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Author Topic: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications  (Read 29125 times)

AbruptSLR

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Both quantifying and dealing with the risk of abrupt SLR this century is typically not yet seriously addressed by the majority of the scientific community, policy makers, insurance companies, nor the general public.  While James Hasen (see accompanying figure, and note that such models as Rahmstorf et. al. 2011 do not address the risk of abrupt SLR this century) and others have warned of this prospect repeated, to date the decision maker have elected to place a high burden of proof of this prospect before they are willing to take action.  Nevertheless, the following two quotes from: "Communicating Uncertainties in Natural Hazard Forecasts" by Stein & Geller, EOS, Transactions, AGU Vol. 93 No 38, 2012, indicate that our current forecasting system is incomplete:

 (1) "One major challenge is that real uncertainties often turn out to have been underestimated.  In many applications, 20%-45% of results are surprises, falling outside the previously assumed 98% confidence limits [Hammitt and Shyakhter, 1999]. …. This effect arise in predicting river floods [Merz, 2012] and earthquake ground motions and may arise for the IPCC uncertainty estimates [Curry, 2011]."

 (2) "The Intergovernmental Panel on Climate Change (IPCC) [2007] report compares the predictions of 18 models for the expected rise in global temperature. … The report further notes that the models "cannot sample the full range of possible warming, in particular, because they do not include uncertainties in the carbon cycle."

Therefore, I am opening this thread to discuss the philosophical and theorical side of decision making to address the risks of abrupt SLR from the WAIS.

« Last Edit: February 25, 2013, 05:42:16 AM by AbruptSLR »
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AbruptSLR

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #1 on: February 25, 2013, 06:06:30 AM »
One of the most common criticisms of James Hansen's projections of 5m eustatic SLR by 2100 is that there was no clear cause and effect relationship demonstrating how the WAIS could collapse so quickly.  Given the complexity ice sheet modeling on top of the complexities of GCM modeling it is likely the case that society will not have clear deductive computer projections of the probability of the collapse of the WAIS before that collapse is unavoidable.  Therefore, much of the information presented in the various threads of this forum are in the form of the type of clear cause and effect relationships that could be used to perform a Hazard Analysis of this risks.  While the scenario presented in the "collapse" thread is as much intuitive as it is cause and effect relationships; nevertheless is one were to accept the feasibility of the scenario presented then one would derive the accompanying graphs for the regional SLR for California.  Rigorous generation of such curves could allow decision makers to both: (a) avoid wasting public money on ineffective defensive measures, and (b) provide better measures to guard against consequences that cannot be avoided by better controlling anthropogenic radiative forcing components in a timely manner.
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #2 on: February 25, 2013, 02:42:48 PM »
In the previous post I cited RSLR values for California (near San Francisco) so that the reader could compare to the accompanying NRC 2012 estimates of West Coast SLR projections and also to V&R's 2009 SLR projections (that also includes error bars for AR4).  It is important to note that the NRC 2012 SLR values are appreciably higher than the AR4 SLR values, and I suspect that the AR5 SLR values will be close to the NRC 2012 SLR values.  However, I also suspect that the AR6 SLR values will be still higher than the AR5 values.  This apparent trend for the IPCC to incrementally increase their SLR projections with each assessment report is counter productive with regard to preparing infrastructure to have resilient behavior under the actual SLR that may occur.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

MikeAinOz

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #3 on: February 26, 2013, 08:28:35 AM »
Hi AbruptSLR! I can see what your passion is! I am interested in what you are saying but find myself a little overwhelmed by the information that you have presented on the WAIS and it's potential for collapse. My first question is what will be the gateway events, are we already witnessing them? My opinion is that WAIS collapse is more a matter of when, rather than if, this will occur. What I would like to know is what will be the harbingers of the collapse, when will we know it is time to move to higher ground. Knowing sooner would be better, and knowing the events to watch out for may help trigger public response. What are your thoughts?
Mike Allen

AbruptSLR

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #4 on: February 26, 2013, 05:00:06 PM »
Hi Mike in Australia,

I agree that this topic has confused many people including the IPCC WG1 on SLR, and I will soon open a new thread to be more methodical about identifying what is confusing a majority of researcher on this topic (but it will that some weeks due to the amount of confusion).  But to give a brief overview view now I subscribe to the position that the Thwaites Glacier (TG) is the "soft underbelly" of the WAIS, and yes I believe that TG is in the initial stages of ramping-up to exhibit a new behavior that will be the first signal that the majority of researchers will not be able to ignore (as the IPCC AR4 and the IPCC SOD AR5 have ignored) the risk of abrupt SLR.  In general terms what you should look for (in reference to the attached figure) is: (a) over the next five to ten years, the combination of the extention of the TG subglacial cavity due to CDW advection and periodic outbursting of the subglacial melt water network (causing surges of the TG resulting in thinning of the gateway ice thickness leading to floatation of the associated thin ice), while gradually expand the gateway to the East causing the ice flow velocities to expand to the East; and (b) this will cause the ice velocities across the current 50 km wide gateway to accelerate to about 4 to 4.5 km/yr.  When this happens you can be sure that the grounding line will retreat across this 50 km width creating a short ice shelf (replacing the current ice tongue), and as shown in the "collapse" thread this ice shelf will have extended to the branching location for the TG subglacial melt water network by 2040 at which point the collapse of TG will be unavoidable and its collapse will accelerate ice loss from the PIG drainage basin through the TG gateway (see the yellow line in the accompanying figure).
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #5 on: February 26, 2013, 06:00:07 PM »
Lennart,

When I referred you to this "philosophical" thread, I realized that I had not previously posted my proposed PDFs and CDFs for Maximum Credible inundation design Events, MCE, associated with RSLR for California for the years 2070 and 2100.  I prepared these for camparison with the NRC 2012 projections for California RSLR and it is my believe that such curves should be used to check the design of exposed infrasture against these MCE curves to check for resilient (or adaptive) behavior.  Please note that due to the nature of uncertainty these curves shift to the right and broaden out the further you go into the future (from a hazard analysis point of view); while the A&B 2013 curves that you referred to in your "collapse" scenario post is only for the present time.  Also, note that the PDFs and CDFs presented in this post are mathematically consistent with the other curves I posted a few days ago for RSLR in California
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #6 on: February 26, 2013, 08:18:56 PM »
Before I open two new threads (for now) on: (a) a critique of the methodology for Pfeffer et al 2008, the NRC 2012, and the IPCC WG1 SOD SLR reports; and (b) projection of the identified "surge" behavior PIG/Thwaites Glacial Basin system ice mass loss into the 2040-2050 timeframe;  I would like to briefly present the two accompanying figures related to a study that the Port of Las Angeles, POLA, hired the Rand Corporation (and PennState) to assess the risk of abrupt SLR on the port's facilities.  The first figure indicates how Rand/PennState used statistical techniques to extend the pdf's from both Pfeffer et al 2008 and Co-CAT (a task for for the Californina Office of Ocean Protection) to include the risk of abrupt SLR (assuming that the abrupt SLR will follow a parabolic function which the researchers expand using staticial techniques) resulting in finding such as shown in the second figure which indicates probabilities vary much in keeping with the probabilities of abrupt SLR that I present above as a MCE resiliency check case.  This is an important concept because currently SLR guidance such as those presented by Pfeffer et al 2008, NRC 2012 and IPCC WG1 SOD on SLR do not include any allowance for the risk of abrupt ice mass loss from either GIS or AIS (but NRC 2012 and IPCC  SOD include some fraction of SLR contribution from both GIS and AIS, but not of an abrupt nature), while the Rand/PennState work gives an idea of what would happen if this abrupt SLR ice sheet (IS) contribution were to follow a parabolic function (as included in USACE SLR guidance) as Hansen and Sato have repeated advised that such abrupt SLR IS contribution will be nonlinear.
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #7 on: February 27, 2013, 04:52:42 PM »
Accompanying is an IPCC table to relate researcher's GCM projections confidence levels into language for the AR5 report now being written.  Using such language the IPCC notes that GCM temperature projections for RCP 8.5 are very unlikely to occur; which gives the impression to the general public that they do not need to worry much about this business as usual, BAU, case that we have been exceeding since the early 1980's; which supports the moral hazard that why should the general public press their public representative and associate authorities to try to prevent a radiative forcing scenario that the scientists have already assured them that is "very unlikely" to occur (as this would apparantly waste the public's money).  Therefore, I believe (as stated in the "collapse" post, that it is imperative that the scientific community (including the NRC and the IPCC [see the thread on "critique of common SLR guidance]) formally recognize the risk of abrupt SLR by creating maximum credible (slr) events, MCE, design check cases to verify that new and existing coastal infrastructure has sufficient resiliency to meet the level of protection that the public expects.  I believe that a hazard analysis (with which I produced the MCE curves for California posted earlier in this thread) is sufficient therefore sufficient to establish such MCE design check loading cases, and that there is no need to wait the many decades that it would take to upgrade GCM ice mass loss projection sufficient to project the possible collapse of portions of the WAIS this century.  In this regard I believe that ensuring resiliency is better than prescience, and that as it will take time to adaptively engineer resiliciency into our affected infrastructure that the sooner that we get started the better.  Additionally, the public should be advised that they cannot rely on insurance or government support to adequately guard them from the magnitude of damages that might result from abrupt SLR but that resilient infrastructure should be part of any future public policy, as say for example an appropriate storm surge barrier for New York Harbor could have prevented tens of billions of dollars of flood damage that occurred to to Superstorm Sandy (and climate change may likely direct more hurricane to follow a similar path, which if combined with SLR could prove to have severe consequences for such coastal areas in the future).
“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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I note here that some of what I had intended to post here I put into my various reponses to Lennart in the "collapse" thread, but after I finish my expected series of posts explaining my hazard analysis for the potential collapse (or patial collapse) of the WAIS by 2100 (which will take several days at least), then I plan to return to this thread to discuss why it is that it is difficult for our current process to both seriously examine the thickness of the tail of the probability density curves for such extreme events and as to why it is difficult to translate such an evaluation of this risk of such an extreme event (which researchers have been aware of for over thirty years) into effective policy for adaptive engineering to address the consequences of such extreme event (assuming that policy maker fail to adequately control anthropogenic radiative forcing to prevent such a collapse, for which I assume the required input of RCP 8.5).
« Last Edit: March 03, 2013, 11:15:16 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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For those of you who prefer numbers (as compared to the curves that I posted previously in this thread) I provide the accompanying table of factors that were used to estimate the RCP 8.5 5%, 50% and 95% CL RSLR projections for California for 2070 and 2100.
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #10 on: March 03, 2013, 11:53:15 PM »
The following are a few selected philosophical observations:

