Hansen et al paper: 3+ meters SLR by 2100

[AbruptSLR]

DeConto and Pollard tipping point is surface melt on the ice shelves (which leads to hydrofracturing which leads to cliff failure). Hansen et al find an ocean surface cooling effect from freshening.  Is this negative feedback actually rather more important than the positive one to melt at the grounding line?

With the attached image of NOAA's one year daily & weekly Mauna Loa CO2 concentration showing a daily value of 409.34 for April 10 2016, I am surprised that you don't recommend that an ESM model with accelerating non-linear CO2 positive feedbacks (indicating the potential for high ESS values earlier than previously expected by most climate scientists), as well as Tan et al (2016)'s ECS value of between 5 and 5.3C, and hosing (ice-climate feedback), and relative sea level rise (with input from the GIS) be used to drive DeConto and Pollard's next round of projections.

Even if the high daily value of 409.34ppm is related to the currently degrading El Nino; it is possible to consider an El Nino event as a small previous of what future global warming will bring, so maybe we need to get used to high natural CO2 emissions (say from heat activated microbes breaking down soil organics).

[Richard Rathbone]

DeConto and Pollard tipping point is surface melt on the ice shelves (which leads to hydrofracturing which leads to cliff failure). Hansen et al find an ocean surface cooling effect from freshening.  Is this negative feedback actually rather more important than the positive one to melt at the grounding line?

With the attached image of NOAA's one year daily & weekly Mauna Loa CO2 concentration showing a daily value of 409.34 for April 10 2016, I am surprised that you don't recommend that an ESM model with accelerating non-linear CO2 positive feedbacks (indicating the potential for high ESS values earlier than previously expected by most climate scientists), as well as Tan et al (2016)'s ECS value of between 5 and 5.3C, and hosing (ice-climate feedback), and relative sea level rise (with input from the GIS) be used to drive DeConto and Pollard's next round of projections.

Even if the high daily value of 409.34ppm is related to the currently degrading El Nino; it is possible to consider an El Nino event as a small previous of what future global warming will bring, so maybe we need to get used to high natural CO2 emissions (say from heat activated microbes breaking down soil organics).

What's this got to do with Hansen et al?

I think DeConto and Pollard shows that Hansen's main accelerating mechanism can't accelerate melt much more than it is already doing, and I suspect Hansen et al shows that the DeConto and Pollard critical point will come somewhat later than their model suggests. Does a colder ocean surface mean its harder to get surface melt on ice shelves? We all know that if the atmosphere is hosed with enough CO2 everything melts, but the implication I see from reading both these papers is that it will take a bit more CO2 to get rapid sea level rise out of Antarctica than might have been expected prior to reading them.

[sidd]

There is not the cold water feedback until the ice gets in the ocean. The latter is triggered after the midsummer 0C isotherm gets to the shelves, collapses them, and the cliff + retrograde bed instability takes over, then you get the surface coldwater feedback dragging back the 0C isotherm, but only after sufficent iceberg/icemelt export, when freshwater hosing reaches large fractions of Sverdrup. But by then it might be too late, since there might be no ice shelves left to collapse.

[AbruptSLR]

..., but the implication I see from reading both these papers is that it will take a bit more CO2 to get rapid sea level rise out of Antarctica than might have been expected prior to reading them.

In addition to sidd's points, both Hansen et al and DeConto & Pollard assume that ECS is about 3C; while Tan et al indicate that ECS may likely be between 5 and 5.3C; which would accelerate DeConto & Pollard's timeframe (and the CO2 concentration increase is yet another possible positive feedback factor that may further accelerate the timeframe for ASLR to occur).

[crandles]

http://julesandjames.blogspot.co.uk/2016/04/climate-sensitivity-is-53c.html

seems quite scathing of that Tan et al 5-5.3C sensitivity paper.

Would you agree that all evidence should be evaluated rather than just pick the latest paper nor be selective choosing papers that suggest either higher or lower sensitivities?

[AbruptSLR]

http://julesandjames.blogspot.co.uk/2016/04/climate-sensitivity-is-53c.html

seems quite scathing of that Tan et al 5-5.3C sensitivity paper.

Would you agree that all evidence should be evaluated rather than just pick the latest paper nor be selective choosing papers that suggest either higher or lower sensitivities?

I am trying to establish a reasonable upper bound scenario; suitable for planning so that 7.4 Billion people aren't caught be surprise (thus I am not cherry picking, just looking at reasonable limits).  Also future projections have uncertainty as observations of future climate conditions are data poor.  Feel free to look at any scenarios that you are interested in.

[AbruptSLR]

Per the linked article and attached image, the Greenland Summer surface ice melt season has begun one to two months early this year (this is not a favorable trend w.r.t. ice-climate feedback acceleration):

https://robertscribbler.com/2016/04/12/the-greenland-summer-melt-season-just-started-in-april/

Extract: "12 Percent. That’s how much of Greenland’s surface experienced melt yesterday according to a report from DMI’s Polar Portal  as an unprecedented flow of warm, wet air slammed into its great ice sheets. 10 Percent. That’s how much of Greenland’s ice sheet surface is required to melt in order to mark an official start to the Summer melt season. Late May or early June. That’s when Greenland melt season typically begins."

Caption for the attached image: "Record early start to Greenland’s ‘Summer’ melt season occurred on April 11, 2016 according to reports from DMI’s Polar Portal"

See also:

http://lists.cryolist.org/pipermail/cryolist-cryolist.org/attachments/20160412/df4b427c/attachment-0001.pdf

[AbruptSLR]

Given our current Greenland Surface Ice melting event (see my last post) the second attached image (from the linked open access reference) of the acceleration of surface ice melting due to elevation change feedback, should provide some concern for the near-term acceleration of cliff failures and hydrofacturing of coastal marine terminating glaciers in Southwestern Greenland such as Jakobshavn; which could contribute to the acceleration of Hansen et al (2016)'s ice-climate feedback:

Levermann, A. and Winkelmann, R.: A simple equation for the surface-elevation feedback of ice sheets, The Cryosphere Discuss., doi:10.5194/tc-2016-60, in review, 2016.

http://www.the-cryosphere-discuss.net/tc-2016-60/

Abstract. In recent decades, the Greenland Ice Sheet is been losing mass and thereby contributed to global sea-level rise. The ice loss is likely to increase under future warming. Beyond a critical temperature threshold, a meltdown of the Greenland Ice Sheet is induced by the self-enforcing feedback between its lowering surface elevation and its increasing surface mass loss: The more ice is lost, the lower the ice surface reaches into the atmosphere and the warmer the surrounding air becomes which fosters melting and further ice loss. The rate of ice loss is highly relevant for coastal protection worldwide. The computation of this rate so far relies on complex numerical models as it should be. In order to contribute a little to the conceptual understanding, we derive here a simple equation for the self-enforcing feedback and use it to estimate the melt time for different levels of warming using three observable characteristics of the ice sheet itself and its surroundings. When the volume loss is dominated by the feedback, the resulting logarithmic equation unifies existing numerical simulations and shows that the melt time depends critically on the level of warming with a critical slowing-down near the threshold: The median time to lose 10 % of the present-day ice volume varies between about 3500 years for a temperature level of 0.5 °C above the threshold and 500 years for 5 °C. Unless future observations show a significantly higher melting sensitivity than currently observed, a complete melt down is unlikely within the next 2000 years without significant ice-dynamical contributions.

[AbruptSLR]

Earlier in this thread I speculated that a pulse of SLR contribution from Greenland's Southwestern marine terminating glaciers could contribute to 10mm of SLR in the next couple of decades (which could then serve to contribute to the destabilization of WAIS marine glaciers due to the bi-polar seesaw mechanism).  The attached photo of meltwater ponds on the fractured surface of such marine-terminating GIS glaciers (from the linked Joe Romm article about the current early ice melt event) adds evidence to my concerns about the potential for hydrofracturing contributing to the acceleration of cliff failures at the calving face of such glaciers:

http://thinkprogress.org/climate/2016/04/13/3768915/greenland-ice-melt-stuns/

Extract: "Blistering temperatures and rainfall over Greenland have jump-started the summer melt season weeks early."

[AbruptSLR]

With a hat-tip to Greenbelt's post in the "Sea Level Rise" thread, the linked insurance article discusses how NOAA has new information indicating that sea level could rise by 3m in the 2050-2060 timeframe due to instabilities in the WAIS:

http://www.insurancejournal.com/news/national/2016/04/12/405089.htm

Extract: "Think sea level rise will be moderate and something we can all plan for? Think again.
Sea levels could rise by much more than originally anticipated, and much faster, according to new data being collected by scientists studying the melting West Antarctic ice sheet – a massive sheet the size of Mexico.

That revelation was made by an official with the National Oceanic and Atmospheric Administration on Tuesday at the annual RIMS conference for risk management and insurance professionals in San Diego, Calif.

The conference is being attended by more than 10,000 people, according to organizers. It was day No. 3 of the conference, which ends Wednesday.
Margaret Davidson, NOAA’s senior advisor for coastal inundation and resilience science and services, and Michael Angelina, executive director of the Academy of Risk Management and Insurance, offered their take on climate change data in a conference session titled “Environmental Intelligence: Quantifying the Risks of Climate Change.”

Davidson said recent data that has been collected but has yet to be made official indicates sea levels could rise by roughly 3 meters or 9 feet by 2050-2060, far higher and quicker than current projections. Until now most projections have warned of sea level rise of up to 4 feet by 2100.
These new findings will likely be released in the latest sets of reports on climate change due out in the next few years.

“The latest field data out of West Antarctic is kind of an OMG thing,” she said.
Davidson’s purpose was to talk about how NOAA is sharing information with the insurance community and the public, and to explain how data on climate change is being collected.

She explained that reports like those from the Intergovernmental Panel on Climate Change and the National Climate Assessment, which come out roughly every five years, are going on old data."

[AbruptSLR]

Davidson said recent data that has been collected but has yet to be made official indicates sea levels could rise by roughly 3 meters or 9 feet by 2050-2060, far higher and quicker than current projections.

Just to state the obvious, NOAA's projection that the GMSLR could be roughly 3m by 2050-2060, is very close of Hansen et al (2016)'s worse assumed case of a 5-year doubling time; which per the first image of Hansen et al's Fig 5 indicates that GMSLR could be roughly 5m by 2060-2100; while the second image (Hansen et al's Fig 7) indicates that such ASLR could decrease the GMST while dramatically increasing Global Energy Imbalance (EEI); which could drive super storms in the 2050 - 2070 timeframe.

[theoldinsane]

Let´s see if I got it right?

With a doubling time of 5-10 years it is going to be a dramatic downturn in GMT sometime around mid century according to figure 7a (according to Hansen et al). Then everbody are going to say "yes, we did it" regarding the 2 C goal. But at the same time everybody near the coast will be fleeing to higher locations.

But there will be hard to find a place that not have blown away by the wind. And the global economy will crash long before because the value of millions of coastal properties will crash in the uh-oh moment when everybody realize the reality.

What am I missing? (I´m not sarcastic, but maybe a risk management thinking person)

[AbruptSLR]

Let´s see if I got it right?

With a doubling time of 5-10 years it is going to be a dramatic downturn in GMT sometime around mid century according to figure 7a (according to Hansen et al). Then everbody are going to say "yes, we did it" regarding the 2 C goal. But at the same time everybody near the coast will be fleeing to higher locations.

But there will be hard to find a place that not have blown away by the wind. And the global economy will crash long before because the value of millions of coastal properties will crash in the uh-oh moment when everybody realize the reality.

What am I missing? (I´m not sarcastic, but maybe a risk management thinking person)

What you are missing is that if most of the ice sheet mass loss comes from Antarctica, then the Southern Hemisphere will be very cool (negative SSTAs and extensive sea ice through 2070) while Arctic Amplification may make the Arctic Region (including Greenland) very hot.

[ritter]

When the insurance industry starts taking 3m by 2050 seriously, deniers had best start paying attention. That is catastrophic from a planning and construction perspective. Organized retreat would be the only real option leaving much critical existing infrastructure nonfunctional and/or submerged permanently or periodically.

Edited to add: This is approximately twice as much rise in half the time as the current "worst case" scenario.

[wili]

Yeah, and it's quite stunning to see it covered in a major insurance company journal.

I can't help but think that predictions like this will soon prompt a massive flight away from the coasts, as no one will want to be left holding property that no one will buy since it would be uninsurable, probably un-mortgagable, and likely under water--literally--before any 30-year mortgage that you might get would be complete.

[theoldinsane]

Let´s see if I got it right?

With a doubling time of 5-10 years it is going to be a dramatic downturn in GMT sometime around mid century according to figure 7a (according to Hansen et al). Then everbody are going to say "yes, we did it" regarding the 2 C goal. But at the same time everybody near the coast will be fleeing to higher locations.

But there will be hard to find a place that not have blown away by the wind. And the global economy will crash long before because the value of millions of coastal properties will crash in the uh-oh moment when everybody realize the reality.

What am I missing? (I´m not sarcastic, but maybe a risk management thinking person)

What you are missing is that if most of the ice sheet mass loss comes from Antarctica, then the Southern Hemisphere will be very cool (negative SSTAs and extensive sea ice through 2070) while Arctic Amplification may make the Arctic Region (including Greenland) very hot.

Thank You AbruptSLR. Your comment improved my understanding a lot.   

[AbruptSLR]

Yeah, and it's quite stunning to see it covered in a major insurance company journal.

I can't help but think that predictions like this will soon prompt a massive flight away from the coasts, as no one will want to be left holding property that no one will buy since it would be uninsurable, probably un-mortgagable, and likely under water--literally--before any 30-year mortgage that you might get would be complete.

As stunning as it is to think about abruptly abandoning major portions of coastal cities like: London, New York, Tokyo, Shanghai, Miami, Houston, etc..  It is still more stunning to think about how we are going to feed 9.7 Billion people (see the three attached images from a 2015 UN World Population Projection), with all the world's major river deltas (Pearl, Mekong, Nile, Mississippi, etc.) and all major world ports (for shipping food) abruptly inundated; while simultaneously being hit by super storms, floods/droughts, heatwaves/polar vortices, etc.

[ritter]

It is still more stunning to think about how we are going to feed 9.7 Billion people

You see a problem there? 
Thanks for all the information you provide. While much of it escapes my mental and time constraints, it is very much appreciated!

[AbruptSLR]

It is still more stunning to think about how we are going to feed 9.7 Billion people

You see a problem there? 
Thanks for all the information you provide. While much of it escapes my mental and time constraints, it is very much appreciated!

To be honest with you, at best the Hansen et al (2016), the DeConto & Pollard (2016) and NOAA's unpublished SLR projections are all rough approximations and the first reasonable approximation of what the future might bring will likely come from the Accelerated Climate Modeling for Energy, ACME, project, when its first phase is completed by the end of 2017 (plus a couple of years to write papers and clear peer-review):

http://climatemodeling.science.energy.gov/projects/accelerated-climate-modeling-energy

[AbruptSLR]

We should also recognize that the repeated formation and loss of ice sheets in both North-Central Greenland and the Byrd Subglacial Basin (in the WAIS); has contributed to atypically high geothermal heating and associated subglacial ice melting; which will contribute to future rapid ice flow from these critical areas.

For Greenland see:

http://www.eurekalert.org/pub_releases/2016-04/tuom-ghc040616.php

Extract: "An international team that includes University of Montana researcher Jesse Johnson has learned that the Earth's internal heat enhances rapid ice flow and subglacial melting in Greenland.
Johnson, a UM computer science professor and ice-sheet modeler, helped discover that about half of the ice-covered area in north-central Greenland rests on a thawed bed and that the meltwater is routed to the ocean through a dense hydrological network beneath the ice."

For the WAIS see:

Variable crustal thickness beneath Thwaites Glacier revealed from airborne gravimetry, possible implications for geothermal heat flux in West Antarctica by Theresa M. Damiani, Tom A. Jordan, Fausto Ferraccioli, Duncan A. Young, and Donald D. Blankenship published in Earth and Planetary Science Letters Volume 407, 1 December 2014, Pages 109–122, DOI: 10.1016/j.epsl.2014.09.023

http://www.sciencedirect.com/science/article/pii/S0012821X14005780

Abstract: "Thwaites Glacier has one of the largest glacial catchments in West Antarctica. The future stability of Thwaites Glacier's catchment is of great concern, as this part of the West Antarctic Ice Sheet has recently been hypothesized to already be en route towards collapse. Although an oceanic trigger is thought to be responsible for current change at the grounding line of Thwaites Glacier, in order to determine the effects of this coastal change further in the interior of the West Antarctic Ice Sheet it is essential to also better constrain basal conditions that control the dynamics of fast glacial flow within the catchment itself. One major contributor to fast glacial flow is the presence of subglacial water, the production of which is a result of both glaciological shear heating and geothermal heat flux. The primary goal of our study is to investigate the crustal thickness beneath Thwaites Glacier, which is an important contributor to regional-scale geothermal heat flux patterns. Crustal structure is an indicator of past tectonic events and hence provides a geophysical proxy for the thermal status of the crust and mantle. Terrain-corrected Bouguer gravity disturbances are used here to estimate depths to the Moho and mid-crustal boundary. The thin continental crust we reveal beneath Thwaites Glacier supports the hypothesis that the West Antarctic Rift System underlies the region and is expressed topographically as the Byrd Subglacial Basin. This rifted crust is of similar thickness to that calculated from airborne gravity data beneath neighboring Pine Island Glacier, and is more extended than crust in the adjacent Siple Coast sector of the Ross Sea Embayment. A zone of thinner crust is also identified near the area's subaerial volcanoes lending support to a recent interpretation predicting that this part of Marie Byrd Land is a major volcanic dome, likely within the West Antarctic Rift System itself. Near-zero Bouguer gravity disturbances for the subglacial highlands and subaerial volcanoes indicate the absence of supporting crustal roots, suggesting either (1) thermal support from a warm lithosphere or alternatively, and arguably less likely; (2) flexural support of the topography by a cool and rigid lithosphere, or (3) Pratt-like compensation. Although forward modeling of gravity data is non-unique in respect to these alternative possibilities, we prefer the hypothesis that Marie Byrd Land volcanoes are thermally-supported by warmer upper mantle. The presence of such inferred warm upper mantle also suggests regionally elevated geothermal heat flux in this sector of the West Antarctic Rift System and consequently the potential for enhanced meltwater production beneath parts of Thwaites Glacier itself. Our new crustal thickness estimates and geothermal heat flux inferences in the Thwaites Glacier region are significant both for studies of the structure of the broader West Antarctic Rift System and for assessments of geological influences on West Antarctic Ice Sheet dynamics and glacial isostatic adjustment models."

See also:
http://www.reportingclimatescience.com/news-stories/article/second-paper-geothermal-heat-melting-west-antarctica.html

[AbruptSLR]

I provide the attached image for those who do not know that the "Fingerprint Effect" causes SLR contributions from ice sheets to re-distribute unevenly around the World's oceans as indicated by the figure for contributions from the GIS (upper panel) and from the WAIS (lower panel).

[tombond]

ASLR

Do you have a legend for the "Fingerprint Effect" of SLR contributions from ice sheets.

I assume that dark blue is the negative extreme (reduction in SLR) and red is the positive extreme (increase in SLR).

Thanks

[Sleepy]

tombond, you can find them here http://iwlearn.net/manuals/documents/mainstreaming-climate-change-marine-documents/the-moving-boundaries-of-sea-level-change-understanding-the-origins-of-geographic-variability at page 33.

[AbruptSLR]

tombond, you can find them here http://iwlearn.net/manuals/documents/mainstreaming-climate-change-marine-documents/the-moving-boundaries-of-sea-level-change-understanding-the-origins-of-geographic-variability at page 33.

For those who do not want to download, I offer the two attached images (with legends) from Tamislea & Mitrovica, Oceanography (2011) showing the normalized RSLR patterns for contribution from the WAIS in the first image and for the GIS & the AIS (left & right panels, respectively) of the second image.

[AbruptSLR]

I note that in my opinion NOAA's announcement that SLR could be 3m by 2050 to 2060 is more bullish than DeConto & Pollard (2016)'s projection, largely because DeConto & Pollard do not account for decadal variations like the PDO cycle; while NOAA probably just took physical measurements of marine glacial grounding line retreat in the WAIS during the strongest El Nino (based on ONI - Nino 3.4) ever recorded (which pushes warm Circumpolar Deep Water against the grounding lines).  Currently, the PDO is +2.40 which is the highest value since the +2.41 value of 1941 (see linked table), and the PDO is likely to stay positive for the next 20 to 30-years (which will increase the frequency and intensity of El Nino events):

http://research.jisao.washington.edu/pdo/PDO.latest

Hopefully, ACME (and/or the AR6 models) will be able to account for such decadal cycles in their forecasts; which is particularly critical when trying to project the risk of abrupt SLR.

[AbruptSLR]

If NOAA is correct that we might experience 3m of SLR by 2050 to 2060, then it is reasonable to expect that we might experience 5m of SLR by 2100. If so the first three images show the areas that would be impacted in the Southeastern US, Northern Europe and Southeast Asia, respectively; while the fourth image shows an informatics map indicating the number of people impacted by country for 5m of SLR.  It would appear that if one of the USA, the EU or China takes such a scenario seriously and successfully defends their coastal infrastructure will have a major economic and military leg-up on nations that do not.

