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AbruptSLR

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Recommendations and Summary wrt the WAIS Collapse Hazard
« on: March 08, 2013, 10:47:59 PM »
It may be more traditional to present the summary before the recommendations, but as I like to think that the recommendations for further research are more important (on the even small chance that some researcher follows-up on even one of the recommendations); therefore, I provide the following abbreviated list:
Possible Office Studies:
- Publish a paper including the results of the October 2012 Icebridge radar survey of the Thwaites Gateway, in order to document any possible subcavities located there.
- Publish a paper addressing the possible correlation between the GRACE satellite reported changes in sea level around the Weddell, Bellingshausen, and Amundsen Seas, and glacier ice melt in these areas.
- Apply the mathematical procedures develop to document the "Jakoshavn Effect", to the geometry and boundary conditions of the Thwaites drainage basin.
- Develop a sophisticated box model for the Thwaites Glacier (including the postulated subglacial cavity) to see how the grounding line retreats into the BSB.
- Run various ice sheet models with the initial starting conditions that have been presented here; particularly the conditions postulated for the Thwaites Glacier after 2060, including the basal melt rate measured at the WAIS-Divide bore hole.
- Run ice shelf models for both FRIS and RIS with CDW (with flow and temperature parameter calibrated to match the reduction of AABW in these respective areas) introduced beneath them in order to evaluate the rate of ice shelf thinning thru 2100.
- Try to hydraulically model the advective (horizontal) interaction between the PIG and Thwaites system to determine whether there is any synergistic advective action.
- Model the hydraulic action of the postulated interconnected sea passageways and side spurs, and their possible influences on local currents around a degraded WAIS (after 2070).
Possible Field Studies:
- Send a research vessel to the Northeast edge of the FRIS to see whether it is true that warm CDW is already entering the Filchner Trough, and monitor the water flow at outer edge of the RIS for indications of possible CDW fluxes.
- Conduct high-resolution ground penetrating radar examinations of the grounding line of the marine ice sheets for Basins A & B near the Southwest edge of the Filchner Ice Shelf, in order to see whether the grounding line has begun to retreat down the negative slope.
- Refine the ground penetrating survey of the ice in the Thwaites drainage basin, in order to more accurately locate, and delineate, the subglacial lakes in this area.
- Deploy a submersible ROV to survey the: (a) Thwaites Hollow/Subglacial cavity; and (b) the gateway to the Ferrigno Glacier to see if a subglacial cavity has formed there.
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #1 on: March 09, 2013, 02:15:56 PM »
I will present all of my summary posts with a related quotation followed by one portion/topic from the hazard assessment that I have presented so far:

"Government agencies, private organizations, and individuals whose futures will be affected by climate change are unprepared, both conceptually and practically, for meeting the challenges and opportunities it presents. Many of their usual practices and decision rules—for building bridges, implementing zoning rules, using private motor vehicles, and so on—assume a stationary climate—a continuation of past climatic conditions, including similar patterns of variation and the same probabilities of extreme events. That assumption, fundamental to the ways people and organizations make their choices, is no longer valid." National Research Council Panel, regarding climate change, 2009

OVERVIEW OF THE HAZARD ASSESSMENT PROCESS USED:
A hazard assessment is something that gives a decent probability of a risk actually becoming a reality (as opposed to our current IPCC WG1 process intended to deductively build on one peer-viewed assessment after another in order to gradually develop scientifically conservative projections).  The basic approach used in my hazard assessment is to use scenario analysis in order to evaluate the risk of the potential partial or complete collapse of the WAIS this century beginning by using published findings of local, regional and global circulation models; and then to apply corrections to these published findings based on such considerations as:
(a) Developing a reasonable interpretation of the interaction between the Eemian ice sheet and the seafloor topology below the WAIS, which resulted in a very clear pattern of ice and water migration; which served as a guarantor for my interpretation of likely ice/water movements during a potential future collapse of the WAIS.
(b) Developing a reasonable interpretation of likely radiative forcing components (including changes in albedo and BC) from now until 2100, based the most current news/interpretations/trends available on the Internet; corrected to some degree for scientific reticence (preference for the least drama).
(c) A re-calibration of the model findings to match: (a) the best information available to me on the current condition of the WAIS and its surrounding ocean, seafloor and atmosphere; and (b) on trend analysis of likely telecommunication of energy from the external environment.
(d) Developing direct cause and effect relationships between all of the various stages of the WAIS collapse scenarios with regard to abrupt sea level rise, ASLR, with corrections to the IPCC WG1 SOD interpretation base primarily on trend analysis corrected for physical mechanisms/limitations.

A major criticism of scenario analysis is that its success with producing meaningful projections is highly dependent on the care used in developing the scenarios, as well as the accuracy of the model used to make the projections.  For instance the IPCC WG1 SOD projections are all scenario based assessments (coupled with local, regional, and global circulation model, LCM, RCM and GCM, analyses), which carefully list their assumptions and limitations, but which are presented to the public in a manner that lead most of the decision makers and engineers to interpret inaccurately.  Despite these criticisms, the scenario analysis methodology was adopted by the IPCC (and others) as being the best methodology for addressing the complex systems of the Earth subjected to anthropogenic radiative forcing.  The hazard assessment presented in my series of posts also uses scenario analysis, but it makes an effort to develop corrections to key IPCC WG1 SOD scenario assumptions/processes/timing with regard to the current/future non-stationary nature of sea level rise, SLR, focusing specifically on the risk of ASLR, due to the full, or the partial, 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.”
― Leon C. Megginson

AbruptSLR

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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #2 on: March 09, 2013, 06:44:03 PM »
"What we need is enough mitigation to avoid unmanageable climate change and enough adaptation to manage unavoidable climate change." John Holdren, US Presidential Science Advisor, 2010

RADIATIVE FORCING CONSIDERATIONS
For the past 30-years radiative forcing (including BC) has most closely followed SRES A1B, which assumes more forcing than RCP 8.5 until approximately 2030 at which point RCP 8.5 assumes more forcing.  Furthermore, ExxonMobil has presented evidence and opinion that it will take close to 100-years to fully transition from a fossil fuel based global economy to one based on more sustainable energy sources; which implies that even if BC emissions are reduced significantly, probably the most likely (not some wishful thinking on the part of IPCC researchers) anthropogenic radiative forcing scenario though 2050 is RCP 8.5.  However, due to the thermal inertia of the oceans, effectively following SRES A1B until 2030 and then following RCP 8.5 until 2045 will, in my opinion, effectively lock-in what I have called RCP 8.5 50% CL in my other posts (which as indicated in the first attached figure [together with Rahmstorf et al 2011 semi-empirical SLR projection for the indicated global surface temperature curve]) of the assumed "RCP 8.5 50% CL" global surface temperature change projections are actually slight above the official RCP 8.5 50% temperature scenario; which is impossible to actually follow as largely BC has driven radiative forcing beyond the official levels immediately since the official scenario was issued). 