- While I agree that it would be better to control radiative forcing (and better still to have started to control radiative forcing over 30-years ago when the seriousness of the climate change issue was first publically recognized), it would seem that in the debate regarding the control of radiative forcing that the parties that care the least exert the most influence per capita as illustrated in the accompanying figure. 

-  Therefore, to me with regard to the risk of abrupt SLR from the potential collapse of the WAIS it appears inevitable that we are entering "the age of consequences, and in this regard I provide the following four philosophical lessons learned from this WAIS collapse hazard analysis include:
•   Authorities need to refocus attention from the mean/mode projections to the fat-tailed end of the Probability Density Functions, PDFs, associated with RSLR design, in order to at least acknowledge the abrupt SLR risks that we are facing rather that to keep cutting off the tail of the SLR PDF when making policy decisions.
•   Authorities need to more carefully consider the thermal inertia of the ocean which is keeping the global-mean surface temperature relatively low at the moment at the cost of roughly 50-years of guaranteed continued significant levels of SLR beyond the time when the combined anthropogenic and natural radiative forcing is brought into equilibrium.  When this is correctly evaluated policy makers will recognize that there is no time to spare before making decisions consider the amount of time it will take to control radiative forcing and then the time for the ocean to reach substantial equilibrium.
•   When authorities evaluate the risk of abrupt SLR they need to carefully consider the fact that the current rates of radiative forcing are one hundred to one thousand times faster than for any period in the past several hundreds of millions of years; which, will create thermal imbalances around the planet leading to extreme weather events and dynamic ice mass loss that can iteratively ratchet the global's former quasi-static equilibrium condition into higher levels of non-stationary risk.  Furthermore, they need to recognize that short-term weather related SLR (such as the storm surge from Superstorm Sandy) needs to be combined with the future abrupt SLR conditions/risks, when making decisions.
•   Authorities need to understand that given our current non-stationary global condition no current GCM projections will adequately match what will happen in the future (with regard to abrupt SLR) and that the use of a supplemental hazard analysis (on top of the GCM projections) in order to evaluate the level of risk that we need to check infrastructure for adequate resilient behavior especially for the risk of abrupt SLR.
•   Authorities need to appreciate that as definitive information with regard to the risk of abrupt SLR will not be available before the consequences are actually occurring, and that as future civil laysuits for damages from the consequences of abrupt SLR will be decided upon a 50% probability that the authorities could have made timely decisions in order to resiliently guard the public; therefore, they need to learn to use "Robust Decision Making" in order to make appropriate decisions based on partial information (as is done both: (a) in the fog of war; and (b) by juries deciding civil liability for damages due to abrupt SLR).
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #11 on: March 04, 2013, 08:35:03 PM »
As a follow-up to my previous post I would like to note that my hazard analysis uses inductive logic and that the philosopher C. D. Broad once said that:

"Induction is the glory of science and the scandal of philosophy."

Thus indicating that it possible to creatively use inductive logic to identify new trends (like the risk of abrup SLR), but that it can be difficult separate correctly identified new trends from the scandalous speculations of biased parties who postulate self-service scenarios of alternate possible trends; and while the "scientific method" is good at sorting out the wheat from the chafe, the "scientific method" is slow and it is possible that the consequences of abrupt SLR will be upon the world before we have a check to take precautionary measures; unless we accept the results of hazard analyses in order to establish limit states for checking resilient behavior for out infrastructure that is at risk.
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #12 on: March 05, 2013, 06:38:07 PM »
The first image from Roe and Baker 2007 shows how a thin tailed probability density function, PDF, subjected to positive feedback is transformed into a fat tailed PDF (in this example for global surface temperature).  The second image from Roe and Armour 2011 shows how when multiple fat tailed PDF are combined they result in a PDF with a still fatter tail.  For estimating the risk of abrupt SLR from the potential collapse of the WAIS this century, there are so many postive feedbacks for both radiative forcing, ocean heat uptake, and ice mass loss, that it is highly believable that the PDF for the total combined risk of abrupt SLR has a much fatter tail than most people who are used to working under thin-tailed PDF conditions are currently prepared to exist.  If one thinks of a thin-tailed PDF as a lion chasing a herd, then the tradional herd mentality is that you do not have to be the fastest runner in the herd to be safe, all that you have to be is faster than the guy next to you.  However, this line of conventional wisdom does not work so well if you think of a fat-tailed PDF as a pride of lion, inwhich case just being faster than the guy next to you is not enough, and one would wish that in accordance with the "Precautionary Principle" that when faced by at fat-tailed PDF (or a pride of lions), that one had made an advance resilient response plan with all of your fellow herd members.
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #13 on: March 08, 2013, 03:48:53 PM »
While it has been pointed out perviously by numerous commentators, but in terms of the previous herd analogy: among the slowest members of the herd are not only the weak but more importantly the young; and exposing our young to a pride of climate change related lions without a very clear resilient defensive plan of action, is morally irresponsible.
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #14 on: March 12, 2013, 11:57:19 PM »
The Hazard Assessment methodology that I used has several key aspects similar to those of the "Black Swan Theory" (BST) regarding how to address "outliers" (unpredictable events) for which most people generally tend to find simplistic explanations for, either retrospectively (in historical cases such as WWI or 9/11), or presumptively (in future case such as developing guidance and projections for RSLR).  The BST evolved from observations made by the epistemologist Nassim Nicholas Tabeb in his popular book The Black Swan: The Impact of the Highly Improbable.  As with my hazard assessment, the main thrust of the BST is not to attempt to predict Black Swan Events, but rather to build robustness measures for negative consequences while being prepared to exploit positive consequences.

Tabeb's position is that a Black Swan Event depends on the observer, and he uses a simple example, what may be a Black Swan surprise for a turkey is not a Black Swan surprise for its butcher, hence the objective should be to "avoid being the turkey" by identifying areas of opportunity in order to "turn the Black Swans white".  In order to help "avoid being the turkey" Tabeb focuses on a single idea: "our blindness with respect to randomness, particularly large deviations."  Without special training most people are ill equipped to properly assess both uncertainties and risks associated with complex systems.  Consequently, most people classify the "fat-tailed" probability distribution risks associated with climate change in the same category of "thin-tailed" probability distribution risk such as those associated with meteor strikes, or other remote catastrophic events.  This is unfortunate as many policymaker respond to the concerns of the majority of their constituents.  The constituents' lack of proper understanding of the true risks of climate change has delayed the timely implementation of effective RSLR guidance and precautions.  Establishing a network governance system would be a major step in overcoming this challenge of decision making for this complex matter.

Tabeb describes history as opaque, essentially a black box of cause and effect, where one sees events go in and events go out, but where one has no way of determining which produced what effect.  Historically, rare and improbable events do occur much more than we dare to think.  Our thinking usually is limited in scope and we make assumptions based on what we see, know, and assume. Reality, however, is much more complicated and unpredictable than we prefer to think. Also, assumptions relevant to average situations are less relevant to irregular situations, especially when the "rules of the game" themselves are changing, as is the case with climate change.  Furthermore, extreme events do happen and have a great effect. The effects of extreme events are even higher due to the fact that they are unexpected.  In this regard, while NRC 2012 correctly note that one must be careful when extrapolating non-linear projections of RSLR; nevertheless, my hazard assessment methodology just as correctly notes that it can be equally hazardous to close ones eyes to potential Black Swan Events (such as abrupt RSLR from a potentially rapid collapse of the WAIS this century) , and that doing so seriously eroded both public, and economic, confidence following extreme flood events such as Hurricane Katrina and the Fukushima Tsunami.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

TerryM

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #15 on: April 14, 2013, 05:54:31 PM »
Probably in the wrong thread, but i thought it interesting that Al Jazeera, funded by governments with a large stake in fossil fuel, has a good article about rising Antarctic temperatures.
http://www.aljazeera.com/weather/2013/04/201341493439476979.html


Terry


AbruptSLR

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #16 on: April 14, 2013, 07:07:18 PM »
Terry,

Thanks for the link.  As Al Gore sold his media company to Al Jazeera recently, it is not surprising that they would post a reasonably good article focused on the Antarctic Peninsula.  That said, I found their discussion of Antarctic sea ice to be reasonable but overly simplified (which could give most readers the wrong impression about the distribution of ice meltwater around the surface layers of the Southern Ocean).  Nevertheless, the information about the ice core data was new to me.