[AbruptSLR]

I note that in my opinion NOAA's announcement that SLR could be 3m by 2050 to 2060 is more bullish than DeConto & Pollard (2016)'s projection, largely because DeConto & Pollard do not account for decadal variations like the PDO cycle; while NOAA probably just took physical measurements of marine glacial grounding line retreat in the WAIS during the strongest El Nino (based on ONI - Nino 3.4) ever recorded (which pushes warm Circumpolar Deep Water against the grounding lines).  Currently, the PDO is +2.40 which is the highest value since the +2.41 value of 1941 (see linked table), and the PDO is likely to stay positive for the next 20 to 30-years (which will increase the frequency and intensity of El Nino events):

http://research.jisao.washington.edu/pdo/PDO.latest

Hopefully, ACME (and/or the AR6 models) will be able to account for such decadal cycles in their forecasts; which is particularly critical when trying to project the risk of abrupt SLR.

While the quote above that DeConto & Pollard  (2016) did not account for decadal ocean-atmospheric oscillations such as our current 20 to 30-yr phase of positive PDO, is true; it may be insufficient to fully account for NOAA's projection that SLR could increase 3m by 2050-2060.  NOAA's projection may also indicate that Tan et al (2016) is correct that ECS is between 5 and 5.3C; assuming that NOAA has access to ice sheet software comparable to, or superior to, DeConto & Pollard (2016) and includes both cliff failures and hydrofracturing.  The rest of this post presents selected reasons why if ECS is actually between 5 and 5.3C, the AR5 projections could have missed this potential truth.

First, I present the following masking considerations that could account for why the AR5 projections support an ECS value closer to 3C (given that most of them were calibrated will both paleo & observed evidence and were spun-up from past initial conditions):
- The near surface waters of the Southern Ocean has been freshening since the late 1970's when the ozone hole formed over Antarctica; which has led to both cooler SSTAs and more sea ice extent in the Southern Ocean than considered in the AR5 projections (largely due to ice melt from ice shelves that do not contribute to SLR); and which have biased the observed GMSTs since that time (due to the artificially cooled surface of the Southern Ocean), which has biased the calculated ECS values from this period.  The same can be said since the cool spot has formed in the Northern Atlantic due to GIS ice mass loss.
- The negative forcing of the BVOCs (& associated SOAs) due to the recent CO₂ driven bloom of plant growth, was not included in the AR5 projections.
- The surge in atmospheric methane concentrations (largely due to both farming & fracking) since 2005 was not considered in the RCP 8.5 scenario, and I note that CO₂-e in the Spring of 2015 was 481ppm when RCP 8.5 assumes that this would not happen until 2020.
- The radiative forcing scenarios used in the spin-up of the AR5 models have ignored the paleo-anthropogenic contribution identified by Ruddiman et al (2014) in the attached image; which prevented the Holocene from steadily declining back toward lower GMST in modern times; which serves to mask high values of ECS from being identified by the AR5 models.
- The negative forcing and the negative feedback associated with anthropogenic aerosols may be stronger than considered by AR5.
Storelvmo, Trude; Leirvik, Thomas; Phillips, Petter; Lohmann, Ulrike; Wild, Martin (2015), "Disentangling Aerosol Cooling and Greenhouse Warming to Reveal Earth's Climate Sensitivity", GU General Assembly 2015, held 12-17 April, 2015 in Vienna, Austria. id.4326, Bibliographic Code: 2015EGUGA..17.4326S

- Recent interpretations of the paleo record concerning time lags between radiative forcing and warming events support high effective ECS values as indicated by the following references:

1. Egbert H. van Nes, Marten Scheffer, Victor Brovkin, Timothy M. Lenton, Hao Ye, Ethan Deyle and George Sugihara (2015), "Causal feedbacks in climate change", Nature Climate Change, doi:10.1038/nclimate2568

http://www.nature.com/nclimate/journal/v5/n5/full/nclimate2568.html
2. Dana L. Royer (2016), "Climate Sensitivity in the Geologic Past", Annual Review of Earth and Planetary Sciences, Vol. 44

http://www.annualreviews.org/doi/abs/10.1146/annurev-earth-100815-024150?src=recsys
3. Köhler, P., de Boer, B., von der Heydt, A. S., Stap, L. B., and van de Wal, R. S. W. (2015), "On the state dependency of the equilibrium climate sensitivity during the last 5 million years", Clim. Past, 11, 1801-1823, doi:10.5194/cp-11-1801-2015.

http://www.clim-past.net/11/1801/2015/cp-11-1801-2015.html
http://www.clim-past.net/11/1801/2015/cp-11-1801-2015.pdf

Second, I present the following physical considerations supporting high current, and future, climate sensitivity values:
- Sherwood et al (& others) have indicated that deep atmospheric tropical convection (leading to the expansion of the Hadley Cell & poleward shifting of the ITCZ) supports ECS values in the 4 to 4.3C range.
- Tan et al (2016) show that starting with a model with a relatively high ECS (circa 4C); that reducing the ice content in appropriate clouds to match satellite observations results in an ECS between 5 and 5.3C.
- TCR is a function of radiative forcing, and we are currently at a low spot, so if we either increase or decrease anthropogenic radiative forcing, then TCR will increase.
- Numerous non-linear positive Earth Systems feedback mechanism appear to be ready to accelerate in the near-term as the Earth continues to warm. I could cite specific mechanisms but they are largely already covered in the "Conservative Scientists ..." thread.

[TerryM]

ASLR
Each of the new theories are showing a possible sea level rise of 5 m by ~ 2050. Are there any indications of when we might expect the first 1 m rise? When should we expect even smaller incremental rises (1ft. or possibly .5 m), if these newer, more extensive studies prove to be right?

Am I correct in assuming that these higher and faster rates of sea level rise are already cooked in, and that nothing we do from here on will stop or substantially slow them? If so, this might be the optimum time to unload any coastal property, head to high ground, & prepare for the hordes that will follow.

Thanks
Terry

[crandles]

3mm per year in 2010, doubling every 5 years reaches 5m by 2049

According to that exponential growth:

.1m  is reached by 2022
.25m  is reached by 2028
.33m is reached by 2030
.5m is reached by 2033
1m reached by 2038

[Xulonn]

Going from the current SLR rate of 36mm (1.4") per decade to a total of 3m (10') by 2050 would require a very serious acceleration of the rate.   

3m (118") cumulative by 2050 (34 years from now) years is an average of almost 823mm (32") per decade or 82mm (3.2") per year. 

(Recent SLR of about 8" to date is factored in.) 

3 inches per year would be noticed very quickly by all in low, flat coastal regions - such as  Annapolis, a city on Chesapeake Bay in the eastern U.S. 

 
 

[ghoti]

Eric Rignot talked in detail about SLR and how much each glacier basin in Greenland and the Antarctica might contribute in his AGU talk this year. It is linked below.

https://climatecrocks.com/2016/04/16/the-weekend-wonk-eric-rignot-at-agu/

[AbruptSLR]

ASLR
Each of the new theories are showing a possible sea level rise of 5 m by ~ 2050. Are there any indications of when we might expect the first 1 m rise? When should we expect even smaller incremental rises (1ft. or possibly .5 m), if these newer, more extensive studies prove to be right?

Am I correct in assuming that these higher and faster rates of sea level rise are already cooked in, and that nothing we do from here on will stop or substantially slow them? If so, this might be the optimum time to unload any coastal property, head to high ground, & prepare for the hordes that will follow.

Thanks
Terry

Terry,

As crandles' and Xulonn's responses indicate the answer to your question depends on how you choose to deal with uncertainty in face of a "Wicked Problem" like climate change.  crandles correctly applies Hansen's rule-of-thumb calibrated to NOAA's warning that 3m (not 5m) of SLR might occur by 2050-2060 (while we have not seen NOAA's evidence; nevertheless, they say they are currently writing paper(s) that we might see by sometime in 2018), and he provides answers to your questions that match Hansen's scientific intuition. Xulonn provides another type of answer to your question, by indicating that no one is going to do much of anything until they see more convincing evidence such as in one of the "Canaries in the Coal Mines" like Chesapeake Bay, which is the hub of US Naval Power and which is currently experiencing more frequent flooding from periodic storm surge and king tide events.

You should realize that DeConto & Pollard (2016)'s is a first of its kind of paper and thus appropriately errs on the side of least drama; and presumably the unpublished NOAA work extends their type of physical model to separately evaluate the contributions of individual ice sheet streams and glaciers (and other sources), as I note that preliminary versions of ACME are fully functional now and NOAA may have access to such preliminary projections.  If this approach interests you then with regards to the attached Figure 4c from DeConto & Pollard (2016), I suggest that you: (a) shift the curve forward in time by about 25 years (due to their ESLD); and (b) integrate the area under the curve up until the date that you are interested in; which will provide a rough estimate to your questions (according to DeConto & Pollard's current physical intuition).

As to whether these projections are already cooked in, that depends very much on what radiative forcing scenario that you believe that we will follow and what effective ECS will be in effect in the next several decades.  Certainly, the WAIS will collapse now (no matter what) but, how fast that collapse occurs still depends on the details of the scenario that we are all about to follow.

Best,
ASLR

Edit: (1) ghoti links to Rignot's Dec 2015 AGU lecture, and Rignot has stated that his scientific intuition leads him to suspect that SLR will rise to about 3m by 2100 (so he is less aggressive than either Hansen or NOAA); however, he also says that he is still working on an upper bound estimate so who knows whether he will reach 5m of SLR by 2100, once he has gather enough data; and (2) my intuition says that if you are going to integrate under DeConto & Pollard (2016)'s Figure 4c that you should use the curve marked RCP 8.5 with ice-climate feedback; and add-in the contributions from steric sources, mountain glaciers, water mining, and from Greenland glaciers and surface ice melting.

Alternately, you could wait until after 2020 when the final phase of ACME is complete, plus two years for the publishing process (so their results might influence AR7).

[AbruptSLR]

To save Terry from integrating Fig 4c, I provide the first attached image of DeConto & Pollard (2016) showing Fig 4 b, c & d (again I note recommend considering accelerating their timeframe by at least 25 years based on NOAA's statement).  The second attached image shows Fig 4h for the years 2015, 2050 and 2100, which not only shows the Pine Ice Glacier, PIG, showing dynamic ice mass loss, but also that the Ferrigno Glacier intersects the PIG, and the third attached image shows the Ferrigno Glacier and Ice Tongue per Sentinel on April 14 2016, showing that this marine glacier continues to rapidly calve glacier ice into the Bellingshausen Sea.

[TerryM]

Thanks so much for the replies.
2022 is probably past my "best before date" and I frankly hadn't considered the 5 year doubling scenario.
Without some very visible dead canary event I can't imagine that we'll back away from what I see as a RCP 8.5 + future.

I dinned this evening with 2 university profs, 2 high school science teachers, their spouses, and 8 other couples, all of whom have tested as being more than 2 standard deviations above the median intellectually. All expressed disbelief that sea level rise could exceed 1 m by 2100 and insisted that even this should be seen as an extremely unlikely, alarmist forecast.

When I brought up the fact that the insurance industry was considering the possibility of a 3 m rise by as early as 2050, I was assured that this should only be seen as a money grab by big insurance, not something to be taken seriously. My concerns about Greenland's early melt, and a full 107 days of above normal temperatures north of 80 degrees were met with assurances that "this too shall pass", and concerns lest I was wasting too much time on "that ice B.S."

The conversation soon veered to why Andrew's insurance wouldn't cover accidents that occur while he is parked on the street. why neighbors were taking pictures of Andrew's Ferrari, the intrinsic value of Peter's meticulously restored classic Mercedes vis a vis that of Millie's very high mileage VW diesel, whether Canada had erred by selling all her gold to prop up the Loonie, a local art show featuring one of our group's work, and whether a hospital gift shop should pony up for DNA based medical treatments. Everything and anything was open for discussion, except possibly climate, ice, and man's responsibility for our uncertain future.

These people are bright, articulate, educated, and opinion makers. I'm generally a persuasive arguer, but tonight I might as well have been selling refrigerators to the Inuit. They weren't buying any of it.
If these  people aren't convinced that what we're seeing isn't so anomalous that it has to exceed any normal fluctuations, then what chance do we have to convince the average voter that something needs to be done, especially when the things that need to be done will cause hardship for some and discomfort for most.
Perhaps I just had an off night, but perhaps, without the sight and stench of a massive, purifying canary, we're all going to just whistle as we march ahead into a dark future that we're all too afraid of to even acknowledge.
Terry

[AbruptSLR]

Perhaps I just had an off night, but perhaps, without the sight and stench of a massive, purifying canary, we're all going to just whistle as we march ahead into a dark future that we're all too afraid of to even acknowledge.

The attached ClimateReanalyzer Temp Anom forecast for April 24 2016 shows Greenland, and the Arctic in general, set-up for large ice mass loss in the coming week.  Just maybe the reality of a seasonally ice free Arctic Ocean will frighten the 1% sufficiently to take some (limited) action (even without support from the masses).

[AbruptSLR]

ASLR
Each of the new theories are showing a possible sea level rise of 5 m by ~ 2050. Are there any indications of when we might expect the first 1 m rise? When should we expect even smaller incremental rises (1ft. or possibly .5 m), if these newer, more extensive studies prove to be right?

Am I correct in assuming that these higher and faster rates of sea level rise are already cooked in, and that nothing we do from here on will stop or substantially slow them? If so, this might be the optimum time to unload any coastal property, head to high ground, & prepare for the hordes that will follow.

Thanks
Terry

Terry,

As crandles' and Xulonn's responses indicate the answer to your question depends on how you choose to deal with uncertainty in face of a "Wicked Problem" like climate change.  crandles correctly applies Hansen's rule-of-thumb calibrated to NOAA's warning that 3m (not 5m) of SLR might occur by 2050-2060 (while we have not seen NOAA's evidence; nevertheless, they say they are currently writing paper(s) that we might see by sometime in 2018), and he provides answers to your questions that match Hansen's scientific intuition.