While my assumed "RCP 8.5 95% CL" global surface temperature change (shown in the second attached figure [together with Rahmstorf et al 2011 semi-empirical SLR projection for the indicated global surface temperature curve]) effectively assumes the anthropogenic emissions pathway of my "RCP 8.5 50% CL" scenario but assumes that the effective equilibrium climate sensitivity that the RCM and GCM are calibrated to is actual 4.5 C rather than 3 C, but that various masking factors (including: unexpectedly high ocean heat uptake; unexpectedly high ice/snow melting [including floating ice; which is temporarily slowing polar amplification of the rate of polar temperature increase], unexpectedly high increase in the water cycle [increasing atmospheric humidity and more precipitation] ; unexpectedly high temporary surface temperature cooling from volcanic and anthropogenic aerosols) are temporarily hiding the evidence of the higher climate sensitivity (possibly due to such factors as: (a) early Arctic albedo flip, (b) methane emissions from permafrost, seafloor methane hydrates [particularly in the East Siberian Arctic Shelf, ESAS] (c) temporary higher than expected CO2 emissions from soil organic sources and reduced CO2 absorption from both the Southern Ocean and the Amazon Forest; and (d) great tropical cloud albedo [related to higher humidity and rate of water/precipitation cycle] than modeled).
Aside from whether the reader believes that the RCP 8.5 radiative forcing scenario is likely, or not; my hazard assessment indicates that for forcing on the order of RCP 8.5 5% CL (comparable to RCP 4.5 50% CL), or less, there is not a significant chance of abrupt collapse of the WAIS by the end of this century, and I find that the SLR projections given by the semi-empirical projections presented in IPCC WG1 SOD Ch 13 are probable.  However, that said, my hazard assessment indicates that the potential collapse of the WAIS this century is more closely related to the ocean heat content in the circumpolar deep water, CDW, than to mean global surface temperatures, and that the ENSO hiatus period from about 2000 to 2013 has accelerated ocean heat uptake in the critical 700 to 2000m water depth range [of which a large portion is delivered from the tropics to the Southern Ocean by currents and eddies] by about 13 to 25 years ahead of that assumed my most RCM's for the Southern Ocean using RCP 8.5.  This implies that chance of following RCP 8.5 5% CL by 2050 is becoming difficult for me to believe; therefore in my posting I have only presented my analysis for what I have called "RCP 50% CL" and "RCP 95% CL" (note that when I worked through my case for RCP 8.5 5% it effectively matched Rahmstorf et al 2011 semi-empirical SLR projection for RCP 8.5 5% CL, so I recommend following that if you believe that RCP 4.5 50% CL is achievable).
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #3 on: March 09, 2013, 11:01:19 PM »
"The dogmas of the quiet past are inadequate to the stormy present. The occasion is piled high with difficulty, and we must rise with the occasion. As our case is new, so we must think anew and act anew." Abraham Lincoln

KEY EXTANT CONDITIONS FOR THE WAIS ICE SHELVES & SHEETS:

The WAIS is the last remaining marine ice sheet in the world, and is considered by many researchers to be the least stable extant ice sheet, with the greatest possibility of collapse this century.  The first attached figure shows a RCM hindcast of vertical ice mass loss (and associated ice mass loss contribution to eustatic sea level, e.s.l.) from various areas of the AIS during various periods of the Holocene period (the past 14,000 years); which shows a significant ice mass loss from all of the continental shelves of the Weddell, Bellingshausen, Amundsen and Ross Sea areas.  Most RCM projections are calibrated to match such paleo-ice mass loss responses rates; and the IPCC WG1 SOD Ch 13 SLR projections appear to assume that we are entitled to rely on such historical response rates to continue within a certain range of sensitivities to such factors as: (a) global mean surface and ocean water temperature increases; (b) basal friction values; and (c) seafloor bathymetry (including the negative slope characteristic of many WAIS basins).  Unfortunately such entitled thinking discounts the non-linear implications of relatively subtle atmospheric/oceanic/ice interactions that appear to be re-occurring now that from a non-stationary/non-equilibrium point of view (including changes in the upwelling, and current directions, of relatively warm CDW) we have already crossed the conditions leading to the Eemian peak (note: there is some paleo-indications that a possible 50 to 100-year long surge of ASLR occurred during this Eemian peak).  Some of the non-linear interactions not accounted for in IPCC SOD that may be extant today include:
(1) the measured 60% reduction in Antarctic Bottom Water, AABW, in the Southern Ocean may currently be: (a) re-directing a warm tongue of CDW current from northern waters into the Filchner Trough and from there to the grounding line for the Filchner Ice Shelf, FIS, and that this may be promoting basal ice shelf melting (which may be supporting the reduced rates of local AABW production) and some grounding line retreat of the ice sheet associated with Basins A & B (see the "Collapse Main Period" thread), which, have seafloor conditions favorable for rapid grounding line retreat down the negative slope; and (b) while the Ross Ice Shelf, RIS, does not presently appear to have a steady inflow of CDW water beneath it does show signs of changing sub-ice-shelf currents, that could result in the inflow of CDW below RIS within the next 10 to 20 years; which would accelerate thinning of the RIS ice thickness.
(2) The IPCC SOD appears to recognize the recent rapid ice shelf/ice tongue retreats in the Bellingshausen and Amundsen Sea areas, and the presence of a subglacial cavity below the PIG and PIIS (Pine Island Ice Shelf); and while they appear to give some ice mass loss contribution to SLR associate with this condition [reduced buttressing from the ice shelves/tongues]; they do not appear to recognize: (a) advective CDW interaction between PIG and the Thwaites Glacier, TG, which appears to have directed CDW into a pre-existing trough (vestige from previous glacier flow pattern); which appear to have advectively carved a subglacial cavity through the TG gateway all the way to the lip of the ridge leading down into the Byrd Subglacial Basin, BSB; (b) due partially to the recently measured high subglacial basal melt rate in the BSB, and partially due to internal ice melting due to internal friction caused by the recent acceleration of the TG ice stream flow velocity; the Thwaites drainage basin contains a well establish interconnected network of pressurized subglacial water streams and subglacial lakes that appears to be facilitating increasingly frequent surges of ice flow through the TG gateway and Thwaites Ice Tongue; (c) that a recent (summer of 2012) surge (700 Gt) of ice mass loss from the Greenland Ice Sheet, GIS, appears to have triggered surges of ice outflow from both the TG, the Ferrigno Glacier, FG, [implying that at least the grounding line for FG is retreating down the negative slope into its rift valley, and the possible presence of a nescent subglacial cavity] and possibly from subglacial basins A&B adjoining the FIS; and (d) that the temporary 2012 surge of ice mass loss from TG, FG and possibly subglacial basins A&B, may have contributed to an apparently on-going (2013) acceleration in ice mass loss rate from these areas (although not at the peak surge levels of 2012) as apparently reflected in the NOAA measured SLR data.
(3) The West Antarctic CDW temperatures appears to be increasing faster than previously projected possibly due to: (a) telecommunication of heat content from the tropical ocean regions (particularly for the Pacific Ocean) into the CDW; (b) reduced mixing with the AABW at the break to the continental slope, due to the reduced volume of AABW being produced; and (c) possible insulation of upwelling CDW near the West Antarctic coastline  by the above average amounts of recent sea ice extent.
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #4 on: March 10, 2013, 02:55:11 AM »
"Preservation of our environment is not a liberal or conservative challenge, it's common sense."  Ronald Reagan