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

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #17 on: April 14, 2013, 08:16:03 PM »
Ice cores on GIS go back to near the end of the Eemian and that period is recent enough to leave a lot of other traces to give us a good picture of those times. Hardwoods on the island of Scandanavia and hippos in the Thames and Rhine just don't lie. That tells me if there are concerns about abrupt SLR from WAIS, the ice cores would have data beyond a philosophical discussion or you could say my philosophy is it's a project important enough to fund for national security reasons. The Dye 3 site on Greenland shows evidence of glaciation on Greenland during the Eemian, which suggests it only contributed 2 m to the 4 to 6 m of sea level rise.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2694912/

Considering the US built the largest Naval Base in the world in an area subsiding from a 35 million year old bolide event, it might be a good idea for the DOD to fund the ice cores and some studies on the rapid melting of glaciers. That information may show it's wise to shift operations somewhere else in the future or build things in ways that can be more easily adapted to future SLR changes.

AbruptSLR

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #18 on: April 14, 2013, 08:39:49 PM »
Ggelsrinc,

Due to the importance of the RICE project I will make two posts in order to provide the entirety of an internet article on this topic which uses an ice core from Rossevelt Island in the Ross Sea Embayment to examine the risk of abrupt ice mass loss from the WAIS:

"Christmas came early to a remote corner of Antarctica last year. After two summers of drilling, the 12-member crew of the Roosevelt Island Climate Evolution Project (RICE) finally made it through nearly 800 metres of solid ice, to bedrock, on December 20, 2012.
In doing so they had, figuratively speaking, travelled back in time more than 100,000 years, to the Earth’s last interglacial period, when the Earth’s ice caps receded and global sea levels rose.
The nine-nation team had spent three months in this remote location on the Ross Ice Shelf — a white expanse roughly the size of France — sleeping in tents, working laboriously in layers of extreme-cold-weather clothing, enduring the regular storms that make even an Antarctic summer a savage environment.
If they toasted their breakthrough, however, it was not without the knowledge that their findings could be cause for anything but celebration.
Because contained within the solid ice cores — which they had painstakingly extracted with the drill rig — lies information that could support a hypothesis that large parts of the frozen continent are more delicate, more dynamic and changing more rapidly than previously thought.
The ice cores are right now locked within two super-refrigerated containers onboard the last ship out of McMurdo Sound before the Antarctic winter closes in, and due to arrive in New Zealand in early March.
It is all precious cargo, but there is one sample that is of particular interest. When the very last ice core was drawn up from a depth of 763 metres, it showed imprints of the sediment on which it had been resting. The team sent the drill down one more time and managed to draw up a little of this sediment — which has the consistency of frozen mud.
The RICE team believes there is a strong probability it will turn out to be marine sediment, most likely from the interglacial period before the last ice age, 105,000 to 130,000 years ago, when temperatures were only a little higher than they are today.
If confirmed, it would mean Roosevelt Island was under water during that interglacial phase. This in turn would mean the Ross Ice Shelf was much smaller than it is today, or had in fact disappeared altogether. The huge West Antarctic ice sheet behind it would have been significantly smaller too.
“Of course,” says ice-core climatologist and RICE project leader Nancy Bertler, “that would mean we are far more susceptible to change than we might think.”
In other words, the pace and scale of Antarctic melting — and therefore the kind of rise in sea levels we all fear — could happen much faster than previously imagined.

COASTAL ICE CORE RESEARCH IS RELATIVELY NEW. Previously, scientists believed the great Antarctic interior, where the ice sheet can reach depths of 4 km, would yield the most useful results.
But in the coastal regions, where the sheet is thinner and the records correspondingly shorter, the cores have provided a complementary picture to those from the interior. “Being at the coast is right at the interface between the ocean and the atmosphere and the ice sheet. This is really where the change is most visible.”
The Roosevelt Island site, then, provides a measure of climatic conditions from the last interglacial period to the present. Within the past 30,000 years of that span, from the end of the last ice age to now, the Earth has experienced a temperature increase of about six degrees. That was enough to melt ice sheets in the northern hemisphere and cause the Ross Ice Shelf to contract up to a thousand kilometres southward to its present perimeter.
As a consequence of this melting, sea levels rose and the big West and East Antarctic ice sheets thinned a little. Throughout this period, Roosevelt Island has been quietly recording a year-by-year snapshot of global warming.
The data extracted from the ice cores will allow the historical CO2 record to be reconstructed, atmospheric and sea-surface temperatures to be calculated, and the sea-ice extent to be estimated. “It allows us now to establish how quickly the Ross Ice Shelf can react to warming and how quickly it retreats because of that warming, both in the ocean and in the atmosphere,” says Bertler.
Roosevelt Island sits at one edge of the Ross Ice Shelf. At the other edge lies Ross Island, home to New Zealand’s Scott Base, which serves as the transport and provisioning hub for the RICE expedition. The $NZ7 million project is a massive logistical operation, involving the transport of some 200 tonnes of cargo 600 kilometres across the ice to the drill site.
At the heart of the site lies a 30-metre-long trench, 10 metres at its deepest point, dug out with chainsaws and shovels. A small complex of caves off to the side serves as storage for the ice cores once they have been hauled up.
Inside the trench and beneath a sheltering tent sits the rig itself, purpose-built for the conditions and with a new hydraulic system designed to break off each ice core sample as cleanly and gently as possible.
According to Bertler, there was some initial skepticism from veteran ice-core drillers about the hydraulic innovation, but it proved ideal for coping with the peculiarities of Antarctic ice.
That is, when under intense pressure beyond a depth of a few hundred metres, Antarctic ice becomes what is known as “brittle ice”. The tiny bubbles of prehistoric atmosphere within — vital for analysing the climatic conditions when they were first formed — react dramatically to even the slightest warming.
Place a sample in your hand, for instance, and it may explode with a radius of several metres. “Imagine when you send an electro-mechanical drill down, then you pull with almost a tonnne of weight on it,” explains Bertler. “Very often this brittle ice comes up in bags rather than cores.”
The ice at Roosevelt Island may be tricky to extract, but it offers a clear window into our planet’s weather history. The island — to the naked eye nothing more than a large rise in the white expanse — is one of the “pinning points” of the Ross Ice Shelf (the other being Ross Island). That is, it anchors the mass of sea ice within the Ross Embayment.
The regular storm tracks that circle Antarctica inevitably penetrate the Ross Sea and the ice shelf, which means Roosevelt Island is a veritable databank of snow precipitation. “And this is our business,” Bertler says. “We read snow. We turn this into climate records.”"


“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #19 on: April 14, 2013, 08:41:55 PM »
Here is the rest of the article (which will be my 300th post on this topic):


