Hansen’s paper, of course. Tee hee. So all you po-faced people who want to be Terribly Serious can go off and put really really silly comments over at ATTP’s (gloss: too many people who haven’t even read the paper are simply pushing their own views via the paper; much in the same way that too many people that want fewer CO2 emissions manage to convince themselves that suing Exxon makes sense1). Peter Thorne has already said almost everything that needs to be said, although since he is a nice chap writing within the scientific style, much of what he said was too subtle for many people; but I’m not going to gloss what he said because no-one but a bozo could mistake his meaning. I don’t really agree with his “It is the absolute right of the journal and its editors to publish any piece using their best judgement upon completion of a proper peer review process”. Or rather, I agree with the literal words but not that they mean anything in this context so they are effectively deceptive (I don’t think they used their best judgement, and the peer review process wasn’t proper). At one point it looked like the editor, F. Dentener, might show some spine but in the end he knuckled under to Da Man.
I jumped the gun a little last time, but not much: compare the original, the “gun jumper” and the final:
| we posit that ice sheet mass loss can be approximated by a doubling time up to sea level rise of at least several meters. Doubling times of 10, 20 or 40 years yield sea level rise of several meters in 50, 100 or 10 200 years | We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years | We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years |
Meh, they’re all the same. The WaPo quotes one “Barbara Ferreira” as saying the paper was subject to “major revisions in terms of organisation, title and conclusions”. But I’m dubious. Indeed the WaPo is too, since it says the paper is “relatively intact”, whatever that means. Here is something from the old and new versions: can you tell which is which?
| The message that the climate science delivers to policymakers, instead of defining a safe “guardrail”, is that fossil fuel CO2 emissions must be reduced as rapidly as practical. | We conclude that the message our climate science delivers to society, policymakers, and the public alike is this: we have a global emergency. Fossil fuel CO2 emissions should be reduced as rapidly as practical. |
There’s a 19-page “shorted version” available. 19. Page. Short. Version. Did you get that?
I don’t think this process says anything about the value, or otherwise, of open peer review2. The problem was the paper and the author, not the review. We all remember RC’s Peer Review: A Necessary But Not Sufficient Condition so we all agree that anyone saying James Hansen’s Bombshell Climate Warning Is Now Part of the Scientific Canon is an idiot.
The silence of the co-authors
Need I say more?
Hence the extreme short-term sea-level rise is not a prediction arising from the model at all, and assertions to the contrary are patently false
PT notes this point, and it seems that many of the less thinking meeja were fooled; e.g. the Graun. Indeed Hansen et al. get it wrong too, stating we conclude that multi-meter sea level rise would become practically unavoidable, probably within 50–150 years. Whereas what they really mean is that they assume large sea level rise.
Apologies for the break in blogging: I’ve been rowing again. Click on the pic for more.
Notes
1. For example the HuffPo and Open Mind are wrong. Ha, the HuffPo think is by Mann, oh well.
2. I pretty well agree with Eli: open review is good.
Refs
* Hyping Hansen’s Paper – DA
* The Arctic sets yet another record low maximum winter extent – also DA
* The Very Odd Idea That Exxon Should Become A Renewable Energy Company – Timmy
wmconnolley: scienceblogs.com/stoat archive 
David Archer in the comments had a different opinion: “This seems like a plausible interplay of mechanisms to me, given that it’s observed happening today, and that something like this is required to explain evidence from the past such as Heinrich events. The conclusions of this paper confirm what I had gloomily expected people would figure out, and they provide a mechanism by which the implications of the past can be explained and cast into a forecast for the future.”
[“This is another Hansen masterwork of scholarly synthesis, modeling virtuosity, and insight”? Not in my opinion; DA and I clearly differ. In particular the assertion of “modeling virtuosity” is weird; its a set of hosing experiments lacking any novelty -W]
LikeLike
Well, it is true that many natural processes can follow exponential laws – anything involving a feedback loop in particular. And the Hansen et al paper argues that they have found such feedbacks: “We find significant impact of meltwater on global climate and feedbacks that support ice melt acceleration”. Now yes, they do “experiment” with several doubling times and clearly haven’t proven this claim beyond a reasonable doubt, but they do provide more than zero evidence for it. I don’t think Thorne or you are being entirely fair here.
LikeLike
So, who has been willing to bet against Hansen’s “Doubling times of 10, 20 or 40 years”? That would be a separate bet for each number.
Because that’s, basically, what the real estate and insurance people are having to decide — how much to risk.
[Doesn’t the continuing popularity of coastal real estate answer that question? Or, to be more explicit: many people are indeed prepared to bet with large amounts of real money that Hansen is wrong -W]
Seems to me this is the real test of confidence.
Hey, you might get lucky.
LikeLike
factor in:
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0391.1
Full Access Has Arctic sea-ice loss contributed to increased surface melting of the Greenland ice sheet?
Jiping Liu1, Zhiqiang Chen, Jennifer Francis, Mirong Song2, Thomas Mote, and Yongyun Hu
DOI: http://dx.doi.org/10.1175/JCLI-D-15-0391.1
Published Online: 26 February, 2016
LikeLike
The “Open Mind” link takes you to HufPo…
[Thanks; fixed -W]
LikeLike
[many people are indeed prepared to bet with large amounts of real money that Hansen is wrong -W]
How could I take the other side of that bet? I’ll like to take the 20 year number, something large enough to offset the Federal Subsidized Flood Insurance risk I face as a taxpayer.
http://www.fema.gov/media-library/assets/documents/272
“Zone V” coastal real estate isn’t a “fair and free” market, at least in the USA. The taxpayers take the risk, the owners hit the beach.
[I agree that you have a problem with subsidised flood insurance. The solution to that is in the hands of the USAnians. However, i’m dubious that the programme covers total replacement. If SLR was 5m then anyone at 4m suffers total loss of their property – are you saying that is covered?
As to the other side of the bet: indeed, it isn’t obvious how to do this. This was one of the things behind the Great Subprime Crisis of a few years back: you want to have some method by which people can shot the market -W]
[Update: these people (http://www.seacoastonline.com/news/20160323/unh-climatologist-sell-portsmouth-south-end-homes-now) don’t seem to trust their flood insurance -W]
LikeLike
> Doesn’t the continuing popularity of coastal real estate answer that question?
Not while there’s cheap flood insurance and good evacuation plans, anyhow.
I was assuming I’d addressed the question — here — to people who have some notion the changes in the odds may be coming fast with climate change. Same people who might take wagers on the temperature change over time.
So would that change your answer?
[I don’t think so; see my response just above -W]
Yeah, I recall Hazel in 1956 rather vividly.
Nonscientists have a different perception of risk.
I meant, y’know, are there any wagers on sea level rate of change among _your_ friends and audience here, like the wagers made about temperature.
[Betting on SLR is difficult because it is so slow. A 20-year bet between individuals isn’t realistic; even 10 years is not very likely to be meaningful, and I doubt even Hansen would commit himself to anything interesting – by which I mean deviation from the existing trend – happening -W]
LikeLike
WC writes: “[DA’s] assertion of “modeling virtuosity” is weird;”
Why do I suspect that many of the blog critics actually haven’t read the paper or – if they did – no longer remember it? Well, after enumerating several changes to the documented model, Hansen writes:
” All of these modifications tend to increase the ocean stratification, and in particular the Southern Ocean state is fundamentally improved. For example, we show in Sect. 3.8.5 that our current model produces Antarctic Bottom Water on the Antarctic coastline, as observed, rather than in the middle of the Southern Ocean as occurs in many models, including the GISS-ER model documented in CMIP5. However, although overall realism of the ocean circulation is much improved, significant model deficiencies remain, as we will describe.”
Now, given that the current state of models fail to accurately reflect the observed Arctic sea-ice loss and the observed Greenland mass loss it is rather ‘weird’ to criticize a scientist for trying to emulate reality by working ‘around’ the models. Apparently they should just have used the ‘standard’ models and shown no effect. See, all is well – no ice melted 🙂
[The hosing H et al are doing “comes from” Greenland and Antarctica, not from the Arctic sea ice. And AFAIK no-one is criticising the concept of hosing, just doubting its novelty. You seem to be under the impression that it is a new thing -W]
Hansen et al at least went to the trouble of trying to inject freshwater at the sources – Greenland and Antarctica coasts corresponding to glacier outlets.
Hansen and Manabe are both on record believing that coarse resolution models can actually be more informative at times than finer resolution models – it’s easier to isolate components, vary them, and run them a number of times to determine their significance and/or effects. Or we can just wait until deh modulz get sea-ice and land ice correct and until then not jump the gun. Of course by that time it may be too late – which is exactly the argument Hansen has made.
[If that is the argument that H is making – “here are some runs, they may well be badly wrong, but never mind we’ll go with them for the moment” – then I think he fails to emphasise that in the paper -W]
LikeLike
Hank,
So, who has been willing to bet against Hansen’s “Doubling times of 10, 20 or 40 years”?
Raises both hands and feet and … on the 5-10 year doublings.
I at least read that part rather thoroughly, IMHO that’s the only part one needs to read with respect to hosing.
Hansen16 doesn’t present any 40-year doubling time results, because … wait for it … Father Time.
5-10-20 year doubling times are what is actually in their paper. From Figure 5 (a), page 3767 (that rumor is true, page 1 has the abstract, really long paper).
The real reason is obvious though, look at the 20-doubling time curve, that 20-year curve falls within the somewhat upper half of the reticent IPCC AR5 WG1 sea level rise range. Exponential though as the IPCC is, as usual, being dangerously reticent, dontcha know..
The 40-year doubling time (need to open that spreadsheet, but it’s been awhile), I believe is toward the somewhat lower half of the reticent IPCC AR1 WG1 sea level rise range.
That one if run and shown might not be so zOMG we’re all D-O-O-M-E-D. Regardless it would have been exponential and 66m of SLE happens in say three centuries, or some such.
So the biggest question I had/have was: Why didn’t Hansen16 run a ‘baseline’ condition to contrast against the zOMG we’re all D-O-O-M-E-D exponential hosing.
Where I from, that IS sacrosanct. One always has to compare what is with what might be. There is always a lower set of conditions run to fully flesh out tipping points (e. g. capsizing for small boat harbors).
Hansen16 only assumes tipping points.
All we got was what might be.
LikeLike
WCwrites: “[The hosing H et al are doing “comes from” Greenland and Antarctica, not from the Arctic sea ice. ”
Perhaps you ought to rethink that. It is quite likely that it is the loss of Arctic sea ice that is driving the Greenland mass loss. Hank’s link above makes precisely that point.
LikeLike
WC – I don’t think David Archer is stupid. The ‘virtuosity’ has little or nothing to do with simple injection of freshwater into the model (though injecting it at -15C to account for ice as opposed to liquid water might be an innovation in itself). Correcting errors and improving the model performance, plus the number of different scenarios that were run, is probably the basis for DA’s statement.
Simply the fact Hansen et al got the model to create ABWF in the correct location is at least one sign of that virtuosity – and a relatively important one when overturning currents is significant to the results.
[I’m dubious about that; it seems to me more likely that DA is being kind to a paper that he likes for other reasons. We may never know for sure -W]
LikeLike
Bit rot ate one of the links I posted above, try this:
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-15-0391.1
doi:10.1175/JCLI-D-15-0391.1, in press.
Their lovely formatting precludes posting an excerpt without massive cleanup.
You know what to do.
[So, I did look. And yes, it finds a connection between increased Arctic ice loss and Greenland melt. But no conversion of that into a rate of SLR that I could see -W]
LikeLike
[ As to the other side of the bet: indeed, it isn’t obvious how to do this. This was one of the things behind the Great Subprime Crisis of a few years back: you want to have some method by which people can shot the market -W]
Exactly. Or even to short the market.
LikeLike
> increased Arctic ice loss
More
> Greenland melt
More
> SLR
More
LikeLike
Hmm, all Hansen all the time for WMC. There were co-authors, including some big names. It’s significant that they didn’t bail.
Re the journal folding, if that indeed happened it looks to me more likely to have been because of VMD than Hansen.
LikeLike
Hamk wrote:
“> increased Arctic ice loss
More
> Greenland melt
More
> SLR
More”
Paper linked says
“Blocking highs enhance the transport of warm, moist air over Greenland, which increases downwelling infrared radiation, contributes to increased extreme heat events, and accounts for the majority of the observed warming trends”
‘Transport of warm moist air over Greenland’ seems likely to increase snow precipitation as well as melting via ‘downwelling infrared radiation’
Does the paper consider increased snow precipitation? Quick look didn’t seem to indicate it did. If it doesn’t, is it reasonable to claim a feedback loop leading to ‘more SLR’?
We know Greenland is losing mass and therefore increased melt may well be more dominant than increased precipitation in recent years. I can’t see why the increased precipitation might be non linear (or perhaps more non linear than increase melt effect) such that increased precipitation doesn’t dominate now but might in the future, but I am no expert.
Maybe you know enough to rule that out if you are making the more SLR feedback loop claim?
Does feel like something you would want to rely on. But perhaps the uncertainty should be stated if making such a claim?
LikeLike
Ugg sorry
Hank not Hamk
also
*Doesn’t* feel like something you would want to rely on.
LikeLike
As I said on FB: “Hansen et al: if a bad thing doubles five times, then it’s really bad.”
LikeLike
IMO you’re suggesting an unphysical result, Chris. For one thing, if that warm moist air is being pulled up from the south in a blocking high, it might not be precipitating much. On longer time scales, expecting warming to result in overall increased accumulation seems unreasonable, even though we might see a short-term balancing with more snow accumulating in colder regions (i.e. at higher altitudes farther north) even while the south (some of which is below the Arctic Circle, note) melts. As it stands, each year during the melt season the lower-altitude periphery of the ice sheet melts down to ice; this is the same area that would tend to get the most added snowfall, IOW it’s not going to accumulate there.
[More warmth = more moisture = more precipitation is a commonplace result. In Greenland, what this does to the overall mass balance probably depends on when (summer / winter) and where (interior / coast) it falls -W]
LikeLike
Perhaps I’ve been misinformed; my impression is that Greenland is going to melt, and we’re only debating the rate and rate of change. That would be water intrusion through channels under the glaciers into the underside of the icecap, and surface melt, and connections from the surface to the underside, and increasing stress exceeding the tensile strength of ice making additional openings.
That’s a long way from the assumption a decade or more ago, that the plastic flow of the ice in winter would always fill any meltwater voids and self-heal the ice cap.
http://www.climatecentral.org/news/new-greenland-ice-melt-fuels-sea-level-rise-concerns-17187
Sustained mass loss of the northeast Greenland ice sheet triggered by regional warming
Nature Climate Change 4, 292–299 (2014)
doi:10.1038/nclimate2161
“… the northeast Greenland ice stream, which extends more than 600 km into the interior of the ice sheet, is now undergoing sustained dynamic thinning, linked to regional warming, after more than a quarter of a century of stability. This sector of the Greenland ice sheet is of particular interest, because the drainage basin area covers 16% of the ice sheet (twice that of Jakobshavn Isbræ) and numerical model predictions suggest no significant mass loss for this sector, leading to an under-estimation of future global sea-level rise. The geometry of the bedrock and monotonic trend in glacier speed-up and mass loss suggests that dynamic drawdown of ice in this region will continue in the near future….”
[I don’t think that’s right. The “eventual melt” was the result 10 years ago, the need to understand the rate is still present today. There are any number of studies talking about “leading to an under-estimation of…” and so on; but converting that into a rate is what is required -W]
LikeLike
Contrariwise, from 2008:
http://www.realclimate.org/index.php/archives/2008/04/moulins-calving-fronts-and-greenland-outlet-glacier-acceleration
Has anyone seen a followup by the researchers to this discussion?
LikeLike
P.S., from that 2008 thread, as quoted hereabouts:
http://scienceblogs.com/stoat/2007/02/05/why-do-science-in-antarctica/#comment-6787
“… No ice sheet or glacier collapses due to riddling by moulins. I still see a persistent misconception about the ability of meltwater to melt glacier ice and riddle the glacier with holes. I work on glaciers with lots of melt and they are not weakened by all the meltwater drainage.”
LikeLike
Can I pop in here to make the arguably obvious but still notable point that this OP and accompanying conversation give the lie to denialist notions that climate “alarmists” are a cabal all colluding to push the worst-case disaster scenarios?
Well, I just did.
LikeLike
>”[More warmth = more moisture = more precipitation is a commonplace result. In Greenland, what this does to the overall mass balance probably depends on when (summer / winter) and where (interior / coast) it falls -W]”
Probably depends? Yes it could depend. But what information do we have? Has mass loss from Greenland accelerated?
http://www.nature.com/nature/journal/v443/n7109/full/nature05168.html
suggests it has.
So it appears any increased precipitation hasn’t been enough to counteract the increased melting at least so far.
If it hasn’t been enough so far, is there any reason to expect a more non linear response in precipitation than in melting? That seems pretty unlikely to me, after all eventually the increased warming will result in enough of the extra precipitation falling as rain instead of snow to stop any further effect of offsetting increased melt. It doesn’t seem likely to be non linear in the good for stability direction.
So while the paper previously linked alone doesn’t seem to include everything you need to make the case for a SLR feedback, adding a bit more data on what has been happening recently seems to make the case quite well unless there are reasons for expecting an increasing response of more increased precipitation.
There may be more gaps in the argument for this SLR feedback, but relying on those gaps to mean the SLR feedback doesn’t exist seems bizarrely optimistic.
Dismissing the SLR feedback because that paper didn’t cover increased precipitation (or ‘probably depends’ answer) is a response that might technically be correct but would seem to me to potentially border on being inadequate to the point of being misleading.
LikeLike
Precipitation is increasing in the arctic. But with global warming it will no longer all fall as snow. And when precipitation falls as rain – not snow – expect dramatically non-linear feedbacks.
LikeLike
http://www.nola.com/environment/index.ssf/2016/03/antarctic_loss_could_double_ex.html
—excerpt follows—-
according to new research published Wednesday (March 30).
The startling findings, published in the journal Nature, paint a far grimmer picture than current consensus predictions, which have suggested that seas could rise by just under a meter at most by the year 2100. Those estimates relied on the notion that expanding ocean waters and the melting of relatively small glaciers would fuel the majority of sea level rise, but did not factor in changes to the massive ice sheets of Greenland and Antarctica.
The scientists behind Wednesday’s study used sophisticated computer models to decipher a longstanding riddle about Antarctica: how did it surrender so much ice during previous warm periods? They found that similar conditions in the future could lead to monumental and irreversible increases in sea levels. If high levels of greenhouse gas emissions continue, they concluded, oceans could rise by close to two meters in total (more than six feet) by the end of the century. The melting of ice on Antarctica alone could cause seas to rise more than 13 meters (42 feet) by 2500.
The projection “nearly doubles” prior estimates of sea level rise, which had relied on a “minimal contribution from Antarctica,” said Rob DeConto of University of Massachusetts, Amherst, who authored the study with David Pollard of Penn State University.
[That PR is too vague to be useful; I was going to whinge that it didn’t even link to the paper but fortunately… -W]
LikeLike
http://www.nature.com/nature/journal/v531/n7596/full/nature17145.html
[Thanks. Annoyingly, I wrote a reply but something swallowed it. Anyway. The key point looks to be “a model… calibrated against Pliocene and Last Interglacial sea-level estimates”. So the point is that the models don’t reproduce what happened in the past, so if you adjust / calibrate your model to reproduce the past, maybe that makes your future predictions better. However, the obvious problems is timescale; it isn’t clear to me how that allows you to know that things will happen on 20, 50, 100, 200 or whatever timescales; as the past stuff would all look the same.
Church and Clark appear to be cautious:
https://theconversation.com/what-does-the-science-really-say-about-sea-level-rise-56807 -W]
LikeLike
Bethlehem is located at an elevation of about 775 meters (2,543 ft) above sea level, so the Beast isn’t at risk of drowning yet.
LikeLike
—-
So this isn’t a new idea, but newly incorporated into a model and doing that made sense of the rate of change in the paleo record:
[Be cautious about believing the meeja – I’ll take you as quoting from them to mean you think what they say is worth reading – stuff about buttressing ice shelves is hardly a new idea -W]
LikeLike
Also note:
http://www.ldeo.columbia.edu/news-events/some-antarctic-ice-forming-bottom
LikeLike
so, anyone got pictures of John Mercer jogging?
http://www.newyorker.com/news/daily-comment/climate-catastrophe-coming-even-sooner
LikeLike
[So the point is that the models don’t reproduce what happened in the past, so if you adjust / calibrate your model to reproduce the past, maybe that makes your future predictions better. However, the obvious problems is timescale; it isn’t clear to me how that allows you to know that things will happen on 20, 50, 100, 200 or whatever timescales; as the past stuff would all look the same. – W]
Exactly. 20 weeks for collapse of the West Antarctic Ice Sheet would be horrible. WAIS is dynamically unstable. In a slightly warmer world, it might mostly just melt in place, taking many centuries to melt. In a much warmer world, WAIS might collapse in hundreds of years. Might collapse much faster. What is the limit on how fast it might collapse?
Lawson B took 2 weeks.
If you claim to know that a WAIS collapse will take longer than any specific amount of time, I’d like to know how you know this.
[I made no such claim -W]
I can see how it might, a slow enough warming might allow for the WAIS to slowly melt, and only the last little bit is melting in a collapse.
Click to access 079020.pdf
LikeLike
> if you adjust / calibrate your model to reproduce the past
Wait, you’re addressing two different models here at least — Hansen et al., and DeConto and Pollard.
[No, I’m addressing just one: DC&P -W]
The latter adjusted their model to incorporate Alley’s observation that a sufficiently high ice cliff undermined from below will collapse under its own weight — slower if the ice is solid, faster if it’s fractured, faster if meltwater from the top has been opening up cracks. That’s not sea ice buttressing slowing down the glacial advance, it’s mass wasting off the full height of now floating ice — less if any back-pressure retarding the glacier, compared to the back pressure from solid and grounded ice.
[I don’t think anyone is talking about sea ice buttressing. Its ice shelf buttressing -W]
Or that’s my amateur reading. Other views?
That’s not in Hansen’s model explicitly, unless I missed it — though it’s a mechanism that could explain the change in rate.
LikeLike
I should add “now-floating _cantilevered_ ice” as I read it — the glacier while grounded could become very thick, then as its downstream end is undermined and comes off the grounding line, the thick ice built up while grounded loses support and that’s where the mass wasting off the ice cliff happens.
LikeLike
op. cit.: http://www.realclimate.org/index.php/archives/2013/08/the-inevitability-of-sea-level-rise/comment-page-2/#comment-404270
Diverse calving patterns linked to glacier geometry
Nature Geoscience (2013)
doi:10.1038/ngeo1887
LikeLike
In #19 above I conflated accumulation and mass balance, which was sloppy since I’m well aware of the distinction. Restating my basic point, yes, accumulation can and has outpaced loss temporarily, but with continued warming it doesn’t seem possible for that effect to scale up enough to avoid increasingly negative mass balances.
LikeLike
Hank, don’t forget the widespread reverse slope situation, which once started could proceed very quickly without undermining. IIRC the ice involved in that process wouldn’t be floating, or at least largely not. Cliffs too high will collapse, not matter how well grounded.
LikeLike
> quoting from them to mean you think
> what they say is worth reading
Well, I don’t mean I trust ‘the media’, but I find Alley worth reading even at one remove. I’d link to a transcript if I found one.
LikeLike
28:
OTOH the Bethlehem Peninsula could be the Next Big Thing in Armageddics
LikeLike
> the Bethlehem Peninsula
With some anticipation and site preparation, removing the toxics and heavy metals, the new intertidal and shallow waters could be vastly productive of seafood, too. Competitive with fresh-from-the-Arctic-Ocean, closer to civilization, and with sunlight every day of the year.
LikeLike
> sea ice buttressing. Its ice shelf buttressing
Er ah – okay, I mean “floating ice buttressing” versus “grounded ice buttressing” because once the ice pushes past the grounded line, it can melt from below and it’s floating so there’s some limit to how tall an ice cliff can persist.
Back at the grounding line and uphill from there, as long as the ice is mostly grounded (but for the meltwater channels being discovered under there) — that ice can be as tall as it can get, supported below and all around.
Well except for the “beehive” pattern of melt-and-refreeze just described. But the ice uphill from the grounding line is thicker (both above sea level and below) than the floating ice shelves. Whether it’s ancient ice or freshly refrozen bottom ice underlying the accumulated snowfall on top.
I was trying to make the same point Steve did more succinctly — once warm water gets in past the grounding line, where the basins get deeper farther inland, that’s where the Alley process has a chance to work.
I’m still glad I came up with my wildly imaginative cli-fic “ice cube catastrophe” scenario in which the ice cap stress fractures, shivers and shatters, and rushes piecemeal to the sea. Even tho’ the fiction only lasted a few days before someone came up with a model suggesting it could happen.
But not, I assure you, not tomorrow or the day after.
How about next Thursday?
LikeLike
Ocean temperature thresholds for Last Interglacial West Antarctic Ice Sheet collapse
GEOPHYSICAL RESEARCH LETTERS
16 March 2016
Johannes Sutter, Paul Gierz, Klaus Grosfeld, Malte Thoma and Gerrit Lohmann
Published Online : 29 MAR 2016
DOI: 10.1002/2016GL067818
Abstract
The West Antarctic Ice Sheet (WAIS) is considered the major contributor to global sea level rise in the Last Interglacial (LIG) and potentially in the future. Exposed fossil reef terraces suggest sea levels in excess of 7 m in the last warm era, of which probably not much more than 2 m are considered to originate from melting of the Greenland Ice Sheet. We simulate the evolution of the Antarctic Ice Sheet during the LIG with a 3-D thermomechanical ice sheet model forced by an atmosphere-ocean general circulation model (AOGCM). Our results show that high LIG sea levels cannot be reproduced with the atmosphere-ocean forcing delivered by current AOGCMs. However, when taking reconstructed Southern Ocean temperature anomalies of several degrees, sensitivity studies indicate a Southern Ocean temperature anomaly threshold for total WAIS collapse of 2–3°C, accounting for a sea level rise of 3–4 m during the LIG. Potential future Antarctic Ice Sheet dynamics range from a moderate retreat to a complete collapse, depending on rate and amplitude of warming.
[Interesting. DC+P also want to raise ocean T by 2-3 oC. But that’s not there today, or any time soon, I think. That may argue for *longer* timescales for collapse -W]
LikeLike
I’ll just whistle by the science being discussed….
1. Re coastal real estate, William sez “to be more explicit: many people are indeed prepared to bet with large amounts of real money that Hansen is wrong”
That’s interesting, I think. Most business markets/prediction markets/weather markets seem very realistic about climate change, but coastal real estate acts as if it’s not going to be harmed by SLR, despite the occasional climatologist advising people to sell. Could be worth investigating. I wonder if institutional investors have changed their attitude but it’s not yet showing up in the overall market.
2. I’ll semi-disagree with William about betting over SLR. He refers to a change in trend being too hard to bet over. That’s fine, but as a continuation of an existing trend, I think SLR is better than temp and is less erratic. I don’t recall there being longer than a 5-year period where SL has declined. For betting against denialists saying the cooling begins today, a 5-year bet over SL is probably safer than temps.
LikeLike
[That may argue for *longer* timescales for collapse -W]
It seems to me that there are multiple times of interest. How long till the point that the collapse starts? How long of delay from exceeding the threshold for a collapse until the majority of the collapse? And how long the majority collapse takes?
The first might be hard to determine even after the fact, if the collapse is slow or there is a long delay from exceeding the threshold until the collapse is easily observable.
The time to collapse would be a good predictor of the economic cost. A collapse over thousands of years would provide a lot of time for relocation of people and assets. A collapse shorter than a decade would be a massive economic and social disaster.
LikeLike
More wild and crazy speculation from those freedom-hating people who keep trying to destroy the livelihood of real estate agents along the coast:
http://www.reportingclimatescience.com/news-stories/article/research-questions-west-antarctic-ice-sheet-stability.html
—-excerpt follows—–
Climate modellers of the Alfred Wegener Institute have therefore analysed the changes to the Antarctic Ice Sheet in the last interglacial period and applied their findings to future projections. … “If the ocean temperature rises by more than two degrees Celsius compared with today, the marine-based West Antarctic Ice Sheet will be irreversibly lost. This will then lead to a significant Antarctic contribution to the sea level rise of some three to five metres”, explains AWI climate scientist Johannes Sutter. This rise, however, will only occur if climate change continues as it has up to now. The researchers make these assessments based on model simulations.
“Given a business-as-usual scenario of global warming, the collapse of the West Antarctic could proceed very rapidly and the West Antarctic ice masses could completely disappear within the next 1,000 years”, says Johannes Sutter, the study’s main author, who has just completed his doctoral thesis on this topic. “The core objective of the study is to understand the dynamics of the West Antarctic during the last interglacial period and the associated rise in sea level. It has been a mystery until now how the estimated sea level rise of a total of about seven metres came about during the last interglacial period. Because other studies indicate that Greenland alone could not have done it”, Prof Gerrit Lohmann, the head of the research project, adds.
[“could proceed very rapidly… could completely disappear within the next 1,000 years” – you have to be careful listening to geologists and glaciologists. They don’t speak the same language as us. To them, 1000 years is “very rapid” -W]
LikeLike
That’s not a steady rise over a thousand years; if you read it …, well, if not, l’ll quote a bit more from the same interview:
The new findings on the dynamics of the ice sheet allow conclusions to be drawn about how the ice sheet might behave … a stable intermediate state only once – put simply – a mountain ridge under the ice temporarily slows down the retreat of the ice masses.
If the ocean temperature continues to rise or if the grounding line of the inland ice reaches a steeply ascending subsurface, then the glaciers will continue to retreat even if the initial stable intermediate state has been reached….
“Two maxima are also apparent in the reconstructions of the sea level rise in the last interglacial period. The behaviour of the West Antarctic in our newly developed model could be the mechanistic explanation for this”, says a delighted Johannes Sutter.
——-end excerpt—-
Slow? Fast? Both?
LikeLike
PPPPPPS, you might enjoy the most recent comment in this thread, which you’ve been following already: http://hannahlab.org/climate-skeptics-peter-wards-ozone-depletion-theory/
LikeLike
Less than 1,000 years is very rapid to a geologist.
“We point out, however, that a rapid WAIS collapse within this millennium is at the far end of conceivable future West Antarctic Ice Sheet dynamics, only triggered in extreme warming scenarios. Such conditions could be reached if future greenhouse gas emissions follow a business as usual path as laid out by the RCP8.5 scenario [Stocker et al., 2013]. Trusel et al. [2015] show that this could subject most Antarctic ice shelves to surface melt rates which have been associated with rapid ice shelf collapse in the Antarctic Peninsula (the collapse of the Larsen A and B ice shelves).”
http://onlinelibrary.wiley.com/doi/10.1002/2016GL067818/abstract
Only problem is that business as usual looks likely to me.
LikeLike
Hmm, so from the Hansen SOM (page 12 of 15, lines 138-141) …
“Most recently, Godefroid and Kindler (2015) added: “The MIS 5e record is remarkable. In particular, beach deposits and an intertidal notch at +11 m above msl strongly suggest that sea-level peaked at a much higher elevation than previously assessed, implying pronounced melting of polar ice.”
Well, Godefroid and Kindler (2015) does state such, B-U-T it also states …
Hmm, Godefroid and Kindler (2015) can be found …
https://archive-ouverte.unige.ch/unige:74695/ATTACHMENT01
Click to access 26_Godefroid_Kindler.pdf
“It is not the aim of this paper to reconstruct the sea-level history during the last interglacial period. However, based on observations made at the Bullet Hill road cut, we can provide constraints to this history that will probably be useful for future researchers.
The occurrence of two laterally juxtaposed rock bodies of MIS 5e age separated by an erosional surface at the Bullet Hill outcrop (Figures 9 and 10) confirms the previous assertions of numerous authors (e.g., Aahron et al., 1980; Hearty and Kindler, 1993; Hearty et al. 2007, Thompson et al., 2011) regarding the occurrence of high-frequency (i.e., “subMilankovitch”) sea-level fluctuations during the last interglacial. Nonetheless, the presence of a fossil intertidal notch carved in and filled by MIS 5e deposits at +11 m above msl (Figure 10) shows that, during one of these fluctuations, sea level probably reached an elevation about 5 m higher than previous estimates (e.g., +6 m, Hearty et al., 2007; Blanchon et al., 2009). Definitely, the elevation of these features (notch and marine deposits) cannot be explained by an uplift of the island, because coral-reef terraces of last interglacial age are found at about the same elevation on Crooked as on all other Bahamian islands (i.e., seldom more than +2 m; Neumann and Hearty, 1996; Figure 5). Further, as indicated by the relatively elevated A/I values measured on this exposure and also by the fairly large volume of marine deposits overlying the erosional surface, this peak highstand was probably reached quite early in the MIS 5e interglacial rather than at the end of this period, as previously suggested (Neumann and Hearty, 1996; Hearty et al., 2007). Finally, the depositional environments of the two rock bodies exposed on either side of the erosional surface at the Bullet Hill road cut (eolian versus intertidal) do not provide evidence for a mid-5e regression (Hearty et al., 2007; Thompson et al., 2011), but rather for a simple sea-level rise from a lower elevation as advocated by Blanchon et al. (2009) and Godefroid (2012).”
Godefroid (2012) (PhD thesis mainly in french) can be found here …
https://archive-ouverte.unige.ch/unige:20295
“Sea-level history during the late Pleistocene (MIS 5e) and the Holocene: The extensive exposures of coastal and reefal deposits dating from the late Pleistocene and the Holocene on Mayaguana provide new and original data about the sea level fluctuations during these time periods. Most previous reconstructions of MIS 5e sea level comprise two highstands, exceeding modern ordnance datum by a few meters, separated by a lowstand phase about 123 ka ago, and followed by a rapid drop of sea level at the end of MIS 5e, about 117 ka ago. No trace of such a lowstand episode was identified on Mayaguana. In contrast, the coral assemblages exposed in the reefal terraces indicate a marked deepening of the sea at about that time. Moreover, the broad seaward progradation of the Big Cove Mb. (late MIS 5e) suggests a slow regression after the mid-MIS 5e sea-level maximum. Contrary to most regions worldwide, the Holocene stratigraphic record from the Bahamas islands has, up to now, not yielded indications of a higher than present sea level during this time interval. However, the occurrence of phreatic cements at about +2 m in 2’000 years-old beach sediments at North West Point (NW Mayaguana) represent a solid piece of evidence that sea level might indeed have been higher at that time.”
“Last but not least, the pristine and complete sediment successions from both this and the previous interglacial periods provide new and original data that complement, albeit contradict, earlier sea-level reconstructions for these time periods.”
I would very kindly like to thank Hansen16, et. al. for providing such counterfactual evidence (at least with respect to their own paper).
LikeLike
EFS – not sure what you consider to be contradictory? That sea levels were actually higher than proposed? Or that the Bullet Hill outcrop “confirms the previous assertions of numerous authors (e.g., Aahron et al., 1980; Hearty and Kindler, 1993; Hearty et al. 2007, Thompson et al., 2011) regarding the occurrence of high-frequency (i.e., “subMilankovitch”) sea-level fluctuations during the last interglacial”?
Both points would seem supportive to me, not contradictory.
LikeLike
Kevin O’Neill,
It’s called cherry picking (e. g. the quote versus what was not quoted).
Hearty -> 3m-4m then 0m then +6m (in ‘several decades’ or some such ‘ecological cycle’ from just one paper even Blanchon (2009)).
Godefroid -> +10m at start of MIS-5e
Now, check out the ramp from the glacial to the beginning of the interglacial MIS-5e versus Holocene LGM to current pre anthropogenic era, via various proxy measurements (say d18O and other very recent high resolution proxy data).
Those two time series don’t suggest “sameness” to me anyways. There are several recent papers that I could point to comparing the transitions from glacial to interglacial, Eemian and Holocene transitions.
No one is contesting 6m-9m or even 10m sea level highstand. No one. Let me repeat that, no one.
What is being contested is the temporal sequence, particularly the part where the Eemian blows the doors off of the Holocene in it’s transition from glacial to interglacial.
Godefroid appears or seems or suggests an entirely different MIS-6e sea level reconstruction then Hearty does. A very early MIS-5e highstand versus a much later (by several Kyr) MIS-5e highstand..
I only tripped over that reference in doing a rather complete literature review. I have two piles of papers, the Hearty pile and the everyone else pile.
I’m now of the rather technical opinion that Hearty is the Junior or Senior of the coastal paleogeomorphology crowd (e. g. very self referential and self sealing).
LikeLike
“In 1995, 10 Argentine soldiers witnessed a cataclysm that no other humans have ever seen, one that has since altered our understanding of climate change.
The men were stationed at Matienzo Base, a dreary cluster of steel huts that sat atop a wedge of volcanic rock jutting from the sea, 50 kilometers off the coast of Antarctica. The island was surrounded by a plain of glacial ice covering 1,500 square kilometers—25 times the area of Manhattan. Although the ice shelf floated on the sea, it was 200 meters thick—as solid as bedrock. Yet Captain Juan Pedro Brückner sensed that something was wrong. Meltwater had formed ponds that dotted the ice. He could hear a gurgling sound as the water seeped down into a network of descending cracks. Day and night, Brückner’s men heard deep convulsions that sounded like subway trains passing underneath their beds. The rumbles grew more and more frequent.
Then one day, while the crew ate lunch inside one of the huts, they were blasted by a boom—“calamitously loud, like a volcano blowing up,” Brückner recalls. They ran outside. The ice shelf bordering their little island was breaking apart. The upheaval was so violent they feared the fracturing ice would tear the island from its foundation and roll it like a log into the ocean. They placed instruments by their feet to warn them if the ground started to tip. After a few tense days the men were evacuated by helicopter to another station 200 kilometers north. The island held, but the map had changed for good.
Brückner and his colleagues had witnessed the collapse of the Larsen A ice shelf, a signature event.”
Less than 1,000 years is very rapid to a geologists and glaciologists.
Very rapid is while eating lunch, even for a geologist or a glaciologist. So is two weeks, which Larsen B took.
Larsen Inlet ice shelf. Larsen A, above. Prince Gustav ice shelf. Then most of Larsen B ice shelf. Up next, the rest of Larsen B ice shelf. Was close this summer. Maybe next. Maybe a few more years. Very rapid, as glaciologists view time. Then Larsen C ice shelf. Then, perhaps the Ross ice shelf. Or the Filchner-Ronne ice shelf. And there is a big difference to these big ice shelves. Behind them isn’t just some little glaciers that will speed up their flow 6x or 10x to the ocean. Behind these is the West Antarctic Ice Sheet.
WAIS, perhaps exposed as a cliff of ice, too tall to be stable. The cliff then collapses, exposing another cliff of ice too tall to be stable. Rinse, lather, repeat. What stops the collapse, other than running out of thick ice resting on rock below sea level? Rinse, lather, repeat.
http://www.scientificamerican.com/article/scientists-trek-collapsing-glaciers-antarctica-meltdown/
LikeLike
EFS – what you suggest is not what the authors suggest. High frequency fluctuations does not equal a single pulse followed by a fall. They agree the data show high frequency fluctuations. The timing of the largest highstand is different, but not the fact there were high frequency fluctuations.
LikeLike
Lots of stress tied up in that ice:
http://www.upi.com/Science_News/2013/07/11/Scientists-track-noisy-icebergs-across-worlds-oceans/50661373589525/
“… The breakup of ice sheets and the calving and grounding of icebergs can create enormous sound energy, they said, but even floating icebergs can be the source of noise.
…
“During one hourlong period, we documented that the sound energy released by the iceberg disintegrating was equivalent to the sound that would be created by a few hundred supertankers over the same period,” marine geologist Robert Dziak said in an OSU release Thursday.
“This wasn’t from the iceberg scraping the bottom,” he noted. “It was from its rapid disintegration as the berg melted and broke apart. We call the sounds ‘icequakes’ …”
———
Seems like a lot of stress and strain there just waiting …
LikeLike
KO,
I’m pretty sure I’m not suggesting anything other than what the authors suggest, which is not an insignificant difference
“Further, as indicated by the relatively elevated A/I values measured on this exposure and also by the fairly large volume of marine deposits overlying the erosional surface, this peak highstand was probably reached quite early in the MIS 5e interglacial rather than at the end of this period, as previously suggested (Neumann and Hearty, 1996; Hearty et al., 2007). ”
“Finally, the depositional environments of the two rock bodies exposed on either side of the erosional surface at the Bullet Hill road cut (eolian versus intertidal) do not provide evidence for a mid-5e regression (Hearty et al., 2007; Thompson et al., 2011), but rather for a simple sea-level rise from a lower elevation as advocated by Blanchon et al. (2009) and Godefroid (2012).”
When the authors say ‘regarding the occurrence of high frequency (i.e., “sub Milankovitch”) sea-level fluctuations during the last interglacial” it becomes a matter of interpretation of what they meant (“high frequency” might mean femtosecond to second to minute to hourly to daily to yearly to decadal to centennial to millennial to multi-millennial, well they are geologists, so my 50 Hz sampling is say similar to their quasi-decadal-to-centennial sampling or some such (for say things greater then 100kyr ago))
I’m not seeing any type of hard and fast rules here, just different interpretations, that, at this point in time, seem or appear or suggest spatiotemporal ambiguities.
In fact, this is rather par for the course, if someone disagrees with you, then point out where they agree with you and omit where they disagree with you. How better to try to deflect a difference of interpretation than by pointing out said a priori paper in an attempt to deflect that line of criticism.
IMHO, in the same fashion that Hearty interprets the MIS-5e highstand spatiotemporal sequence.
Heck, I’ve been there done that, more than once even. Bog standard boilerplate discussion where scores are NOT settled.
I think I’ve just shown that to be the case, in fact, quite similarly to us bickering about this, your opinion is not my opinion and vice versa.
LikeLike
LikeLike
IMHO, the best Yes album evar!
LikeLike
William, one more?
LikeLike
Isn’t this where …
(c/o: Pink Floyd – The Wall)
LikeLike
EFS – Your point was that Godefroid contradicts Hansen, by proxy you bring up Hearty – but I don’t see where on this issue Hearty is a good proxy for Hansen.
Hansen postulates that sea level can increase rapidly based on data from MIS5e. What Godefroid suggests is that sea level in MIS5e increased to a higher level and even more rapidly than others believe.
Think of it as a rate. If the highstand is later in MIS5e, then the rate has to be slower. It’s also a matter of amplitude; Godefroid says 11m, this too affects the rate, making it even higher still.
Combining an earlier highstand with a higher MSL makes the rate much, much faster.
LikeLike
KO,
Hansen is not a SME on sea level rise, and, for that matter, neither is Hearty. I actually don’t give a flip what Hansen has ever stated with respect to SLR. Exponential to five meters by the middle of this century? ROTFLMFAO!
Hearty is the 3rd author on said paper, perhaps you missed that one? Yes, I think you did miss that one.
But you are almost there, I sort of figured it out a week or so ago. Hint: Keep looking into the prior art. It does help once one abandons the “sameness” style of argumentation though.
LikeLike
KO.
Someone whom I do trust, sent me this …
” … collected many other papers (~1000) describing coastal sequences worldwide … “
LikeLike
> Hint: Keep looking …
Hint: inviting someone to find your citations is inconsiderate toward the readers who are trying to follow the subject and smacks of posturing and perhaps an invitation to bickering.
Pray cite your sources.
Think of the children trying to follow the conversation.
LikeLike
Hank,
I’ve already said too much, in more ways than one.
But here’s a perimeter-peripheral paper, so to speak.
Mid-Pliocene shorelines of the US Atlantic Coastal Plain — An improved elevation database with comparison to Earth model predictions
http://www.sciencedirect.com/science/article/pii/S0012825215000355
(paywalled, but Google is your friend, the one I found was a direct download with a rather very long cryptic Google search URL).
What they did in that 2015 paper, elevation-wise, we were doing over two decades ago at sub-centimeter RMS accuracies on moving ships (6-DOF ship navigation motions).
I can only say that, as a former land surveyor from the early 70’s (hey we were using HP EDM equipment and theodolites at that time), is that, if it took them this long to get a clue, then they are beneath contempt.
Now the paper does mention and does do DT and GIA, but even there, they appear to be missing a key feature (Section 5. Warping of the mid-Pliocene shoreline is the must read section IMHO).
Long story short? I am currently in a rather serious learning curve mode (mostly related to my own understandings of the inception of the LIG, its leading edge as it were), Hansen16 is just more water under the bridge as far as I am concerned. Beating a dead horse as it were.
LikeLike
The extinction of the giant Antarctic bees doomed Antarctica’s marsupial bears to death by insulin shock, and led to the rise of the penguin empire that sill rules the Ross ice shelf
LikeLike
William,
Historic Victory in Court
http://csas.ei.columbia.edu/2016/04/08/historic-victory-in-court/
Click to access 20160408_CourtOrder.pdf
Meh, 14 days for Hansen to file the official published version of his paper.
“The nascent nature of these proceedings dictate further development of the record before the court can adjudicate whether any claims or parties should not survive for trial.”
Footnote 7 mentions “prayer for remedies” – that one, I’d like to see in person even …
Our Hansen who art in heaven,
hallowed be thy name.
Thy kingdom come.
Thy will be done
on earth as it is in heaven.
Give us this day our daily bread,
and forgive us our trespasses,
as we forgive those who trespass against us,
and lead us not into temptation,
but deliver us from evil.
LikeLike
So you’re saying planning ahead is premature?
http://assets.amuniversal.com/92abb910dcc001334fd6005056a9545d
LikeLike
Per Insurance Journal: Sea Level Rise Will Be Worse and Come Sooner
“Davidson [NOAA’s senior advisor for coastal inundation and resilience science and services] said recent data [WAIS] 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 seal level rise of up to 4 feet by 2100.”
HT/Jeff Lemieux over at Neven’s.
[Interesting. But some more details, and (obvs) publication, would be good -W]
Did Hansen underestimate the doubling rate?
LikeLike
[Interesting. But some more details, and (obvs) publication, would be good -W]
Click to access MARGARET-DAVIDSON-Bio.pdf
“”She earned a juris doctorate in natural resources law from Louisiana State University and a master’s degree in marine policy and resource economics from the University of Rhode Island.”
Policy person. Go figure. Kind of doubt much in the way of actual physical climate science expertise (e. g. IPCC AR5 WG1).
“Did Hansen underestimate the doubling rate?”
Well, 3m in 45 years has a doubling time of 5.2 years and 3m in 35 years has a doubling time of 4.0 year (starting in 2015 with initial rate of 1 mm/yr per Hansen initial hosing rate).
Did curves for 2050 3m horizon, exponential and partial power series exponential (linear (one Sv continuous) quadratic (two Sv in 2050) cubic (2.8 Sv in 2050) quartic (3.5 Sv in 2050) sextic (4.4 Sv in 2050) and exponential (6.3 Sv in 2050)).
One Sv = 85.9 mm/yr, current rate is ~1mm/yr (per Hansen) or 0.012 Sv.
Approximate time horizons to see hosing in CU GMSL (currently at say 3.3 mm/yr) record:
linear, two weeks
quadratic, six months
cubic, two years
quartic, 3.5 years
sextic, 5 years
exponential, 6.5 years
YMMV
LikeLike
Well, sometimes industry does get pre-publication information — the rest of you, wait for the next IPCC report:
http://www.insurancejournal.com/news/national/2016/04/12/405089.htm
—–excerpt follows—–
… 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. …
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 seal 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….
LikeLike
Geophysical Research Letters
Early View
Online Version of Record published before inclusion in an issue
Research Letter
Bathymetry data reveal glaciers vulnerable to ice-ocean interaction in Uummannaq and Vaigat glacial fjords, west Greenland
“… Here we present a multibeam echo sounding survey of 14 glacial fjords in the Uummannaq and Vaigat fjords, west Greenland, which extends from the continental shelf to the glacier fronts. The data reveal valleys with shallow sills, overdeepenings (>1300 m) from glacial erosion, and seafloor depths 100–1000 m deeper than in existing charts. Where fjords are deep enough, we detect the pervasive presence of warm, salty Atlantic Water (AW) (>2.5°C) with high melt potential, but we also find numerous glaciers grounded on shallow (<200 m) sills, standing in cold (<1°C) waters in otherwise deep fjords, i.e., with reduced melt potential. Bathymetric observations extending to the glacier fronts are critical to understand the glacier evolution."
—-
hat tip to: https://www.reddit.com/r/climate
First published: 25 March 2016
DOI: 10.1002/2016GL067832
LikeLike
Ms Davidson based her remarks in part on Hansen et al and on the current field season in Antarctica. She said that “marine glacier collapse is accelerating” and several glaciers have become ungrounded due to water running beneath them.
In other words, I don’t think anyone’s sitting on a bombshell.
LikeLike
http://scenarios.globalchange.gov/accouncement/1158
“For physical climate science analyses, NCA4 will use the full range of IPCC RCPs and CMIP5 products. For assessments of impacts, vulnerability, and adaptation responses, NCA4 will focus on RCP 8.5 as a high- end scenario and RCP 4.5 as a low-end scenario. Other scenarios (e.g., RCP 2.6) may be used in addition where instructive, such as in analyses of mitigation issues. The use of RCPs 8.5 and RCP 4.5 as core scenarios is generally consistent with the range of emission scenarios used in the Third National Climate Assessment (NCA3).”
Click to access External%20memo%20NCA4%20scenarios%20framing_20150506.pdf
“All of the RCPs demonstrate similar global temperature and sea level rise outcomes for the next few decades. However, by mid-century and beyond, differences between RCPs and their implied emission pathways have a substantial effect on the climate and impact outcomes.”
It looks like 0.98m SLR (maximum in 2100) is a lock for 2018 NCA4 report. Or not. Whatever they do do, does need to be grounded in more than one summer’s worth of Antarctica data though. Quantitative observational data even.
Kind of like this presentation (and referenced peer reviewed publication) …
Refining satellite era estimates of global mean sea level rise
Click to access Plenary_08_04.pdf
(February 4-8, 2016)
Similarly for SMB data and sea level budgets etceteras.
You could probably post 10 new Greenland or Antarctica peer reviewed articles per day. What needs to be done is turn those qualitative reports into quantitative numbers to say calibrate (or tune) parameter-process based dynamic ice sheet numerical models.
After all, you have to start somewhere, other than assuming SLR curves. That’s what coastal planners do. I should expect much more than that from actual climate scientists.
LikeLike
EFS: “That’s what coastal planners do”
Davidson advises coastal planners. She has said, “Designing infrastructure for a 3′ [1 meter] rise over next 80 yrs is increasingly likely to be a waste of monies.”
LikeLike
KO,
I know at least two people that know her.
USACE ERDC CHL
There is only one person who I will ever talk about openly from that organization, James R Houston.
All coastal permitting goes through the USACE, navigation and structures in the coastal zone.
Note to self: I am not, was not and never will be a Sand Engineer.
Oh, and I’ve been told by the SME that NOAA’s SLOSH is a royal POS and that NOAA’s WAVEWATCH beats the piss out of USACE’s STWAVE.
Oh, and talking about mission creep, check out the DHS …
Coastal Resilience Center
http://coastalresiliencecenter.unc.edu/
I know about 8 people there. How did I find that one, you ask?
http://coastalhazardscenter.org/margaret-davidson-accepts-new-position-noaa/
“This website covers the Coastal Hazards Center of Excellence, which was funded between 2008-2015. To learn about the Coastal Resilience Center of Excellence, visit coastalresiliencecenter.org.
At the end of the day the USACE is the major player as that is part of their mission statement, NOAA not so much.
The USACE is older than our federal government, you dimwit.
LikeLike
KO,
Here you go …
Executive Order – Establishing a Federal Flood Risk Management Standard and a Process for Further Soliciting and Considering Stakeholder Input
https://www.whitehouse.gov/the-press-office/2015/01/30/executive-order-establishing-federal-flood-risk-management-standard-and-
Click to access DCPD-201500068.pdf
Click to access Staying-Relevant-in-the-21st-Century.pdf
(presentation from the Director of Civil Works dated 17 September 2015 to implement EO 13690 (but this EO applies to all federal agencies, not just the USACE)
Current timeline suggests implementation before Election Day (after that day, this all might go poof if an R is elected POTUS).
Click to access 2014_sec_1014a_trans_letter.pdf
Click to access 2014_sec_1014b_204f_trans_letter.pdf
Click to access 2014_sec_1014a.pdf
Click to access 2014_sec_1014b_204f_rev01.pdf
The above basically requires non-federal entities to submit documents to the USACE as the USACE is the permitting approving agency.
Finally, this is the current USACE … PROCEDURES TO EVALUATE SEA LEVEL CHANGE: IMPACTS, RESPONSES, AND ADAPTATION (4th iteration to date, the 1st was on 01 September 2009, prior to that it followed the NRC/NOAA guidance (1987) in another USACE EM document dated to 1989)
(http://www.publications.usace.army.mil/Portals/76/Publications/EngineerTechnicalLetters/ETL_1100-2-1.pdf
AFAIK, the absolute current maximum SLR is two meters in 2100 (quadratic). That will change if a D stays in da house, so to speak, per the new EO (or improved IPCC guidance or NCA4 guidance)..
LikeLike