2012 to 2040/2060 Scenario SUMMARY FOR THE BELLINGSHAUSEN & AMUNDSEN SEA AREAS:

This summary assumes that the IPCC SOD ice mass loss projections for the Bellingshausen and Amundsen Sea areas are reasonable except for those projections associated with TG, PIG and FG; and all three glaciers serve as the focus for the following summary discussion (see the "Hazard Analysis for PIG/Thwaites for 2012 to 2060 Timeframe" thread for details).  Of these three the relatively well studied/documented PIG response serves as a baseline for measured grounding line retreat rate (taken to be 1.75 km/yr) and ice shelf basal melt rates (from CDW ranging from 30 to 80 m/yr); to which correction factors are applied (together with LGM [advective CDW box model projections, including the interactions of offshore CDW, the subglacial cavity, and subglacial topological conditions] to determine the hazard assessment responses from 2012 to 2040/2060 for TG, PIG and FG.
Of these three the TG response is most critical due both to: (a) its potentially large SLR component input from ice mass loss; and (b) its fragility and risk of rapid acceleration of ice mass loss.  The TG scenario from 2013 to 2040/2060 assumes that: (i) a combination of advective expansion of the tip region of the subglacial cavity and thinning of the ice stream thickness (associated with what is assumed to be increasingly frequent and active surges of the ice steam) allows the assumed newly formed Thwaites ice shelf (replacing the former ice tongue) to float over the top of the submerge sea mount in the TG gateway by 2015, thus allowing the east and west ice streams to merge into one ice stream and to allow the associated gateway grounding line to retreat about 100 km down into the BSB between 2015 and 2040  to the location of a recently identified ridge is damming a subglacial lake (and where the TG subglacial meltwater network branches upstream).  During the 25 year period from 2015 to 2040, the rate of grounding line retreat is taken to be: 1.75 (the average rate of groundling line retreat for PIG) x 1.5 (due to CDW temp increase) x 1.5 (due to the basal meltwater effect for TG) = 4 km/yr or equal to 100 km in 25 years.
Due to a rough subglacial topology for the PIG, its grounding line is taken to retreat from 40 to 50km in the same timeframe (from 2012 to 2040), see the "Collapse" thread for pictures.  In the same time period the grounding line retreat associated with the subglacial cavity for FG is taken to be about 35 to 40 km.

For the 2040 to 2060 period the TG groundling line retreats are assumed to accelerate by an additional factor of 3.0 (about the 2040 rate) as follows: 1.7 (Jakobshavn Effect)x1.1 (CDW temp rise effect)x1.1(Zwally Effect)x1.1(basal meltwater increase effect)x1.1(storm activity effect)x 1.1 (albedo effect) x 1.1(methane hydrate emission effect) = 3.0, which supports the rate of grounding line retreat postulated for these two 200-km arcs by 2060.
From 2040 to 2060 the grounding lines for both PIG & FG are taken to retreat another approximately 60 km each, as the CDW temperature has increased, and the bottom topology has changed.

Due to the complexity of this topic I highly recommend that the reader review both the "Hazard Analysis for PIG/Thwaites for 2012 to 2060 Timeframe" thread (especially for the discussion of the Jakobshavn Effect which is highly dependent on the ice viscosity that is assumed to decrease as the ice velocity increase, the basal friction which is assumed to decrease due to the high basal melt rate in the BSB, and the gravity driving stress that is assumed to be high due to the assumed high reduction in ice surface elevation [resulting in a steep ice surface gradient] along the two 200km arcs) and the "Collapse" thread for details.
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #5 on: March 10, 2013, 03:39:59 AM »
"The true test of character is not how much we know how to do, but how we behave when we do not know what to do."   John Holt

2012 to 2040/2060 SCENARIO SUMMARY FOR THE WEDDELL and ROSS SEA AREAS:
For the Weddell Sea Embayment from 2012 to 2040 it is assumed that the AABW reduction related intrusion of a warm CDW tongue of water extends further and further along the Filchner Trough, and this warm CDW tongue is assumed to melt the underside of the FRIS above the Filchner Trough at an average rate of about 10m/year thus resulting in an average thickness reduction of the ice shelf in this area of about 280 m.  As this is assumed leave the ice shelf in this area to be about 250m thick, it is believed to provide sufficient buttressing action to the adjoining marine ice sheet to effectively limit the thinning of the adjoining marine ice sheet thus preventing the ice floatation required for significant grounding line retreat, even though the warm CDW is assumed to melting the ice at the base of the adjoining marine ice sheet (see the "Collapse" thread for 2040).  For the period from 2040 to 2060, the sub-ice-shelf melt rate is taken to increase to about 15 m/yr (due both to increase CDW inflow due to the degradation of the sea ice in the Weddell Sea and due to the increase in CDW temperature); which implies that the ability of the FRIS to buttress the adjoining marine ice sheet is assumed to be lost resulting in surge of grounding line retreat into Subglacial Basins A&B as shown in the "Collapse" thread for 2060.
For the Ross Ice Shelf, RIS, from 2012 to 2040 it is assumed that the current rate of ice shelf face retreat (due to calving) of 1.1km/yr accelerates to an average rate of approximately 2 km/yr (due to ice shelf basal melting, increased storm intensity, and periodic temporary intrusions of CDW), thus resulting in an ice shelf face retreat of about 56 km by 2040; which it is assumed allows the tidal flexing of the RIS near the coastline to increase thus accelerating the associated ice stream flow velocities, resulting in sufficient ice thinning to result in the groundling line retreat indicated in the "Collapse" images for 2040.  By 2040 it is assumed that the adjoining Antarctic Slope Front current is sufficient disrupted by fresh meltwater in the surround sea water that it weakens sufficiently to allow an upwelling flow of warm CDW water to penetrate beneath RIS resulting in an average sub-ice-shelf basal melt rate of 15 m/yr, which (as the RIS is already thinner than the FRIS) is believed to result in sufficient ice shelf thinning so that around 2060 the RIS is assumed to collapse due to a melt pond effect, resulting in the grounding line retreat for the Siple Coast ice sheet as indicated in the "Collapse" thread for 2060.
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #6 on: March 10, 2013, 04:22:21 AM »
"People tend to focus on the here and now. The problem is that, once global warming is something that most people can feel in the course of their daily lives, it will be too late to prevent much larger, potentially catastrophic changes."  Elizabeth Kolbert