"THE RICE PROJECT WAS IN PART DESIGNED TO SOLVE A MYSTERY left by a previous New Zealand-led drilling project, known as Andrill. Andrill involved the exploration of Antarctic marine sediment from the mid-Pliocene period, about three to five million years ago, and it showed that at some point during that epoch the entire Ross Ice Shelf had disintegrated.
The mid-Pliocene is important because we have to go that far back to find atmospheric CO2 concentrations equivalent to those of today. At about 400 parts per million (ppm) they were slightly higher than our 397 ppm, and the temperatures were slightly warmer than we’re experiencing now. But human activity is increasing current CO2 levels by about two ppm per year, with temperatures following close behind — suggesting we are rapidly approaching a known tipping point.
As Bertler points out, the collapse of the Ross Ice Shelf would have been dramatic in itself, but because the shelf is made of sea ice it already displaces its own mass and does not affect sea levels. However, what Andrill also showed was that the whole West Antarctic ice sheet had collapsed.
While the West Antarctic ice sheet is smaller than the East Antarctic sheet, it still contains more than two million cubic kilometres of frozen fresh water. The ice mass is so heavy it depresses the underlying rock by up to a kilometre.
When it previously collapsed — in conditions which also caused the northern hemisphere ice sheets to melt, and the margins of the East Antarctic sheet to collapse — global sea levels rose about 20 metres. “That’s very significant, obviously,” says Bertler with admirable understatement.
What Andrill couldn’t show, due to the much lower resolution of sedimentary records, but what RICE is expected to reveal, is how quickly the sea ice retreated or the ice sheet collapsed. It might have taken anywhere between 50 and 500 years — the blink of an eye in geological terms.
Such a broad margin of error poses huge problems for policy makers, who need more accurate predictions when planning for the potentially alarming consequences of multi-metre rises in sea level. “This is where Roosevelt Island comes in,” says Bertler.
As she puts it, ice contains a “memory” within its compressed crystals that we can now recover and interpret, to determine not just what happened in the past, but what will happen in the future.
There are many variables influencing these major climate shifts, from the Earth’s elliptical orbit around the sun to the feedback loops created by ocean warming or ice-sheet accumulation.
And we are only now beginning to understand the true relationship between atmospheric CO2 levels and rising temperatures. As the New York Times recently reported, more sophisticated ice core analysis suggests there is a much closer link than previously argued by some climate change sceptics.
By reconstructing a past that is comparable to our present, Bertler explains, we can “train” our computer climate models to accurately “predict the past”, which in turn will give us more confidence in their ability to forecast future climate conditions.
This is the huge advantage ice cores have over Andrill’s sedimentary record. “We can read the cores like a seasonal diary. So we can tell you exactly what a summer 29,000 years ago looked like in this area.”
The cores’ records aren’t quite as obvious to the eye as the rings of a tree, but are as clear as day to scientists with the right measuring equipment. Bertler: “You see wonderful oscillations, you see warmer and colder temperatures from summers and winters, you see marine air masses dominating during the summer, the sea ice extent that has its maximum sometime in August then reduces to its minimum in January or February. We can see those things for each year, every year, in the ice-core record.”
The RICE research, like the other ice-core projects around Antarctica, exists in the context of a rapidly expanding field of knowledge about the West Antarctic ice sheet’s recent, disconcerting behaviour. Satellite imagery now shows the ice sheet has a negative “mass balance”; that is, the rate of melt is outstripping the rate of snow precipitation, and therefore West Antarctica is losing mass very quickly.
At the inaccessible and inhospitable Amundsen Sea Embayment, the massive Pine Island Glacier, which drains about 10 per cent of West Antarctica’s ice sheet directly into the sea, has been moving faster and thinning out over the past decade, as has the nearby Thwaites Glacier.
Because much of the ice sheet is grounded on rock thousands of metres below sea level, the danger is that sea water will eventually pour in over the lip of the continent and effectively float the ice above it.
“At the moment,” says Bertler, the loss of mass balance “is all due to melt ice being transported into the ocean. But if the water reaches underneath, as soon as you lift that mass, you increase the sea level by the equivalent of that mass.” Such a lifting of the entire West Antarctic sheet “could cause a five- to seven-metre rise in sea levels, but just the Pine Island area [could] raise levels by one to two metres”.
At the same time the Southern Ocean is absorbing more CO2, and warming faster and to a greater depth than previously imagined. Instead of only the first hundred or so metres of water being affected, temperatures have risen at depths of up to 3,000 metres. The increase might be very small (0.2 degrees Celsius in a decade), but the amount of energy required to warm such a vast body of water is huge. The fact that the ocean is absorbing so much of the warming also explains why atmospheric temperatures haven’t risen as steeply as might have been expected.
“In the short term that is really great,” Bertler suggests, “because it buys us a little time. But in the long term it is really bad. The ocean has a very long memory, and the warmth we are currently putting into the ocean will be with us for a very long time. So we are committed to that for many generations to come.”
Pine Island is one indicator of the possible consequences of this warming. Back at Roosevelt Island, the same rules apply for the Ross Ice Shelf. “If you put warm water under an ice shelf, ice shelves don’t like that. They warm rather quickly and melt quickly from underneath. You can’t see that until it collapses.”
In May this year representatives from all the RICE member nations will arrive at the New Zealand Ice Core Research Facility in Wellington to begin analysing the ice cores from Roosevelt Island. Working around the clock and using an ultra-pure nickel disk to melt each sample, they will begin with the most recent cores and work back (or down) towards the past. Hundreds of thousands of measurements will be taken to reveal the history of this surprisingly sensitive and dynamic part of the planet.
But that crucial sample of frozen mud from the surface of the sub-glacial rock will be analysed much more quickly, hopefully by mid-March. If, as the researchers have hypothesised, it turns out to be marine sediment, it will be yet more evidence of the potentially alarming implications of global warming."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

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Re: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #20 on: April 14, 2013, 10:47:00 PM »
I wouldn't expect to find glacier ice on Roosevelt Island older than the Eemian. It's only 550 meters above sea level. The evidence points to WAIS contributing to SLR during the Eemian, but it hasn't been proven. Hardwood trees on the island of Scandinazia were mentioned with a link about trees on southern Greenland from ice core analysis. There is fossil evidence of trees on Baffin Island during that time. You have to be an ambitious hippo to go to England when the sea level was 4 to 6 meters higher. The ice cores on Greenland only go back to around 110,000 years, but it's possible some glaciers still existed. If the sea level estimates are correct, some water had to come from somewhere and WAIS is the logical choice.

As for Andrill, the mid-Pliocene was before North and South America connected, meaning the Earth's thermohaline circulation is so different that CO2 comparisons are meaningless without changing the CO2 climate sensitivity. There was a circum-equatorial current back then which made the Atlantic much warmer. Greenland didn't have an ice sheet. There was no modern Gulf Stream and Africa was colliding with Europe. The Earth was slowly cooling and getting dryer. Tropical rainforests were limited to narrow zone around the equator and savanahs were forming. They claim it moved our ancestors out of the trees. The Pliocene is a fascinating time of major climate changes and since it's so recent, we have good records. The times between mid-Pliocene and today are so different, it's like comparing two different worlds. Look what a thermohaline circulation change did to temperature during Younger Dryas!

$7NZ million equals $6US million. Considering the hundreds of billions of dollars involved in future navy expenditures, paying for a half dozen ice cores projects isn't a bad idea. They could use some military personnel and consider it cold weather training and a military exercise to further cut costs. They should be able to prove whether WAIS was there or not during other interglacials.

AbruptSLR

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Getting philosophical again, I note that Kelly and Tan, 2011 & 2013, have built a preliminary integrated assessment model to test how fat tails (for temperature change PDFs) due to uncertainties in the climate system affect economic growth, and examine whether and how fast uncertainties could be diminished through Bayesian learning.  This research finds that if the climate system is close to equilibrium then Bayesian learning will quickly provide evidence against fat tail uncertainties; while if the climate system is not close to equilibrium (implying that true climate sensitivity is high) then Bayesian learning occurs more slowly, and the implications of a fat tail on the demand loading distribution would have a significant increase in the risk of failure.   Weitzman, 2009, argues that fat tails reflect the "deep structural uncertainty for the low-probability, high-impact catastrophes" and that: "… It is inherently difficult to learn from finite samples alone enough about the probabilities of extreme events to thin down the bad tail of the PDF because, by definition, we don't get many data point observations of such catastrophes".  The uncertainty about the reality, or non-reality, of the fat tail PDF appears to be one of the fundamental issues behind the difficulties that policymakers have regarding the determination of cost effective policy to address SLR.  Therefore Kelly and Tan (2011 & 2013) propose to use Bayesian learning about the climate feedback parameter, to address this fat tail issue.  Unfortunately, several decades of observations have not yet thinned the fat-tail of climate change uncertainty; and it is likely that society will be slow to accept/learn the true risks of abupt SLR this century.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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In the "Liability" thread I noted that many deniers rely on "plausible deniability" about abrupt climate change (and abrupt SLR, ASLR) in order to justify ignoring the risks associated with these possibilities.  Indeed, such deniers frequently state that abrupt climate change and ASLR would be a Black Swan event, and thus by definition would be unpredictable and thus not anything that a policy maker should consider.  However, I point out here that if such abrupt behavior occurs, jury members in any civil liability cases will likely look back on the wealth of scientific evidence available at this time (such as that cited throughout this Antarctic folder) regarding the true risk of ASLR and they will likely decide retroactively that there was a "preponderance of evidence" that the policy makers should have followed the precautionary principle to safeguard the public.  Furthermore, the recommendations in the "Novel" thread provide such policy makers with time stamped practical options to deal with the risk of ASLR, that such jury members may note that the policy makers willfully disregarded.

Indeed, James Hansen has warned widely of the Faustian Bargain that such policy makers are currently exposing society to, due to temporary "masking" effects that such deniers are using as "plausible deniability" of the true risks including such "masking" factors as:
- Smog, primarily in Asia and Africa, that is temporarily reflecting solar irradiance, but which when cleaned-up will leave behind the associated CO2 in the atmosphere from the fossil fuels burned to create the smog in the first place.
- The biomass that is currently absorbing up to about 50% of anthropogenic CO2 emissions, but which are projected to wither with increasing global warming; which would then release this temporarily sequestered CO2 back into the atmosphere.
- The relative high current rates of heat uptake by the ocean which is reducing the rate of increase of atmospheric warming; but which will guarantee hundreds of years of future SLR.
- The latent heat of both the Northern Hemisphere permafrost and of the Arctic Sea Ice, may be a small fraction of the heat uptake by the oceans; but they are temporarily guarding the world from the more serious consequences of CO2 and methane emissions from the permafrost and of albedo flip from the Arctic Ocean.

