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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

"


“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 #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 »
“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 #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.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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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?

Bruce Steele

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

Neven

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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:

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

AbruptSLR

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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

“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 #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.”
― Leon C. Megginson

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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Daniel B.

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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.

RoxTheGeologist

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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.

salbers

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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.

AbruptSLR

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