SUMMARY FOR THE "COLLAPSE MAIN PERIOD" FROM 2060 TO 2070:

I will start this summary by re-posting the accompanying figure (from the "Collapse Main Period" thread) showing a plan view of the my RCP 8.5 50% CL scenario estimates of WAIS areas that may have experienced grounding line retreat by 2070.  This figure indicates several significant areas of proposed grounding line retreat including:
(a) the transparent orange area with Jakobshavn Effect acceleration and associated "ice melange" discussed extensively in the thread on the PIG/Thwaites system thread behavior up to 2060 show the two significant changes: (i) the Eastern trough ice stream has continued to exhibit "Jakobshavn Effect" acceleration behavior and the grounding line retreat for this ice stream has extended about an additional 200km in 10 years, while the grounding line retreat for the Western trough ice stream is proposed to slow dramatically as the seafloor becomes rough at the western end of this trough; and (ii) with the extension of the Western trough ice stream slowed, this allows for the extension of the grounding line retreat in the Southernly direction into several different branching troughs in this direction at a slower rate than for Eastern trough ice stream.
(b) the Ferrigno Subglacial cavity showed marked rate of extension driven largely by advection associate with relatively high CDW in the Bellingshausen Sea (with no Jakobshavn Effect), while the PIG subglacial cavity extension (ie groundling line retreat) remains slow due to rough seafloor conditions.
(c) The grounding line retreat for the Siple Coast ice stream accelerates as the Ross Ice Shelf buttressing action is assumed to be degraded.
(d) The Weddell Sea Embayment, WSE, glaciers show a major surge of grounding line retreat due both to a projected acceleration of the advective warm CDW intrusion into the WSE (below the Filchner-Ronne Ice Shelf, supported by Hellmer et al 2012's projections), and due to ideal seafloor conditions (in the area of indicated grounding line retreat) to support the classic gravitationally driven marine ice sheet retreat behavior).
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #7 on: March 10, 2013, 12:37:55 PM »
"All tyranny needs to gain a foothold is for people of good conscience to remain silent." Thomas Jefferson

SUMMARY FOR THE "COLLAPSE MAIN PERIOD" FROM 2070 TO 2090:

For ease of reference I have re-posted the relevant image from the "Collapse" thread of areas postulated to have experienced grounding line retreat (and/or floatation/calving) for RCP 8.5 50% CL.  The key consideration for this portion of the "Collapse Main Period" is that while the "Jakobshavn/Thwaites Effect" is assumed to have slowed, or stopped; an acceleration of ice mass loss still occurs primarily due to the interconnection of multiple sea passageways, and side spurs of drainage valleys; which is assumed to lead to a large number of concurrent positive feedback factors including:
(1) CDW flow through interconnected subglacial cavities (such as assumed between the FG and PIG subglacial cavities) is assumed to increase dramatically as compared to the salinity driven advective process before interconnection.  This increased CDW flow rate is assumed to be driven by both tidal and ocean current between interconnected seas; which is assumed to induce sufficiently high sub-ice-shelf melting that any ice floating above the interconnected subglacial cavities soon collapse.  As indicated in the Arctic regions, tidal current velocity increase two to five times when the covering ice disappears; which it is postulated leads to an increase in the convergent-estuary-effect thus amplifying the peak tidewater elevation amplitude several times; which is postulated to lead to extensive calving all along the lengths of the ice valley sidewalls of both the sea passageways and their numerous side spur drainage valleys.
(2) The rapid ice mass loss associated with this period is assumed to dramatically increase the frequency and magnitude of local: earthquakes, volcanoes, tsunamis and submarine landslides; all over which are assumed to lead to periodic rapid ice calving events along the length of the various sea passageways and side spurs.
(3)  Furthermore, the rapid ice mass loss associated with this period is assumed to lead to a meaningful increase in the rate of magma flow under the relatively thin seafloor crust resulting in: (a) increase basal ice melting and thus reduced basal friction; and (b) more significantly when combine with the release of confining pressure on methane hydrates in seafloor sediment, should lead to sufficient rapid rates of hydrate decomposition to trigger multiple submarine landslides thus leading to both tsunamis and major ice calving events along the sidewall of the sea passageways and side spurs.
(4) The surface temperatures in the WAIS are postulated to increase rapidly in this period due to: (a) the rapid exposure of large areas of warm CDW (both due to seasonal collapse of the sea ice and along lengths of the sea passageways and side spurs) releasing large amounts of ocean heat content into the atmosphere and (b) a rapid decrease in seasonal albedo from the ice extent loss (sea ice, ice shelve and ice sheet).  This increase in surface temperatures is assumed to increase both ice surface melting and rain fall; thus increasing both the Zwally Effect, but more importantly periodically sending periodic (austral summer) pulses of meltwater run-off along the lengths of the sea passageways and especially the side spurs, leading to periodic major calving events.
(5) Both the assumed rapid warming of the West Antarctic atmosphere and the rapid cooling of the entire Southern Ocean (focused on the West Antarctic), should (per Hansen and Sato 2012) result in a dramatic increase in the frequency and intensity of regional cyclones, whose wave action, storm surge/tide, and changes in barometric pressure (as the eye of the cyclones move); which should all contribute to significant ice calving events along the sea passageways and side spurs.
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #8 on: March 10, 2013, 01:50:40 PM »
"The real voyage of discovery consists not in seeking new landscapes but in having new eyes." 
Marcel Proust

THE COLLAPSE MAIN PERIOD UNTIL 2100:

As my WAIS collapse scenario for RCP 8.5 50% CL does not result in the complete collapse of the WAIS by 2100; instead I pre-post the accompanying figure for my RCP 8.5 95% CL case which indicates that given an unlucky combination of: (a) early starts to positive feedback mechanisms; (b) extreme forcing conditions; and (c) high response functions; could lead to the complete floatation of all relevant ice in the WAIS by 2100 (note that much of this floating ice would not have melted by 2100).

Thus in summary I also re-post my RSLR Maximum Credible Event, MCE, curves for California assuming the abrupt collapse scenarios for the WAIS, presented throughout these threads; where are intended to provide an example of the type of MCE loading that could be used future check case in the design/evaluation of coastal infrastructure subjected to the risk of inundation associated with abrupt sea level rise by the end of 2100 (with some data shown until 2200).
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #9 on: March 13, 2013, 05:36:38 PM »

At some point there is a transition from trying to avoid the collision to bracing for the impact.

After seeing the video at this link:

http://www.businessinsider.com/mini-submarine-in-antarcticas-lake-whillans-2013-3

I thought that I should add another recommendation that as economically feasible boreholes could be drilled into the locations of the subglacial cavities that I have postulated for Thwaites, Ferrigno and the grounding line for FRIS, and well as into any major subglacial lakes identified in the Thwaites Drainage basin.  Then money permitting an "eel" shaped (or baseball shaped) mini submarine could be launched down the drill holes to observe, and record the conditions in these subglacial/sub-ice-shelve bodies of water.
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #10 on: May 04, 2013, 01:09:19 AM »
"The danger is that global warming may become self-sustaining, if it has not done so already. The melting of the Arctic and Antarctic ice caps reduces the fraction of solar energy reflected back into space, and so increases the temperature further. Climate change may kill off the Amazon and other rain forests, and so eliminate once one of the main ways in which carbon dioxide is removed from the atmosphere. The rise in sea temperature may trigger the release of large quantities of carbon dioxide, trapped as hydrides on the ocean floor. Both these phenomena would increase the greenhouse effect, and so global warming further. We have to reverse global warming urgently, if we still can." Stephen Hawking, 2006

In light of the article at the following website:

http://prq.sagepub.com/content/66/2/267.abstract?etoc

Which indicates that the significant numbers of "End-Time" believers in the US Congress are effectively blocking the US from implementing more effective climate change policy, I have the following additional recommendation:

-  It is important to immediately introduce mandatory climate change curriculum at all levels of the US public educational school system, in a professional scientific manner; even though it may take a generation, or two, for such education to influence US Congressional voting patterns.
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AbruptSLR

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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #11 on: May 04, 2013, 11:51:17 PM »
The following recommendations are from: Abrupt Climate Change a report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research, U.S. Geological Survey, Reston, VA. Lead Author: Konrad Steffen, University of Colorado:
Recommendations
•   Reduce uncertainties in estimates of mass balance. This includes continuing mass-balance measurements on small glaciers and completing the World Glacier Inventory.
•   Maintain climate networks on ice sheets to detect regional climate change and calibrate climate models.
•   Derive better measurements of glacier and ice-sheet topography and velocity through improved observation of glaciers and ice sheets. This includes utilizing existing satellite interferometric synthetic aperture radar (InSAR) data to measure ice velocity.
•   Use observations of the time-varying gravity field from satellites to estimate changes in ice sheet mass.
•   Survey changes in ice sheet topography using tools such as satellite radar (e.g., Envisat and Cryosat-2), laser (e.g., ICESat-1/2), and wide-swath altimeters.
•   Monitor the polar regions with numerous satellites at various wavelengths to detect change and to understand processes responsible for the accelerated ice loss of ice sheets, the disintegration of ice shelves, and the reduction of sea ice. It is the integrated satellite data evaluation that provides the tools and understanding to model the future response of cryospheric processes to climate change.
•   Utilize aircraft observations of surface elevation, ice thickness, and basal characteristics to ensure that such information is acquired at high spatial resolution along specific routes, such as glacier flow lines, and along transects close to the grounding lines.
•   Improve coverage of longer term (centennial to millennial) records of ice sheet and ocean history from geological observations.
•   Support field, theoretical, and computational investigations of physical processes beneath and along ice shelves and beneath glaciers, especially near to the grounding lines of the latter, with the goal of understanding recent increases in mass loss.
•   Develop ice-sheet models on a par with current models of the atmosphere and ocean. Particular effort is needed with respect to the modeling of ocean/ice-shelf interactions and physical processes, of surface mass balance from climatic information, and of all (rather than just some, as now) of the forces which drive the motion of the ice
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AbruptSLR

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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #12 on: August 03, 2013, 01:03:46 AM »
Key Quotes from: "Communicating Uncertainties in Natural Hazard Forecasts" by Stein & Geller, EOS, Transactions, AGU Vol. 93 No 38, 2012
›   "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]."
›   "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."


The IPCC (and similar) projections on SLR are not only non-conservative (from a public safety point of view) "… because they do not include uncertainties in the carbon cycle…", but in addition to the factors cited in previous posts in this thread,  because: (a) the SLR budgets based on the IPCC SLR projections do not consider: (i) the 40% increase in WAIS ice mass measured by GRACE due to GIA corrections; (ii) the water lost to increase atmospheric specific humidity; and (iii) wind driven snow scour from Antarctic; (b) increase CO2 atmospheric content due to increase upwelling in the Southern Ocean; (c) possible transition of the current 3 (Hadley, Ferrel and Polar) atmospheric cells to a single cell this century; (d) decreased tundra albedo and increased tundra fire hazard, from increased tundra shrub growth; (e) increased atmospheric methane concentration over Antarctica (possibly from marine hydrate degradation due to warming of the Southern Ocean); (f) the expected return to a positive Pacific Decadal Oscillation index within a few years-time; and (g) analytical confirmation of the risks of accelerated calving on the Thwaites Glacier.  See other threads for discussion of other risk factors not fully accounted for by the current IPCC SLR projection methodology.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #13 on: January 11, 2014, 02:14:54 AM »
The following represents an update of selected issues that increase the probability of abrupt SLR contribution from Antarctica since mid-2013:

- Research confirms that due to the influence of updrafts that cloud formation in the tropics will be less than previously expected, therefore equilibrium climate sensitivity will between 3 and 5 degrees C, with a mean value somewhere between 4.25 and 4.5 degrees C.

- For the first time in recorded observations a portion of the calving front on the PIIS has retreated upstream in the interface with the SW Tributary Glacier; furthermore, it has been identified that an acceleration of the SW Tributary Glacier Ice velocities due to a reduction of the buttressing action from the PIIS, would increase the stress on the Eastern Shear Margin of the Thwaites Glacier, thus effectively decreasing the stability of the Thwaites Glacier.

- Both the observed reductions in AABW volumes and the observed increases in AABW temperatures have been observed to increase basal ice melting in several Antarctic ice shelves.

- It has been observed that in some areas the ACC is shifting southward which has been observed to increase the local areas of some marine terminating glaciers/ice streams/ice sheets.

- AR5 formally recognized that the Global Warming Potential, GWP, of methane over a 100-yr period is currently about 35 times that of CO2; however, AR5 it not include the global warming influence of most of the methane emissions from permafrost decomposition and as these methane emissions are approximately 2% of all permafrost carbon emissions this amounts to a 2 times 35 = a 70% error in the GHG warming potential from permafrost degradation.

- Some experts have projected that a large El Nino event will occur during the austral summer of 2014 - 2015; which if it were to occur has been estimated to increase the rates of ice mass loss from ASE ice streams/glaciers.
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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #14 on: January 11, 2014, 03:22:18 AM »
Thanks for these, ASLR. Wasn't there also something recently about the bedrock under part of the Antarctic starting to shift and move as a result of the loss of weight of the overlying ice mass? Couldn't that also increase the likelihood of sudden ice loss and SLR?
"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."

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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #15 on: January 11, 2014, 05:08:43 PM »
Wili,

There are so many factors to be considered, that I do not have time to list them all let alone put them in to context.  But yes, increasing tectonic activity (volcanic, seismic, upwell of magma, plate movement and high basal heating) in the West Antarctic is a major concern, but even at its fastest it changes over decades.  A few other relatively fast changes that I did not list in my last post include:
- The ice at the base of the Thwaites Ice Tongue has been observed to have a significant amount of crevasse cracks after its October 2012 surge event, which could lead to another surge of the tongue in the next few years (particularly if an El Nino event occurs in the next few years).
- New calculations indicate that marine terminating glaciers with profiles comparable to either Jakobshavn or Thwaites are subjected to rapid calving once their grounding line has retreated into the correct location in the bed topology.
- The paleo-evidence from the Pine Island embayment indicate that in the past the subglacial hydrological systems have contribution abrupt ice mass loss events from this area, and that the basal conditions beneath the Thwaites Glacier parallel these contributions, indicating that the Thwaites Glacier has a good probability of undergoing such an abrupt ice mass loss event in the future.

I do not have time to post more such summaries as I am traveling, and such summaries slow me down from posting new observations, so feel free to scan through my prior posts in the various threads of this Antarctic folder.
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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #16 on: January 11, 2014, 07:00:29 PM »
Thanks, ASLR. Travel well. I would just point out that even slight changes in the tilt of bedrock could potentially change a part of an icesheet from being on a level surface to being on a sloping one.

If a marble is sitting on a level table, even a few millimeters of tilt can be the difference between it remaining there and it rolling off the table edge.
« Last Edit: January 11, 2014, 08:27:12 PM by wili »
"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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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #17 on: March 01, 2014, 04:22:37 PM »
I am re-posting the following from the Science folder from a thread about the British AVOID program to document the measures needs to achieve the goal of limiting mean global temperature rise to 2 degrees C:

The references in the list at the end of this post discuss positive feedback mechanisms (and related topics), that in my opinion, were not adequately accounted for in IPCC's AR5 (nor in the AVOID model projections). 

While I do not have time to do any of this findings justice; nevertheless, I will say that to whatever RCP scenario that your value system allows you to accept as realistic, you need to add the following factors that were left out of AR5 (and AVOID) projections:

(a) Sherwood et al (2014) and Fasullo & Trenberth (2012) show that the most likely value for ECS is about 4.5 degrees C instead of the assumed mean value of 3 degrees C; therefore, you should multiply the old projections by a factor of about 1.5, due to the low amount of cloud cover near the equator.
(b) Pistone et al. (2014) shows that the decrease in Arctic albedo (including land snow, sea ice and black carbon effects) beyond that previously assumed results in additional radiative forcing equal to ¼ of the CO₂ in the atmosphere.
(c) Schuur & Abbott (2011) shows that the permafrost emits about 2% of its carbon emissions as methane instead of as CO₂ (as assumed by AVOID), and as over a one hundred year period, methane has a global warming potential at least 35 times that of CO₂, this means at least a 70% error in the carbon emissions from the permafrost degradation.  See also Monday et al. (2014) and Isaksen et al. (2011).
(d) Cowtan & Way (2013); England et al. (2014); Santer et al (2014); and Rosenfeld (2014); all provide solid evidence that the current mean global temperature has been masked by such causes as: limited data; the negative phase of the PDO cycle; volcanoes, and aerosols, respectively.  Furthermore, once corrections are applied to the GCM projections to account for these masking mechanisms, one will find that the ECS is actually higher than previously assumed, which supports my points (a), (b) and (c).
(e) Hansen et al. (2013) and Previdi (2013) show that the inclusion of slow-response feedback mechanisms can cause Earth Systems Sensitivity to be as high as 6 degrees C (while work such as Pistone et al. (2014) shows that the "slow response" feedback mechanisms are occurring very quickly).

I do not have time to comment on the other excellent references cited below, but I would also like to say many negative feedback mechanisms are shrinking quickly (such as the absorption of CO₂ by plankton, etc.), so that it is not only positive feedback mechanisms that we need to be realistic about.

Best,
Abrupt SLR

References:

[1]   Cai, W., Borlace, S., Lengaigne, M., Rensch, P.V., Collins, M., Vecchi, G., Timmermann, A., Santoso, A., McPhaden, M., Lixin Wu, Matthew H. England, Guojian Wang, Eric Guilyardi & Fei-Fei Jin, (2014), "Increasing frequency of extreme El Niño events due to greenhouse warming", Nature Climate Change, doi:10.1038/nclimate2100.
[2]   Cowtan, K. & Way, R.G., (2013), "Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends", Quarterly Journal of the Royal Meteorological Society, DOI: 10.1002/qj.2297.
[3]   England, M.H., McGregor, S., Spence, P., Meehl, G.A., Timmermann, A., Cai, W., Gupta, A.S., Michael J. McPhaden, M.J., Purich A. & Santoso, A., (2014), "Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus", Nature Climate Change, doi:10.1038/nclimate2106.
[4]   Fasullo, J.T. and Trenberth, K.E., (2012), "A Less Cloudy Future: The Role of Subtropical Subsidence in Climate Sensitivity", Science, vol. 338, pp. 792-794, 2012. http://dx.doi.org/10.1126/science.1227465.
[5]   Frederick, J.M., and Buffett, B.A., (2014), "Taliks in relict submarine permafrost and methane hydrate deposits: Pathways for gas escape under present and future conditions", Journal of Geophysical Research: Earth Surface, DOI: 10.1002/2013JF002987.
[6]   Hansen, J., Kharecha, P. and Sato, M., (2013), "Climate forcing growth rates: Doubling down on our Faustian bargain", Environ. Res. Lett., 8, 011006, doi:10.1088/1748-9326/8/1/011006.
[7]   Hansen, J., Sato, M., Russell, G. and Kharecha, P., (2013), "Climate sensitivity, sea level, and atmospheric carbon dioxide", Phil. Trans. R. Soc. A, 371, 20120294, doi:10.1098/rsta.2012.0294.
[8]   Hosking, J. Scott; Orr, Andrew; Marshall, Gareth J.; Turner, John; Phillips, Tony, (2013), "The influence of the Amundsen–Bellingshausen Seas low on the climate of West Antarctica and its representation in coupled climate model simulations", Journal of Climate, 26 (17). 6633-6648. 10.1175/JCLI-D-12-00813.1
[9]   Isaksen, I. S. A., Gauss M., Myhre, G., Walter Anthony, K. M. and Ruppel, C.,  (2011), "Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions", Global Biogeochem. Cycles, 25, GB2002, doi:10.1029/2010GB003845.
[10]   Ludescher, J., Gozolchiani, A., Bogachev, M.I.,  Bunde, A.,  Havlin, S., and Schellnhuber, H.J., (2014), "Very early warning of next El Niño", PNAS, 111 (6) 2064-2066, doi: 10.1073/pnas.1323058111.
[11]   Marks, A. A. and King, M. D.: "The effect of snow/sea ice type on the response of albedo and light penetration depth (e-folding depth) to increasing black carbon", The Cryosphere Discuss., 8, 1023-1056, doi:10.5194/tcd-8-1023-2014, 2014.
[12]   Meehl, G.A., Hu, A., Arblaster, J.M., Fasullo, J., Trenberth, K.E., (2013), "Externally Forced and Internally Generated Decadal Climate Variability Associated with the Interdecadal Pacific Oscillation", J. Climate, 26, 7298–7310. doi: http://dx.doi.org/10.1175/JCLI-D-12-00548.1
[13]   Mondav, R., Woodcroft, B.J., Kim, E.-H. McCalley, C.K., Hodgkins, S.B., Crill, P.M., Chanton, J., Hurst, G.B., VerBerkmoes, N.C., Saleska, S.R., Hugenholtz, P., Rich, V.I., & Tyson, G.W. (2014), "Discovery of a novel methanogen prevalent in thawing permafrost", Nature Communications, 5,3212doi:10.1038/ncomms4212.
[14]   National Research Council (NRC), (2013), Abrupt Impacts of Climate Change: Anticipating Surprises, Washington, D.C.: The National Academies Press.
[15]   Nisbet, E.G., Dlugokencky, E.J. and Philippe Bousquet, P.B., (2014), "Atmospheric Science: Methane on the Rise—Again", Science 31 January 2014: Vol. 343 no. 6170 pp. 493-495, DOI: 10.1126/science.1247828.
[16]   Rosenfeld, D., Sherwood, S., Woodand, R. and Donner, L., (2014), "Climate Effects of Aerosol-Cloud Interactions", Science 24 January 2014: Vol. 343 no. 6169 pp. 379-380. DOI: 10.1126/science.1247490.
[17]   Pistone, K., Eisenman, I. and Ramanathan, V., (2014), "Observational determination of albedo decrease caused by vanishing Arctic sea ice", PNAS, doi: 10.1073/pnas.1318201111.
[18]   Pithan, F. & Mauritsen, T., (2014), "Arctic amplification dominated by temperature feedbacks in contemporary climate models", Nature Geoscience, doi:10.1038/ngeo2071.
[19]   Power, S., Delage, F., Chung, C.,  Kociuba, G. and Keay, K., (2013), “Robust twenty-first-century projections of El Nino and related precipitation variability”, Nature, 502, 541-545, doi:10.1038/nature12580.
[20]   Previdi, M., Liepert, B.G., Peteet, D., Hansen, J., Beerling, D.J., Broccoli, A.J., Frolking, S., Galloway, J.N., Heimann, M., Le Quéré, C., Levitus, S. and Ramaswamy, V., (2013), "Climate sensitivity in the Anthropocene". Q. J. R. Meteorol. Soc., 139, 1121-1131, doi:10.1002/qj.2165.
[21]   Santer, B.D., Bonfils, C., Painter, J.F., Zelinka, M.D., Mears, C., Solomon, S., Schmidt, G.A., Fyfe, J.C., Cole, J.N.S., Nazarenko, L., Taylor, K.E. & Wentz, F.J., (2014), "Volcanic contribution to decadal changes in tropospheric temperature", Nature Geoscience, doi:10.1038/ngeo2098.
[22]   Schaller, N., Cermak, J., Wild, M., and Knutti, R., (2013), "The sensitivity of the modeled energy budget and hydrological cycle to CO2 and solar forcing", Earth Syst. Dynam., 4, 253-266, doi:10.5194/esd-4-253-2013.
[23]   Schuur, E.A.G. and Abbott, B., (2011), "High risk of permafrost thaw", Nature, 480, 32-33, Dec. 2011.
[24]   Sherwood, S.C., Bony, S., and Dufresne, J.D. (2014), "Spread in model climate sensitivity traced to atmospheric convective mixing", Nature; 505, pp 37–42; doi:10.1038/nature12829.
[25]   Vitale, D. and Bilancia, M., (2013) "Role of the natural and anthropogenic radiative forcings on global warming: evidence from cointegration–VECM analysis"; Environmental and Ecological Statistics; Volume 20, Issue 3, pp 413-444.
[26]   Wang, X., Piao, S., Ciais, P., Friedlingstein, P., Myneni, R.B., Cox, P., Heimann, M., Miller, J., Peng, S.P., Wang, T., Yang, H. and Chen, A., (2014), "A two-fold increase of carbon cycle sensitivity to tropical temperature variations", Nature, 2014; DOI: 10.1038/nature12915.
[27]   Wenju Cai, Simon Borlace, Matthieu Lengaigne, Peter van Rensch, Mat Collins, Gabriel Vecchi, Axel Timmermann, Agus Santoso, Michael J. McPhaden, Lixin Wu, Matthew H. England, Guojian Wang, Eric Guilyardi & Fei-Fei Jin, (2014), "Increasing frequency of extreme El Niño events due to greenhouse warming", Nature Climate Change, doi:10.1038/nclimate2100.
[28]   Xichen, L., Holland, D.M., Gerber, E.P., & Yoo, C., (2014), "Impacts of the north and tropical Atlantic Ocean on the Antarctic Peninsula and sea ice"; Nature; 505, 538–542; doi:10.1038/nature12945.
[29]   Zeebe, R., (2013), "Time-dependent climate sensitivity and the legacy of anthropogenic greenhouse gas emissions", PNAS, August 5, 2013, doi: 10.1073/pnas.1222843110.
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #18 on: July 13, 2014, 04:35:44 PM »
Robert Scribbler (with links to related information from SKS) provides a useful summary of some of the recent new findings of how unstable the WAIS is to continuing forcing from anthropogenic global warming.  I have provides some links and some extracts (and one attached figure which supports the possibility that AGW could increase mean global temperature by up to 9 degrees C by the end of the century).  I also note that Scribbler does not talk about: (a) the fact that sea level rise contribution from the WAIS should be multiplied by a factor of up to 1.4 for much of the Northern Hemisphere in order to calculate RSLR, and (b) the recent Spence et al (2014) GCM finding that continued poleward migration of the Southern Hemisphere Westerlies will continue to contribute to the advection of warm CDW to the grounding lines of key Antarctic marine glaciers, which guarantees the continued acceleration of ice mass loss from Antarctica:

http://robertscribbler.wordpress.com/2014/05/29/nature-human-destabilized-antarctica-capable-of-glacial-outbursts-contributing-to-sea-level-rise-of-14-feet-per-century/