Terry,

I realize that I was distracted when I said that crandles analysis correctly applies Hansen's rule-of-thumb and matches Hansen's scientific intuition.  First, crandles picked up on your mistaken statement that anyone was projecting 5m of SLR by 2050 (which is not the case), and then he applied his own homemade doubling rule to begin with a 3mm/year rate of SLR in 2010 in order to back into a 5m sea level rise by 2050.  While this may be correct math, it does not match Hansen's doubling-time rule-of-thumb, nor Hansen's scientific intuition.  Second, to apply the rule correctly (given physical reality) one should determine separate double times for SLR contributions from: the WAIS, the EAIS, the GIS, from Mountain Glaciers, and steric contributions and then use weighting to average the different projections.  As physically the WAIS is the only source that could dominate the contributions to NOAA's 3m SLR by 2050-2060 (say 2055), one could guess that all the other sources might contribute 0.5m by 2055 leaving 2.5m from the WAIS.  The attached image of GRACE determined ice mass changes from 2003 to 2011, shows that a 5-year doubling-time for ice mass loss from the WAIS could achieve this projection.

Best,
ASLR

[AbruptSLR]

With a hat-tip to jai mitchell in Reply #549 of the "Sea Level Rise ..." thread, the following linked references indicate the importance of monitoring & reporting Earth Energy Imbalance, EEI (or Global Energy Imbalance or Planetary Energy Imbalance), as focusing on GMST can be misleading (especially if abrupt ice sheet mass loss changes SSTAs at high latitudes):


K. von Schuckmann, M. D. Palmer, K. E. Trenberth, A. Cazenave, D. Chambers, N. Champollion, J. Hansen, S. A. Josey, N. Loeb, P.-P. Mathieu, B. Meyssignac & M. Wild (2016), "An imperative to monitor Earth's energy imbalance", Nature Climate Change Volume: 6, Pages:  138–144, doi:10.1038/nclimate2876

http://www.nature.com/nclimate/journal/v6/n2/full/nclimate2876.html
&
https://www.researchgate.net/publication/292188056_An_imperative_to_monitor_Earth%27s_energy_imbalance

Abstract: "The current Earth's energy imbalance (EEI) is mostly caused by human activity, and is driving global warming. The absolute value of EEI represents the most fundamental metric defining the status of global climate change, and will be more useful than using global surface temperature. EEI can best be estimated from changes in ocean heat content, complemented by radiation measurements from space. Sustained observations from the Argo array of autonomous profiling floats and further development of the ocean observing system to sample the deep ocean, marginal seas and sea ice regions are crucial to refining future estimates of EEI. Combining multiple measurements in an optimal way holds considerable promise for estimating EEI and thus assessing the status of global climate change, improving climate syntheses and models, and testing the effectiveness of mitigation actions. Progress can be achieved with a concerted international effort."

See also:

Matthew D. Palmer, Met Office Hadley Centre, Exeter, United Kingdom (2016), "Earth’s energy imbalance and the global warming ‘hiatus’: insights from climate models and ocean reanalyses"

https://agu.confex.com/agu/os16/preliminaryview.cgi/Paper88665.html

Abstract: "Earth’s energy imbalance is the most fundamental metric defining the rate of global climate change. Using CMIP5 climate model simulations, we show that trends in surface temperature are only weakly indicative of the net energy imbalance on decadal timescales, due to the ocean’s ability to re-arrange large quantities of heat on these timescales. Therefore, the apparent ‘hiatus’ in global surface temperature rise may tell us nothing about the rate of global climate change over the recent past. CMIP5 models suggest that the ocean becomes dominant term in Earth’s energy budget at timescales longer than about 1 year, illustrating the need to improve estimates of the rate-of-change of ocean heat content (OHC) in order to better monitor ongoing anthropogenic climate change. An intercomparison of OHC changes in an ensemble of ocean reanalyses shows some robust signals in the upper few hundred metres but little agreement for deeper layers. This work highlights the need to maintain the Argo observations of the upper 2000m and extend the ocean observing array into the deep and abyssal ocean in order to better monitor and understand variability and long-term changes in Earth’s energy imbalance."
&

Matt Palmer and Doug McNeall (UK Met Office) (2016), "Earth's energy imbalance"

http://www.climate-lab-book.ac.uk/2016/earths-energy-imbalance/

Extract: " All the energy that enters or leaves the Earth system does so via radiation at the top of the atmosphere. For a stable climate, the sunlight absorbed by the planet must be balanced by thermal infra-red radiation emitted to space. Increased atmospheric greenhouse gas concentrations give rise to an imbalance in Earth’s energy budget by initially reducing the amount of emitted thermal infra-red radiation. The result of this imbalance is an accumulation of excess energy in the Earth system over time. The size of the imbalance, or equivalently, the rate of energy accumulation in the Earth system, is the most fundamental metric determining the rate of climate change.
The vast majority (>90%) of the excess energy is absorbed by the ocean, with much smaller amounts going into heating of the land, atmosphere and ice cover (Figure 1). Therefore, if we want to track the increase in Earth system energy content over time it is essential to have comprehensive measurements of temperature, and the associated heat content, throughout our vast oceans.
As a result of the energy imbalance, the Earth system adjusts in a number of ways that have a direct impact on both the marine and terrestrial environment. The various elements of global warming that we are familiar with – including global surface temperature rise, reductions in snow and ice cover, and sea level rise – can be thought of as symptoms of EEI (Figure 2). In our thinking and communication around climate change, it is important not to confuse any of these symptoms with the underlying cause.
A large part of the controversy around the recent slowdown in surface temperature rise, or ‘hiatus’, stems from the fact that many commentators view global surface temperature rise as the primary indicator of global climate change. If surface warming has paused, climate change has paused, right? Wrong. Both observational studies and computer simulations show that there is only a weak relationship between Earth’s energy imbalance and surface temperature change over a decade or so (Figure 3a). This is because natural climate fluctuations can re-arrange ocean heat content, to either offset or add to the long-term rate of global surface temperature rise over a decade or so.
Since the ocean becomes the dominant term in Earth’s energy budget on timescales longer than about 1 year changes in ocean heat content provide a much more reliable indicator of EEI (and therefore climate change) than surface temperature on decadal timescales (Figure 3). Indeed, time series of upper ocean heat content and satellite measurements agree on a fairly steady rate of heat uptake over the past 20 years or so, suggesting that EEI has also been relatively constant during this time (Figure 4). When viewed in terms of EEI, there is little or no evidence for a recent ‘hiatus’ in the rate of global climate change."

[jai mitchell]

cheers (I think)

keep your eyes on this space:

http://data.nodc.noaa.gov/woa/DATA_ANALYSIS/3M_HEAT_CONTENT/DATA/basin/3month/ohc2000m_levitus_climdash_seasonal.csv

updates for 1Q 2016 are forthcoming.

[TerryM]

Sorry

My 5 m by 2050 error screwed up everyone's math I'm afraid. Mia culpa.

That said, it's the exponential doublings that will preclude most from ever recognizing the severity of what lies ahead.

While sea level rise is measured in mm or inches per year, most every brain multiplies by 10, 100 or some other convenient multiplicand, determines that at 10 or a 100 times the increase, it is either too little or too far in the future to be a problem now, that building dams or levies can be put off for decades. and that today's problems must take precedence.

They believe that facing tomorrow's problems with empty checkbooks will be problematic, so we must burn all the cheap energy available to assure full employment. When small island nations are inundated, we'll want to have the resources to mitigate their transition. When major financial and transportation hubs sink below the waves we'll need to have the funds, and shutting down production or strangling industry with regulation won't put money in the polk.

Our penchant for linear thinking will I fear be our downfall.

Terry

[Laurent]

Jai Mitchell, What are these data please ? The heat content from 0 to 2000 ? what are the numbers ? 
2005 year -3 ? 8.972987 ?

[magnamentis]

That said, it's the exponential doublings that will preclude most from ever recognizing the severity of what lies ahead.

Our penchant for linear thinking will I fear be our downfall.

you nailed it, and not the first time, nice (not the consequences of course

[AbruptSLR]

Antarctic polynyas play an important role in Hansen et al (2016)'s ice-climate feedback mechanism, and the linked reference investigates the complexities of polynyas interaction with Antarctic Bottom Water (AABW) production & identifies that not only are atmospheric parameters important but also the 'icescape" is equally important to understand.  The reference recommends more research into complex interaction between polynyas response & AABW production:

Takeshi Tamura, Kay I. Ohshima, Alexander D. Fraser & Guy D. Williams (15 April 2016), "Sea ice production variability in Antarctic coastal polynyas", Journal of Geophysical Research Oceans, DOI: 10.1002/2015JC011537


http://onlinelibrary.wiley.com/doi/10.1002/2015JC011537/abstract


Abstract: "Enhanced sea ice production (SIP) in Antarctic coastal polynyas forms dense shelf water (DSW), leading to Antarctic Bottom Water (AABW) formation that ultimately drives the lower limb of the meridional overturning circulation. Some studies suggest that the variability of SIP in Antarctic coastal polynyas is driven by the influence of atmospheric forcing, i.e., surface winds and air temperature. Our previous mapping of SIP in 13 major Antarctic coastal polynyas from 1992 to 2007, using a heat-flux calculation with ice thickness data derived from satellite data, is extended here to examine the interannual and seasonal variability of SIP from 1992 to 2013. The interannual variability of total ice production correlates more strongly with polynya extent than with atmospheric forcing, with the exception of the Shackleton Polynya, which correlates well with wind. There is no coherent signal in the interannual variability between the major Antarctic coastal polynyas. We find that stochastic changes to the coastal ‘icescape', i.e., ice shelves, floating glaciers, fast ice, together with offshore first-year ice, are also important factors driving SIP variability on multiyear timescales. Both the Ross Ice Shelf Polynya and Mertz Glacier Polynya experienced a significant reduction in SIP due to calving events and the re-positioning of icebergs and fast-ice. Our results also show opposing trends between polynya-based SIP and sea ice extent in key regions of Antarctic sea ice change. Close monitoring of coastal icescape dynamics and change is essential to better understand the long-term impact of coastal polynya variability and its influence on regional AABW production."

[AbruptSLR]

That said, it's the exponential doublings that will preclude most from ever recognizing the severity of what lies ahead.

Our penchant for linear thinking will I fear be our downfall.

you nailed it, and not the first time, nice (not the consequences of course

People do not like uncertainty (it causes psychological distress) and as the inappropriate use of exponential doublings can give wildly different projections (like crandles inappropriate use of a homemade doubling rule to project 5m of SLR by 2049; which is physically impossible), people discount such non-linear projections and instead focus on the next couple of decades that will still exhibit approximately linear SLR response (thus relieving their psychological distress).  Another way to relieve the psychological distress of uncertainty is to just follow the guidance of either an authority, or of "traditional social norms"; which can be a good idea in a slowly changing situation, but which is likely to lead to increased future distress in an rapidly changing situation (like the possibility of 3m of SLR in the 2050-2060 timeframe).

[AbruptSLR]

That said, it's the exponential doublings that will preclude most from ever recognizing the severity of what lies ahead.

Our penchant for linear thinking will I fear be our downfall.

you nailed it, and not the first time, nice (not the consequences of course

People do not like uncertainty (it causes psychological distress) and as the inappropriate use of exponential doublings can give wildly different projections (like crandles inappropriate use of a homemade doubling rule to project 5m of SLR by 2049; which is physically impossible), people discount such non-linear projections and instead focus on the next couple of decades that will still exhibit approximately linear SLR response (thus relieving their psychological distress).  Another way to relieve the psychological distress of uncertainty is to just follow the guidance of either an authority, or of "traditional social norms"; which can be a good idea in a slowly changing situation, but which is likely to lead to increased future distress in an rapidly changing situation (like the possibility of 3m of SLR in the 2050-2060 timeframe).

I suspect that NOAA announced that there could be 3m of SLR by 2050-2060 at an insurance conference because actuarials understand probabilities.  As a chance that 3m of SLR might occur by 2050-2060 does not mean a 50%CL but probably a 95% CL exceedance level, as indicated by the attached plot that I created, & posted on this forum, over three years ago.

[AbruptSLR]

Needless to say, if the WAIS contributes 2.5m of SLR by 2050-2060, there will be an associated increase in methane seeps from the seafloor in West Antarctica, as implied by the linked article:

M. Römer, M. Torres, S. Kasten, G. Kuhn, A.G.C. Graham, S. Mau, C.T.S. Little, K. Linse, T. Pape, P. Geprägs, D. Fischer, P. Wintersteller, Y. Marcon, J. Rethemeyer, G. Bohrmann and shipboard scientific party ANT-XXIX/4 (1 October 2014), "First evidence of widespread active methane seepage in the Southern Ocean, off the sub-Antarctic island of South Georgia", Earth and Planetary Science Letters, Volume 403, Pages 166–177, doi:10.1016/j.epsl.2014.06.036


http://www.sciencedirect.com/science/article/pii/S0012821X1400421X

Abstract: "An extensive submarine cold-seep area was discovered on the northern shelf of South Georgia during R/V Polarstern cruise ANT-XXIX/4 in spring 2013. Hydroacoustic surveys documented the presence of 133 gas bubble emissions, which were restricted to glacially-formed fjords and troughs. Video-based sea floor observations confirmed the sea floor origin of the gas emissions and spatially related microbial mats. Effective methane transport from these emissions into the hydrosphere was proven by relative enrichments of dissolved methane in near-bottom waters. Stable carbon isotopic signatures pointed to a predominant microbial methane formation, presumably based on high organic matter sedimentation in this region. Although known from many continental margins in the world's oceans, this is the first report of an active area of methane seepage in the Southern Ocean. Our finding of substantial methane emission related to a trough and fjord system, a topographical setting that exists commonly in glacially-affected areas, opens up the possibility that methane seepage is a more widespread phenomenon in polar and sub-polar regions than previously thought."

[jai mitchell]

Jai Mitchell, What are these data please ? The heat content from 0 to 2000 ? what are the numbers ? 
2005 year -3 ? 8.972987 ?

Sorry, Yes, the numbers are 0-2000m basin wide (whole ocean heat content) the units are in 10^22 joules and correspond to this graphic

[AbruptSLR]

This is a re-post from the "Greenland 2016 Melt Season" thread:

The ratio of the NOAA Temp Anoms for the Land vs Land-Ocean is much higher for the 2015-16 Super El Nino event than for the 1997-98 Super El Nino event (see the data at the following links):

http://www.ncdc.noaa.gov/cag/time-series/global/globe/land/p12/12/1880-2016.csv
http://www.ncdc.noaa.gov/cag/time-series/global/globe/land_ocean/p12/12/1880-2016.csv

I suspect that this is partially the case because in 2016 the cold spots in the North Atlantic, and the Southern, Oceans are much more pronounced than in 1998, which reduces the Land-Ocean Temp Anom while leaving the Land Temp Anom largely unaffected (see the attached image from the linked NOAA State of the Climate report for March 2016):

https://www.ncdc.noaa.gov/sotc/global/201603

I would like to know if anyone here has the skills to analyze the amount that the North Atlantic, and Southern, Oceans cold sports are suppressing the global mean land-ocean surface temperature anom, by integrating the color coding of the attached NOAA temp anom map (note that per Hansen et al 2016 the magnitude of this suppression will likely increase rapidly if we stay on the RCP 8.5 90%CL pathway that we are currently following, as indicated by the second image in Reply #460).

[AbruptSLR]

If NOAA is correct that SLR might increase by up to 3m by 2050-2060, then the radiative forcing that occurs in the next 10, 20 and 30-years becomes critical.  In this regards I provide the attached AR5 SOD image from Chapter 8 on radiative forcing showing the global warming potential (GWP) and global temperature potential (GTP) of the indicated anthropogenic emission components; which indicates the importance of limiting methane emissions (and properly accounting for aerosol reduction) as soon as possible:

[AbruptSLR]

I have previously cited Zhang et al (2016), but I would like to emphasize its conclusion that: "Experiments based on the Representative Concentration Pathway (RCP) 4.5 given in IPCC AR5 shows the dramatic decrease in three anthropogenic aerosols in 2100 will lead to an increase of ∼2.06 K and 0.16 mm day−1 in global annual mean surface temperature and precipitation, respectively, compared with those in 2010."  Thus as the world rapidly reduces its aerosol emissions we can expect to experience an associated significant increase in GMST:

Hua Zhang, Shuyun Zhao, Zhili Wang, Xiaoye Zhang & Lianchun Song (25 January 2016), "The updated effective radiative forcing of major anthropogenic aerosols and their effects on global climate at present and in the future", International Journal of Climatology, DOI: 10.1002/joc.4613

http://onlinelibrary.wiley.com/doi/10.1002/joc.4613/abstract

Abstract: "The effective radiative forcing (ERF), as newly defined in the Intergovernmental Panel on Climate Change's Fifth Assessment Report (IPCC AR5), of three anthropogenic aerosols [sulphate (SF), black carbon (BC), and organic carbon (OC)] and their comprehensive climatic effects were simulated and discussed, using the updated aerosol-climate online model of BCC_AGCM2.0.1_CUACE/Aero. From 1850 to 2010, the total ERF of these anthropogenic aerosols was −2.49 W m−2, of which the aerosol–radiation interactive ERF (ERFari) and aerosol–cloud interactive ERF (ERFaci) were ∼ −0.30 and −2.19 W m−2, respectively. SF was the largest contributor to the total ERF, with an ERF of −2.37 W m−2. The ERF of BC and OC were 0.12 and −0.31 W m−2, respectively. From 1850 to 2010, anthropogenic aerosols brought about a decrease of ∼2.53 K and ∼0.20 mm day−1 in global annual mean surface temperature and precipitation, respectively. Surface cooling was most obvious over mid- and high latitudes in the northern hemisphere (NH). Precipitation change was most pronounced near the equator, with decreased and increased rainfall to the north and south of the equator, respectively; this might be largely related to the enhanced Hadley Cell in the NH. Relative humidity near surface was increased, especially over land, due to surface cooling induced by anthropogenic aerosols. Cloud cover and water path were increased, especially in or near the source regions of anthropogenic aerosols. Experiments based on the Representative Concentration Pathway (RCP) 4.5 given in IPCC AR5 shows the dramatic decrease in three anthropogenic aerosols in 2100 will lead to an increase of ∼2.06 K and 0.16 mm day−1 in global annual mean surface temperature and precipitation, respectively, compared with those in 2010."

[AbruptSLR]

At least in the linked Climate Central article Gavin Schmidt acknowledges that: "There's a huge amount of unknowns," in accurately modeling the timing and amount of ice mass loss from Greenland and Antarctica this century, and the article concludes that field research to be undertaken by Columbia University professor Maureen Raymo in Western Australia later this year will help to better clarify what happened in Antarctica during the late-Eemian "highstand", w.r.t. better calibrating the risk of abrupt SLR over the coming decades:

http://www.climatecentral.org/news/fate-of-worlds-coastlines-melting-antarctic-ice-20270

Extract: "Even as humanity slips into a flooding crisis of its own making, however, scientists can’t pinpoint how much worse the flooding will become. That’s partly because scientists don’t know how much climate pollution will be released during the decades ahead. But it’s also because they’re still trying to figure out how ice sheets in Greenland and Antarctica will be affected by warming.

“There’s a huge amount of unknowns,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, which is a leader in earth modeling.
…
Now, as the ice sheets begin melting, and as ice sheet modeling improves, the prognosis is getting worse.

“We already know that we’re in a danger zone in terms of sea level rise,” Schmidt said. “It’s not that anybody is thinking, ‘Oh, well, maybe the ice sheets will be fine.’ Nobody thinks that.”
…
In that paper, published last month in Nature, UMass professor Rob DeConto and Penn State scientist David Pollard developed an ice sheet model and used it simulate the effects of two processes they think could be crucial. Meltwater seeped into the ice sheet in the model and cracked it, exposing towering cliffs of ice that toppled under their own weight into the Southern Ocean.

The results, however, were highly tentative. “It’s very much not the last word on this,” Schmidt said. They were the latest trickle of information in a growing gush of findings as climate scientists strive to solve what may be the biggest single mystery currently facing them.
…
The main question is no longer whether the ice sheets in Antarctica and Greenland will melt. It’s how quickly the changes will occur.
…
“We know, with reasonable confidence now, that we have destabilized enough ice, such as through the melting of the west Antarctic ice shelves, to eventually give 10 to 14 feet of sea level rise,” Mann said. “What’s less certain is how quickly that could happen.”
…
While Hansen focuses on a worse-case scenario, other scientists are trying to determine the likelihood of such a scenario playing out in real life. Better understanding heights of prehistoric shorelines is considered key for honing science’s projections for future sea level rise.

“We’re using these models to predict the future, and one of the best ways to evaluate them is to ask, ‘Do they capture what happened in the past?’ ” Columbia University professor Maureen Raymo said. “So you have field geologists like myself who are trying to unravel the history from the rocks.”

Raymo is planning research in Western Australia later this year that could help determine whether seas rose to 25 feet above today’s levels prior to an ice age, which appears possible based on fossils of corals that grew a little more than 100,000 years ago. Periods of high sea levels are called highstands.

“Whether or not that late highstand is real or not is really important,” Raymo said. “If that late highstand is real, it really points to the West Antarctic ice sheet and probably parts of the East ice sheet collapsing dramatically.”"