Hopefully, denier policy makers will soon see that "plausible deniability" is an illusion and they will take steps to address climate change and adaptive engineers for the consequences that are already to late to avoid.
“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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I thought that I would note that in order to reduce the consequences of abrupt sea level rise, ASLR, individuals within areas subjected to a common risk of future inundation will likely need to band together in order to form local flood authorities to build, maintain and operate flood defense systems; as I doubt that central governments will have the political will to address these risks at the national levels.  Unfortunately, this local approach will likely leave poorer areas exposed to inundation unless they band together early enough (now) to at leave begin planning measures for ASLR risks.
“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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I would like to remind some readers that my many posts related to the risks of abrupt SLR, ASLR, are presented as part of a hazard analysis rather than as part of a formal projection, or prediction of SLR this century.  In this regard, I am focusing on the risks to coastal infrastructure/populations beyond the normal design levels; which implies that my findings are more suitable for use in resilience analyses for a future maximum credible sea level rise event, that needs to be combined future maximum credible storm surge and related short-term SLR events.

Currently, areas such as New York City and New Orleans are conducting resilience analyses largely without evaluating the risks of ASLR from the potential collapse of the WAIS this century.  Therefore, if resilience measures taken in these areas are copied around the nation, or world, it is possible that the measures taken will have been of marginal value.  Therefore, I recommend that policy makers at least require designers to consider what adaptive measures could be taken to deal with a maximum credible sea level rise event associated with the potential collapse of the WAIS this century.
“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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I could not resist posting the following extracts (indicating that the military can acknowledge risks that many scientists, and policy makers, currently are not) from:

http://www.guardian.co.uk/environment/2013/jun/30/climate-change-security-threat-envoy

"Climate change poses grave threat to security, says UK envoy
Rear Admiral Neil Morisetti, special representative to foreign secretary, says governments can't afford to wait for 100% certainty
Climate change poses as grave a threat to the UK's security and economic resilience as terrorism and cyber-attacks, according to a senior military commander who was appointed as William Hague's climate envoy this year.
In his first interview since taking up the post, Rear Admiral Neil Morisetti said climate change was "one of the greatest risks we face in the 21st century", particularly because it presented a global threat. "By virtue of our interdependencies around the world, it will affect all of us," he said.

Morisetti's central message was simple and stark: "The areas of greatest global stress and greatest impacts of climate change are broadly coincidental."
He said governments could not afford to wait until they had all the information they might like. "If you wait for 100% certainty on the battlefield, you'll be in a pretty sticky state," he said.
….
Morisetti is far from the only military figure emphasising the climate threat to security. America's top officer tackling the threat from North Korea and China has said the biggest long-term security issue in the region is climate change.
In a recent interview, Admiral Samuel J Locklear III, who led the US naval action in Libya that helped topple Muammar Gaddafi, said a significant event related to the warming planet was "the most likely thing that is going to happen that will cripple the security environment, probably more likely than the other scenarios we all often talk about".
There is a reason why the military are so clear-headed about the climate threat, according to Professor John Schellnhuber, a scientist who briefed the UN security council on the issue in February and formerly advised the German chancellor, Angela Merkel.
"The military do not deal with ideology. They cannot afford to: they are responsible for the lives of people and billions of pounds of investment in equipment," he said. "When the climate change deniers took their stance after the Copenhagen summit in 2009, it is very interesting that the military people were never shaken from the idea that we are about to enter a very difficult period."
….
In the same year Chuck Hagel, now Obama's defence secretary, said: "I don't think you can separate environmental policy from economic policy or energy policy."
….
Morisetti's former employer, the Ministry of Defence, agrees that the climate threat is a serious one. The last edition of the Global Strategic Trends analysis published by the MoD's Development, Concepts and Doctrine Centre concludes: "Climate change will amplify existing social, political and resource stresses, shifting the tipping point at which conflict ignites … Out to 2040, there are few convincing reasons to suggest that the world will become more peaceful."
Schellnhuber was also clear about the consequences of failing to curb global warming. "The last 11,000 years – the Holocene – was characterised by the extreme stability of global climate. It is the only period when human civilisation could have developed at all," he said. "But I don't think a global, interconnected world can be managed in peace if climate change means we are leaving the Holocene. Let's pray we will have a Lincoln or a Gorbachev to lead us."
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #26 on: August 20, 2013, 01:02:30 AM »
The following link is to but one of many articles on the topic of climate change leading to increasing future violence.

http://www.cnn.com/2013/08/01/us/climate-change-violence

While the authors of the article how that policy makers will try to avoid this future increase in violence by limiting climate change; but as some level of SLR is already baked into the future world; hopefully, people will also practice cooperation in order to avoid some of this increase in violence.  As Darwin noted human's natural tendency towards cooperation is one of the most significant reason that natural selection accelerated human evolution beyond all other animals on Earth.  Thus, most likely the natural selection induced by the future anthropogenic climate change, will also favor those who cooperate; as any violent resolution to climate change induced stress can only be temporary in nature, while almost certainly the climate change induced stress will be long-term in nature, requiring cooperation in order for the group prosper.
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #27 on: September 14, 2013, 07:00:04 PM »
The information provided at the following link indicates that merely providing better scientific information about climate change is generally insufficient to turn reticence into climate activism.  This supports my contention that the world will likely follow or exceed RCP 8.5 95%CL through the end of this century, and that policy makers would be well advised to start taking measures now to guard against the increasing risks of damage from inundation due to both increasing levels of SLR and of increasing levels of storm surge:

http://www.theguardian.com/environment/2013/sep/13/climate-change-scienceofclimatechange
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #28 on: January 09, 2014, 12:32:26 AM »
The following quote from: "Communicating Uncertainties in Natural Hazard Forecasts" by Stein & Geller, EOS, Transactions, AGU Vol. 93 No 38, 2012; indicates that on a philosophical basis the IPCC's SLR projections could be significantly too low:

"One major challenge is that real uncertainties often turn out to have been underestimated.  In many applications, 20%-45% of results are surprises, falling outside the previously assumed 98% confidence limits [Hammitt and Shyakhter, 1999]. …. This effect arise in predicting river floods [Merz, 2012] and earthquake ground motions and may arise for the IPCC uncertainty estimates [Curry, 2011]."
“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: Philosophical Discussion About Abrupt SLR from WAIS & Its Implications
« Reply #29 on: January 20, 2014, 05:44:44 PM »
Philosophically, I would like to note that probability density functions, PDFs, for ASLR are not like those for earthquakes, riverine flooding, or other familiar catastrophic events, in that: (a) there currently is not sufficient historical calibration of the earth's current non-stationary situation in order to establish a correct PDF (such as meteorologist did for local stationary weather patterns, or seismologist did for earthquakes, in the 1970's), therefore, most PDFs issued today by sea level rise experts to not adequately represent risks associated with newly developing non-stationary trends; (b) the risks associated with the PDFs for most familiar hazards either: (i) converge asymptotically to an upper limit state, or (ii) exhibit thinning tails for extreme hazards; while ASLR events are better represented by black swan, or dragon king, events that typically have fat or bulging extreme tails; and finally (c) if an ASLR event is real then we call all expect their PDFs determined by sea level rise experts to change with time to recognize increasing risk as more evidence is developed (as is represented by the numerous referenced research that I cite throughout this Antarctic folder).
“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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Ethics, Science and Projection of WAIS Collapse
 
Some believe that general discussions about the overall uncertainties associated with abrupt sea level rise, SLR, projections are a waste of time and that the only path forward is to allow the "deductive" process-based approach (characterized by the IPCC process) to continue working only with extant model projections (and their associated model spreads), and then to develop isolated-incremental improvements to the nature and/or input to those existing models.  If you are one of these individuals then you may not be interested in reading any further, as the following focuses on ways to make better use of "induction" (together with "deduction") for helping decision makers to deal with the inherent fat-tailed risks of the potential the West Antarctic Ice Sheet, WAIS.

The philosopher C. D. Broad once said that: "Induction is the glory of science and the scandal of philosophy."  One interpretation of this statement is that induction only works well when one is honestly seeking the truth, and does not work well when bias/deceit is not actively rooted out of the process; and note that the "Scientific Method" inherently makes extensive use of induction, as indicated in the attached image.  However, neither deductive, nor inductive, reasoning is infallible since in inductive reasoning premises of an argument may support a conclusion, but does not necessarily ensure it; and, in deductive reasoning an argument is dependent on the truth of its premises. That is, a false premise may lead to a false result and an inconclusive premise will yield an inconclusive conclusion.
 
The basic problem with using either deductive, or inductive, reasoning when examining the potential collapse of the WAIS, is the high uncertainty when it comes to rare events, as there are limited past samples and such cases therefore require strong extrapolating theories; accordingly events depend more and more on theories when their probability is small. In the case of the potential collapse of the WAIS, knowledge is both uncertain and the consequences are large, thus requiring more robust policies founded on solid research focused on the fat-tail of the collapse PDF.

Taleb argues that the proposition "we know", in many cases, is an illusion, albeit a necessary one; the human mind tends to think it knows, but it does not always have a solid basis for this delusion of "I know". Similarly, to those who might argue that the advancement of science has rendered the world well-known, Taleb argues that while science added knowledge, we always run the risk of experiencing the improbable, rare, and novel. We can be shocked by this knowledge/experience or we can be open to it. As with the dictum of Socrates, "the only thing I know is that I do not know", is as true as ever.  Of course both the natural human physiological propensity and the cultural phenomenon are somewhat a necessary precondition to learning, since complete openness to every event would be inefficient. Bertrand Russell observed, "An open mind is an empty mind." So we cannot be completely open, but we must guard against being completely closed as well. It would be most efficacious if we could find a balance between the known and unknown and for the limits/uncertainties of our knowledge and experience.

In order to find such a balance:

(1) We need to fill our models (mental or numerical) with good experience/data, and actively weed-out misleading/deceptive input.  This includes making better input forcing functions for WAIS ice mass loss (e.g. note that Rignot et al 2014 merely linearly projected the forcing from the past decade (or so) into the future without even trying to quantify future: atmospheric, oceanic, geothermal, etc. forcing's), and better modeling of uncertain boundary conditions for WAIS models (e.g. note that Pfeffer et al 2008's assumed kinematic constraints on the WAIS have been found to be incorrect and too limiting).
(2) We need to continuously update, refine and strengthen our models/theories.  We need to use a "Big Data" approach to cross disciplines (including: glacio, paleo, bio, geo, etc) in order to better identify likelihood of collapse scenarios for our models (note Rignot is currently working on just such a "Big Data" approach).
(3) We need to look for insightful, and ethical, solutions from our models/theories, that can help society at large by seeking to minimize systemic suffering.  Currently, neither scientists, nor economists, are trained to prepare their information/outputs in formats conducive for decision makers to focus on the "greater good".

Unfortunately, process-based SLR projections are crafted for decision makers that are part of the current global capitalist-style economic system which is based on a mindset of survival of the fittest, SF, rather than true natural selection, NS.  The distinction between SF and NS may not be apparent to many, but Darwin believed that natural selection resulted in mankind's better qualities such as empathy and cooperation; much as mathematician John Nash demonstrated that optimal systemic solutions must evaluate group cooperation rather than only individual benefit.  In a SF capitalist-style world economy captains of industry think of themselves as warriors and study works such as Sun Tzu's "The Art of War", and follow advise such as: "All warfare is based on deception", which they translate into all competitive business practices are based on deception, with the goal of establishing repetitive cycles of temporary monopoly power and increasingly of temporary Ponzi schemes.  In such a non-cooperative socio-economic system uncertainty is used as a device to provide "plausible deniability" for those who want to maintain their monopoly power and/or Ponzi schemes; thus never achieving an optimized Nash/Darwin – type sustainable solution that considers the good of the whole group in order to provide a balanced approach to the Tyranny of the Commons, TC, issues rife in climate change challenges, including the potential collapse of the WAIS.
 
NS has typically taken millennia to select cooperative biological systems to handle TC issues; while mankind has evolved elaborate mental and social constructs that can be used to reduce the time required to select more optimized sustainable solutions to TC problems, provided these mental and social constructs do not use uncertainty to provide plausible deniability/deception to the dis-benefit of the whole.  However, built into the very nature of our mental constructs/models is the human propensity to extend existing knowledge and experience to future events and experiences; which is an inherently hazardous situation for evaluating the non-stationary conditions of the WAIS.  To exacerbate this natural propensity much of our cultural education both formal and otherwise is built upon historical knowledge directed by others. Better incorporation of the likely effects of unexpected events (such as the collapse of the WAIS) in to our mental/numerical constructs is fundamental to finding a balanced approach to addressing the common good. Thus, addressing the rare and unexpected is far more significant to our formation of knowledge than people often imagine, or incorporate into our decision making processes (note that the AR5 report explicitly [in writing] excluded the potential collapse of the WAIS this century from their report to policy makers).  Currently, too many decision makers seek to "keep their eye on the ball" by chopping-off the long-tail of PDFs; which may be a practicable approach for a "thin-tailed" PDF; but can be a disastrous approach for a "fat-tailed" PDF, such as that associated with the consequences of the collapse of the WAIS this century.

While it may seem esoteric, "Quantum Contextuality", QC, means that the measurement result of a quantum observable depends on the physical arrangement prepared to measure it, and recent research indicates that addressing QC is critical to gaining the full benefits of future quantum computing.  Furthermore, we all need to realize that our perception of reality is a result of our continuous chain of QC measurements of the world's non-stationary quantum function.  So in this sense if we make QC measurements with a SF mindset then we will see SF observables, while if we make QC measurements with a NS mindset then we see NS observables of reality.  So to quote Sun Tzu (the Art of War) again: "If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.”

In this sense in order to make better use of inductive reasoning, we need to treat fat-tailed uncertainty as the enemy otherwise we will fall victim to Pogo's (aka cartoonist Walt Kelly) truism that: "We have met the enemy and he is us"; as we will use our mental constructs and numerical models to get SF answers rather than NS answers.

To many these statements will seem like hokum, and for these people this is hokum; but for others it can provide better insights on how best to use inductive tools like: "Robust Decision Making", "Bottom up" adaptive planning, and "Big Data" analyses.
« Last Edit: June 15, 2014, 12:39:05 AM by AbruptSLR »
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AbruptSLR

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Many scientists believe that consideration of climate change issues beyond what they can model belongs to the realm of personal values, where individual tolerances for risk can influence opinions about the probabilities of various climate change consequences.  Be-that-as-it-may, I believe that many scientists, and policy makers, select their language in ways that tends to obscure a large portion of the true risks associated with climate change (possibly in an attempt to error on the side of least drama).  For example:

(A) The term "Business as Usual" is typically used to describe the most extreme Recommended Concentration Pathway, RCP, considered by the IPCC; which is RCP 8.5.  However, by definition our "usual" radiative forcing input scenario for GCMs, implies that still higher such input could feasibly occur; thus indicating that RCP 8.5 does not in fact consider the highest feasible radiative forcing input scenario, as indeed it does not include such probable radiative forcing as that from: methane contribution from permafrost degradation, methane leakage from shale gas development and transmission, tar sands development, or that the use of methane from liquefied natural gas, LNG, has more global warming potential than coal.

(B) While the attached image presents the IPCC's Definitions of likelihood associated with their GCM projections; the following key quotes from: "Communicating Uncertainties in Natural Hazard Forecasts" by Stein & Geller, EOS, Transactions, AGU Vol. 93 No 38, 2012; indicate that when considering uncertainties outside of the GCM process that the true likelihoods of occurrence are actually much higher than published by the IPCC:
›   "The Intergovernmental Panel on Climate Change (IPCC) [2007] report compares the predictions of 18 models for the expected rise in global temperature. … The report further notes that the models "cannot sample the full range of possible warming, in particular, because they do not include uncertainties in the carbon cycle."
›   "One major challenge is that real uncertainties often turn out to have been underestimated.  In many applications, 20%-45% of results are surprises, falling outside the previously assumed 98% confidence limits [Hammitt and Shyakhter, 1999]. …. This effect arise in predicting river floods [Merz, 2012] and earthquake ground motions and may arise for the IPCC uncertainty estimates [Curry, 2011]."
Therefore, when AR5 makes a statement with "virtual certainty" about their model projections, there may be a 20% to 45% chance that the statement is wrong (note that denialist frequently state that this is a good reason to ignore model based climate change projections; however, I believe that it means that the public is accepting a higher risk of negative climate change consequences than policy makers are providing warnings about, because the policy makers are talking about model spread rather than about actual risk).

(C) The AR5 summary for policy makers contains the following quote regarding sea level rise, SLR: "The contributions from ice sheet rapid dynamical change and anthropogenic land water storage are treated as having uniform probability distributions, and as largely independent of scenario. This treatment does not imply that the contributions concerned will not depend on the scenario followed, only that the current state of knowledge does not permit a quantitative assessment of the dependence. Based on current understanding, only the collapse of marine-based sectors of the Antarctic ice sheet, if initiated, could cause global mean sea level to rise substantially above the likely range during the 21st century."  Therefore, the AR5 SLR projections not only do not consider the influence of forcing on ice sheet contribution to SLR, they also do not include the risk that any of the Antarctic marine ice sheets could begin to collapse this century; however, Rignot et al 2014 showed that there is a 100% that the ASE marine glaciers will initiate collapse by no later than 2200 even without considering any increasing forcing (such as from: ocean heating, geothermal basal heating, the end of the hiatus period, etc.).

(D)  The IPCC's currently defines a target for mean global temperature rise of 2 C as victory over climate change; however, many scientists have encouraged the IPCC to adopt a mean global warming target of 1.5 C.  Furthermore, global warming is only one measure of climate change and if one were to consider interactions of global warming with other metrics such as: ocean acidification, bio-diversity loss, uncertainties of climate sensitivity, SLR, and pollution from fossil fuels; then anthropogenic fossil fuel emissions should be even more severely restricted than considered by RCP 2.6/3-PD.  By setting an easier target, policy makers have been postponing tough decision about climate change for several decades, to the point where it is already almost inconceivable that the 2 C limit can be achieved, and greater climate change associated disruption is almost guaranteed.