Robert Scribbler's extract on the attached image: (Temperature and CO2 increase from 22,000 YBP through 6,000 YBP. Note that major glacial outburst events in Antarctica began after only .2 C of atmospheric warming and 10 ppm of CO2 increase around 20,000 years ago. Such a response shows a very high degree of glacial and Earth Systems climate sensitivity. Also note that total warming over a 12,000 year timeframe was 3.7 C. Warming of 4, 6 and even 9 C is possible by the end of this Century under BAU human greenhouse gas forcing. Image source: Nature via Skeptical Science.)

http://www.skepticalscience.com/co2-lags-temperature.htm

Extract from SKS: "A 2012 study by Shakun et al. looked at temperature changes 20,000 years ago (the last glacial-interglacial transition) from around the world and added more detail to our understanding of the CO2-temperature change relationship.  They found that:
•   The Earth's orbital cycles triggered warming in the Arctic approximately 19,000 years ago, causing large amounts of ice to melt, flooding the oceans with fresh water. 
•   This influx of fresh water then disrupted ocean current circulation, in turn causing a seesawing of heat between the hemispheres.
•   The Southern Hemisphere and its oceans warmed first, starting about 18,000 years ago.  As the Southern Ocean warms, the solubility of CO2 in water falls.  This causes the oceans to give up more CO2, releasing it into the atmosphere.
While the orbital cycles triggered the initial warming, overall, more than 90% of the glacial-interglacial warming occurred after that atmospheric CO2 increase (Figure 2)."

Caption: "Figure 2: Average global temperature (blue), Antarctic temperature (red), and atmospheric CO2 concentration (yellow dots).

[Original Caption: "Figure 1: The global proxy temperature stack (blue) as deviations from the early Holocene (11.5–6.5 kyr ago) mean, an Antarctic ice-core composite temperature record (red), and atmospheric CO2 concentration (yellow dots). The Holocene, Younger Dryas (YD), Bølling–Allerød (B–A), Oldest Dryas (OD) and Last Glacial Maximum (LGM) intervals are indicated. Error bars, 1-sigma; p.p.m.v. = parts per million by volume.  Shakun et al. Figure 2a.", see also: http://www.skepticalscience.com/skakun-co2-temp-lag.html ]


Extracts from Scribbler:
•   Current human CO2 heat forcing at 400 ppm + is enough to raise sea levels by 75 feet according to paleoclimate estimates.
•   Current human CO2e heat forcing at 481 ppm + is enough to raise sea levels by 120 feet according to paleoclimate estimates.
….

The top range of a 3 foot sea level rise for this century under IPCC modeling is likely, given current realities, to instead be a low estimate. A more realistic range, given a greatly reduced true glacial inertia, is probably 3-9 feet through 2100 with higher outside potentials during large glacial outburst flood events.
Given changing ocean and atmospheric conditions together with the rising potential of large rainfalls over certain glacial zones during summer as the 21rst century progresses, climate analysts should consider such large glacial outburst floods to be a potential high risk event under current extreme human warming. It is also worth noting that these glacial systems have probably never experienced a set of forces so powerful or rapid as they are likely to face as the 21rst century progresses. Recent scientific assessments are essentially playing catch-up to these new and emerging realities."
“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: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #19 on: July 29, 2014, 05:57:53 PM »
The following linked website contains an article describing how IBM will be assisting climate change researchers to use the "Big Data" approach to reducing uncertainties in climate change forecasts.  Hopefully, ice sheet researchers will be granted some of IBM's support:

http://www.pcbdesign007.com/pages/zone.cgi?a=102177&artpg=1
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Re: Recommendations and Summary wrt the WAIS Collapse Hazard
« Reply #20 on: August 01, 2014, 02:47:08 AM »
The White House recently released a report from the Council of Economic Advisers that shows the consequences of not doing something about climate change now (see the following link with a free access pdf).  This report includes the following extract about abrupt climate change, including abrupt destabilization of the WAIS:

http://www.whitehouse.gov/sites/default/files/docs/the_cost_of_delaying_action_to_stem_climate_change.pdf

Extract: "The National Research Council’s 2013 report, Abrupt Impacts of Climate Change: Anticipating Surprises, discusses a number of abrupt climate changes with potentially severe consequences. These events include:

• Late-summer Arctic sea ice disappearance: Strong trends of accelerating late-summer sea ice loss have been observed in the Arctic. The melting of Arctic sea ice comprises a positive feedback loop, as less ice means more sunlight will be absorbed into the dark ocean, causing further warming.
• Sea level rise (SLR) from destabilization of West Antarctic ice sheets (WAIS): The WAIS represents a potential SLR of 3-4 meters as well as coastal inundation and stronger storm surges. Much remains unknown of the physical processes at the ice-ocean frontier. However, two recent studies (Joughin, Smith, and Medley 2014, Rignot et. al. 2014) report evidence that irreversible WAIS destabilization has already started.
• Sea level rise from other ice sheets melting: Losing all other ice sheets, including Greenland, may cause SLR of up to 60 meters as well as coastal inundation and stronger storm surges. Melting of the Greenland ice sheet alone may induce SLR of 7m, but it is not expected to destabilize rapidly within this century.
• Disruption to Atlantic Meridional Overturning Circulation (AMOC): Potential disruptions to the AMOC may disrupt local marine ecosystems and shift tropical rain belts southward. Although current models do not indicate that an abrupt shift in the AMOC is likely within the century, the deep ocean remains understudied with respect to measures necessary for AMOC calculations.
• Decrease in ocean oxygen: As the solubility of gases decrease with rising temperature, a warming of the ocean will decrease the oxygen content in the surface ocean and expand existing Oxygen Minimum Zones. This will pose a threat to aerobic marine life as well as release nitrous oxide—a potent GHG—as a byproduct of microbial processes. The NRC study assesses a moderate likelihood of an abrupt increase in oxygen minimum zones in this century.
• Increasing release of carbon stores in soils and permafrost: Northern permafrost contains enough carbon to trigger a positive feedback response to warming temperatures. With an estimated stock of 1700-1800 Gt, the permafrost carbon stock could amplify considerably human-induced climate change. Small trends in soil carbon releases have been already observed.
• Increasing release of methane from ocean methane hydrates: This is a particularly potent long-term risk due to hydrate deposits through changes in ocean water temperature; the likely timescale for the physical processes involved spans centuries, however, and there is low risk [of climate change surprises from this source] this century.
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“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson