity):

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."


Edit, also see 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."
« Last Edit: February 08, 2018, 07:49:54 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #103 on: February 08, 2018, 09:43:21 PM »
While I am not a scientist, the fact that the linked reference associates climate change with a Cambrian true wander event and associated changes in the paleomagnetic data, indicates to me that qualified scientist should model what impacts that abrupt sea level rise this century would have on both Earth's rotational and magnetic axes:

Wen-Jun Jiao et al. (16 January 2018", "Paleomagnetism of a well-dated marine succession in South China: A possible Late Cambrian true polar wander (TPW)", Physics of the Earth and Planetary Interiors, https://doi.org/10.1016/j.pepi.2018.01.009

https://www.sciencedirect.com/science/article/pii/S0031920117301905

Abstract: "The Cambrian true polar wander (TPW) hypothesis remains controversial largely because of the uncertainties in the quality and/or fidelity of the paleomagnetic data as well as their chronological control. Testing the TPW hypothesis requires high-quality paleomagnetic data of sufficient spatial and temporal resolutions. Here, we present paleomagnetic results of a continuous Cambrian shallow marine succession from South China where available detailed biostratigraphy provides exceptional chronological constraints. Forty-three sites of paleomagnetic samples were collected from this limestone-dominated succession. Stepwise thermal demagnetization generally reveals three-component magnetizations. Low- and intermediate-temperature components can be cleaned by ∼330°C, and the high-temperature component (HTC) was isolated typically from ∼350 to ∼450°C. A positive fold test and the presence of reversed polarity in the strata, together with rock magnetic data as well as the scanning electron microscopic (SEM) and transmission electron microscopic (TEM) results, collectively suggest that the HTCs are likely primary. A directional shift of the HTCs occurs between the lower-middle Cambrian and the upper Cambrian strata in the succession and is tentatively interpreted to indicate a ∼57° polar wander from ∼500.5 to 494 Ma. Because the rate of polar wander is too fast to be a tectonic origin, this polar wander is interpreted to represent a Late Cambrian TPW. This TPW appears coeval with the Steptoean positive carbon isotope excursion (SPICE) and the major trilobite mass extinctions, suggesting a potential link between the TPW and the Late Cambrian biotic and climatic changes. Because the proposed TPW event is exceptionally well-dated, it should be testable through examination of other worldwide sections."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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gerontocrat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #104 on: February 08, 2018, 10:14:35 PM »
And on the way to a reversal of poles, some scientists have said the magnetic field will do a polar vortex, i.e. weaken and become erratic. Bad news for our electro-magnetic society when a solar storm hits it.

(No source - dredged up from a rusty filing cabinet in the brain from a long time ago at Uni when plate tectonics was still just a hypothesis and these flipflops played a big part to prove it).
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #105 on: February 09, 2018, 09:35:14 PM »
I thought that I would offer the following comments and associated images regarding ECS in our warming world:

1.  The first image shows calculated values of inferred ECS with latitude based on recent surface temperature observations (and thus do not include slow response contributions.  Things to note include: a. the inferred ECS near the North Pole is approximately 4.2C; b. the inferred ECS over the Southern Ocean is around 1.3C because Antarctic ice shelves have lost so much ice mass that they are already activating Hansen's ice-climate feedback mechanism, and c. the inferred ECS over most of Antarctica is around 2.5C, which is much less than that for the Arctic because of the relatively high surface elevation for most of Antarctica; which will change is the WAIS collapses.

2. The second image shows paleo values for Gain (in 'C per W/sq-m') compared to the AR5 likely range for these values vs frequency (in cycles/year).  This shows both that the IPCC is highlighting linear response for what is a highly non-linear behavior and that long/fat tailed events (like freshwater hosing events) can have Gain values that are 2.5 times higher than assumed by the IPCC; which translates into higher than recognized resists for mankind.

3. The third image shows how the product of the frequency PDF for bad events times the expected magnitude of such bad events results in maximum risk towards 65% to 75% confidence level for the PDF.  This means that policy makers should be working with the upper end of expected ECS range rather than with mean or mode values.
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steve s

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #106 on: February 10, 2018, 01:59:28 AM »
"ECS" refers to what?

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #107 on: February 10, 2018, 04:24:54 AM »

FishOutofWater

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #108 on: February 10, 2018, 05:00:27 AM »
Sea level rise is already slowing the earth's rate of rotation.

http://www.climatecentral.org/news/glacial-melt-slowing-of-earths-rotation-19843

To get the rotational pole to wander there must be differential rotation of the crust, mantle and/or core. Angular momentum of the earth moon system is conserved. Over long periods of time tides slow earth's rotation and the rotational energy is transferred to the moon.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #109 on: March 14, 2018, 11:02:03 PM »
If the findings of the linked reference are correct then "chain-reactions of fast draining lakes" could threaten the stability of key portions of Greenland's ice sheet over the coming 50 years:

Poul Christoffersen et al, Cascading lake drainage on the Greenland Ice Sheet triggered by tensile shock and fracture, Nature Communications (2018). DOI: 10.1038/s41467-018-03420-8

http://www.nature.com/articles/s41467-018-03420-8

Abstract: "Supraglacial lakes on the Greenland Ice Sheet are expanding inland, but the impact on ice flow is equivocal because interior surface conditions may preclude the transfer of surface water to the bed. Here we use a well-constrained 3D model to demonstrate that supraglacial lakes in Greenland drain when tensile-stress perturbations propagate fractures in areas where fractures are normally absent or closed. These melt-induced perturbations escalate when lakes as far as 80 km apart form expansive networks and drain in rapid succession. The result is a tensile shock that establishes new surface-to-bed hydraulic pathways in areas where crevasses transiently open. We show evidence for open crevasses 135 km inland from the ice margin, which is much farther inland than previously considered possible. We hypothesise that inland expansion of lakes will deliver water and heat to isolated regions of the ice sheet’s interior where the impact on ice flow is potentially large."

See also:

Title: "Chain reaction of fast-draining lakes poses new risk for Greenland ice sheet"

https://phys.org/news/2018-03-chain-reaction-fast-draining-lakes-poses.html

Extract: "A growing network of lakes on the Greenland ice sheet has been found to drain in a chain reaction that speeds up the flow of the ice sheet, threatening its stability."
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Adam Ash

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #110 on: March 15, 2018, 10:49:06 AM »
Comparing the size of the heat sinks represented by the main ice masses:
Arctic              25,600 cu km (mid winter)
Greenland   2,850,000 cu km
Antarctic  26,500,000 cu km

So Arctic peak winter ice volume is about 1% of Greenland's, and Greenland's is 10% of Antarctica's.  Thus the heat which disposes of most of the Arctic's ice in summer, is having a significant input to Greenland's ice mass too.  The less Arctic ice there is, the more the heat goes into the Greenland heat sink, and the adjacent ocean. 

Its kinda the inverse of a scheme to pay off debts.  Pay off the smallest first, then there is much more to pay off the next.  Get rid of Arctic ice, then with that job done that heat will hit Greenland hard.  Hanson's exponential rate of change of SLR becomes more likely every day.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #111 on: March 15, 2018, 10:57:35 AM »
Hansen, James Hansen.

This is Hanson:

Compare, compare, compare

FishOutofWater

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #112 on: March 15, 2018, 03:31:50 PM »
Whoa, Neven, the sea ice has been restored and we're back in the '90s. Kids having innocent fun. These days kids here are acting like adults and the adults are acting like kids.

These are dizzying times. It's so hard to get a handle on the rates of change and the probabilities of extreme events like rapid sea level rise. I wish we could retreat to the innocence of that video but we can't.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #113 on: March 15, 2018, 03:52:00 PM »
... However, my general point is that a some portion of the changes in the magnetic pole can be associated with changes in the rotational pole (the attached image illustrates how fast this is currently changing), due to changes in the magma flow associated with ice mass redistribution.  Furthermore, my point is that due to the current exceptionally high rate of anthropogenic forcing and the bipolar seesaw mechanism that possible abrupt changes in ice mass loss can make faster changes in tectonic behavior than observed in the paleorecord.

https://forum.arctic-sea-ice.net/index.php/topic,2205.50.html

ASLR"

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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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #114 on: March 15, 2018, 10:42:34 PM »
The very generation of earths magnetic field is poorly understood. Magnetic pole reversal is even less well understood. The impact of changing tectonics in response to ice unloading is also poorly understood and it's influence on magnetic field generation is not understood at all.  I am aware of no literature suggesting that ice unloading will cause magnetic pole reversal, and i consider the notion quite farfetched.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #115 on: March 16, 2018, 12:34:17 AM »
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

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #116 on: March 16, 2018, 07:32:29 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."
“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 #117 on: March 31, 2018, 12:38:36 PM »

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."

It may (or may not) be a coincidence that a tectonic fissure has recently formed in south-western Kenya, in an area close to the recently identified weakening of the Earth's geomagnetic fields ???:

Title: "Large crack in East African Rift is evidence of continent splitting in two"

https://www.the-star.co.ke/news/2018/03/31/large-crack-in-east-african-rift-is-evidence-of-continent-splitting-in_c1739076

Extract: "A large crack, stretching several kilometres, made a sudden appearance recently in south-western Kenya. The tear, which continues to grow, caused part of the Nairobi-Narok highway to collapse and was accompanied by seismic activity in the area.
...
The East African Rift is unique in that it allows us to observe different stages of rifting along its length. To the south, where the rift is young, extension rates are low and faulting occurs over a wide area. Volcanism and seismicity are limited.

Towards the Afar region, however, the entire rift valley floor is covered with volcanic rocks. This suggests that, in this area, the lithosphere has thinned almost to the point of complete break up. When this happens, a new ocean will begin forming by the solidification of magma in the space created by the broken-up plates. Eventually, over a period of tens of millions of years, seafloor spreading will progress along the entire length of the rift. The ocean will flood in and, as a result, the African continent will become smaller and there will be a large island in the Indian Ocean composed of parts of Ethiopia and Somalia, including the Horn of Africa."

« Last Edit: April 02, 2018, 04:11:03 AM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #118 on: March 31, 2018, 02:53:37 PM »
I guess it is possible that the fissure was responsible for the weakening.  We would need to seek out someone better knowledgeable in this area.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #119 on: March 31, 2018, 06:59:35 PM »

The crack is probably the continuing extension of east African Rift system and thinning of the lithosphere the 'crack' is just the latest brittle fault that represents the continuing plate movement. The development of this rift system has been understood for at least 20 years, and has been going on for 10s of millions of years (the red sea is an extension of African plate boundary, Somalia I believe, is considered to be on its own plate)

There may be a relationship between the plate movement (essentially the top of mantle convection cells) and the deep mantle structure, but spreading is happening in may other places (the gulf of California is somewhat analogous to the red sea), and is just part of the normal tectonic cycle. My best guess is that the two aren't casual.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #120 on: April 02, 2018, 12:24:50 AM »
As I mentioned elsewhere, a recent PNAS paper shows SLR is accelerating at .08mm/yr^2. One can look at the doubling time of each component and there we see Antarctic Ice Sheets have a relatively low contribution now, though the shortest doubling time, on the order of 6 years. The overall doubling rate of the rise is roughly 35 years.

http://www.pnas.org/content/early/2018/02/06/1717312115

And GRACE data shows the more specific acceleration of the Antarctic Ice Sheets.

Comparing the size of the heat sinks represented by the main ice masses:
Arctic              25,600 cu km (mid winter)
Greenland   2,850,000 cu km
Antarctic  26,500,000 cu km

So Arctic peak winter ice volume is about 1% of Greenland's, and Greenland's is 10% of Antarctica's.  Thus the heat which disposes of most of the Arctic's ice in summer, is having a significant input to Greenland's ice mass too.  The less Arctic ice there is, the more the heat goes into the Greenland heat sink, and the adjacent ocean. 

Its kinda the inverse of a scheme to pay off debts.  Pay off the smallest first, then there is much more to pay off the next.  Get rid of Arctic ice, then with that job done that heat will hit Greenland hard.  Hanson's exponential rate of change of SLR becomes more likely every day.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #121 on: April 11, 2018, 12:30:05 AM »
The linked open access reference is highly relevant to Hansen's ice-climate feedback mechanism, as an abrupt collapse of key WAIS marine glaciers, would increase ocean temperatures at key Greenland marine-terminating glaciers via the bipolar seesaw:

Tabone, I., Blasco, J., Robinson, A., Alvarez-Solas, J., and Montoya, M.: The sensitivity of the Greenland Ice Sheet to glacial–interglacial oceanic forcing, Clim. Past, 14, 455-472, https://doi.org/10.5194/cp-14-455-2018, 2018.

https://www.clim-past.net/14/455/2018/

Abstract. Observations suggest that during the last decades the Greenland Ice Sheet (GrIS) has experienced a gradually accelerating mass loss, in part due to the observed speed-up of several of Greenland's marine-terminating glaciers. Recent studies directly attribute this to warming North Atlantic temperatures, which have triggered melting of the outlet glaciers of the GrIS, grounding-line retreat and enhanced ice discharge into the ocean, contributing to an acceleration of sea-level rise. Reconstructions suggest that the influence of the ocean has been of primary importance in the past as well. This was the case not only in interglacial periods, when warmer climates led to a rapid retreat of the GrIS to land above sea level, but also in glacial periods, when the GrIS expanded as far as the continental shelf break and was thus more directly exposed to oceanic changes. However, the GrIS response to palaeo-oceanic variations has yet to be investigated in detail from a mechanistic modelling perspective. In this work, the evolution of the GrIS over the past two glacial cycles is studied using a three-dimensional hybrid ice-sheet–shelf model. We assess the effect of the variation of oceanic temperatures on the GrIS evolution on glacial–interglacial timescales through changes in submarine melting. The results show a very high sensitivity of the GrIS to changing oceanic conditions. Oceanic forcing is found to be a primary driver of GrIS expansion in glacial times and of retreat in interglacial periods. If switched off, palaeo-atmospheric variations alone are not able to yield a reliable glacial configuration of the GrIS. This work therefore suggests that considering the ocean as an active forcing should become standard practice in palaeo-ice-sheet modelling.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #122 on: April 14, 2018, 06:47:38 PM »
As bad as the linked article about a potential collapse of the Atlantic overturning circulation sounds, just consider that the article does not even talk about the impacts of the bipolar seesaw and a potential collapse of the WAIS this century, on the ocean current conveyor belt:

Title: "Avoid Gulf stream disruption at all costs, scientists warn"

https://www.theguardian.com/environment/2018/apr/13/avoid-at-all-costs-gulf-streams-record-weakening-prompts-warnings-global-warming

Extract: "Serious disruption to the Gulf Stream ocean currents that are crucial in controlling global climate must be avoided “at all costs”, senior scientists have warned. The alert follows the revelation this week that the system is at its weakest ever recorded.

Past collapses of the giant network have seen some of the most extreme impacts in climate history, with western Europe particularly vulnerable to a descent into freezing winters. A significantly weakened system is also likely to cause more severe storms in Europe, faster sea level rise on the east coast of the US and increasing drought in the Sahel in Africa.

The new research worries scientists because of the huge impact global warming has already had on the currents and the unpredictability of a future “tipping point”."

Edit, see also:

Title: "Stronger evidence for a weaker Atlantic overturning circulation"

http://www.realclimate.org/index.php/archives/2018/04/stronger-evidence-for-a-weaker-atlantic-overturning-circulation/
« Last Edit: April 14, 2018, 07:10:07 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #123 on: April 24, 2018, 06:08:05 PM »
While the two attached images are not from the linked research, the first image (from 2000 Richard Alley data for Greenland) illustrates how quickly temperatures warmed in Greenland 15,000 kya; while the second image should how 14,700 to 13,5000 kya the subsequent Meltwater pulse 1A rapidly drove-up sea level (& I note that Meltwater pulse 1A appears to have been triggered by a collapse of portions of the Pine Island embayment marine glacier, see the last link about Meltwater pulse 1A).  This paleo-data illustrates how rapidly the bipolar seesaw can change global climate, and I note that we appear to be entering a parallel phase of bipolar seesaw, with rapidly shifting North Atlantic (see the immediate previous post) and North Pacific ocean circulation patterns, and with the PIG and Thwaites marine glaciers at risk of rapidly collapsing due to associated changes in local ocean circulation patterns:

Title: "Shift in ocean circulation triggered the end of the last ice age"

https://www.upi.com/Shift-in-ocean-circulation-triggered-the-end-of-the-last-ice-age/8381524574301/

Extract: ""This gives us an example of the way that different parts of the climate system are connected, so that changes in circulation in one region can drive changes in CO2 and oxygen all the way over on the other side of the planet," researcher Will Gray said.

The end of the last ice age was precipitated by a shift in the circulation of the North Pacific Ocean some 15,000 years ago.

Scientists modeled the ancient shifts in circulation and ocean-atmosphere gas exchange by measuring the chemical composition of foraminifera, the tiny fossil shells left behind by plankton. Their analysis -- published this week in the journal Nature Geoscience -- revealed an uptick in the amount of CO2 released by the North Pacific beginning 15,000 years ago. Previous studies have found evidence of shifting circulation patterns in the Atlantic at roughly the same time.

Earlier this month, another group of researchers published a study showing the Atlantic's circulation is slowing down. Scientists suggest a slowdown could significantly alter climate patterns across the globe.

"In our study we see very rapid changes in the climate of the North Pacific that we think are linked to past changes in ocean currents in the Atlantic," lead researcher Will Gray, an environmental scientist at St. Andrews, said in a news release. "This gives us an example of the way that different parts of the climate system are connected, so that changes in circulation in one region can drive changes in CO2 and oxygen all the way over on the other side of the planet.""

See also:

Gray et al. (2018), "Deglacial upwelling, productivity and CO₂ outgassing in the North Pacific Ocean", Nature Geoscience, doi: 10/1038/s4156-018-0108-6

https://www.nature.com/articles/s41561-018-0108-6

&

Title: "Meltwater pulse 1A"

https://en.wikipedia.org/wiki/Meltwater_pulse_1A
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #124 on: April 26, 2018, 10:22:43 PM »
The linked 2008 Editor's Note, discusses the 'John Mercer effect' that "… stands for the fact that scientists (in this case glaciologists) are wary of being similarly characterized as alarmists, particularly because of the impact that this may have on future funding."  This is due to what " … Rachel Carson called "the gods of profit and production", and it will likely lead to a "Climate Catastrophe":

https://list.uvm.edu/cgi-bin/wa?A3=ind0802&L=SCIENCE-FOR-THE-PEOPLE&E=0&P=163360&B=--%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D_-1010152671%3D%3D_ma%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D&T=text%2Fhtml;%20charset=us-ascii

Extract: "Twenty years ago climatologist James Hansen of NASA's Goddard Institute of Space Studies, widely considered to be the world's leading authority on global warming, first brought the issue into the public spotlight in testimony before the U.S. Congress. Recently, Hansen published an article entitled "Climate Catastrophe" in the New Scientist (July 28, 2007), http://www.newscientist.com. There he presented evidence suggesting that under "business as usual," in which greenhouse gas emissions continue to increase unchecked, a rise in sea level by several meters during the present century due to the melting of polar ice sheets is a "near certainty."

A sea level rise of this extent (up to five meters or sixteen feet) would mean the loss of land areas on which much of the earth's population lives at present (10 percent of the world's population live less than ten meters above the mid-tide sea level.). Yet, most scientists, even glaciologists, still downplay the full extent of the danger, failing to acknowledge probable nonlinear processes associated with climate change, and are especially reticent when it comes to making public statements in that regard.

Why? Hansen calls this the "John Mercer effect." In the 1970s John Mercer, a glaciologist at Ohio State University's Institute of Polar Studies, drew attention to the West Antarctic Ice Sheet, which is separated from the bulk of Antarctica by a mountain range. Ice shelves floating on its rim put it in a delicate balance so that global warming, Mercer claimed, could within a mere forty years cause it to disintegrate and slide into the sea, raising the sea level by five meters.

Other glaciologists looked into Mercer's model and decided based on the data collected that what he described could indeed happen. But most climatologists and geologists publicly dismissed the idea that an ice sheet as big as Mexico could disintegrate in less than a few centuries (Spencer R. Weart, The Discovery of Global Warming, pp. 79-80). According to Hansen, although it was not obvious at the time whether Mercer or his critics were correct, "researchers who suggested that his paper was alarmist were regarded as more authoritative." Hansen believes that Mercer lost funding opportunities as a result. This discouraged other scientists from speaking out.

The John Mercer Effect then stands for the fact that scientists (in this case glaciologists) are wary of being similarly characterized as alarmists, particularly because of the impact that this may have on future funding. "Scientists downplaying the dangers of climate change [or other threats to the status quo] fare better when it comes to getting funding." Hansen points to his own experience. In 1981, based on the first reliable estimates of average global temperature by NASA, he pointed to the dangers of global warming from fossil fuel use. The result: his research group had some of its funding pulled by the Department of Energy, which specifically criticized aspects of that paper. Hansen argues that such economic/funding constraints have the effect of inhibiting scientific criticisms of the status quo: "I believe there is pressure on scientists to be conservative." To be sure, scientists are trained to be skeptics, but "excessive caution also holds dangers. 'Scientific reticence' can hinder communication with the public about the dangers of global warming. We may rue reticence if it means no action is taken until it is too late to prevent future disasters."

Hansen's description of the John Mercer Effect reflects the way in which a system devoted to what Rachel Carson called "the gods of profit and production" (see the Review of the Month in this issue) constrains scientists (along with everyone else), whenever issues arise that potentially threaten the vested interests-even when it is a question of protecting human life and the planetary environment. In the United States, where so much of the scientific funding comes from the Pentagon and the large corporations, the John Mercer Effect is especially strong in limiting what scientists are willing to say and do. As Richard Levins and Richard Lewontin have written "the irrationalities of a scientifically sophisticated world come not from failure of intelligence but from the persistence of capitalism, which as a by-product also aborts human intelligence" (Dialectical Biologist, p. 208; see also their Biology Under the Influence [Monthly Review Press, 2007])."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #126 on: April 27, 2018, 01:03:36 AM »
The linked reference provides a current, limited-scale, real-world example of Hansen's ice-climate feedback.

Alessandro Silvano et al. (18 Apr 2018), "Freshening by glacial meltwater enhances melting of ice shelves and reduces formation of Antarctic Bottom Water", Science Advances, Vol. 4, no. 4, eaap9467, DOI: 10.1126/sciadv.aap9467

http://advances.sciencemag.org/content/4/4/eaap9467

Extract: "Strong heat loss and brine release during sea ice formation in coastal polynyas act to cool and salinify waters on the Antarctic continental shelf. Polynya activity thus both limits the ocean heat flux to the Antarctic Ice Sheet and promotes formation of Dense Shelf Water (DSW), the precursor to Antarctic Bottom Water. However, despite the presence of strong polynyas, DSW is not formed on the Sabrina Coast in East Antarctica and in the Amundsen Sea in West Antarctica. Using a simple ocean model driven by observed forcing, we show that freshwater input from basal melt of ice shelves partially offsets the salt flux by sea ice formation in polynyas found in both regions, preventing full-depth convection and formation of DSW. In the absence of deep convection, warm water that reaches the continental shelf in the bottom layer does not lose much heat to the atmosphere and is thus available to drive the rapid basal melt observed at the Totten Ice Shelf on the Sabrina Coast and at the Dotson and Getz ice shelves in the Amundsen Sea. Our results suggest that increased glacial meltwater input in a warming climate will both reduce Antarctic Bottom Water formation and trigger increased mass loss from the Antarctic Ice Sheet, with consequences for the global overturning circulation and sea level rise."

See also:

Title: "One of the most worrisome predictions about climate change may be coming true"

https://bangordailynews.com/2018/04/23/environment/one-of-the-most-worrisome-predictions-about-climate-change-may-be-coming-true/

Extract: "Two years ago, former NASA climate scientist James Hansen and a number of colleagues laid out a dire scenario in which gigantic pulses of fresh water from melting glaciers could upend the circulation of the oceans, leading to a world of fast-rising seas and even superstorms.

Hansen’s scenario was based on a computer simulation, not hard data from the real world, and met with skepticism from a number of other climate scientists. But now, a new oceanographic study appears to have confirmed one aspect of this picture — in its early stages, at least.

The new research, based on ocean measurements off the coast of East Antarctica, shows that melting Antarctic glaciers are indeed freshening the ocean around them. And this, in turn, is blocking a process in which cold and salty ocean water sinks below the sea surface in winter, forming “the densest water on the Earth,” in the words of study lead author Alessandro Silvano, a researcher with the University of Tasmania in Hobart, Australia.

Hansen said that “this study provides a nice small-scale example of processes that we talk about in our paper.”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #127 on: April 29, 2018, 10:50:04 AM »
The linked reference finds that:
"… Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately AD 1850) compared with the preceding 1,500 years.

We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA – sourced from melting glaciers and thickened sea ice that developed earlier in the LIA – weakened Labrador Sea convection and the AMOC.  The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet."

These findings support Hansen's ice-climate feedback mechanism.

Thornalley et al. (2018), "Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years", Nature, doi:10.1038/s41586-018-0007-4

https://www.nature.com/articles/s41586-018-0007-4
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #128 on: April 30, 2018, 04:28:24 PM »
There is a reason why Thwaites Glacier has been nicknamed the 'doomsday' glacier, and why research institutions keep spending more and more research dollars to study this important marine glacier.

Title: "Penn State researchers join international effort to study Antarctic ‘doomsday’ glacier"

https://stateimpact.npr.org/pennsylvania/2018/04/30/penn-state-researchers-join-international-effort-to-study-antarctic-doomsday-glacier/

Extract: "Researchers from Penn State University will be part of a major, international effort to better understand an Antarctic glacier, dubbed the “doomsday glacier” for its potential to contribute significantly to global sea level rise.

The Thwaites Glacier on the West Antarctic Ice Sheet is about the size of Pennsylvania. The threat of it collapsing is so significant that the National Science Foundation and the United Kingdom’s National Environmental Research Council today announced $25 million in funding for eight research efforts."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #129 on: May 07, 2018, 11:38:12 PM »
The linked reference provides a mathematical framework for modeling cascading tipping mechanisms resulting in abrupt climate change; and as an illustration of this methodology it provides a conceptual model for coupling the North Atlantic Ocean Overturning Current and the ENSO system in the Pacific.  Consensus climate science should use such a methodology to better evaluate the risks associated with Hansen's ice-climate feedback mechanism:

Dekker, M. M., von der Heydt, A. S., and Dijkstra, H. A.: Cascading transitions in the climate system, Earth Syst. Dynam. Discuss., https://doi.org/10.5194/esd-2018-26, in review, 2018.

https://www.earth-syst-dynam-discuss.net/esd-2018-26/
https://www.earth-syst-dynam-discuss.net/esd-2018-26/esd-2018-26.pdf

Abstract. We provide a theory of cascading tipping, i.e., a sequence of abrupt transitions occurring because a transition in one subsystem changes the background conditions for another subsystem. A mathematical framework of elementary deterministic cascading tipping points in autonomous dynamical systems is presented containing the double-fold, fold-Hopf, Hopf-fold and double-Hopf as most generic cases. Statistical indicators which can be used as early warning indicators of cascading tipping events in stochastic, non-stationary systems are suggested. The concept of cascading tipping is illustrated through a conceptual model of the coupled North Atlantic Ocean – El-Niño Southern Oscillation (ENSO) system, demonstrating the possibility of such cascading events in the climate system.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #130 on: May 11, 2018, 05:03:32 PM »
The DOE has now released computer code & preliminary results from ACME (Accelerated Climate Model for Energy) while the DOE has renamed the program E3SM (Energy Exascale Earth System Model), and this world's most sophisticated climate model projects that ECS for the rest of this century will be about 5.2C (& this relatively high value is likely attributable to the state-of-the-art way that ACME/E3SM models aerosols and cloud feedback mechanisms).

While some consensus scientists (like Bjorn Stevens) have said that it is difficult to determine whether the ACME findings are any more relevant than other models in the CMIP6 program; I believe that these findings from the world's most advanced ESM warrant the adoptions of the Precautionary Principle, particularly as the ACME results only partially address Hansen's ice-climate feedback mechanism:

Title: "DOE’s maverick climate model is about to get its first test"
doi:10.1126/science.aau0578

http://www.sciencemag.org/news/2018/05/does-maverick-climate-model-about-get-its-first-test

Extract: "In 2017, after President Donald Trump took office and pulled the nation out of the Paris climate accords, DOE dropped "climate" from the project name. The new name, the Energy Exascale Earth System Model (E3SM), better reflects the model's focus on the entire Earth system, says project leader David Bader of Lawrence Livermore National Laboratory in California.
..
One preliminary result, on the climate's sensitivity to carbon dioxide (CO2), will "raise some eyebrows," Bader says. Most models estimate that, for a doubling of CO2 above preindustrial levels, average global temperatures will rise between 1.5°C and 4.5°C. The E3SM predicts a strikingly high rise of 5.2°C, which Leung suspects is due to the way the model handles aerosols and clouds. And like many models, the E3SM produces two bands of rainfall in the tropics, rather than the one seen in nature near the equator.

The first test of the E3SM will be its performance in CMIP6. Nearly three dozen modeling groups, including newcomers from South Korea, India, Brazil, and South Africa, are expected to submit results to the intercomparison between now and 2020."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #131 on: May 11, 2018, 07:54:29 PM »
" like many models, the E3SM produces two bands of rainfall in the tropics, rather than the one seen in nature near the equator. "

O dear. I had hoped it would do better. But further discussion should probably be i a thread on models, perhaps.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #132 on: June 14, 2018, 12:43:59 AM »
Remember that ice mass loss from Antarctica is expected to accelerate nonlinearly with continued global warming, so while the current Antarctic contribution to sea level rise of 0.5mm/y may seem small, when it is increased nonlinearly to 2100, this small value could become big:

Title: "Antarctica’s Ice Sheet Is Melting Three Times Faster Than We Thought"

https://www.thedailybeast.com/antarcticas-ice-sheet-is-melting-three-times-faster-than-we-thought

Extract: "Antarctica’s ice sheet is melting three times faster than previously forecasted, according to a report published Wednesday in the journal Nature by 80 scientists. The team said that the ice sheet is melting so fast that 219 billion tons of ice is pouring into the ocean annually—enough to raise sea levels by a half millimeter per year. Between 1992 and 1997, Antarctica was losing 49 billion times of ice per year; from 2012 to 2017, that number increased more than eightfold, according to the Ice Sheet Mass Balance Inter-comparison Exercise. At this rate of acceleration, scientists warn that oceans would rise faster than ever, which means a reduced amount of time for low-lying communities to prepare adequately. “We’re still talking about roughly a half a millimeter per year,” one scientist told The Washington Post. “That isn’t going to sound horribly unmanageable. But remember for the northern hemisphere, for North America, the fact that the location in West Antarctica is where the action is amplifies that rate of sea level rise by up to an about additional 25 percent in a city like Boston or New York.”"
« Last Edit: June 14, 2018, 11:21:39 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #133 on: June 15, 2018, 05:57:33 AM »
Recent findings indicate that as the oceans continue to warm the less the oceans will be able to act as a carbon sink for atmospheric CO₂.  This means that the concentration of atmospheric CO₂ will increase faster than previously expected:

Title: "Invisible scum on sea cuts CO2 exchange with air 'by up to 50%'"

https://www.theguardian.com/environment/2018/may/28/invisible-scum-on-sea-cuts-co2-exchange-with-air-by-up-to-50

Extract: "The world’s oceans absorb around a quarter of all man-made carbon dioxide emissions, making them the largest long-term sink of carbon on Earth.

They found surfactants can reduce carbon dioxide exchange by up to 50%.

Dr Ryan Pereira, a Lyell research fellow at Heriot-Watt University in Edinburgh, said: “As surface temperatures rise, so too do surfactants, which is why this is such a critical finding.
“The warmer the ocean surface gets, the more surfactants we can expect, and an even greater reduction in gas exchange.

Rob Upstill-Goddard, professor of marine biogeochemistry at Newcastle University, said: “These latest results build on our previous findings that, contrary to conventional wisdom, large sea surface enrichments of natural surfactants counter the effects of high winds.”"
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #134 on: June 15, 2018, 06:58:03 PM »
The linked reference discusses the finding of improved modeling near the Eocene–Oligocene transition (EOT) that are of particular interest for calibrating climate models to including Hansen's ice-climate feedback mechanism (that is highly related to the response of the meridional overturning circulation).  These new finding indicate higher climate sensitivity than projected by earlier (as in those used by AR5) less-sophisticated models.  These findings increase the probability that Hansen's warnings about the risks of abrupt climate change this century are correct:

Hutchinson, D. K., de Boer, A. M., Coxall, H. K., Caballero, R., Nilsson, J., and Baatsen, M.: Climate sensitivity and meridional overturning circulation in the late Eocene using GFDL CM2.1, Clim. Past, 14, 789-810, https://doi.org/10.5194/cp-14-789-2018, 2018.

https://www.clim-past.net/14/789/2018/

Abstract. The Eocene–Oligocene transition (EOT), which took place approximately 34 Ma ago, is an interval of great interest in Earth's climate history, due to the inception of the Antarctic ice sheet and major global cooling. Climate simulations of the transition are needed to help interpret proxy data, test mechanistic hypotheses for the transition and determine the climate sensitivity at the time. However, model studies of the EOT thus far typically employ control states designed for a different time period, or ocean resolution on the order of 3°. Here we developed a new higher resolution palaeoclimate model configuration based on the GFDL CM2.1 climate model adapted to a late Eocene (38 Ma) palaeogeography reconstruction. The ocean and atmosphere horizontal resolutions are 1°  ×  1.5° and 3°  ×  3.75° respectively. This represents a significant step forward in resolving the ocean geography, gateways and circulation in a coupled climate model of this period. We run the model under three different levels of atmospheric CO2: 400, 800 and 1600 ppm. The model exhibits relatively high sensitivity to CO2 compared with other recent model studies, and thus can capture the expected Eocene high latitude warmth within observed estimates of atmospheric CO2. However, the model does not capture the low meridional temperature gradient seen in proxies. Equatorial sea surface temperatures are too high in the model (30–37 °C) compared with observations (max 32 °C), although observations are lacking in the warmest regions of the western Pacific. The model exhibits bipolar sinking in the North Pacific and Southern Ocean, which persists under all levels of CO2. North Atlantic surface salinities are too fresh to permit sinking (25–30 psu), due to surface transport from the very fresh Arctic ( ∼  20 psu), where surface salinities approximately agree with Eocene proxy estimates. North Atlantic salinity increases by 1–2 psu when CO2 is halved, and similarly freshens when CO2 is doubled, due to changes in the hydrological cycle.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #135 on: June 21, 2018, 09:26:51 PM »
Another reason that DeConto & Pollard (2016)'s projection for the loss of the Thwaites ice plug may be too slow, is that they (and essentially all other modelers) have based their estimates of current ice mass loss from the ASE largely on data from the GRACE satellite.  However, the past GRACE data may have been corrected using a conservative estimate of the associated glacial isostatic adjustment, GIA, in this area.

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

Abstract
The marine portion of the West Antarctic Ice Sheet (WAIS) in the Amundsen Sea Embayment (ASE) accounts for one-fourth of the cryospheric contribution to global sea-level rise and is vulnerable to catastrophic collapse. The bedrock response to ice mass loss, glacial isostatic adjustment (GIA), was thought to occur on a time scale of 10,000 years. We used new GPS measurements, which show a rapid (41 millimeters per year) uplift of the ASE, to estimate the viscosity of the mantle underneath. We found a much lower viscosity (4 × 1018 pascal-second) than global average, and this shortens the GIA response time scale from tens to hundreds of years. Our finding requires an upward revision of ice mass loss from gravity data of 10% and increases the potential stability of the WAIS against catastrophic collapse.


Title: "Bedrock in West Antarctica rising at surprisingly rapid rate"

https://phys.org/news/2018-06-bedrock-west-antarctica-surprisingly-rapid.html
Extract: "The findings, reported in the journal Science, have surprising and positive implications for the survival of the West Antarctic Ice Sheet (WAIS), which scientists had previously thought could be doomed because of the effects of climate change.

The unexpectedly fast rate of the rising earth may markedly increase the stability of the ice sheet against catastrophic collapse due to ice loss, scientists say.

Moreover, the rapid rise of the earth in this area also affects gravity measurements, which implies that up to 10 percent more ice has disappeared in this part of Antarctica than previously assumed.

Researchers led by scientists at The Ohio State University used a series of six GPS stations (part of the POLENET-ANET array) attached to bedrock around the Amundsen Sea Embayment to measure its rise in response to thinning ice.

The "uplift rate" was measured at up to 41 millimeters (1.6 inches) a year, said Terry Wilson, one of the leaders of the study and a professor emeritus of earth sciences at Ohio State.

In contrast, places like Iceland and Alaska, which have what are considered rapid uplift rates, generally are measured rising 20 to 30 millimeters a year.
"The rate of uplift we found is unusual and very surprising. It's a game changer," Wilson said.

And it is only going to get faster. The researchers estimate that in 100 years, uplift rates at the GPS sites will be 2.5 to 3.5 times more rapid than currently observed.

While modeling studies have shown that bedrock uplift could theoretically protect WAIS from collapse, it was believed that the process would take too long to have practical effects.

"We previously thought uplift would occur over thousands of years at a very slow rate, not enough to have a stabilizing effect on the ice sheet. Our results suggest the stabilizing effect may only take decades," Wilson said.

Wilson said the rapid rise of the bedrock in this part of Antarctica suggests that the geology underneath Antarctica is different from what scientists had previously believed.

Some scientists suggest that WAIS may have passed a tipping point in which ice loss can no longer be stopped, which could be catastrophic, Wilson said. The glaciers there contain enough water to raise global sea levels up to four feet.

The problem is that much of this area of Antarctica is below sea level. Relatively warm ocean water has flowed in underneath the bottom of the ice sheet, causing thinning and moving the grounding line—where the water, ice and solid earth meet—further inland.

The process seemed unstoppable, Wilson said. "But we found feedbacks that could slow or even stop the process."

One important feedback involves "pinning points—elevated features of the earth rising from the surface below the grounding line that pin the ice sheet to solid earth. These pinning points are going up in response to the uplift of the earth and could prevent further retreat of the ice sheet.

Another feedback is lowering sea levels. Massive ice sheets along the ocean have their own gravitational pull and raise the sea level near them. But as the ice thins and retreats, the gravitational pull lessens and the sea level near the coast goes down.

"The lowering of the sea level, the rising of pinning points and the decrease of the inland slope due to the uplift of the bedrock are all feedbacks that can stabilize the ice sheet," Wilson said.

Other researchers had estimated how much the earth would have to rise to protect WAIS given a range of future climate warming scenarios.

Results of this study estimate that the bedrock at the Pine Island Glacier grounding line (which is part of WAIS) will have risen about 8 meters in 100 years. That is about three times higher than values shown by others to reduce run-away retreat in this area.

"Under many realistic climate models, this should be enough to stabilize the ice sheet," Wilson said.

She said while this study delivers some potentially good news for the Amundsen Sea Embayment, that doesn't mean all is well in Antarctica.

"The physical geography of Antarctica is very complex. We found some potentially positive feedbacks in this area, but other areas could be different and have negative feedbacks instead," she said. Regardless of feedbacks, models suggest that the WAIS will collapse if future global warming is large."
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #136 on: June 21, 2018, 10:03:31 PM »
Regardless of ice models, Barletta(2018) is good news. In all cases, faster uplift is a stabilizing force. So i do not agree with the statement that:

"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."

Barletta's work shows that bedrock in the Amundsen sea is rising at two to three times the previously estimated rate, and will rise even faster in future. I quote from the paper:

"The extremely low upper mantle viscosity that we constrain supports the possibility of increased stability of the WAIS with respect to previous studies (16, 17). Lower mantle viscosity leads to faster bedrock uplift in response to ice mass loss. Rapidly rising bedrock shallows the ocean at the grounding line and reduces the buoyancy forces experienced by the edge of the ice sheet while reducing the slope of the bed beneath the ice sheet (fig. S3)"

"In 100 years, uplift rates at the GPS sites will be between 2.5 and 3.5 times larger than currently observed (Fig. 3B), and the bedrock at the Pine Island Glacier grounding line will have risen by about 8 m compared to the present (Fig. 3, C and D). This is about three times higher than values shown to reduce runaway ice surface velocities within 100 years (15). The time required to build sufficient deformation to trigger the stabilization effect is much shorter (27) than in (16). Under low and medium climate forcing, with the onset of the stabilization feedback about two times faster (27), the condition for ice-sheet stability and its possible readvance can reasonably be expected to occur much earlier than predicted in previous studies (16, 17). Based on our estimates, it might produce a deformation large enough and early enough in the deglaciation phase to prevent the complete collapse of the WAIS even under strong climate forcing."

The bad news in Barlettta's work is that because of the revised GIA, it turns out that actual ice mass loss over the last few decades is larger than previously thought.

"We thus contend that published GRACE-derived ice mass loss estimates for ASE, for example, ~108 Gt/year (1) (drainage basins of Pine Island and Thwaites and Smith glaciers), are systematically underestimated by between 10.0 and 13.9 Gt/year, which is more than 10% of the total ice mass loss estimate for the ASE."

i attach fig S3.

sidd

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #137 on: June 21, 2018, 11:39:49 PM »
Regardless of ice models, Barletta(2018) is good news. In all cases, faster uplift is a stabilizing force. So i do not agree with the statement that:

"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."

Everyone is entitled to their own opinions; and while Barletta et al (2018) can believe that their findings will help to pin Thwaites, their Figure S3 (see first image), looks a rather similar to Rignot et al (2017) for the Thwaites gateway (see second & third images), and I believe that marine cliff failures (see the fourth image from Wise et al (2017), will mean that the suspected pinning point will not be able to stop DeConto & Pollard (2016)'s ice cliff and hydrofracturing from occurring within the next twenty to thirty years:

Yu, H., Rignot, E., Morlighem, M., & Seroussi, H. (2017). Iceberg calving of Thwaites Glacier, West Antarctica: full-Stokes modeling combined with linear elastic fracture mechanics. The Cryosphere, 11(3), 1283, doi:10.5194/tc-11-1283-2017

https://www.the-cryosphere.net/11/1283/2017/tc-11-1283-2017.pdf
https://www.the-cryosphere.net/11/1283/2017/tc-11-1283-2017-assets.html
&
Wise et al. (2017), "Evidence of marine ice-cliff instability in Pine Island Bay from iceberg-keel plough marks", Nature 550, 506-510, doi:10.1038/nature24458

https://www.nature.com/articles/nature24458
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #138 on: June 22, 2018, 12:00:52 AM »
The associated summary by Langin (doi: 10.1126/science.360.6395.1283 ) in the same issue of Science lays out your both point and mine:

Some extracts from that article:

--
“It may just buy the world a few extra decades,” says Rick Aster

“It’s not a get out of jail free card,” says Ted Scambos, a glaciologist at the National Snow and Ice Data Center in Boulder, Colorado. “It’s more of a refinement on the pace of [ice sheet] collapse,” he says, especially if we continue “stomping on the climate gas pedal.” Ingo Sasgen, a geophysicist at the Alfred Wegener Institute in Bremerhaven, Germany, agrees. “It’s still a rather slow process compared to melting,” he says. “If you have a very strong warming from the ocean, the ice sheet will disintegrate whatever the solid earth does.”
--

I take the Barletta results as good news, since this is the one of the few results that suppress WAIS mass loss rather than enchance it. So the situation is slightly better than I thought.

That summary also references an article in Nature by Kingslake et al. on which i commented earlier:

https://forum.arctic-sea-ice.net/index.php/topic,622.msg159185.html#msg159185

That article looks at GIA as well. But in light of Barletta results, I think they need to revisit their calculations in the Amundsen sector, since the crust beneath is more labile than they assumed. That may explain the lack of skill in that sector.

sidd


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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #139 on: June 22, 2018, 03:57:39 AM »
I take the Barletta results as good news, since this is the one of the few results that suppress WAIS mass loss rather than enchance it. So the situation is slightly better than I thought.

sidd,

All of your points are well taken, however considerations that might make the situation slight worse than you might (or might not) have been thinking include:

a) The low viscousity of the magma almost certainly means that it is convecting heat upward from the Earth's core faster than previously thought by consensus scientists; which means that the geothermal heat flux through the bedrock is greater, which means that both basal ice melting is higher and that the stiffness of the basal ice is lower.  Both of these factors should increase conventional ice flow.
b) The local Earth's crust is rising because more rock mass is moving into this area from surrounding areas.  This means that as ice mass is lost, the local sea level will not fall as fast as it would have with more viscous magma; which means that there will be more buoyant force on the marine glacier which means it will be less stable.
c) More local Earth movement means more seismic and volcanic activity, both of which reduce ice stability.

Ice sheet models will need to improve considerably before anyone can conclude that we are all safer than consensus scientists thought before this research was available.

Best regards,
ASLR
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #140 on: June 22, 2018, 05:57:28 AM »
Gaia is even more amazing than I thought.  :o

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #141 on: June 22, 2018, 06:03:28 PM »



sidd,

All of your points are well taken, however considerations that might make the situation slight worse than you might (or might not) have been thinking include:

a) The low viscousity of the magma almost certainly means that it is convecting heat upward from the Earth's core faster than previously thought by consensus scientists; which means that the geothermal heat flux through the bedrock is greater, which means that both basal ice melting is higher and that the stiffness of the basal ice is lower.  Both of these factors should increase conventional ice flow.


This is the asthenosphere, the top part of the mantle where the solidus and the geothermal gradient converge. There isn't necessarily any partial melt (magma), but the viscosity is lower than the upper mantle and the lithosphere (the brittle part of the top of the mantle and the crust). The asthenosphere does flow, and that is where the compensation mechanism for PGR is thought to originate. The ductile flow that is thought to happen as the mechanism for isostatic compensation will not affect mantle convection or necessarily increase or decrease the temperature at the base of the lithosphere. Even if it did the timescales for this change are much greater than the time for ice melt.

Thinning or thickening of the lithosphere can effect the geothermal gradient (e.g. you get volcanic activity at rifts). Melting ice effectively thins the lithosphere, and you get pressure release, but also you change the temperature at the crust/ice boundary. I'm not sure how that would effect the solidus/geothermal gradient, but if you do increase partial melt, again, that will take a long time to effect the surface unless you already have existing magma chambers at high levels in the crust.





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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #142 on: June 23, 2018, 12:03:07 AM »
This is the asthenosphere, the top part of the mantle where the solidus and the geothermal gradient converge. There isn't necessarily any partial melt (magma), but the viscosity is lower than the upper mantle and the lithosphere (the brittle part of the top of the mantle and the crust). The asthenosphere does flow, and that is where the compensation mechanism for PGR is thought to originate. The ductile flow that is thought to happen as the mechanism for isostatic compensation will not affect mantle convection or necessarily increase or decrease the temperature at the base of the lithosphere. Even if it did the timescales for this change are much greater than the time for ice melt.

Thinning or thickening of the lithosphere can effect the geothermal gradient (e.g. you get volcanic activity at rifts). Melting ice effectively thins the lithosphere, and you get pressure release, but also you change the temperature at the crust/ice boundary. I'm not sure how that would effect the solidus/geothermal gradient, but if you do increase partial melt, again, that will take a long time to effect the surface unless you already have existing magma chambers at high levels in the crust.

Rox,

Please review the linked pdf, and see if you are interested in revising any of your statements.

Best,
ASLR

Begeman, C. B., Tulaczyk, S. M., & Fisher, A. T. (2017). Spatially variable geothermal heat flux in West Antarctica: Evidence and implications. Geophysical Research Letters, 44. https://doi.org/10.1002/2017GL075579

https://websites.pmc.ucsc.edu/~afisher/CVpubs/pubs/Begeman2017_GRL_AntWGZ-HF.pdf

Abstract Geothermal heat flux (GHF) is an important part of the basal heat budget of continental ice sheets. The difficulty of measuring GHF below ice sheets has directly hindered progress in the understanding of ice sheet dynamics. We present a new GHF measurement from below the West Antarctic Ice Sheet, made in subglacial sediment near the grounding zone of the Whillans Ice Stream. The measured GHF is 88 ± 7 mW m_2, a relatively high value compared to other continental settings and to other GHF measurements along the eastern Ross Sea of 55 mW m_2 and 69 ± 21 mW m_2 but within the range of regional values indicated by geophysical estimates. The new GHF measurement was made ~100 km from the only other direct GHF measurement below the ice sheet, which was considerably higher at 285 ± 80mWm_2, suggesting spatial variability that could be explained by shallow magmatic intrusions or the advection of heat by crustal fluids. Analytical calculations suggest that spatial variability in GHF exceeds spatial variability in the conductive heat flux through ice along the Siple Coast. Accurate GHF measurements and high-resolution GHF models may be necessary to reliably predict ice sheet evolution, including responses to ongoing and future climate change.

Extract: "Current geophysical GHF models underestimate the observed magnitude and spatial variability of GHF, which may be enhanced by magmatism or advection of crustal fluids."

Caption for the first image: "Figure 2. (a) GHF measurements and estimates for West Antarctica (Engelhardt, 2004a; Fisher et al., 2015; Foster, 1978; Fudge et al., 2013) and the western Ross Sea region (Morin et al., 2010, and references therein; Schröder et al., 2011) overlain on ice velocity (Rignot et al., 2011). Grounding line outlined black (Bindschadler et al., 2015). Profile line (A-A0) shown in black. Extent of GHF estimates below Thwaites glacier (THW, dashed line) (Schroeder et al., 2014). (b) Estimates of spatial variability in heat conduction and production along the profile line shown in Figure 2a, as difference from mean conductive heat flux along that profile (79mWm_2). (c) Shear heat flux estimates calculated from ice velocity and associated errors. GHF measurements and estimates close to the profile line are plotted (mean ±1 SE, SLW value lies off axis)."

Caption for the second image: "Figure 3. (a) Analytical model for GHF based on Fox Maule et al. (2005) (black and gray lines) compared with GHF measurements and estimates (blue) as a function of magnetic crustal thickness. The SLW value lies well above the plot. Dotted lines show the envelope of ±15% variation in crustal thermal conductivity from 2.8 W m_1 °C_1. (b) GHF anomaly due to modeled magmatic intrusions with cubic geometry. Intrusion depths are the distance from the surface of the crust to the top of the intrusion. GHF values are the maximum achieved at the surface over the center of the intrusion. Black contours represent mean ±1 SE bounds on GHF at SLW. Gray contours mark the time since emplacement at which the maximum GHF values plotted are achieved. (c) Probability density functions of GHF models for West Antarctica (An=An et al., 2015; FM=Fox Maule et al., 2005; SR=Shapiro & Ritzwoller, 2004) and GHF measurements in the Basin and Range Province, USA, 16% of which exceed 300 mW m_2 (National Geothermal Data System). In Figures 3a and 3c, GHF measurements and estimates for West Antarctica are plotted as mean ±1 SE, where available (references in Figure 2). GHF estimates below Thwaites glacier (THW), shown in Figure 3a, plotted as mean, ±1 SD (solid line), and the full range of THW values (dotted line) which extend off axis to 375 mW m_2 (Schroeder et al., 2014)."
« Last Edit: June 23, 2018, 12:11:27 AM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #143 on: June 23, 2018, 12:18:38 AM »
With regards to a more specific near-term cryosphere prediction, I predict that in less than 2.5-years, the PIIS and the SW Tributary Ice Shelf will experience a concurrent major calving event (along the intersecting cracks shown in the attached Sentinel-1 image from Nov 28 2017) that will temporarily cause the ice velocities in the SW Tributary Glacier to accelerate.

The attached Sentinel-1 image from June 21, 2018, indicates that the SW Tributary Ice Shelf has already experienced a major calving event, and we will see whether the PIIS experiences a major calving event in the same vicinity within the next year.
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RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #144 on: June 23, 2018, 08:00:32 PM »

Rox,

Please review the linked pdf, and see if you are interested in revising any of your statements.

Best,
ASLR


To paraphrase the paper "There's magmatic activity in the rift under the ice sheets; it shows up as concentrated hot spots under the ice; it looks like modern rift regimes; models underestimate the special variation and intensity; but we don't have a lot of data; it might be important"

What I wrote was really to correct your first paragraph. Low viscosity magma does not conduct heat from the earths core. Heat is transported from the core by mantle convection, and that is certainly not magma;  It also takes a LONG time, it's about 2500km and it convection is thought to move at 20mm a year. Changes to it are not likely to effect the ice regime in the next 10000 years. I probably should have been more direct and not got into where magma actually forms and how pressure/temperature changes could produce more magma.



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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #145 on: June 23, 2018, 10:03:26 PM »
This paper finds an extremely high heat flow and low viscosity that is best explained by partial melting in the upper mantle. The heat flow is higher than the basin and range which has a low velocity zone and ongoing volcanism. If there's a rapid ice mass loss there will be decompression melting. This could increase volcanic activity as the ice melts as happened during the late Pleistocene in Alaska and Iceland.

This rapid isostatic adjustment is only good news if we stop emitting GHGs. Perhaps, then, the ice would find a new grounding line. If we keep the heat on with GHG emissions this will only add to the melting which we now know is already worse than we thought.

This isostatic adjustment rates found in the study are stunning, but the will not be fast enough to compensate for accelerated melting if we keep our feet on the gas pedal.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #146 on: June 24, 2018, 02:10:27 AM »

Rox,

Please review the linked pdf, and see if you are interested in revising any of your statements.

Best,
ASLR


To paraphrase the paper "There's magmatic activity in the rift under the ice sheets; it shows up as concentrated hot spots under the ice; it looks like modern rift regimes; models underestimate the special variation and intensity; but we don't have a lot of data; it might be important"

What I wrote was really to correct your first paragraph. Low viscosity magma does not conduct heat from the earths core. Heat is transported from the core by mantle convection, and that is certainly not magma;  It also takes a LONG time, it's about 2500km and it convection is thought to move at 20mm a year. Changes to it are not likely to effect the ice regime in the next 10000 years. I probably should have been more direct and not got into where magma actually forms and how pressure/temperature changes could produce more magma.

Thank you for the clarifications.  I concur that the main points of concur are the numerous pre-existing concentrated hotspots under the ice, and I also concur with FishOutofWater that if we continue BAU emissions for much longer, the isostatic adjustment rates will not be fast enough to compensate for the other consequences of ice mass loss.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #147 on: June 25, 2018, 09:13:07 PM »
After many tens of millions of years of repeated ice sheet collapse, it is not surprising that many of the pre-existing hotspots beneath the WAIS are located in critical areas like underneath the PIG:

Title: "Researchers discover volcanic heat source under major Antarctic glacier"

https://phys.org/news/2018-06-volcanic-source-major-antarctic-glacier.html

Extract: " A researcher from the University of Rhode Island's Graduate School of Oceanography and five other scientists have discovered an active volcanic heat source beneath the Pine Island Glacier in Antarctica.

The scientists conclude by writing: "The magnitude and the variations in the rate of the volcanic heat supplied to the Pine Island Glacier, either by internal magma migration, or by an increase in volcanism as a consequence of ice sheet thinning, may impact the future dynamics of the Pine Island Glacier, during the contemporary period of climate-driven glacial retreat.""

See also:

Brice Loose et al. Evidence of an active volcanic heat source beneath the Pine Island Glacier, Nature Communications (2018). DOI: 10.1038/s41467-018-04421-3

http://www.nature.com/articles/s41467-018-04421-3

“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

steve s

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #148 on: June 25, 2018, 11:06:31 PM »
Makes me wonder more about what's happening under the Thwaites. Sea ice concentration is much lower near its outflow than by the PIG. From NSIDC  for June 24th:

« Last Edit: June 26, 2018, 09:36:59 AM by steve s »

steve s

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #149 on: June 28, 2018, 10:24:37 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.