I believe that selecting language to talk about climate change that obscures the total risk (beyond what models can project), is a disservice to society, as it delays society from taking appropriate action. Also, while the potential partial collapse of the WAIS this century is only a portion of the climate change consequences that need clearer discussion; the entire IPCC reporting process could be improved.
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Lennart van der Linde

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ASLR,

Thanks for your nice reflections on the risk of ASLR and other risks. I pretty much fully agree. I'm just wondering what these two statements are based on exactly:

You say (on June 15):
"Pfeffer et al 2008's assumed kinematic constraints on the WAIS have been found to be incorrect and too limiting"

And (today):
"Rignot et al 2014 showed that there is a 100% that the ASE marine glaciers will initiate collapse by no later than 2200"

I would be very interested to know which paper(s) have found Pfeffer et al 2008 to be incorrect and too limiting. I know of some remarks by Hansen & Sato 2012 and of expert assessments that estimate a small chance of more than 2m SLR by 2100, but without specifying how or why Pfeffer et al would by incorrect. They may well be, and Hansen & Sato do make suggestions why and how, but I'm not sure that would be enough to conclude Pfeffer et al to be incorrect. But maybe I'm wrong or maybe I've missed some specific paper(s)?

Also Rignot et al 2014 did not talk of 2200, I think, but Joughin et al 2014 did:
http://www.sciencemag.org/content/344/6185/735.abstract

Their abstract ends:
"Except possibly for the lowest-melt scenario, the simulations indicate that early-stage collapse has begun. Less certain is the time scale, with the onset of rapid (>1 mm per year of sea-level rise) collapse in the different simulations within the range of 200 to 900 years."

So, according to this paper depending on the definition of collapse it has either likely already begun (early-stage collapse) or will begin (rapid, full-scale collapse) within 200-900 years.

Rignot commented on this paper, I think, by arguing how this may be sort of a best-case scenario, and rapid collapse may actually start much sooner in a worst-case, because of the reasons you note.

If I misunderstood something, let me know. And I don't think these two points change the importance of your reflections above. I just want to make sure I understand the science as well as I can.

AbruptSLR

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Lennart,
My time is very short but I will say the following:

(a) The NRC 2013 Abrupt Climate Change report (page 48) states: "A retreat of Thwaites Glacier in West Antarctica could give a much wider and deeper calving front than any observed today, so the "speed limits" suggested by Pfeffer et al. (2008) may not apply (Parizek et al., 2013).

Parizek, B. R. Christianson, K., Anandakrishnan, S., Alley, R. B., Walker, R. T., Edwards, R. A., Wolfe, D. S., Bertini, G. T., Rinehart, S. K.,  . Bindschadler, R. A., and Nowicki, S. M. J., (2013), "Dynamic (in)stability of Thwaites Glacier, West Antarctica", Journal of Geophysical Research, Article first published online: 16 MAY 2013, DOI: 10.1002/jgrf.20044.

(b) Regarding Rignot et al. 2014, the big point in their study is that they show that for the current conditions there is nothing (no pinning points) that will slow-down the rate of grounding line retreat.

Rignot, E., Mouginot, J., Morlighem, M., Seroussi, H. and Scheuchl, B., (2014), "Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011", Geophysical Research Letter, DOI: 10.1002/2014GL060140

However, as pointed out in the following article at the current rate of grounding line retreat, the Thwaites Glacier will initiate collapse within 200-yrs:

http://www.theguardian.com/commentisfree/2014/may/17/climate-change-antarctica-glaciers-melting-global-warming-nasa?commentpage=4

Extract from the Guardian: "Two centuries – if that is what it takes – may seem like a long time, but there is no red button to stop this process.

All these results indicate a progressive collapse of this area. At the current rate, a large fraction of the basin will be gone in 200 years, but recent modelling studies indicate that the retreat rate will increase in the future."


(c) As a thought experiment say that prior to Rignot et al 2014 that a SLR expert believed that for the ASE marine glaciers under RCP 8.5 that there was a zero percent change to initiate the rapid phase of collapse today, a 10% chance by 2100 and a 20% chance by 2200.  After Rignot et al 2014 this same expert would realize that there is a 100% chance for these ASE marine glaciers to initiate the rapid phase of collapse by 2200, and give the 0% chance remains today, this expert might then interpolate a 50% chance for these ASE marine glaciers to initiate the rapid phase of collapse by 2100.  Given that abrupt sea level rise, ASLR, can be defined as achieving a 30 mm/yr rate of SLR; which the rapid phase of collapse of the ASE marine glaciers could achieve by themselves; one would think that if one were to survey SLR experts today that they would recognize at least a 50% probability of achieving ASLR this century.

Best,
ASLR
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wili

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Thanks, ASLR. You may be too busy to answer this now, but it seems to me that I read somewhere that the 200+ year time frame for the tipping point assumed a linear progression up till then, even though there is no reason to expect it to be linear. I don't keep as close track of this stuff as you, though, so I don't have the reference at hand and I have learned not too trust over-much on my dimming memory at my age. Any help from you or others on this would be most appreciated.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

AbruptSLR

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wili,

I am multi-tasking at the moment, but the discussion in the "WAIS Collapse" thread beginning at Reply #135 addresses this matter; but yes Rignot's work assumes a linear continuation of grounding line retreat in ASE marine glaciers (which is what the 200-yr number is based on), so if the grounding line retreat rate were to accelerate (as it currently is doing) then the initiation of the rapid phase of collapse could begin before 2200 (however, Rignot et al's model cannot yet handle all of these cases).

Best,
Dale
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Lennart van der Linde

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ASLR,

Thanks for the reference to NRC 2013 and Parizek et al 2013. I had apparently not read those carefully yet.

Rignot did refer to 200 years or less in his Guardian piece, but it seems to me that's based on Joughin et al. 2014 since I cannot find any such reference in Rignot et al. 2014. I understand him as saying that collapse could well be initiated within 200 years, but I don't think he says that's a 100% chance. But maybe I'm missing that implication.

AbruptSLR

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Lennart,

I will admit that there is some wiggle room for doubt about what Rignot is saying, but the following is a direct quote of his:

"All these results indicate a progressive collapse of this area. At the current rate, a large fraction of the basin will be gone in 200 years, but recent modelling studies indicate that the retreat rate will increase in the future. How did this happen? A clue is that all the glaciers reacted at the same time, which suggested a common force that can only be the ocean. Ocean heat is pushed by the westerly winds and the westerlies have changed around Antarctica in response to climate warming and the depletion of the ozone. The stronger winds are caused by a world warming faster than a cooling Antarctica. Stronger westerlies push more subsurface warm waters poleward to melt the glaciers, and push surface waters northward."

Here he clearly states that at the current rate of degradation a large fraction of the ASE glacial basin will be gone in 200-years (without considering that models indicate that the rate of degradation is accelerating); which he attributes primarily to ocean forcing.  Joughlin et al did not rely on ocean forcing in their work, so I believe that this statement is Rignots' own position on this matter.  In any event, if we are patient, more papers will be released on this critical topic.

Best,
ASLR
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wili

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" At the current rate, a large fraction of the basin will be gone in 200 years, but recent modelling studies indicate that the retreat rate will increase in the future."

That, to me, is the crucial quote. It essentially says that it will definitely not take 200 years to reach this tipping point. Whenever the tipping point is reached in the next two centuries, it will go relatively fast when it goes.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Lennart van der Linde

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ASLR, Wili,

OK, yes, from his Guardian piece it seems Rignot thinks it's likely that most of or all of the Amundsen Basin will be gone by 2200. A question is what he means by a 'large fraction'. Let's say its current SLR-contribution is almost 0.5 mm/jr, then at the current rate by 2200 its total contribution would be about 50 cm. To me as well, it seems 200 years is enough time for a speed-up to at least the 1 mm/yr of Joughin et al. Let's hope the models will improve enough soon, to tell us more about how fast this speed-up could be.

AbruptSLR

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Lennart,

I believe that the point of Rignot et al 2014's research is that they measured the actual current rate of the grounding line retreat, not the contribution to SLR.  This is a critical distinction because the location of the grounding line is the most important consideration for determining when the rapid phase of floating iceberg discharge can occur (see the following evidence that a flotilla of icebergs were launched from Antarctica during Meltwater Pulse 1A):

M. E. Weber, P. U. Clark, G. Kuhn, A. Timmermann, D. Sprenk, R. Gladstone, X. Zhang, G. Lohmann, L. Menviel, M. O. Chikamoto, T. Friedrich & C. Ohlwein, (2014), "Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation", Nature, (2014), doi:10.1038/nature13397


http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13397.html

Furthermore, Rignot warns that his 2200 estimate for the beginning of the rapid collapse phase is based on a linear extension of the current rate of grounding line retreat (while you assume a linear extension of the current SLR contribution); however both the rate of grounding line retreat and of SLR contribution are accelerating.  While it is true that this situation is so complex that models are required to keep track of the large number of interactions; I am convinced that the models will never catch-up in time to be able to accurately predict how much acceleration will occur; and my only hope in this matter is that Rignot is currently following the "Big Data" approach:

The following abstract comes from the International Glacial Society Proceeding 65 at the following link:

http://www.igsoc.org/symposia/2014/chamonix/proceedings/procsfiles/procabstracts_65.htm

"Big data for advanced ice-sheet modeling"
Eric RIGNOT
Corresponding author: Eric Rignot
Corresponding author e-mail: erignot@uci.edu

Abstract: "Current uncertainties in projections of sea-level rise from ice sheets and glaciers are embarrassingly large because we are lacking large-scale, high-resolution models coupled with the ocean, sea ice and the atmosphere, and constrained by massive data assimilation to minimize the impact of unresolved physics. Progress is being made in those directions, however, under the impetus of new remote-sensing observations that reveal rapid, significant changes affecting the outlet glaciers and that help constrain ice-sheet models in a new, effective way; furthermore, high-resolution, higher-order physics ice-sheet models are being developed and applied to ice-sheet-wide problems with encouraging results; ice–ocean–sea-ice–atmosphere coupled models are also starting to emerge; and efforts are made on the remote-sensing side to alleviate our most significant knowledge gaps such as bed topography and ice thickness, and sea-floor bathymetry beneath ice shelves, along glacial fjords and on continental shelves, to name a few. While one might easily argue that ice sheets and glaciers will remain fundamentally unpredictable, I will discuss current progress and frameworks that are likely to provide significant advances in projecting ice-sheet and glacier evolution. A most fundamental aspect of this new framework, however, is that the problem is of a multidisciplinary nature, beyond glaciology."

I, for one, very much appreciate that Rignot is taking this Big Data approach, as timely action is paramount as we many not have 200 years, nor 100 years, nor even 50-yrs to get our arms around this problem.

Furthermore, all modern militaries in the world include climate change (including SLR) as a stress-factor that increases the likelihood of conflicts and "The Bulletin of the Atomic Scientists" now considers the fact that climate change increases the likelihood of nuclear war (so that moved the Doomsday Clock from 11:43 to 11:55, due to that fact that although the nuclear stockpile has recently been downsized, climate change has increased the likelihood of the use of the remaining stockpile.
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AbruptSLR

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In regards to by last post, the following extract comes from the following link, and indicates that the stress of climate change (including of ASLR) increases the likelihood of military conflict, including nuclear war:

http://thebulletin.org/clock/2012

2012: "IT IS 5 MINUTES TO MIDNIGHT
"The challenges to rid the world of nuclear weapons, harness nuclear power, and meet the nearly inexorable climate disruptions from global warming are complex and interconnected. In the face of such complex problems, it is difficult to see where the capacity lies to address these challenges." Political processes seem wholly inadequate; the potential for nuclear weapons use in regional conflicts in the Middle East, Northeast Asia, and South Asia are alarming; safer nuclear reactor designs need to be developed and built, and more stringent oversight, training, and attention are needed to prevent future disasters; the pace of technological solutions to address climate change may not be adequate to meet the hardships that large-scale disruption of the climate portends."
“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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See also the philosophical discussion in the following linked reference about climate change and geoengineering:
 
F. ClingermanK. J. O'Brien, (2014), "Playing God: Why religion belongs in the climate engineering debate", Bulletin of the Atomic Scientists, Vol. 70, Issue 3

http://thebulletin.org/2014/may/playing-god-why-religion-belongs-climate-engineering-debate7133

Abstract: "Religion will play an important role in public perceptions of geoengineering—the intentional manipulation of the planet’s environment to counteract anthropogenic climate change. Religious leaders and scholars can therefore be valuable contributors to the geoengineering debate that has already begun among scientists, engineers, and policy makers. The authors offer four reasons why religion should be part of this debate: Religion is fundamental to how most human beings and societies understand themselves and their place in the world; religion can both challenge and justify scientific authority; religious narratives and symbols can provide frames for understanding geoengineering; and religion offers vocabulary for moral debate. Scholars of theology, ethics, and religious studies can act as mediators between the scientific and faith communities, providing a critical voice in understanding how religion affects the climate conversation, and in engaging a wider public."
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Lennart van der Linde

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ASLR,

Thanks for the additional info and reflections. It makes me wonder: what is the relationship between grounding line retreat and SLR? I would think the faster the grounding line retreats, the higher the SLR-contribution. But it is unclear to me if this is in a fixed or variable proportion.

So to continue my speculation on Joughin et al. 2014 and Rignot et al 2014: if the WAIS SLR-contribution is now almost 0.5 mm/yr, mainly from the Amundsen Basin, how fast should the grounding line retreat accelerate to reach 1 mm/yr by 2200? And is it likely there will be some 'speed limit' as Pfeffer et al suggested, or could this acceleration continue way beyond their suggested limit? Is it possible to answer these questions in a meaningful way, or can we only speculate at this time? Hopefully the big data approach will deliver on its promise, but I agree that we don't have time to wait for that.

Thanks also for the reference to the doomsday clock: I was not aware that it now so strongly and specifically connects the risk of nuclear war to the risks of global warming. I'd been wondering if other people are making that connection, as I've been doing for several years. Someone like Noam Chomsky sees nuclear war and global warming as the two greatest current threats to humanity, but I'm not sure even he has made the reinforcing connection between them as clearly as the Bulletin of Atomic Scientists. So I'm glad they're stressing this point and hope it will help making more people aware of these risks.

sidd

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WAIS mass waste doubling time is faster than decadal. I expect it to hit 1mm/yr SLR before 1950. I repost the Shepherd graph below

AbruptSLR

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Lennart,

While grounding line retreat is clearly related to ASE SLR contribution, they are not the same, and I can only suggest that you look at the various posts in the following link to gain a better understanding of the differences:

http://forum.arctic-sea-ice.net/index.php?topic=72.0

However, some key differences include that once the grounding line retreats far enough: (a) the ice shelf may detach as has occurred for the Jakobshavn Glacier (and Zachariae to name another); (b) the glacial ice can float above basal pinning points that previously slowed the rate of ice mass loss; and (c) when the grounding line reaches the reverse slope headed into the BSB, the ice mass loss will accelerate non-linearly.

Certainly, the Shepherd graph that sidd posted provides an indication that the SLR contribution is already accelerating; however, when the grounding line for most ASE marine glaciers retreats beyond the current gateway for these glaciers, this indicated rate of acceleration will increase non-linearly.

Best,
ASLR
« Last Edit: June 28, 2014, 06:06:46 AM by AbruptSLR »
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AbruptSLR

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The following link leads to an recent (June 24 2014) interview with Sheppard where he talks about his work, Joughlin et al (2014) and Rignot et al 2012 and 2014. 

http://www.sciencepoles.org/interview/putting-antarcticas-ice-mass-loss-into-perspective

One word of caution that I would offer is that Joughlin et al (2014) model does not consider the influence of ocean temperature in the ASE, and thus does not represent a true projection but rather a lower bound estimate of SLR contribution from this source.
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sidd

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it seems i just predicted 1950 for 1mm/yr from WAIS
that should read 2050

sidd

AbruptSLR

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Not to restate the obvious, but the linked National Geographic article (and associate image and extract) shows that there is no fixed pinning point holding back the Thwaites Glacier, and that melting has reduced the basal resistances to sliding, and when the groundling for Thwaites has retreated sufficient far, the ice will slide into the ocean break off and float away, contribution rapidly (much faster than the trend indicated by Shepard [cited by sidd]) to SLR:

http://news.nationalgeographic.com/news/2014/05/140512-thwaites-glacier-melting-collapse-west-antarctica-ice-warming/

Extract: "Joughin says the breakup of the Thwaites glacier will resemble mechanical failure more than straight-up melting.
The ice will slide into the ocean, where it will break off and float away, adding to the volume of water in the sea.
A mixture of rock and frozen water has been holding the glacier back. Contrary to recent thinking, however, the glacier is no longer being held in place, Joughin says.
The ice shelf that has extended out over the ocean is melting, thanks to warmer temperatures, and that has decreased the friction that has held the glacier behind it in place. As pieces of the shelf break off, more of the ice behind it slides forward.
"It's a little like how you get more flow out of a thicker hose than a thinner hose," says Joughin, referring to an acceleration of the glacier sliding into the ocean.
Scientists had previously thought that a sill of bedrock, a vertical rock formation under the ocean, was holding back the advance of the glacier like a dam. But the work of Joughin and team suggests melting has greased the way over the rock."
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AbruptSLR

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Getting back to the theme of this thread, the following linked The Guardian article discusses issues that annoy scientists in the climate change debate with denialists and reticent policy makers:

http://www.theguardian.com/environment/planet-oz/2014/jun/26/what-really-annoys-scientists-about-the-state-of-the-climate-change-debate

While I agree with all of the points that the scientists make in this article, I believe that the scientists need better training in order to better make their points in the argument with these denialists, as currently I believe that these (and other scientists) have great difficulty in conveying the implications of uncertainty in their models to the public.  The current society (and economic system) is based on managing risk, and uncertainty increases risk, which threatens the underpinning of modern society.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson