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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1850 on: November 06, 2019, 07:44:10 PM »
Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand

    Eelco J. Rohling, Fiona D. Hibbert, Katharine M. Grant, Eirik V. Galaasen, Nil Irvalı, Helga F. Kleiven, Gianluca Marino, Ulysses Ninnemann, Andrew P. Roberts, Yair Rosenthal, Hartmut Schulz, Felicity H. Williams & Jimin Yu

Nature Communications volume 10, Article number: 5040 (2019)
Quote
...
Finally, we infer intra-LIG sea-level rises with event-mean rates of rise of 2.8, 2.3, and 0.6 m c−1. Such high pre-anthropogenic values lend credibility to similar rates inferred from some ice-modelling approaches51. The apparent reality of such extreme pre-anthropogenic rates increases the likelihood of extreme sea-level rise in future centuries.
This research reveals up to 2.8 meters/century sea level rise (without people mucking things up).

Edit:  LIG = The last interglacial

For convenience I provide the associated image, and a link to an associated article that summarizes that Antarctic glacial ice mass loss due to a warming Southern Ocean was the key factor for the rapid sea level rise during the Eemian (LIG):

Title: "Antarctica likely to drive rapid sea-level rise under climate change"

https://phys.org/news/2019-11-antarctica-rapid-sea-level-climate.html

Extract: ""Our study shows clearly that Antarctica, long thought a sleeping giant when it comes to sea-level rises, is in fact the key player.

"And it appears that it can change by large amounts on timescales that are highly relevant to society and in ways that would have profound effects on human infrastructure."

The study shows for the first time by how much ice loss in the last interglacial first took place in Antarctica, followed by Greenland.

Early Antarctic ice loss was caused by Southern Ocean warming at the onset of the interglacial. Next, the meltwater from Antarctica caused changes in global ocean circulation that resulted in northern polar warming and associated Greenland ice loss.

Co-lead author, Dr. Fiona Hibbert, said that in today's greenhouse-gas-driven climate change, rapid atmospheric and oceanic warming happens in both polar regions at the same time.

"This drives simultaneous ice-loss in Antarctica and Greenland," Dr. Hibbert said.
"But, what's vital to remember is that today's climatic disturbance is greater and develops faster than that of the last interglacial.

"As a result, rates of sea-level rise may develop over the next several centuries that are even higher than those found for the interglacial we have studied.""
“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 #1851 on: November 06, 2019, 10:53:28 PM »
Given the importance of Milillo et al. (2019), I have decided to repost the reference and abstract and portions of Fig 1 A/B, C, partial D & partial E and Fig 3 A, B & C.  Also, I noted that:

1. Fig 1 panel D shows that the upstream side of the Big Ear subglacial cavity has a negative ice surface height above floatation (meaning that it is experiencing positive buoyance).

2. Fig 3 panel C shows that between 2011 and 2017 the upstream side of the Big Ear subglacial cavity has uplifted about 20m possibly associated with the positive buoyancy that it is experiencing.

P. Milillo, E. Rignot, P. Rizzoli, B. Scheuchl, J. Mouginot, J. Bueso-Bello, and P. Prats-Iraola (2019), "Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica", Sci Adv. 5(1): eaau3433, doi: 10.1126/sciadv.aau3433
PMCID: PMC6353628
PMID: 30729155

https://advances.sciencemag.org/content/5/1/eaau3433
&
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6353628/

Abstract: "The glaciers flowing into the Amundsen Sea Embayment, West Antarctica, have undergone acceleration and grounding line retreat over the past few decades that may yield an irreversible mass loss. Using a constellation of satellites, we detect the evolution of ice velocity, ice thinning, and grounding line retreat of Thwaites Glacier from 1992 to 2017. The results reveal a complex pattern of retreat and ice melt, with sectors retreating at 0.8 km/year and floating ice melting at 200 m/year, while others retreat at 0.3 km/year with ice melting 10 times slower. We interpret the results in terms of buoyancy/slope-driven seawater intrusion along preferential channels at tidal frequencies leading to more efficient melt in newly formed cavities. Such complexities in ice-ocean interaction are not currently represented in coupled ice sheet/ocean models."

Caption for the first image (Fig 1): "Thwaites Glacier, West Antarctica.
(A) Map of Antarctica with Thwaites Glacier (red box). (B) Shaded-relief bed topography (blue) with 50-m contour levels (white) (16), grounding lines color-coded from 1992 to 2017, and retreat rates for 1992–2011 (green circle) versus 2011–2017 (red circle) in kilometer per year. Thick yellow arrows indicate CDW pathways (32). White boxes indicate outline of figs. S1 and S2 (C) DInSAR data for 11 to 12 and 27 to 28 April 2016, with grounding lines in 2011, 2016, and 2017 showing vertical displacement, dz, in 17-mm increments color-coded from purple to green, yellow, red, and purple again. Points A to F are used in Fig. 2. (D) Height of the ice surface above flotation, hf, in meters. (E) Change in ice surface elevation, dh, between decimal years 2013.5 and 2016.66 color-coded from red (lowering) to blue (rising). (F) Ice surface speed in 2016–2017 color-coded from brown (low) to green, purple, and red (greater than 2.5 km/year), with contour levels of 200 m/year in dotted black."

Caption for the second image (Fig 3): "Ice thickness change of Thwaites Glacier.
(A) Ice surface elevation from Airborne Topographic Mapper and ice bottom from MCoRDS radar depth sounder in 2011, 2014, and 2016, color-coded green, blue, and brown, respectively, along profiles T1-T2 and (B) T3-T4 with bed elevation (brown) from (16). Grounding line positions deduced from the MCoRDS data are marked with arrows, with the same color coding. (C) Change in TDX ice surface elevation, h, from June 2011 to 2017, with 50-m contour line in bed elevation and tick marks every 1 km."

I thought that I should provide an incomplete list of factors that could cause the glacial ice between the upstream edge of the Big Ear subglacial cavity to the open ocean besides thinning of the ice due to increasing ice velocity, including any combination of the following:

1. Surge from a tsunami.
2. Storm surge.
3. A well positioned ABSL.
4. A strong El Nino event.
5. A local earthquake.
6. An abrupt collapse of the Big Ear subglacial cavity and/or a collapse of the ice tongue.
7. An outburst of subglacial meltwater from the BSB.
8. A sufficient retreat of the grounding line within the Big Ear cavity and on the seaward face.
“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 #1852 on: November 06, 2019, 11:28:21 PM »
More than 11,000 climate scientists believe that we are headed towards a climate emergency unless we get off our current BAU pathway very soon:

Title: "More than 11,000 scientists issue fresh warning: Earth faces a climate emergency"

https://www.nbcnews.com/science/environment/more-11-000-scientists-issue-fresh-warning-earth-faces-climate-n1076851

Extract: "An international consortium of more than 11,000 scientists is backing a study with a dire warning: Earth is facing a climate emergency."
“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 #1853 on: November 09, 2019, 02:43:15 AM »
As I suspect that may readers likely do not know what I mean by the various ice-climate feedback mechanisms, thus over the next week, or so, I plan to provide a brief description of the over 25 different ice-climate feedback mechanisms that I have already listed in this thread.

I begin by providing the following brief descriptions (& associated images) of three such ice-climate mechanisms:

1.   From the 1980's thru about 2015 the Antarctic sea ice extent was above average, while during this period the Antarctic Ozone hole was actively increasing the westerly wind velocities over the Southern Ocean; which resulted in an upwelling of the warm CDW (circumpolar deep water).  As the surface waters of the Southern Ocean, during this period, were not as fresh as they were after this period the greater sea ice extent served to insulate the warm CDW from the chilling affects of the Antarctic atmosphere; which allowed it to reach the basal side of Antarctic ice shelves resulting in extensive melting of the underside of such ice shelves ever since the 1980's; which has in turn resulting in a freshening of the southern portions of the Southern Ocean (see the first two attached images).

2.   After 2015, the Antarctic sea ice extent has been trending downward, but the freshening of the Southern Ocean near surface water has proceeded sufficiently so that the surface water near the Antarctic continental shelf has started to deflect the upwell warm CDW towards the grounding lines of Antarctic marine glaciers with, or without, the actions of the local sea ice, as shown in the third image.

3.   The fourth image shows how warm CDW (the white arrows) becomes entrained by the Weddell Gyre (for example); which directs this entrained modified CDW towards the calving fronts of the local ice shelves (such as the FRIS),where it promotes basal ice melting near the calving front.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

blumenkraft

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1854 on: November 09, 2019, 07:08:59 AM »
Deep Adaptation: A Map for Navigating ClimateTragedy

Quote
Abstract
The purpose of this conceptual paper is to provide readers with an opportunity to reassess their work and life in the face of an inevitable near- term social collapse due to climate change.
The approach of the paper is to analyse recent studies on climate change and its implications for our ecosystems, economies and societies, as provided by academic journals and publications direct from research institutes.
That synthesis leads to a conclusion there will be a near-term collapse in society with serious ramifications for the lives of readers. The paper reviews some of the reasons why collapse-denial may exist, in particular, in the professions of sustainability research and practice, therefore leading to these arguments having been absent from these fields until now.
The paper offers a new meta-framing of the implications for research, organisational practice, personal development and public policy, called the Deep Adaptation Agenda. Its key aspects of resilience, relinquishment and restorations are explained. This agenda does not seek to build on existing scholarship on “climate adaptation” as it is premised on the view that social collapse is now inevitable.
The author believes this is one of the first papers in the sustainability management field to conclude that climate-induced societal collapse is now inevitable in the near term and therefore to invite scholars to explore the implications.

Link >> https://www.lifeworth.com/deepadaptation.pdf
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nanning

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1855 on: November 09, 2019, 11:08:30 AM »
Thank you ASLR for educating us :).
Thanks blumenkraft for that link. Very interesting.

Some interesting excerpts:

it is time we consider the implications of it being too late to avert a global environmental catastrophe in the lifetimes of people alive today.

The simple evidence of global ambient temperature rise is undisputable. Seventeen of the 18 warmest years in the 136-year record all have occurredsince 2001, and global temperatures have increased by 0.9°C since 1880 (NASA/GISS, 2018). The most surprising warming is in the Arctic, where the 2016 land surface temperature was 2.0°C above the 1981-2010 average, breaking the previous records of 2007, 2011, and 2015 by 0.8°C, representing a 3.5°C increase since the record began in 1900 (Aaron-Morrison et al, 2017)

using, but not relying solely on, academic journal articles and the slowly produced reports of the Intergovernmental Panel on Climate Change (IPCC). This international institution has done useful work but has a track record of significantly underestimating the pace of change, which has been more accurately predicted over past decades by eminent climate scientists.

Non-linear changes are of central importance to understanding climate change, as they suggest both that impacts will be far more rapid and severe than predictions based on linear projections and that the changes no longer correlate with the rate of anthropogenic carbon emissions. In other words - ‘runaway climate change.’
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blumenkraft

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1856 on: November 09, 2019, 04:57:08 PM »
Welcome, Nanning. It's one devastating paper, eh? 
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nanning

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1857 on: November 09, 2019, 06:12:07 PM »
I wish it will be picked up, but it is not a recent one so maybe not.
The professor who wrote that must be praised for being so outspoken. Respect \/

It overlaps with my view on this and I see also non-climate related trends that can lead to collapse: Fear and hatred through manipulated information (profiling, personal censorship) resulting in violence; big mistakes because of war on truth; Uproar because of loss of human rights; big mistakes through increasing incompetence because the human brain in contemporary civilisation is almost completely separated from living nature and reality, not working to parameters, very suboptimal (it's difficult to make this point clear).

I'm curious about what our forumfriends think of this paper. What would ASLR think? :)
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kassy

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1858 on: November 09, 2019, 08:16:29 PM »
The linked articles on 'deep adaptation' to coming climate change ignores almost all ice-climate feedbacks, but it does provide discussion of philosophical considerations of 'deep adaptation':

Title: "The End of the Line – A Climate in Crisis"

https://www.counterpunch.org/2018/08/03/the-end-of-the-line-a-climate-in-crisis/

Extract: “Disruptive impacts from climate change are now inevitable. Geoengineering is likely to be ineffective or counter-productive. Therefore, the mainstream climate policy community now recognizes the need to work much more on adaptation to the effects of climate change… societies will experience disruptions to their basic functioning within less than ten years due to climate stress. Such disruptions include increased levels of malnutrition, starvation, disease, civil conflict and war – and will not avoid affluent nations.”

See also:

"Deep Adaptation: A Map for Navigating Climate Tragedy", 2018 by Jem Bendel

https://www.lifeworth.com/deepadaptation.pdf

&

https://jembendell.wordpress.com/2018/07/26/the-study-on-collapse-they-thought-you-should-not-read-yet/
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1859 on: November 10, 2019, 12:51:59 AM »
As a follow-on to my last post (Reply #1853 ), I first remind readers that AR5 projections did not include most of the ice-climate feedback mechanisms that I am citing in this series of posts, and that the coming AR6 projections (with higher values of ECS than what AR5 projected) only include MISI mechanisms and not MICI mechanism.

The first attached image shows the atmospheric geopotential patterns associated with the Antarctic ozone hole, which is largely responsible for the acceleration of the westerly winds over the Southern Ocean since the 1970's; and most consensus climate models assume that this ozone hole will heal itself faster than what is likely to be the case; particularly considering that since the 1980's the geopotential associated with this hole has kept the westerly wind in a velocity 'sweet-spot' nearly ideal for accelerating the ocean surface currents around Antarctica (which upwells the warm CDW), and that as the ozone slowly heals itself, the increasing GHG atmospheric concentrations over Antarctica has been and likely will continue to keep the westerly wind velocities near their current 'sweet-spot' for some time to come.

The second image shows the three major ocean gyres around Antarctica; which as a follow-on to the third point in Reply #1853 implies that not only is the Weddell gyre entraining warm CDW and advecting modified CDW to the calving face of the FRIS (where it accelerates calving of the ice shelf; but that the Ross gyre is doing the same to the RIS and the Un-named gyre is doing the same to the Totten ice shelf.

The third and fourth images provide additional illustrations of how the global thermohaline circulation interacts with both the Southern Ocean and with Antarctica (to upwell the warm CDW).
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1860 on: November 10, 2019, 12:53:42 AM »
4. The first image shows how the influence of sea ice seaward of cold ice shelves like FRIS and RIS create a local protective ocean circulation pattern that prevents upwelling CDW from flowing underneath such cold ice shelves.  However, climate models, particularly those including regional ice-climate feedback mechanisms project that will continuing global warming the local wind patterns will change sufficiently to disperse the ice in front of such cold ice shelves thus eliminating the local protective ocean circulation patterns thus likely transforming such previously cold ice shelves into warm ice shelves were the inflow of warm CDW along the bottom of the ice shelve causing basal ice melt as has been occurring for decades for current warm ice shelves as shown in the second image.

5. The third and fourth images show plan and profile views of potential seaways thru West Antarctica; which could act as a positive ice-climate feedback mechanism, once sufficient glacial ice has been lost from the WAIS to form such seaways (which would also change local ocean current circulation patterns).

“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 #1861 on: November 10, 2019, 05:15:32 AM »

 What would ASLR think? :)

In short, I think that: 'The meek shall inherit the Earth.'

Edit, see:

Title: "Unsettling Study Finds People Just Don't Care That Much if Humans Go Extinct"

https://www.sciencealert.com/scientists-find-we-don-t-care-all-that-much-if-humans-go-extinct

Extract: "… researchers asked more than 2,500 people in the United States and the United Kingdom to rank three possible scenarios from best to worst: no major catastrophe, a catastrophe that wipes out 80 percent of the human population, and a catastrophe that causes complete human extinction.

As you might expect, most people ranked no catastrophe as the best possibility and complete human extinction as the worst. But when asked to think about the difference in "badness" between the possibilities, most people were more bothered by the possibility of losing 80 percent of humanity than losing all of it."
« Last Edit: November 10, 2019, 03:10:49 PM by AbruptSLR »
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Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1862 on: November 10, 2019, 01:16:45 PM »
...
The first attached image shows the atmospheric geopotential patterns associated with the Antarctic ozone hole, which is largely responsible for the acceleration of the westerly winds over the Southern Ocean since the 1970's; and most consensus climate models assume that this ozone hole will heal itself faster than what is likely to be the case; particularly considering that since the 1980's the geopotential associated with this hole has kept the westerly wind in a velocity 'sweet-spot' nearly ideal for accelerating the ocean surface currents around Antarctica (which upwells the warm CDW), and that as the ozone slowly heals itself, the increasing GHG atmospheric concentrations over Antarctica has been and likely will continue to keep the westerly wind velocities near their current 'sweet-spot' for some time to come.


ASLR, you have some reference to the statement about increasing winds? On what latitudes would that be?
The long term wind data I can get hold of, seem to display a small decrease in winds at least in the Pacific.
Data from NOAA, showing 850 Mb trade winds.
https://www.cpc.ncep.noaa.gov/data/indices/

I might be misreading the data, though.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1863 on: November 10, 2019, 03:36:48 PM »

ASLR, you have some reference to the statement about increasing winds? On what latitudes would that be?


You appear to have confused 'westerly winds over the Southern Ocean' (also known as westerlies or by South latitude as the roaring forties, furious fifties and screaming sixties, see linked article) with westerly winds in other regions of the Earth.

Title: "Increases in westerly winds weaken the Southern Ocean carbon sink"

https://phys.org/news/2018-07-westerly-weaken-southern-ocean-carbon.html

Extract: "A new study of lake sediments from the sub-Antarctic reveals for the first time that increases in westerly winds are likely to reduce the ability of the Southern Ocean to absorb carbon dioxide from the atmosphere. The results are significant as the Southern Ocean currently absorbs over 40% of human-produced carbon dioxide, so any weakening of this 'carbon sink' could accelerate climate change. The findings are published today (Monday 23 July 2018) in the journal Nature Geoscience.

The Southern Hemisphere westerly winds (known by latitude as the roaring forties, furious fifties, and screaming sixties) are particularly strong due to the absence of continental landmasses between South America and Antarctica to slow them down."

As for proof that the westerlies (over the Southern Ocean) wind velocity has increased in recent decades, just search the term 'westerlies' in this thread and you will find dozens of peer reviewed references that have documented this fact.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1864 on: November 10, 2019, 03:52:29 PM »
As a continuation from Reply #1860 of my series of posts on ice-climate feedback mechanisms:

6.  Grouping together ocean stratification, sea level rise and superstorms, Hansen et al. (2016), "Ice Melt, Sea Level Rise, and Superstorms", discusses in the first linked documents (also see the attached image showing Hansen's illustration of both the ocean stratification and precipitation feedback mechanisms) that these positive ice-climate feedback mechanisms all reinforce each other and were all ignored by AR5 projections:

James Hansen (October 26, 2017), "Scientific Reticence: a DRAFT Discussion" and "Scientific Reticence and the Fate of Humanity"

http://www.columbia.edu/~jeh1/mailings/2017/20171026_ScientificReticence.pdf
https://unfccc.int/event/abibimman-foundation-james-hansen-scientific-reticence-a-threat-to-humanity-and-nature

Extract: "Frank Dentener, an editor of Atmospheric Chemistry and Physics, in a recent note to me observed that Ice Melt, Sea Level Rise, and Superstorms, hereafter Ice Melt, was not highly cited or mainstream in climate impact discussions. He was concerned because he thought it important for peer-reviewed extreme scenarios to be included in the upcoming IPCC AR6 cycle."
&

Furthermore, the second linked reference indicates that consensus climate science has been largely ignoring Hansen's warnings about fat-tail climate risks since well before 2007:

Hansen (2007), "Scientific Reticence and Sea Level Rise", Environmental Research Letters, Volume 2, Number 2, doi:10.1088/1748-9326/2/2/024002

http://iopscience.iop.org/article/10.1088/1748-9326/2/2/024002
https://arxiv.org/abs/physics/0703220

Abstract: "I suggest that a "scientific reticence" is inhibiting communication of a threat of potentially large sea level rise. Delay is dangerous because of system inertias that could create a situation with future sea level changes out of our control. I argue for calling together a panel of scientific leaders to hear evidence and issue a prompt plain-written report on current understanding of the sea level change issue."

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1865 on: November 10, 2019, 11:53:10 PM »
To continue my series of posts on ice-climate feedback mechanisms, here I note a number of such methane related ice-climate feedback mechanisms:

7.  The first image shows that if the entire WAIS where to collapse, a considerable amount of methane hydrates in the prior glacial beds could be abruptly exposed to relatively warm ocean water; which might degrade the hydrates fast enough for some methane gas to reach the ocean surface before being absorbed by the water column or by associated microorganisms (note that the second image shows how such methane hydrates formed beneath the Hakjerrigdjupet ice stream in Scandinavia during the Last Glacial Maximum).

8. The third and fourth images indicates that as global warming continues Arctic permafrost degradation will resulting in methane emissions from both associated thermokarst lakes and directly from the degraded permafrost.  In this regards, the bipolar seesaw mechanism from a collapse of the WAIS (or just a freshening of the Southern Ocean surface waters) would accelerate Arctic permafrost degradation.
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Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1866 on: November 11, 2019, 05:35:31 AM »

ASLR, you have some reference to the statement about increasing winds? On what latitudes would that be?


You appear to have confused 'westerly winds over the Southern Ocean' (also known as westerlies or by South latitude as the roaring forties, furious fifties and screaming sixties, see linked article) with westerly winds in other regions of the Earth.

Title: "Increases in westerly winds weaken the Southern Ocean carbon sink"

https://phys.org/news/2018-07-westerly-weaken-southern-ocean-carbon.html

Extract: "A new study of lake sediments from the sub-Antarctic reveals for the first time that increases in westerly winds are likely to reduce the ability of the Southern Ocean to absorb carbon dioxide from the atmosphere. The results are significant as the Southern Ocean currently absorbs over 40% of human-produced carbon dioxide, so any weakening of this 'carbon sink' could accelerate climate change. The findings are published today (Monday 23 July 2018) in the journal Nature Geoscience.

The Southern Hemisphere westerly winds (known by latitude as the roaring forties, furious fifties, and screaming sixties) are particularly strong due to the absence of continental landmasses between South America and Antarctica to slow them down."

As for proof that the westerlies (over the Southern Ocean) wind velocity has increased in recent decades, just search the term 'westerlies' in this thread and you will find dozens of peer reviewed references that have documented this fact.

Thanks, ASLR.
I have searched in all threads of the forum. Nothing comes up in terms of proof of increasing westerlies. The only thing that comes up is speculation that the westerlies are likely to increase with increase global warming. E.g. in this article:
https://www.pnas.org/content/116/4/1095

Actually there is no empirical support of increasing westerlies. I ran different datasets from Climate reanalyzer, and the westerlies is what is the vector that is called U-winds.
Neither the U-wind nor the V-wind nor the overall wind speed show any increase at all. There is no trend.

https://climatereanalyzer.org/reanalysis/monthly_tseries/

(The figures I provided above are from the Pacific Ocean and show the decline in trade winds. It's not even close to the westerlies, but still interesting that there is a negative wind speed trend)

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1867 on: November 11, 2019, 07:05:24 AM »
https://www.researchgate.net/publication/279014699_Evolution_of_the_Southern_Annular_Mode_during_the_past_millennium

The Southern Annular Mode (SAM) is the primary pattern of climate variability in the Southern Hemisphere(1,2), influencing latitudinal rainfall distribution and temperatures from the subtropics to Antarctica. The positive summer trend in the SAM over recent decades is widely attributed to stratospheric ozone depletion(2); however, the brevity of observational records from Antarctica(1)-one of the core zones that defines SAM variability-limits our understanding of long-term SAM behaviour. Here we reconstruct annual mean changes in the SAM since AD 1000 using, for the first time, proxy records that encompass the full mid-latitude to polar domain across the Drake Passage sector. We find that the SAM has undergone a progressive shift towards its positive phase since the fifteenth century, causing cooling of the main Antarctic continent at the same time that the Antarctic Peninsula has warmed. The positive trend in the SAM since similar to AD 1940 is reproduced by multimodel climate simulations forced with rising greenhouse gas levels and later ozone depletion, and the long-term average SAM index is now at its highest level for at least the past 1,000 years. Reconstructed SAM trends before the twentieth century are more prominent than those in radiative-forcing climate experiments and may be associated with a teleconnected response to tropical Pacific climate. Our findings imply that predictions of further greenhouse-driven increases in the SAM over the coming century(3) also need to account for the possibility of opposing effects from tropical Pacific climate changes.



https://science.sciencemag.org/content/364/6440/548
Abstract
In this study, global satellite data were analyzed to determine trends in oceanic wind speed and significant wave height over the 33-year period from 1985 to 2018. The analysis uses an extensive database obtained from 31 satellite missions comprising three types of instruments—altimeters, radiometers, and scatterometers. The analysis shows small increases in mean wind speed and significant wave height over this period, with larger increases in extreme conditions (90th percentiles). The largest increases occur in the Southern Ocean. Confidence in the results is strengthened because the wind speed trends are confirmed by all three satellite systems. An extensive set of sensitivity analyses confirms that both the mean and 90th percentile trends are robust, with only small impacts caused by satellite calibration and sampling patterns.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1868 on: November 11, 2019, 08:10:45 AM »
https://www.researchgate.net/publication/279014699_Evolution_of_the_Southern_Annular_Mode_during_the_past_millennium

The Southern Annular Mode (SAM) is the primary pattern of climate variability in the Southern Hemisphere(1,2), influencing latitudinal rainfall distribution and temperatures from the subtropics to Antarctica. The positive summer trend in the SAM over recent decades is widely attributed to stratospheric ozone depletion(2); however, the brevity of observational records from Antarctica(1)-one of the core zones that defines SAM variability-limits our understanding of long-term SAM behaviour. Here we reconstruct annual mean changes in the SAM since AD 1000 using, for the first time, proxy records that encompass the full mid-latitude to polar domain across the Drake Passage sector. We find that the SAM has undergone a progressive shift towards its positive phase since the fifteenth century, causing cooling of the main Antarctic continent at the same time that the Antarctic Peninsula has warmed. The positive trend in the SAM since similar to AD 1940 is reproduced by multimodel climate simulations forced with rising greenhouse gas levels and later ozone depletion, and the long-term average SAM index is now at its highest level for at least the past 1,000 years. Reconstructed SAM trends before the twentieth century are more prominent than those in radiative-forcing climate experiments and may be associated with a teleconnected response to tropical Pacific climate. Our findings imply that predictions of further greenhouse-driven increases in the SAM over the coming century(3) also need to account for the possibility of opposing effects from tropical Pacific climate changes.


Thanks KiwiGriff.
The first paper you link to investigates a very long term trend in SAM, and find that it is positive and has become increasingly so for 100s of years.
But as the paper is paywalled there is no access to data or figures.
It says in the abstract that the positive SAM causes "cooling of the main Antarctic continent at the same time that the Antarctic Peninsula has warmed". This conclusion is interesting as it might imply that MISI and MICI processes are less likely to occur on the continent.

The second paper claims that "The analysis shows small increases in mean wind speed and significant wave height over this period, with larger increases in extreme conditions (90th percentiles). The largest increases occur in the Southern Ocean. Confidence in the results is strengthened because the wind speed trends are confirmed by all three satellite systems."

The conclusion is refuted by the satellite data available at Climate reanalyzer.

I ran the Climate reanalyzer again for the Southern Ocean. There are two datasets available for wind speed, the ECMWF and the NCAP, both in different versions. Above is the figure for ECMWF in differences. Here I attach the NCAP in absolute values. Doesn't matter which data set you use, the conclusion seems to be the same:
There is no positive trend in wind speed since the beginning of satellite data.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1869 on: November 11, 2019, 12:30:56 PM »
D K...... :D

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1870 on: November 11, 2019, 04:49:14 PM »
The linked article by Gavin Schmidt indicates that the CMIP6 models with relatively high ECS values (for values thru August 2019 see the attached image) collectively show higher skill scores than those for earlier models (like CMIP5).  We will all have to wait and see what AR6 does with this new information:

Title: "Sensitive But Unclassified"

http://www.realclimate.org/index.php/archives/2019/11/sensitive-but-unclassified/

Extract: "Why might the numbers be correct? All the preliminary analyses I’ve seen with respect to matches to present day climatologies and variability indicate that the skill scores of the new models (collectively, not just the high ECS ones) are improved over the previous versions. This is discussed in Gettelman et al. (2019) (CESM2), Sellar et al (2019) (UKESM1) etc. Indeed, this is a generic pattern in model development.

What is clear is that (for the first time) the discord between the GCMs and the external constraints is going to cause a headache for the upcoming IPCC report. The deadline for papers to be submitted for consideration for the second order draft is in December 2019, and while there will be some papers on this topic submitted by then. I am not confident that the basic conundrums will be resolved. Thus the chapter on climate sensitivity is going to be contrasted strongly with the chapter on model projections. Model democracy (one model, one vote) is a obviously a terrible idea and if adopted in AR6, will be even more problematic. However, no other scheme has been demonstrated to work better."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1871 on: November 11, 2019, 05:12:18 PM »

I have searched in all threads of the forum. Nothing comes up in terms of proof of increasing westerlies. The only thing that comes up is speculation that the westerlies are likely to increase with increase global warming.
...

The linked UCAR empirical data (i.e. using satellite data in the post-1979 era), clearly shows that between 40S and 60S latitude the westerly winds over the Southern Ocean have increased in recent decades (see the first image):

Bracegirdle, Thomas J. & National Center for Atmospheric Research Staff (Eds). Last modified 11 Jan 2019. "The Climate Data Guide: Southern Hemisphere westerly jet strength and position." Retrieved from https://climatedataguide.ucar.edu/climate-data/southern-hemisphere-westerly-jet-strength-and-position.

https://climatedataguide.ucar.edu/climate-data/southern-hemisphere-westerly-jet-strength-and-position
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1872 on: November 11, 2019, 06:25:04 PM »
Continuing my list of ice-climate feedback mechanisms from Reply #1,865:

9. The first image shows that if the grounding line of the Jakobshavn Glacier were to retreat a few more kilometers (say due to an intrusion of relatively warm ocean water to the calving face); due to the retrograde bed slope that the calving face would reach would likely cause a rapid retreat of the calving face due to ice cliff instability (& Helheim Glacier calving is also sensitive to warm ocean water intrusion.  Thus, it is possible an armada of icebergs could float-out from key Greenland tidewater glaciers in the next decade or so; which due to the bipolar seesaw could trigger the rapid collapse of key ice shelves on the eastern coast of the Antarctic Peninsula (see the second image).  If so this could trigger an abrupt increase of upwelling and advection of warm CDW to the grounding lines of key Antarctic marine glaciers; which would serve as a positive feedback for global warming.

See also:

W.A. Dickens et al. (2019), "Enhanced glacial discharge from the eastern Antarctic Peninsula since the 1700s associated with a positive Southern Annular Mode", Scientific Reports, DOI: 10.1038/s41598-019-50897-4

https://www.nature.com/articles/s41598-019-50897-4

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1873 on: November 11, 2019, 07:39:48 PM »
To continue my list of ice-climate feedback mechanisms:

10.  The first image illustrates the current Artic situation where the Beaufort Gyre is accumulating freshwater (due the typically high pressure system over the Beaufort Gyre) and hurricane ally is advecting warm tropical energy from the Tropical Atlantic directly into the Arctic where the warmth increases the chances that a low atmospheric pressure system would form over the Beaufort Gyre; which increases the likelihood that the Beaufort Gyre will release relatively fresh relatively cold water into the North Atlantic (as would rainfall events on to Arctic Sea Ice).  Panel A of the second image shows the current situation of ocean circulation from the North Atlantic into the Arctic Ocean; while panels B & C show computer runs of what would happen if the Beaufort Gyre were to abruptly release the indicated amounts of relatively fresh relatively cool water into the North Atlantic; while Panel D shows how for cases shown in Panels B & C the warm Gulf Stream waters flow northward under the freshwater hosing event to deliver relatively warm ocean water to the coastal regions of the Siberian Continental Shelf.  The third image shows that in this region of the Siberian Continental Shelf there currently exist substantial quantities of metastable methane hydrates in the subsea soil that are subject to abrupt degradation from an influx of warm ocean water such as that shown in Panels B, C and D of the second image.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1874 on: November 11, 2019, 08:54:55 PM »
As a continuation of my list of ice-climate feedback mechanisms:

11. The first two images illustrate how troughs plowed by paleo-marine glaciers lead warm CDW directly to the most vulnerable portions of key Antarctic marine glaciers like those in the ASE and Totten.  The third image shows how such troughs direct warm CDW directly at the base of the Thwaites Ice Tongue; while the fourth image shows just how close to floatation the narrow zone of grounded glacier ice is between the base of the Thwaites Ice Tongue and the Big Ear subglacial cavity.  If say a strong pulse of warm CDW were to reach the ice on this narrow subglacial ridge (say due to a strong El Nino event or the collapse of Antarctic Peninsular ice shelves) then this could trigger an MICI-type of failure of the Thwaites Glacier; which would likely destabilize the other marine glaciers in the ASE and Totten.
« Last Edit: November 11, 2019, 09:58:39 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1875 on: November 12, 2019, 07:11:07 AM »

I have searched in all threads of the forum. Nothing comes up in terms of proof of increasing westerlies. The only thing that comes up is speculation that the westerlies are likely to increase with increase global warming.
...

The linked UCAR empirical data (i.e. using satellite data in the post-1979 era), clearly shows that between 40S and 60S latitude the westerly winds over the Southern Ocean have increased in recent decades (see the first image):

Bracegirdle, Thomas J. & National Center for Atmospheric Research Staff (Eds). Last modified 11 Jan 2019. "The Climate Data Guide: Southern Hemisphere westerly jet strength and position." Retrieved from https://climatedataguide.ucar.edu/climate-data/southern-hemisphere-westerly-jet-strength-and-position.

https://climatedataguide.ucar.edu/climate-data/southern-hemisphere-westerly-jet-strength-and-position

Thanks, ASLR.
i dug a bit deeper and checked those data.
The westerly winds that have been increasing are 850 hPa winds, i.e. at 1500 meters of altitude, which is above the low clouds. The figure you provided doesn't show the velocity increase. I downloaded the data and put in a graph, it's the annual means. From looking at the graph (see below), the velocity increase seems to be around 5%, and definitely less than 10%.
But surface winds haven't been affected at all, see my two figures with Solar Ocean surface winds in posts above.

In your recapitulation of ice-climate feedback mechanisms you wrote:
Quote
1.   From the 1980's thru about 2015 the Antarctic sea ice extent was above average, while during this period the Antarctic Ozone hole was actively increasing the westerly wind velocities over the Southern Ocean; which resulted in an upwelling of the warm CDW (circumpolar deep water).
Question: How can the CDW start to upwell if there is no surface wind increase?

In your reply #1859 you wrote that the ozone hole had kept:
Quote
the westerly wind in a velocity 'sweet-spot' nearly ideal for accelerating the ocean surface currents around Antarctica (which upwells the warm CDW)
Question: How can the ocean surface currents accelerate if there is no surface wind increase?

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1876 on: November 12, 2019, 04:37:48 PM »
To continue my series of posts on ice-climate feedback mechanisms (from Reply #1874):

12. The ice-albedo feedback mechanism (see image) is so commonly discussed in this forum that I list it here only for completeness (see the linked references/article):

Pistone, Kristina; Eisenman, Ian; Ramanathan, Veerabhadran (2019), "Radiative Heating of an Ice-Free Arctic Ocean", Geophysical Research Letters, 46 (13): 7474–7480, doi:10.1029/2019GL082914

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL082914

Abstract: "During recent decades, there has been dramatic Arctic sea ice retreat. This has reduced the top‐of‐atmosphere albedo, adding more solar energy to the climate system. There is substantial uncertainty regarding how much ice retreat and associated solar heating will occur in the future. This is relevant to future climate projections, including the timescale for reaching global warming stabilization targets. Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year. Assuming constant cloudiness, we calculate a global radiative heating of 0.71 W/m2 relative to the 1979 baseline state. This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years."


See also:

Title: "Ice–albedo feedback"

https://en.wikipedia.org/wiki/Ice%E2%80%93albedo_feedback

Extract: "Ice–albedo feedback is a positive feedback climate process where a change in the area of ice caps, glaciers, and sea ice alters the albedo and surface temperature of a planet. Ice is very reflective, therefore some of the solar energy is reflected back to space. Ice–albedo feedback plays an important role in global climate change."

&

I note that a collapse of the WAIS would lead to a very large heat flux from the North Pacific into the Arctic Ocean; which would cause an abrupt decrease in Arctic sea ice extent:

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

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

Abstract: "Arctic amplification is a consequence of surface albedo, cloud, and temperature feedbacks, as well as poleward oceanic and atmospheric heat transport. However, the relative impact of changes in sea surface temperature (SST) patterns and ocean heat flux sourced from different regions on Arctic temperatures are not well constrained. We modify ocean-to-atmosphere heat fluxes in the North Pacific and North Atlantic in a climate model to determine the sensitivity of Arctic temperatures to zonal heterogeneities in northern hemisphere SST patterns. Both positive and negative ocean heat flux perturbations from the North Pacific result in greater global and Arctic surface air temperature anomalies than equivalent magnitude perturbations from the North Atlantic; a response we primarily attribute to greater moisture flux from the subpolar extratropics to Arctic. Enhanced poleward latent heat and moisture transport drive sea-ice retreat and low-cloud formation in the Arctic, amplifying Arctic surface warming through the ice-albedo feedback and infrared warming effect of low clouds. Our results imply that global climate sensitivity may be dependent on patterns of ocean heat flux in the northern hemisphere."
« Last Edit: November 12, 2019, 05:08:37 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1877 on: November 12, 2019, 05:04:20 PM »
...
Question: How can the CDW start to upwell if there is no surface wind increase?
...

It seems to me that your averaging is masking the signal that I am talking about, as the linked reference makes it very clear that the westerlies wind stress driving the Antarctic Circumpolar Current (ACC) has increased"… by almost 40% …" over the past 40 years. 

Also, I remind readers that in the Southern Hemisphere the Coriolis effect acts to deflect the ACC away from Antarctica; so the local (between 40S and 60S latitude) acceleration of the ACC over the past 40 years has caused an increase in the local upwelling of the warm CDW:

Xia Lin et al. (2018), "Mean, Variability, and Trend of Southern Ocean Wind Stress: Role of Wind Fluctuations", Journal of Climate, https://doi.org/10.1175/JCLI-D-17-0481.1

https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-17-0481.1

Abstract: "The Southern Ocean (SO) surface westerly wind stress plays a fundamental role in driving the Antarctic Circumpolar Current and the global meridional overturning circulation. Here, the authors investigate the contributions of atmospheric wind fluctuations to the mean, variability, and trend of SO wind stress over the last four decades using NCEP reanalysis and ERA-Interim products. Including wind variability at synoptic frequencies (2–8 days) and higher in the stress calculation is found to increase the strength of the mean SO wind stress by almost 40% in both reanalysis products. The southern annular mode index is found to be a good indicator for the strength of the mean wind and mean wind stress, but not as good an indicator for wind fluctuations, at least for the chosen study period. Large discrepancies between reanalysis products emerge regarding the contributions of wind fluctuations to the strengthening trend of SO wind stress. Between one-third and one-half of the stress trend in NCEP can be explained by the increase in the intensity of wind fluctuations, while the stress trend in ERA-Interim is due entirely to the increasing strength of the mean westerly wind. This trend discrepancy may have important climatic implications since the sensitivity of SO circulation to wind stress changes depends strongly on how these stress changes are brought about. Given the important role of wind fluctuations in shaping the SO wind stress, studies of the SO response to wind stress changes need to account for changes of wind fluctuations in the past and future."


Caption: "FIG. 4. The 1979–2016 zonal-mean and time-mean zonal wind velocity (dashed; m s−1), zonal wind stresses (solid; N m−2), and MKE and EKE (m2 s−2) from (a),(b) NCEP-1 and (c),(d) ERA-Interim.  is kinetic energy associated with the annual-mean winds, and  ,  ,  , and  are kinetic energy calculated from wind fluctuations on time scales of 6 h–2 days, 2–8 days, 6 h–8 days, and 6 h–1 yr, respectively (see Table 1)."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1878 on: November 12, 2019, 06:12:12 PM »
To continue my series of posts listing various ice-climate feedback mechanisms:

13. The first image (and first linked article) discuss the Moho discontinuity near a subduction zone such as is the case for the West Antarctic Rift System (see the second image [which also shows active volcanoes near both PIG and Thwaites] and the second linked article).  The third image makes it clear that the depth to the Moho discontinuity in West Antarctica is notable shallow; thus if the Thwaites Glacier were to collapse abruptly due to an ice cliff mechanism; the associated uplift of the local lithosphere would increase both the geothermal heat flux in the BSB but also would increase volcanic activity potentially in the Hudson and/or Takahe volcanoes; which would likely trigger an abrupt increase in ice mass loss from the WAIS:

Title: "Mohorovičić discontinuity"

https://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuity

Extract: " The Moho lies almost entirely within the lithosphere; only beneath mid-ocean ridges does it define the lithosphere–asthenosphere boundary. The Mohorovičić discontinuity is 5 to 10 kilometres (3–6 mi) below the ocean floor, and 20 to 90 kilometres (10–60 mi) beneath typical continental crusts, with an average of 35 kilometres (22 mi)."

&

Title: "West Antarctic Rift"

https://en.wikipedia.org/wiki/West_Antarctic_Rift

Extract: "The West Antarctic Rift is the source of all the recently active volcanoes within Antarctica and all the recently active volcanoes on the continent. It is responsible for most of the major mountain systems outside the Antarctic Peninsula. Volcanism has been attributed to the rifting and also a mantle hotspot.

Glaciology

The WARS is also believed to have a major influence on ice flows in West Antarctica. In western Marie Byrd Land active glaciers flow through fault-bounded valleys (grabens) of the WARS. Sub-ice volcanism has been detected and proposed to influence ice flow. Fast-moving ice streams in the Siple Coast adjacent to the east edge of the Ross Ice Shelf are influenced by the lubrication provided by water-saturated till within fault-bounded grabens within the rift, which could cause rapid breakup of the ice sheet if global warming accelerates."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1879 on: November 12, 2019, 06:24:24 PM »
I worry for future generations and the young humans today. What will they inherit?
Sorry for the off topic post.
I guess that I'm bothered by a good imagination, long term view and empathy,
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1880 on: November 12, 2019, 06:46:14 PM »
The linked reference calibrates a MISI model to recently observed grounding line retreats for the Smith, Pope and Kohler glaciers (in the ASE), and projects the MISI trends for this catchment basin as summarized in the associate image where:

1.  Panel A shows the volume above floatation for the catchment and the equivalent sea level rise (in mm);
2. Panel B shows the melt rate with time for the catchment;
3. Panel C shows the grounding line retreat for Smith Glacier; and
4. Panel D shows the grounding line retreat for Kohler Glacier.

These MISI analyses show that: "Given the rapid progression of grounding-line retreat in the model simulations, thinning associated with the retreat of Smith Glacier may reach the ice divide and undermine a portion of the Thwaites catchment as quickly as changes initiated at the Thwaites terminus."

However, I note here that if the Thwaites catchment collapses due to a MICI-type of mechanism in the next few decades; then both the glaciers in the Smith, Pope & Kohler catchment and in the Pine Island catchment would be undermined:

Lilien, D. A., Joughin, I., Smith, B., and Gourmelen, N.: Melt at grounding line controls observed and future retreat of Smith, Pope, and Kohler glaciers, The Cryosphere, 13, 2817–2834, https://doi.org/10.5194/tc-13-2817-2019, 2019.

https://www.the-cryosphere.net/13/2817/2019/

Abstract

Smith, Pope, and Kohler glaciers and the corresponding Crosson and Dotson ice shelves have undergone speedup, thinning, and rapid grounding-line retreat in recent years, leaving them in a state likely conducive to future retreat. We conducted a suite of numerical model simulations of these glaciers and compared the results to observations to determine the processes controlling their recent evolution. The model simulations indicate that the state of these glaciers in the 1990s was not inherently unstable, i.e., that small perturbations to the grounding line would not necessarily have caused the large retreat that has been observed. Instead, sustained, elevated melt at the grounding line was needed to cause the observed retreat. Weakening of the margins of Crosson Ice Shelf may have hastened the onset of grounding-line retreat but is unlikely to have initiated these rapid changes without an accompanying increase in melt. In the simulations that most closely match the observed thinning, speedup, and retreat, modeled grounding-line retreat and ice loss continue unabated throughout the 21st century, and subsequent retreat along Smith Glacier's trough appears likely. Given the rapid progression of grounding-line retreat in the model simulations, thinning associated with the retreat of Smith Glacier may reach the ice divide and undermine a portion of the Thwaites catchment as quickly as changes initiated at the Thwaites terminus.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1881 on: November 12, 2019, 07:05:45 PM »
I worry for future generations and the young humans today. What will they inherit?
Sorry for the off topic post.
I guess that I'm bothered by a good imagination, long term view and empathy,

For what it is worth, I try to focus on those who will survive the likely coming global socio-economic contraction.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1882 on: November 12, 2019, 08:03:36 PM »
As a follow-on to Reply #1878, who knows what lies in mankind's future should a collapse of the WAIS this century should trigger similar volcanic eruptions in West Antarctica as cited in the linked reference & associated image:

Joseph R. McConnell el al., "Synchronous volcanic eruptions and abrupt climate change ∼17.7 ka plausibly linked by stratospheric ozone depletion," PNAS (2017). www.pnas.org/cgi/doi/10.1073/pnas.1705595114

https://www.pnas.org/content/114/38/10035

Significance
Cold and dry glacial-state climate conditions persisted in the Southern Hemisphere until approximately 17.7 ka, when paleoclimate records show a largely unexplained sharp, nearly synchronous acceleration in deglaciation. Detailed measurements in Antarctic ice cores document exactly at that time a unique, ∼192-y series of massive halogen-rich volcanic eruptions geochemically attributed to Mount Takahe in West Antarctica. Rather than a coincidence, we postulate that halogen-catalyzed stratospheric ozone depletion over Antarctica triggered large-scale atmospheric circulation and hydroclimate changes similar to the modern Antarctic ozone hole, explaining the synchronicity and abruptness of accelerated Southern Hemisphere deglaciation.

Abstract
Glacial-state greenhouse gas concentrations and Southern Hemisphere climate conditions persisted until ∼17.7 ka, when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the Southern Hemisphere, with many changes ascribed to a sudden poleward shift in the Southern Hemisphere westerlies and subsequent climate impacts. We used high-resolution chemical measurements in the West Antarctic Ice Sheet Divide, Byrd, and other ice cores to document a unique, ∼192-y series of halogen-rich volcanic eruptions exactly at the start of accelerated deglaciation, with tephra identifying the nearby Mount Takahe volcano as the source. Extensive fallout from these massive eruptions has been found >2,800 km from Mount Takahe. Sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface UV radiation indicate that the eruptions led to stratospheric ozone depletion. Rather than a highly improbable coincidence, circulation and climate changes extending from the Antarctic Peninsula to the subtropics—similar to those associated with modern stratospheric ozone depletion over Antarctica—plausibly link the Mount Takahe eruptions to the onset of accelerated Southern Hemisphere deglaciation ∼17.7 ka

Caption for first image: "Spatial extent of the glaciochemical anomaly. Evidence of the ∼192-y anomaly has been found >2,800 km from Mount Takahe in ice core (circles) chemical records (SI Appendix, Fig. S3) as well as radar surveys from much of West Antarctica. Also shown are area volcanoes (triangles). September/October horizontal wind vectors at 600 hPa based on 1981–2010 National Centers for Environmental Prediction reanalysis fields show transport patterns consistent with observations."

Also, the second attached image shows representative consequences of paleo-volcanic eruptions in West Antarctic erupting both above and below the glacial ice surface level
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1883 on: November 12, 2019, 09:39:59 PM »
Yes, we should start thinking ahead to 2200.

As I have time I will try to provide more information about GIS and EAIS risks for 2200, ...

both SLR and climate change much sooner than consensus climate scientists have projected to date:

Title: "Polar Warning: Even Antarctica’s Coldest Region Is Starting to Melt"

https://e360.yale.edu/features/polar-warning-even-antarctica-coldest-region-is-starting-to-melt

Extract: "East Antarctica is the coldest spot on earth, long thought to be untouched by warming. But now the glaciers and ice shelves in this frigid region are showing signs of melting, a development that portends dramatic rises in sea levels this century and beyond.

In January, Rignot and colleagues published a paper that looked back to 1979. Like the IMBIE study, they found an acceleration in ice loss over the continent as a whole: it went up six times over the four decades of their study. But, more strikingly, they could say that East Antarctica was a big player in that loss: from 2009 to 2017, they concluded, West Antarctica accounted for 63 percent of the continent’s ice loss, and East Antarctica accounted for 20 percent — more than the Antarctic Peninsula’s contribution of 17 percent.

In the face of rapid change and limited data, it is extremely challenging to predict what the Antarctic will do in the future. The models, says Rignot, “all have fundamental flaws. None of them are right.” Their resolution is coarse and they don’t include all the physics; plus they are lacking in critical input data. Very little is known, for example, about water temperatures and the seafloor shape off the coast of much of East Antarctica. That affects things like ocean currents and sea ice buildup, both of which affect glacier flow.

For now, DeConto says, his models show that “the East Antarctic is stable for a few decades, but in the high emissions scenarios it starts to become a player in the late 21st century.” But, he adds, “If I went back and put [Rignot’s] numbers in…” He trails off, waving his hands at the potentially large, unknown increase that would cause."

See also:

Eric Rignot, Jérémie Mouginot, Bernd Scheuchl, Michiel van den Broeke, Melchior J. van Wessem, and Mathieu Morlighem (January 22, 2019), "Four decades of Antarctic Ice Sheet mass balance from 1979–2017", PNAS, 116 (4) 1095-1103; https://doi.org/10.1073/pnas.1812883116

https://www.pnas.org/content/116/4/1095

Significance Statement
We evaluate the state of the mass balance of the Antarctic Ice Sheet over the last four decades using a comprehensive, precise satellite record and output products from a regional atmospheric climate model to document its impact on sea-level rise. The mass loss is dominated by enhanced glacier flow in areas closest to warm, salty, subsurface circumpolar deep water, including East Antarctica, which has been a major contributor over the entire period. The same sectors are likely to dominate sea-level rise from Antarctica in decades to come as enhanced polar westerlies push more circumpolar deep water toward the glaciers.

Abstract
We use updated drainage inventory, ice thickness, and ice velocity data to calculate the grounding line ice discharge of 176 basins draining the Antarctic Ice Sheet from 1979 to 2017. We compare the results with a surface mass balance model to deduce the ice sheet mass balance. The total mass loss increased from 40 ± 9 Gt/y in 1979–1990 to 50 ± 14 Gt/y in 1989–2000, 166 ± 18 Gt/y in 1999–2009, and 252 ± 26 Gt/y in 2009–2017. In 2009–2017, the mass loss was dominated by the Amundsen/Bellingshausen Sea sectors, in West Antarctica (159 ± 8 Gt/y), Wilkes Land, in East Antarctica (51 ± 13 Gt/y), and West and Northeast Peninsula (42 ± 5 Gt/y). The contribution to sea-level rise from Antarctica averaged 3.6 ± 0.5 mm per decade with a cumulative 14.0 ± 2.0 mm since 1979, including 6.9 ± 0.6 mm from West Antarctica, 4.4 ± 0.9 mm from East Antarctica, and 2.5 ± 0.4 mm from the Peninsula (i.e., East Antarctica is a major participant in the mass loss). During the entire period, the mass loss concentrated in areas closest to warm, salty, subsurface, circumpolar deep water (CDW), that is, consistent with enhanced polar westerlies pushing CDW toward Antarctica to melt its floating ice shelves, destabilize the glaciers, and raise sea level.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1884 on: November 12, 2019, 10:15:08 PM »
More bad news about wildfires in South America:

Title: "Brazil's next fire disaster, in the Pantanal wetlands"

https://www.dw.com/en/brazils-next-fire-disaster-in-the-pantanal-wetlands/a-51199164

Extract: "Brazil's Pantanal wetlands are on fire. While the world was shocked by the wildfires that ravaged the Amazon, few seem to have noticed the destruction of the world's largest tropical wetland area.

Felipe Dias estimates that at least 1.5 million hectares have burned since August. "It's normal to have fires here but what's not normal is the extent; the amount of burned areas," he points out. He says that one reason for the fires is that it has been so dry. Some fires were caused by lightning.

He also partly blames Brazil's neighboring states Bolivia and Paraguay. The Pantanal wetlands span all three countries. Dias says that some of the fires that have devastated the Brazilian Pantanal this year broke out across the border. "This year, the whole Pantanal caught fire.""
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1885 on: November 12, 2019, 10:49:32 PM »
To continue my series of posts listing various ice-climate feedback mechanisms (from Reply #1876):

14. While it is clear now that the slowing of the MOC due to ice mass loss from the AIS and GIS is contributing to an increase in deep atmospheric convection cells over the tropical oceans (see the first image by Sherwood 2014); not all climate scientists concur that the associated expansion of the atmospheric Hadley Cells (see the second image) is contributing to an increase in ECS (due to cloud feedback), and still fewer climate scientists acknowledge the risk that if the tropical ocean SSTs increase by about 5C that the atmosphere could flip into an equable pattern (see the last two images).  Personally, I am concerned that by the time that consensus climate scientists recognize this ice-climate feedback mechanism, it may be too late to prevent the atmosphere in the Northern Hemisphere from changing into an equable pattern (even with an equivalent atmospheric carbon dioxide concentration much lower than that indicated in the last two images).
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1886 on: November 12, 2019, 11:17:37 PM »
I note that DeConto and Pollard (2016) indicated that Totten Glacier (located in the Aurora Subglacial Basin) is susceptible to an MICI-type of ice mass loss this century, and the attached image from the linked reference shows that the Wilkes Subglacial Basin is interconnected with the Aurora Subglacial Basin.  Thus, if Totten Glacier were to sustain an MICI-type of collapse this century, it would likely undermine the ice in the Wilkes Subglacial Basin:

Rachel A.Bertram et al. (15 July 2018), "Pliocene deglacial event timelines and the biogeochemical response offshore Wilkes Subglacial Basin, East Antarctica", Earth and Planetary Science Letters, Vol. 494, pp 109-116, https://doi.org/10.1016/j.epsl.2018.04.054

https://www.sciencedirect.com/science/article/pii/S0012821X18302632

Abstract
Significantly reduced ice coverage in Greenland and West Antarctica during the warmer-than-present Pliocene could account for ∼10 m of global mean sea level rise. Any sea level increase beyond this would require contributions from the East Antarctic Ice Sheet (EAIS). Previous studies have presented low-resolution geochemical evidence from the geological record, suggesting repeated ice advance and retreat in low-lying areas of the EAIS such as the Wilkes Subglacial Basin. However, the rates and mechanisms of retreat events are less well constrained. Here we present orbitally-resolved marine detrital sediment provenance data, paired with ice-rafted debris and productivity proxies, during three time intervals from the middle to late Pliocene at IODP Site U1361A, offshore of the Wilkes Subglacial Basin. Our new data reveal that Pliocene shifts in sediment provenance were paralleled by increases in marine productivity, while the onset of such changes was marked by peaks in ice-rafted debris mass accumulation rates. The coincidence of sediment provenance and marine productivity change argues against a switch in sediment delivery between ice streams, and instead suggests that deglacial warming triggered increased rates of iceberg calving, followed by inland retreat of the ice margin. Timescales from the onset of deglaciation to an inland retreated ice margin within the Wilkes Subglacial Basin are on the order of several thousand years. This geological evidence corroborates retreat rates determined from ice sheet modeling, and a contribution of ∼3 to 4 m of equivalent sea level rise from one of the most vulnerable areas of the East Antarctic Ice Sheet during interglacial intervals throughout the middle to late Pliocene.

Caption: "Fig. 1. (A) Topography and bathymetry (meters above sea level, m asl) of the Antarctic continent (modified from Fretwell et al., 2013), highlighting areas below sea level, including the three largest subglacial basins in East Antarctica: the Aurora Subglacial Basin, the Recovery Subglacial Basin and the Wilkes Subglacial Basin. The location of IODP Expedition 318 drill site U1361A (64°24.57′S, 143°53.20′E; 3454 m water depth) offshore of the Wilkes Subglacial Basin is marked. (B) Geological map of the area around the Wilkes Subglacial Basin (after Cook et al., 2013). Topographic map of the Wilkes Subglacial Basin (from Bedmap2; Fretwell et al., 2013) with simplified lithologies and their isotopic characteristics. Areas of inferred Jurassic Ferrar Large Igneous Province (FLIP) from airborne geophysics are shown in hatched marking (Ferraccioli et al., 2009, Frederick et al., 2016, Studinger et al., 2004). CB denotes the Central Basin. (For interpretation of the colors in the figure, the reader is referred to the web version of this article.)"
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1887 on: November 12, 2019, 11:46:57 PM »
It will be interesting to see whether Thwaites Glacier sustains a MICI-type of collapse before peak oil demand is reached, as if we are following a 5-year double time for ice sheet mass loss as indicated in the attached image, climate change could continue getting worse for decades due to ice-climate feedbacks even if anthropogenic GHG emissions are capped after 2035:

Title: "The Saudi Aramco IPO is shining a spotlight on peak oil demand"

https://www.axios.com/saudi-aramco-ipo-peak-oil-demand-98bdc276-a0c4-4982-a225-1481117b2b58.html

Extract: "The release of the Saudi Aramco IPO prospectus is putting a fresh spotlight on a big question: the date when global oil demand will peak.

Driving the news
: The document released over the weekend includes estimates that demand will grow until around 2035 before leveling off, but that the inflection point could occur by the late 2020s."
“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 #1888 on: November 13, 2019, 04:19:55 AM »
...
Question: How can the CDW start to upwell if there is no surface wind increase?
...

It seems to me that your averaging is masking the signal that I am talking about, as the linked reference makes it very clear that the westerlies wind stress driving the Antarctic Circumpolar Current (ACC) has increased"… by almost 40% …" over the past 40 years. 
...

Thanks again, ASLR. From this paper it's clear that it's not the mean wind velocities that have increased much, but the shear surface stress from winds. This is mainly due to an increase in wind variability over those years. There are pretty big differences between the different reanalysis products though.

I attach another figure from that paper, showing wind stress trends, as well as eddy kinetic energy (EKE) trends over time that demonstrate these issues.

Caption: Fig. 12. Time series (solid) and trends (dashed) of the (a),(c) seasonal-mean (N m−2) and (b),(d) EKE (m2 s−2) averaged between 35° and 65°S during 1979–2016 from (a),(b) NCEP-1 and (c),(d) ERA-Interim. Percentages in brackets show statistical significance of the trends.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1889 on: November 13, 2019, 05:08:14 PM »
To continue my series of posts listing various ice-climate feedback mechanisms (see Reply #1885):

15. Even well before any possible flip to an atmospheric equable pattern, an ice meltwater induced slowing of the MOC would progressively start warming the tropical oceans SST; which among other issues would increase the intensity of both La Nina and El Nino events; which would propagate tropical ocean energy poleward via atmospheric Rossby waves as indicated by the first three attached images (note that although such Rossby waves do not typically directly deliver energy poleward of about 70 degrees latitude, the local winds [such as those created by the Amundsen Sea Low that can blow warm ocean currents directly into the ASE, as shown by the fourth image]  and ocean currents typically advect this energy poleward of 70 degrees latitude where it melts both glacial, and sea, ice).
« Last Edit: November 13, 2019, 05:13:19 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1890 on: November 13, 2019, 05:17:40 PM »
...
Thanks again, ASLR. From this paper it's clear that it's not the mean wind velocities that have increased much, but the shear surface stress from winds. This is mainly due to an increase in wind variability over those years.


I think that it is also useful for readers to remember that note only wind variability but also variability of any relevant Earth System is a sign of high and/or increasing ECS values; thus for instance the so called faux 'hiatus' on global warming is actually an example of increasing climate variability; which supports the probability that ECS is currently increasing.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1891 on: November 13, 2019, 06:13:06 PM »
Per the linked article under the recently released IEA's STEPS projection, due to increased: plastic, chemical, SUV, aircraft and natural gas (see image) production; anthropogenic GHG emissions are not likely to plateau before 2040.  If the WAIS collapses before that timeframe, the associated decadal-long increasing in planetary energy imbalance could likely push many Earth Systems past tipping points in the 2040 to 2050 timeframe:

Title: "‘Profound shifts’ underway in energy system, says IEA World Energy Outlook"

https://www.carbonbrief.org/profound-shifts-underway-in-energy-system-says-iea-world-energy-outlook

Extract: "The world’s CO2 emissions are set to continue rising for decades unless there is greater ambition on climate change, despite the “profound shifts” already underway in the global energy system.

That is one of the key messages from the International Energy Agency’s (IEA) World Energy Outlook 2019, published today. This year’s 810-page edition is notable for its renamed central “Stated Policies Scenario” (STEPS), formerly known as the “New Policies Scenario”.

In this scenario, which aims to mirror the outcome of policies already set out by governments, a surge in wind and solar power would see renewable sources of energy meeting the majority of increases in global energy demand. But a plateau for coal, along with rising demand for oil and gas, would mean global emissions continue to rise throughout the outlook period to 2040.

Oil demand for freight, shipping, aviation and chemicals “continues to grow”, the IEA says, with the growing popularity of SUVs another potential factor propping up demand. (Notably, documentation for the Saudi Aramco share sale also has global oil demand levelling off from around 2035.)"
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1892 on: November 13, 2019, 06:37:47 PM »
I note that DeConto and Pollard (2016) indicated that Totten Glacier (located in the Aurora Subglacial Basin) is susceptible to an MICI-type of ice mass loss this century, and the attached image from the linked reference shows that the Wilkes Subglacial Basin is interconnected with the Aurora Subglacial Basin.  Thus, if Totten Glacier were to sustain an MICI-type of collapse this century, it would likely undermine the ice in the Wilkes Subglacial Basin:

...

You're mistaken about that.  Here are the projections for RCP 8.5 from DeConto and Pollard 2016:

https://www.geo.umass.edu/climate/papers2/DeConto2016.pdf

Quote
In RCP8.5, increased precipitation causes an initial, minor gain in total ice mass (Fig. 4d), but rapidly warming summer air temperatures trigger extensive surface meltwater production and hydrofracturing of ice shelves by the middle of this century (Extended Data Fig. 4). The Larsen C is one of the first shelves to be lost, about 2055. Around the same time, major thinning and retreat of outlet glaciers commences in the Amundsen Sea Embayment, beginning with Pine Island Glacier (Fig. 4h), and along the Bellingshausen margin. Massive meltwater production on shelf surfaces, and eventually on the flanks of the ice sheet, would quickly overcome the buffering capacity of firn. In the model, the meltwater accelerates WAIS retreat via its thermomechanical influence on ice rheology (Methods) and the influence of hydrofacturing on crevassing and structural failure of the retreating margin. Antarctica contributes 77 cm of GMSL rise by 2100, and continued loss of the Ross and Weddell Sea ice shelves drives WAIS retreat from three sides simultaneously (the Amundsen, Ross, and Weddell seas), all with reverse-sloping beds into the deep ice-sheet interior. As a result, WAIS collapses within 250 years. At the same time, steady retreat into the Wilkes and Aurora basins, where the ice above floatation is >2,000 m thick, adds substantially to the rate of sea-level rise, exceeding 4 cm yr−1 (Fig. 4c) in the next century, which is comparable to maximum rates of sea-level rise during the last deglaciation. At 2500, GMSL rise for the RCP8.5 scenario is 12.3 m. As in our LIG simulations, atmosphere–ice sheet coupling accounting for the warming feedback associated with the retreating ice sheet adds an additional 1.3 m of GMSL to the RCP8.5 scenario (Fig. 4b).

So in the worst case emissions scenario, which is no longer feasible because we aren't going to burn that much coal, the West Antarctic ice shelves collapse after the Larsen C, which collapses in the 2050s.  The Wilkes and Aurora basins would contribute to sea level rise next century, after 2100.

And Rob DeConto has publicly backed off of these projections.

https://www.theatlantic.com/science/archive/2019/01/sea-level-rise-may-not-become-catastrophic-until-after-2100/579478/

Quote
Two years ago, the glaciologists Robert DeConto and David Pollard rocked their field with a paper arguing that several massive glaciers in Antarctica were much more unstable than previously thought. Those key glaciers—which include Thwaites Glacier and Pine Island Glacier, both in the frigid continent’s west—could increase global sea levels by more than three feet by 2100, the paper warned. Such a rise could destroy the homes of more than 150 million people worldwide.

They are now revisiting those results. In new work, conducted with three other prominent glaciologists, DeConto and Pollard have lowered some of their worst-case projections for the 21st century. Antarctica may only contribute about a foot of sea-level rise by 2100, they now say. This finding, reached after the team improved their own ice model, is much closer to projections made by other glaciologists.

It is a reassuring constraint placed on one of the most alarming scientific hypotheses advanced this decade. The press had described DeConto and Pollard’s original work as an “ice apocalypse” spawned by a “doomsday glacier.” Now their worst-case skyrocketing sea-level scenario seems extremely unlikely, at least within our own lifetimes.

Skeptical Science has a very good overview of MICI.

https://skepticalscience.com/new-light-antarctica-contribution-slr.html

Quote
DeConto and Pollard are also currently revisiting their 2016 results in a new paper. DeConto says he is not able to comment on it directly as it is undergoing peer review. However, he has presented some preliminary results at the Fall Meeting of the American Geophysical Union (AGU) in December.

An article published in the Atlantic shortly afterwards reported that DeConto and Pollard “have lowered some of their worst-case projections for the 21st century” after making improvements to their model. The results are likely to put Antarctica’s contribution to sea level rise in 2100 at “about a foot” (30cm), the article says, which is “much closer to projections made by other glaciologists”.

And new models of ice sheet failure published just last month indicate that when realistic time frames of ice shelf collapse (such as the two weeks it took for Larsen B when the it collapsed) are applied to high ice cliffs, the ice cliffs flow semi-viscously instead of shattering in brittle collapse, which is what the MICI model predicts.

There are also studies that show that past incidents of sea-level rise can be explained without MICI and that water can flow (and does in Antarctica) off of the surface of an ice sheet instead of penetrating down into crevasses to create the hydrofractures necessary for the  initiation of MICI.

So to recap:

- AbruptSLR continues to confuse the timeframes of the original MICI models published in 2016
- The authors of the original MICI models now state that the 2016 projections were too pessimistic
- Other studies have shown that ice flows instead of fails in a brittle manner, which casts doubt on the mechanism needed for MICI to occur.
- Past sea level rise could have occurred without needing the MICI mechanism
- MICI needs hydrofracturing to occur before MICI can occur and yet there are areas in Antarctica where water flows off the ice sheet rather than penetrating through it to create hydrofractures
- Coal is now more expensive than solar and wind power and coal use is expected to peak next decade, so the emission projections of RCP 8.5 from the 2020s through 2100 aren't possible.







Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1893 on: November 13, 2019, 06:51:55 PM »
Per the linked article under the recently released IEA's STEPS projection, due to increased: plastic, chemical, SUV, aircraft and natural gas (see image) production; anthropogenic GHG emissions are not likely to plateau before 2040.  If the WAIS collapses before that timeframe, the associated decadal-long increasing in planetary energy imbalance could likely push many Earth Systems past tipping points in the 2040 to 2050 timeframe:

Title: "‘Profound shifts’ underway in energy system, says IEA World Energy Outlook"

https://www.carbonbrief.org/profound-shifts-underway-in-energy-system-says-iea-world-energy-outlook

Extract: "The world’s CO2 emissions are set to continue rising for decades unless there is greater ambition on climate change, despite the “profound shifts” already underway in the global energy system.

That is one of the key messages from the International Energy Agency’s (IEA) World Energy Outlook 2019, published today. This year’s 810-page edition is notable for its renamed central “Stated Policies Scenario” (STEPS), formerly known as the “New Policies Scenario”.

In this scenario, which aims to mirror the outcome of policies already set out by governments, a surge in wind and solar power would see renewable sources of energy meeting the majority of increases in global energy demand. But a plateau for coal, along with rising demand for oil and gas, would mean global emissions continue to rise throughout the outlook period to 2040.

Oil demand for freight, shipping, aviation and chemicals “continues to grow”, the IEA says, with the growing popularity of SUVs another potential factor propping up demand. (Notably, documentation for the Saudi Aramco share sale also has global oil demand levelling off from around 2035.)"

The EIA and IEA continue to underestimate the growth of renewables (as they have every year for decades).  And they overstate the projected growth of the US fracking production, which is near peak and starved for investment funds because most of the operations lose money.

https://www.dw.com/en/is-the-iea-underestimating-renewables/a-43137071

Quote
Is the IEA underestimating renewables?

Scenarios from the International Energy Agency (IEA) have failed to predict the growth of renewables and overestimated the role of nuclear. Critics say that's a political choice.

Last year, the world's photovoltaic power capacity overtook nuclear for the first time – reaching 402 gigawatts, compared to 353 (GW). Wind power outstripped nuclear back in 2014, and by the end of 2017 amounted to 539 GW.

Quote
Back in 2010, you might not have predicted such a shift in the global energy mix – at least, not if you were basing your predictions on the International Energy Agency's annual Word Energy Outlook (WEO), which estimated annual deployment of less than 10 GW of photovoltaic capacity.

According to this scenario, globally installed solar capacity would hit around 85 GW last year – 315 GW less than the actual figure.

Critics say this is part of a pattern of the IEA consistently underestimating the growth of renewables while making unrealistic assumptions about the development of nuclear.

https://cleantechnica.com/2017/09/06/iea-gets-hilariously-slammed-continuously-pessimistic-renewable-energy-forecasts/

Quote
IEA Gets Hilariously Slammed For Obsessively Inaccurate Renewable Energy Forecasts

One of our readers recently shared this beauty of a post on Quora. Author Paul Mainwood starts out his short post like this:
I was trawling through the International Energy Agency reports (the way you do) and was struck by two features.
The close similarity of their projections to those put out by the fossil fuel industry (e.g., Shell’s Outlook)
The extraordinary consistency with which they under-forecast the role that renewables will play in energy mix
Like the US Energy Information Administration, the IEA uses various methodologies and assumptions that just consistently bias their forecasts against renewables. It’s easy to assume there are some nefarious ulterior motives underneath these consistent errors — crony capitalism and controlling hand of the pollution industry kind of stuff. That’s certainly possible, but I haven’t seen strong evidence of it and won’t jump to conclusions.



Quote
Hard to see which line stands out from the rest, eh?

Looking at the IEA forecasts without the corrected projection, the growth can look positive at first glance … but also depressingly slow. Looking at the corrected projection, we get an adoption trend that is much more in line with the disruptive S-curve many people closely following clean energy have been expecting.

https://oilprice.com/Energy/Crude-Oil/The-EIA-Is-Grossly-Overestimating-US-Shale.html

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The EIA Is Grossly Overestimating U.S. Shale
By Nick Cunningham - Nov 12, 2019, 6:00 PM CST

The prevailing wisdom that sees explosive and long-term potential for U.S. shale may rest on some faulty and overly-optimistic assumptions, according to a new report.

Forecasts from the U.S. Energy Information Administration (EIA), along with those from its Paris-based counterpart, the International Energy Agency (IEA), are often cited as the gold standard for energy outlooks. Businesses and governments often refer to these forecasts for long-term investments and policy planning.

In that context, it is important to know if the figures are accurate, to the extent that anyone can accurately forecast precise figures decades into the future. A new report from the Post Carbon Institute asserts that the EIA’s reference case for production forecasts through 2050 “are extremely optimistic for the most part, and therefore highly unlikely to be realized.”

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He notes that in some instances, the EIA’s forecasts are so optimistic that the production volumes exceed the agency’s own estimates for proven reserves plus unproven reserves. The EIA also assumes that every last drop of proven reserves is produced, along with a high percentage of unproven reserves by 2050.

“Although the ‘shale revolution’ has provided a reprieve from what just 15 years ago was thought to be a terminal decline in oil and gas production in the U.S.,” Hughes writes, “this reprieve is temporary, and the U.S. would be well advised to plan for much-reduced shale oil and gas production in the long term.”

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1894 on: November 13, 2019, 06:53:43 PM »
To continue my series of posts listing various ice-climate feedback mechanisms (see Reply #1889):

16. An abrupt slowdown of the MOC due to an abrupt (MICI-type) collapse of the WAIS in coming decades would trigger an abrupt increase of rainfall in rainfall in both the Arctic (see that linked references and the first image) and the Antarctic (although the Arctic is more sensitive to this feedback), including due to atmospheric river events.  When such rainfall is added to the volume of surface water in meltwater ponds on: snow, marine glaciers, ice shelves and/or sea ice resulting degradation can be much more rapid than what is currently being observed in these snow/ice features:

R. Bintanja (2018), "The impact of Arctic warming on increased rainfall", Scientific Reports,  8, Article number: 16001, DOI: https://doi.org/10.1038/s41598-018-34450-3

https://www.nature.com/articles/s41598-018-34450-3

Abstract: "The Arctic region is warming two to three times faster than the global mean, intensifying the hydrological cycle in the high north. Both enhanced regional evaporation and poleward moisture transport contribute to a 50–60% increase in Arctic precipitation over the 21st century. The additional precipitation is diagnosed to fall primarily as rain, but the physical and dynamical constraints governing the transition to a rain-dominated Arctic are unknown. Here we use actual precipitation, snowfall, rainfall output of 37 global climate models in standardised 21st-century simulations to demonstrate that, on average, the main contributor to additional Arctic (70–90°N) rainfall is local warming (~70%), whereas non-local (thermo)dynamical processes associated with precipitation changes contribute only 30%. Surprisingly, the effect of local warming peaks in the frigid high Arctic, where modest summer temperature changes exert a much larger effect on rainfall changes than strong wintertime warming. This counterintuitive seasonality exhibits steep geographical gradients, however, governed by non-linear changes in the temperature-dependent snowfall fraction, thereby obscuring regional-scale attribution of enhanced Arctic rainfall to climate warming. Detailed knowledge of the underlying causes behind Arctic snow/rainfall changes will contribute to more accurate assessments of the (possibly irreversible) impacts on hydrology/run-off, permafrost thawing, ecosystems, sea ice retreat, and glacier melt."

&

E.C. Massoud et al. (12 October 2019), "Global Climate Model Ensemble Approaches for Future Projections of Atmospheric Rivers", Earth's Future, https://doi.org/10.1029/2019EF001249

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019EF001249?af=R

Abstract
Atmospheric rivers (ARs) are narrow jets of integrated water vapor transport that are important for the global water cycle, and also have large impacts on local weather and regional hydrology. Uniformly‐weighted multi‐model averages have been used to describe how ARs will change in the future, but this type of estimate does not consider skill or independence of the climate models of interest. Here, we utilize information from various model averaging approaches, such as Bayesian Model Averaging (BMA), to evaluate 21 global climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Model ensemble weighting strategies are based on model independence and atmospheric river performance skill relative to ERA‐Interim reanalysis data, and result in higher accuracy for the historic period, e.g. RMSE for AR frequency (in % of timesteps) of 0.69 for BMA vs 0.94 for the multi‐model ensemble mean. Model weighting strategies also result in lower uncertainties in the future estimates, e.g. only 20‐25% of the total uncertainties seen in the equal weighting strategy. These model averaging methods show, with high certainty, that globally the frequency of ARs are expected to have average relative increases of ~50% (and ~25% in AR intensity) by the end of the century.

&

B. Teufel  & L. Sushama (2019),"Abrupt changes across the Arctic permafrost region endanger northern development", Nature Climate Change, volume 9, pages858–862, DOI: https://doi.org/10.1038/s41558-019-0614-6

https://www.nature.com/articles/s41558-019-0614-6

Abstract: "Extensive degradation of near-surface permafrost is projected during the twenty-first century, which will have detrimental effects on northern communities, ecosystems and engineering systems. This degradation is predicted to have consequences for many processes, which previous modelling studies have suggested would occur gradually. Here we project that soil moisture will decrease abruptly (within a few months) in response to permafrost degradation over large areas of the present-day permafrost region, based on analysis of transient climate change simulations performed using a state-of-the-art regional climate model. This regime shift is reflected in abrupt increases in summer near-surface temperature and convective precipitation, and decreases in relative humidity and surface runoff. Of particular relevance to northern systems are changes to the bearing capacity of the soil due to increased drainage, increases in the potential for intense rainfall events and increases in lightning frequency. Combined with increases in forest fuel combustibility, these are projected to abruptly and substantially increase the severity of wildfires, which constitute one of the greatest risks to northern ecosystems, communities and infrastructures. The fact that these changes are projected to occur abruptly further increases the challenges associated with climate change adaptation and potential retrofitting measures."

&

Rebecca B. Neumann, Colby J. Moorberg,  Jessica D. Lundquist,  Jesse C. Turner,  Mark P. Waldrop,  Jack W. McFarland,  Eugenie S. Euskirchen,  Colin W. Edgar & Merritt R. Turetsky (03 January 2019), "Warming Effects of Spring Rainfall Increase Methane Emissions From Thawing Permafrost" Geophysical Research Letters, https://doi.org/10.1029/2018GL081274

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018GL081274

Abstract

Methane emissions regulate the near‐term global warming potential of permafrost thaw, particularly where loss of ice‐rich permafrost converts forest and tundra into wetlands. Northern latitudes are expected to get warmer and wetter, and while there is consensus that warming will increase thaw and methane emissions, effects of increased precipitation are uncertain. At a thawing wetland complex in Interior Alaska, we found that interactions between rain and deep soil temperatures controlled methane emissions. In rainy years, recharge from the watershed rapidly altered wetland soil temperatures, warming the top ~80 cm of soil in spring and summer and cooling it in autumn. When soils were warmed by spring rainfall, methane emissions increased by ~30%. The warm, deep soils early in the growing season likely supported both microbial and plant processes that enhanced emissions. Our study identifies an important and unconsidered role of rain in governing the radiative forcing of thawing permafrost landscapes.

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

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1895 on: November 13, 2019, 07:13:21 PM »
Let's take a look at RCP 8.5.  Basically, all of the IPCC RCPs look very similar until the 2020s and then diverge rapidly in the rest of the 21st century.



So when you read that we are currently closer to RCP 8.5 then we are RCP 4.5 or RCP 2.6, it sounds pretty alarming.  However, we still have 80 years left in this century.

Here is what RCP 8.5 assumes for fossil fuel use for this century.





Coal is that huge black portion.  Wind is barely visible and solar is only a small sliver of gold on top of the tiny sliver of wind in pink.

In short, RCP 8.5 assumed that renewables would continue to be too costly to be deployed widely and that coal would be mined extensively for the rest of the century.  The scenario predicted that coal use would accelerate from 2030 on.

In 2018, new wind and solar power plants were both cheaper than operating coal power plants in most of the world.  That means that power customers will save money as soon as their suppliers can build a new renewable power plant and shut down the coal plant.

Here is what that looks like for coal use today.

https://energypost.eu/peak-coal-on-the-horizon-a-country-by-country-review/

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Peak coal on the horizon: a country-by-country review

September 2, 2019 by Christine Shearer

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Though the global coal fleet still increased by 17GW in the first half of 2019, net of retirements, the pipeline is definitely shrinking. Two thirds of proposed projects never even get started. Notably, in China existing coal plants have been running, on average, only 50% of the time since 2015, evidence of a large excess of capacity. But is it enough? The IPCC’s pathway to 1.5C requires unabated coal power generation to fall by 55-70% by 2030 and be effectively phased out by 2050. That’s why all eyes are on the 15 countries – headed by China (49%), the US (13%) and India (11%) – responsible for 91% of the global coal fleet, generating 2,027GW worldwide, to turn that shrinking pipeline into shrinking capacity. Christine Shearer of Global Energy Monitor dives deep into the latest global stats.

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In 2019 to date, about 12.7GW of coal power capacity has been newly proposed across eight countries and 12GW of new construction has started across five countries. These developments are concentrated in China, India, Indonesia, the Philippines and Bangladesh. China also resumed construction on nearly 9GW of capacity that had been postponed under central government restrictions.

Conversely, 132GW of planned new capacity was cancelled in 2019, mainly from lack of activity. The largest numbers of cancellations were in China, India, Myanmar and Turkey.

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Despite this shrinking pipeline, the global coal fleet increased by 17GW in the first half of 2019, net of retirements. New capacity remains highly concentrated: nearly 85% (23GW) of the 27GW commissioned in 2019 was in China (17.9GW) or India (4.8GW).

The other 11 countries that commissioned coal-fired capacity in 2019 added less than 1GW each. Meanwhile over 10GW of capacity was retired in 2019, led by the US (6.4GW) and European Union (2GW). To date, 2019 is on track to be the fourth highest year for coal plant retirements on record in the US.

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China continues to push forward with previously postponed coal plants. However, new proposals are slowing and existing coal plants have been running only around 50% of the time since 2015 on average, indicating a large excess of capacity.

India has undergone a large downscaling in its future coal plans, in favour of lower-cost renewables. Turkey has 34GW of coal in the pipeline, but has commissioned only 12% of its proposed capacity since 2010 – a rate that would lead to only 4GW of the 34GW being completed. In reality, the figure may ultimately be even lower than this.

Japan, South Korea, and Taiwan have all reduced their proposed coal capacity, with no new large proposals since 2015. Meanwhile Japan and Korea are also facing public pressure to cut their international financial support for coal, which would leave only China as a significant source of global coal funding – given over 100 financial institutions are restricting coal financing.

Vietnam, Indonesia, Thailand, and Pakistan have all scaled back plans for coal in their future national energy plans, with many of them experiencing significant coal-related financial problems.

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Unabated coal power generation falls by 55-70% by 2030 and is effectively phased out by 2050 in pathways outlined by the Intergovernmental Panel on Climate Change last October for limiting global temperatures to no more than 1.5C above pre-industrial temperatures – the aspirational goal of the Paris Agreement.

As the pipeline for new coal dries up and older capacity reaches retirement, the lifetime and running hours of the world’s younger coal plants will therefore be a key determinant of whether global climate goals can be met.




Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1896 on: November 13, 2019, 07:32:50 PM »
Even the IEA, which consistently underestimates the growth of renewables and makes the best case for fossil fuels, thinks oil demand will peak in the next decade.

https://oilprice.com/Energy/Crude-Oil/IEA-Peak-Oil-Demand-Is-Less-Than-A-Decade-Away.html

Quote
IEA: Peak Oil Demand Is Less Than A Decade Away
By Irina Slav - Nov 13, 2019, 9:00 AM CST

Global oil demand will reach its peak in the mid-2020s and plateau around 2030, the International Energy Agency said in its World Energy Outlook for 2019.

Until about 2025, the IEA said, global oil demand will expand by about 1 percent annually, exceeding 100 million bpd and reaching 105.4 million bpd. After that growth will shrink substantially and demand will reach a plateau at less than 110 million bpd—106.4 million bpd.

The key to how long the plateau will last is how fast transportation will be electrified.  Most projections of when battery electric vehicles (BEVs) become cheaper than gas or diesel fueled (internal combustion engine abbreviated ICE) vehicles indicate the cross over will occur between 2022 and 2026. 

https://singularityhub.com/2019/04/29/electric-cars-are-estimated-to-be-cheaper-than-regular-cars-by-2022/

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Electric cars have developed a reputation as the ultimate status symbol of the champagne environmentalist, but that could be very close to changing. New research from BloombergNEF says they could be cheaper than combustion-engine cars by 2022.

Ten years ago, few would have predicted the meteoric rise of the electric vehicle industry. In 2010 the global stock was about 12,500, but more than two million were sold in 2018, accounting for around 2 percent of car sales. There are now five million on the road.

That’s been driven by a steady reduction in the price and size of batteries, as well as a healthy kick up the backside from Tesla that jolted automotive incumbents into prioritizing electric vehicle development. Despite the progress, though, these cars still lag behind their gas-guzzling cousins on price, range, and refueling time.

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That’s been changing rapidly, though. In a recent blog post, BloombergNEF energy analyst Nathaniel Bullard notes that in 2017 the point at which an electric vehicle would become cheaper than a combustion-engine vehicle of the same size was estimated to be 2026. Last year that closed to 2024, and he says the latest analysis suggests it’s now 2022 for large vehicles in the European Union.

That’s because the falling price of lithium-ion batteries means they account for a shrinking share of the total cost of a vehicle. While a few years ago they made up around half the price of a car, today they account for about 33 percent of the total cost, and that’s due to drop to about 20 percent by 2025. Those same dynamics are likely to see the range of electric vehicles broaden, says Bullard, to include battery-powered diggers and electric boats and planes.

And, with the emergence of the "transportation as a service" model affecting automobile use, global oil demand could decrease quite rapidly.

https://energi.media/markham-on-energy/electric-vehicles-will-kill-global-oil-industry-by-2030-says-stanford-economist-tony-seba/

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Electric vehicles will kill global oil industry by 2030, says Stanford economist Tony Seba
May 5, 2017 JZadmin Markham on Energy

Will the emerging electric vehicle “transportation as a service” business model kill the global oil industry in 10 years? Tony Seba thinks it will. The Stanford economist released a landmark study Thursday about the revolutionary changes soon to be wrought by electrification of the transportation sector.

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If EVs compete head-to-head as a replacement for internal combustion engine cars, then there are far more constraints than accelerators to adoption. And the effect of the constraints – high cost, range anxiety, lack of choice, etc. – is much more intense.

The replacement model argued for a traditionally gradual rise up the diffusion S-curve, perhaps reaching 70 to 80 per cent marketshare in 50 years.

But a business model disruption – like transportation as a service – that dramatically enhances the value of EVs to consumers is another animal altogether.

In Rethinking Transportation 2020-2030: The Disruption of Transportation and the Collapse of the ICE Vehicle and Oil Industries, Seba not only explains why the new business model disruption will triumph, and how its success will be so complete that by 2030 “95 per cent of US passenger miles traveled will be served by on-demand Autonomous Electric Vehicles (A-EVs) owned by companies providing Transport as a Service (TaaS).”

“We are on the cusp of one of the fastest, deepest, most consequential disruptions of transportation in history,” the RethinkX think tank founder says in a press release. “But there is nothing magical about it. This is driven by the economics.”

Economics that include:

    A-EVs engaged in TaaS will make up 60 per cent of U.S vehicle stock.

    As fewer cars travel more miles, the number of passenger vehicles on American roads will drop from 247 million in 2020 to 44 million in 2030.

    Using TaaS will be four to 10 times cheaper per mile than buying a new car, and two to four times cheaper than operating an existing paid-off vehicle, by 2021.

    The cost of TaaS will be driven down by several factors, including utilization rates that are 10 times higher; electric vehicle lifetimes exceeding 500,000 miles; and far lower maintenance, energy, finance and insurance costs.

    The average American household will save $5,600 per year by giving up its gas-powered car and traveling by autonomous, electric TaaS vehicles.

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And what of the mighty oil industry? The impact will be “catastrophic,” says Seba: “Global oil demand will peak at 100 million barrels per day by 2020, dropping to 70 million barrels per day by 2030. This will impact different companies and countries disproportionately — and in many cases, dramatically — depending on their exposure to high-cost oil.”

Here's a link to the report.

https://www.rethinkx.com/transportation




AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1897 on: November 13, 2019, 09:38:02 PM »
I note that DeConto and Pollard (2016) indicated that Totten Glacier (located in the Aurora Subglacial Basin) is susceptible to an MICI-type of ice mass loss this century, and the attached image from the linked reference shows that the Wilkes Subglacial Basin is interconnected with the Aurora Subglacial Basin.  Thus, if Totten Glacier were to sustain an MICI-type of collapse this century, it would likely undermine the ice in the Wilkes Subglacial Basin:

...



So to recap:

- AbruptSLR continues to confuse the timeframes of the original MICI models published in 2016
- The authors of the original MICI models now state that the 2016 projections were too pessimistic
- Other studies have shown that ice flows instead of fails in a brittle manner, which casts doubt on the mechanism needed for MICI to occur.
- Past sea level rise could have occurred without needing the MICI mechanism
- MICI needs hydrofracturing to occur before MICI can occur and yet there are areas in Antarctica where water flows off the ice sheet rather than penetrating through it to create hydrofractures
- Coal is now more expensive than solar and wind power and coal use is expected to peak next decade, so the emission projections of RCP 8.5 from the 2020s through 2100 aren't possible.

Ken,

It seems to me that the majority of your comments fall into a left-tail category with a few of your comments falling into the mode range of a relevant PDF; while my comments fall into a category of right-of-the-mode of a relevant PDF (related to deep uncertainty).  Thus, in the following I only provide brief responses that provide information/explanations supporting my right-of-the-mode interpretations

- AbruptSLR continues to confuse the timeframes of the original MICI models published in 2016

The first attached image is from the extended DeConto & Pollard (2016) projections that include some local ice-climate feedbacks.  In this image: AP = Antarctic Peninsula; ASE = Amundsen Sea Embayment, T = Totten Glacier; and TG = Thwaites Glacier.  Thus, while Totten is part of the Aurora Subglacial Basin, it is activated prior to 2100; in a similar fashion the authors choice to distinguish ASE, TG and the Interior WAIS, while they overlap portions of the Byrd Subglacial Basin.

Also, DeConto & Pollard (2016) assumed a grounding line retreat rate that was one-half of the maximum observed retreat rate for Jakobshavn Glacier.

- The authors of the original MICI models now state that the 2016 projections were too pessimistic

First, when DeConto & Pollard revised their 2016 projections it was with the caveat that they were applying an AR5/CMIP5 mode value for ECS; however, if they were to go back and apply an ECS value around 5C per many models for CMIP6 they would likely get higher projected ice mass losses than from their 2016 findings.

Second, per the following article, and associated Rignot et al (2019) reference, if DeConto when back and re-calibrated his model values for the EAIS to match Rignot et al. (2019)'s observed values; he would get significantly higher ice mass loss values at much earlier dates.

Title: "Polar Warning: Even Antarctica’s Coldest Region Is Starting to Melt"

https://e360.yale.edu/features/polar-warning-even-antarctica-coldest-region-is-starting-to-melt

Extract: "In January, Rignot and colleagues published a paper that looked back to 1979. Like the IMBIE study, they found an acceleration in ice loss over the continent as a whole: it went up six times over the four decades of their study. But, more strikingly, they could say that East Antarctica was a big player in that loss: from 2009 to 2017, they concluded, West Antarctica accounted for 63 percent of the continent’s ice loss, and East Antarctica accounted for 20 percent — more than the Antarctic Peninsula’s contribution of 17 percent.

In the face of rapid change and limited data, it is extremely challenging to predict what the Antarctic will do in the future. The models, says Rignot, “all have fundamental flaws. None of them are right.” Their resolution is coarse and they don’t include all the physics; plus they are lacking in critical input data. Very little is known, for example, about water temperatures and the seafloor shape off the coast of much of East Antarctica. That affects things like ocean currents and sea ice buildup, both of which affect glacier flow.

For now, DeConto says, his models show that “the East Antarctic is stable for a few decades, but in the high emissions scenarios it starts to become a player in the late 21st century.” But, he adds, “If I went back and put [Rignot’s] numbers in…” He trails off, waving his hands at the potentially large, unknown increase that would cause."

See also:

Eric Rignot, Jérémie Mouginot, Bernd Scheuchl, Michiel van den Broeke, Melchior J. van Wessem, and Mathieu Morlighem (January 22, 2019), "Four decades of Antarctic Ice Sheet mass balance from 1979–2017", PNAS, 116 (4) 1095-1103; https://doi.org/10.1073/pnas.1812883116

https://www.pnas.org/content/116/4/1095


- Other studies have shown that ice flows instead of fails in a brittle manner, which casts doubt on the mechanism needed for MICI to occur.

The other studies only indicate that ice flows like honey when given sufficient time; while I have provided numerous plausible scenarios over roughly the next ten years where ice cliffs with heights more than 100m over sea level could be abruptly exposed in the Thwaites gateway due to an abrupt collapses of the Thwaites Ice Tongue (as has been observed in recent decades) and the float-out of ungrounded icebergs between the base of the Thwaites Ice Tongue and the Thwaites gateway leading directly into the BSG.  In this regard, the second and third images show both how narrow the submerged ridge at the base of the Thwaites Ice Tongue is and how close to flotation the fractured glacial ice is in this narrow area; while the fourth image shows how slumping cliff failures would result in relatively shallow draft icebergs that could readily float-out to sea without becoming pinned.
“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 #1898 on: November 13, 2019, 09:40:47 PM »
I note that DeConto and Pollard (2016) indicated that Totten Glacier (located in the Aurora Subglacial Basin) is susceptible to an MICI-type of ice mass loss this century, and the attached image from the linked reference shows that the Wilkes Subglacial Basin is interconnected with the Aurora Subglacial Basin.  Thus, if Totten Glacier were to sustain an MICI-type of collapse this century, it would likely undermine the ice in the Wilkes Subglacial Basin:

...


So to recap:

- AbruptSLR continues to confuse the timeframes of the original MICI models published in 2016
- The authors of the original MICI models now state that the 2016 projections were too pessimistic
- Other studies have shown that ice flows instead of fails in a brittle manner, which casts doubt on the mechanism needed for MICI to occur.
- Past sea level rise could have occurred without needing the MICI mechanism
- MICI needs hydrofracturing to occur before MICI can occur and yet there are areas in Antarctica where water flows off the ice sheet rather than penetrating through it to create hydrofractures
- Coal is now more expensive than solar and wind power and coal use is expected to peak next decade, so the emission projections of RCP 8.5 from the 2020s through 2100 aren't possible.

As a continuation of my last post:


- Past sea level rise could have occurred without needing the MICI mechanism

The linked Rohling et al. (2019) reference represents some of the most refined paleo-assessments to date regarding the rate of ice mass loss during the Eemian (MIS 5e) era; and it indicates that under ice conditions similar to today (but with many times slower rates of radiative forcing as compared to modern times) glacial ice mass loss drove rates of sea level rise as fast as 2.8m/century (see the first image); which, indicates that MICI mechanisms may very well have been active during this period.  The second attached images shows how fast a grounding line can retreat with ice face geometries relevant to the BSB/Thwaites.

Eelco J. Rohling, et al. (2019), "Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand", Nature Communications,  10, Article number: 5040, DOI: https://doi.org/10.1038/s41467-019-12874-3

https://www.nature.com/articles/s41467-019-12874-3

Abstract: "The last interglacial (LIG; ~130 to ~118 thousand years ago, ka) was the last time global sea level rose well above the present level. Greenland Ice Sheet (GrIS) contributions were insufficient to explain the highstand, so that substantial Antarctic Ice Sheet (AIS) reduction is implied. However, the nature and drivers of GrIS and AIS reductions remain enigmatic, even though they may be critical for understanding future sea-level rise. Here we complement existing records with new data, and reveal that the LIG contained an AIS-derived highstand from ~129.5 to ~125 ka, a lowstand centred on 125–124 ka, and joint AIS + GrIS contributions from ~123.5 to ~118 ka. Moreover, a dual substructure within the first highstand suggests temporal variability in the AIS contributions. Implied rates of sea-level rise are high (up to several meters per century; m c−1), and lend credibility to high rates inferred by ice modelling under certain ice-shelf instability parameterisations."

Caption for the first image : "Identification of Greenland Ice Sheet and Antarctic Ice Sheet contributions to Last Interglacial sea-level variations. a Global Mean Sea Level (GMSL) approximation based on the probabilistically assessed KL11 PM (black line) and its 95% probability interval (grey). This record is shown in terms of RSL in Fig. 2f, but here includes the glacio-isostatic correction and its propagated uncertainty. Black triangles identify limits between which sea-level rises R1, R2, and R3 were measured. Rates of rise with 95% bounds: R1 = 2.8 (1.2–3.7) m c−1; R2 = 2.3 (0.9–3.5) m c−1; R3 = 0.6 (0.1–1.3) m c−1. b Blue: GrIS sea-level contribution from the model-data assimilation of ref. 9 (shading represents the 95% probability interval). Grey: GrIS contribution based on Eirik Drift δ18Osw. Uncertainties as in Fig. 2a. Orange: AIS contribution from subtraction of the blue GrIS reconstruction from the record in a. Green: AIS contribution found by subtracting the grey GrIS reconstruction from the record in a. Orange and green AIS reconstructions are shown as medians (lines) and 95% confidence intervals (shading). Reconstructed AIS contributions cross downward through a fine dashed when they fall below –10 m, which indicates a rough maximum AIS growth limit in terms of sea-level lowering (AIS growth is limited by Antarctic continental shelf edges). When the green/orange curves fall below these limits, North American and/or Eurasian ice-sheet growth is likely implied. The key result from the present study lies in identification of GrIS and AIS sea-level contributions above 0 m. c Southern Ocean ODP (Ocean Drilling Program) Site 1094 authigenic uranium mass accumulation rates, on its original, Antarctic Ice Core Chronology (AICC2012) tuned, age model. Dashed lines indicate potential offsets (within uncertainties) between the ODP 1094 AICC2012-based chronology36 and our LIG chronology (see refs. 10,19 and this study)"

- MICI needs hydrofracturing to occur before MICI can occur and yet there are areas in Antarctica where water flows off the ice sheet rather than penetrating through it to create hydrofractures

The third image shows currently how fractured the ice is at the base of the Thwaites Ice Tongue; which has not been included in any MICI or MISI model to date.  This image supports the right-tail idea that the fractured glacial ice between the base of the Thwaites Ice Tongue and the Thwaites gateway could simply float away without the need for hydraulic fracturing of either the Thwaites Ice Tongue or the ice leading to the Thwaites gateway.

- Coal is now more expensive than solar and wind power and coal use is expected to peak next decade, so the emission projections of RCP 8.5 from the 2020s through 2100 aren't possible.

First, the fourth attached image from Scripps shows that thru 2019 we are following RCP 8.5; and it is a matter of opinion when anthropogenic radiative forcing falls below this pathway.

Second, Hansen et al (2016) shows that if the WAIS were to collapse in the next few decades, the planetary energy imbalance would essentially double for several decades; which means that even if mankind becomes carbon neutral after 2040; we may still experience a cascade of Earth System tipping points.

“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 #1899 on: November 13, 2019, 10:03:19 PM »
Let's take a look at RCP 8.5.  Basically, all of the IPCC RCPs look very similar until the 2020s and then diverge rapidly in the rest of the 21st century.



So when you read that we are currently closer to RCP 8.5 then we are RCP 4.5 or RCP 2.6, it sounds pretty alarming.  However, we still have 80 years left in this century.



While I imagine that some readers benefit from your posts, it seems to that:

1. Many readers may very well take your posts on anthropogenic radiative forcing scenarios to mean that they have plenty of time left before they need to take effective action; and if this the case then your posts are increasing the likelihood that society will remain on, or close to, a BAU pathway than we would have without your posts, thus moving us away from the left-tail of the first attached image towards the right tail of that conceptual PDF.

2. If some of my observations about ice-climate mechanisms, and MICI-type of failure modes, prove correct then even if society becomes carbon neutral by 2040 a cascade of ice-climate feedback mechanisms could have a major impact on mankind anyway (see the second image)

Edit: The third image from Hansen et al. (2016) shows a representative temporary increase in planetary energy imbalance for a 5-year Doubling time; which is close to my assumed scenario where at least the Byrd Subglacial Basin sustains a MICI-type of collapse circa 2040.  Such a pulse of the planetary energy imbalance could conceptually trigger the ice-climate cascade illustrated by the second image.
« Last Edit: November 13, 2019, 10:44:30 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