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gerontocrat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1200 on: May 29, 2019, 08:04:17 PM »
The article is paywalled but I think the ROSETTA derived images used in the Nature article can be found at .....
https://www.researchgate.net/figure/Ross-Ice-Shelf-bathymetry-ocean-temperatures-and-basal-melt-a-Modelled-bathymetry-under_fig4_333406046

One should remember that the Ross Ice Shelf, RIS, not only buttresses key WAIS marine glaciers but also key EASI marine glaciers.
https://www.nature.com/articles/s41561-019-0370-2
Quote
Here, we use data from the ROSETTA-Ice airborne survey and ocean simulations to identify the principal threats to Ross Ice Shelf stability. We locate the tectonic boundary between East and West Antarctica from magnetic anomalies and use gravity data to generate a new high-resolution map of sub-ice-shelf bathymetry.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1201 on: May 30, 2019, 04:35:31 AM »
Attaching the above paper.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1202 on: May 30, 2019, 06:35:07 PM »
I just had a thought...
Could SLR (and other AGW effects) have a hysteresis? So say CO2e doubles (to 560 ppm) and these effects occur, then through superhuman effort we get the CO2e back down to 280 ppm, but the effects don't go back to "normal"?
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1203 on: May 30, 2019, 08:32:20 PM »
I just had a thought...
Could SLR (and other AGW effects) have a hysteresis? So say CO2e doubles (to 560 ppm) and these effects occur, then through superhuman effort we get the CO2e back down to 280 ppm, but the effects don't go back to "normal"?
I was looking at an ice shelf that collapsed, Larsens B I believe, and they said the last time their wasn't a shelf was something like 10,000 years ago. In some parts of the antarctic is over a mile thick! I would think some of that ice is much older. So any damage done is permanent in the short to medium term.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1204 on: May 30, 2019, 08:33:57 PM »
Re: hysteresis

Yes, there are such effects. ASLR has posted on many, not a few on this very thread.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1205 on: May 31, 2019, 07:25:33 AM »
Yup, and then we also have the worst and unfortunately still present hysteresis, maybe best depicted with Meadows bathtub analogy? First an old quote by Donella and then Dennis version from last year in one image.
http://donellameadows.org/archives/on-bathtubs-carbon-dioxide-and-disrespect/
Quote
–August 23, 1990–
...
The real issues here, the underlying fears that trigger our anger, are that on the one hand a bunch of environmental alarmists will force unnecessary changes in our fossil-fuel-powered way of doing things, and that on the other hand a bunch of technological conservatives with heavy stakes in fossil-fuel industries will drive the climate and the earth’s ecosystems into overheated chaos.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1206 on: May 31, 2019, 03:52:55 PM »
While I have no problem with those who like to be positive; in my book being positive does not mean ignoring the honest evaluation of right-tailed climate risks:

Title: "Paris + 2: Climate jolted faster than projected"

https://www.axios.com/two-years-since-trump-withdrew-paris-climate-agreement-2a680e45-0c87-4dbf-81d7-6b8d55feee40.html

Extract: "While virtually all countries except the U.S. remain committed to the 2015 Paris Climate Agreement, many aren’t on track to meet their targets — which are mostly too weak anyway, according to the Climate Action Tracker, a research group following the Paris deal pledges.

Diringer said. “I’d say it’s a fair bet that over time continued U.S. inaction will have a corrosive effect on political will globally.”"
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1207 on: June 01, 2019, 12:58:43 AM »
Re: hysteresis

Yes, there are such effects. ASLR has posted on many, not a few on this very thread.

sidd

For convenience, the following are some selected extracts from some of my posts in this thread on hysteresis:

Furthermore, the hysteresis loops in Figures 3 & 4 make it clear that once the stratocumulus clouds dissipate (say partially due to a temporary decades-long perturbation like the collapse of the WAIS and associated feedbacks, and partially due to a temporary pulse of methane emission from Arctic thermokarst lakes [as well as a rapid reduction in anthropogenic aerosols]), it is difficult for them to reestablish themselves even at CO2-equivalent levels well below 1,200ppm.

Tapio Schneider , Colleen M. Kaul and Kyle G. Pressel (2019), "Possible climate transitions from breakup of stratocumulus decks under greenhouse warming", Nature Geoscience, https://doi.org/10.1038/s41561-019-0310-1

https://www.nature.com/articles/s41561-019-0310-1

Abstract: "Stratocumulus clouds cover 20% of the low-latitude oceans and are especially prevalent in the subtropics. They cool the Earth by shading large portions of its surface from sunlight. However, as their dynamical scales are too small to be resolvable in global climate models, predictions of their response to greenhouse warming have remained uncertain. Here we report how stratocumulus decks respond to greenhouse warming in large-eddy simulations that explicitly resolve cloud dynamics in a representative subtropical region. In the simulations, stratocumulus decks become unstable and break up into scattered clouds when CO2 levels rise above 1,200 ppm. In addition to the warming from rising CO2 levels, this instability triggers a surface warming of about 8 K globally and 10 K in the subtropics. Once the stratocumulus decks have broken up, they only re-form once CO2 concentrations drop substantially below the level at which the instability first occurred. Climate transitions that arise from this instability may have contributed importantly to hothouse climates and abrupt climate changes in the geological past. Such transitions to a much warmer climate may also occur in the future if CO2 levels continue to rise."

Extract: "The CO2 level at which the instability occurs depends on how largescale dynamics change with climate, which is heuristically parameterized in our simulations and hence is uncertain. In particular, the large-scale subsidence in the troposphere weakens under warming, which lifts the cloud tops and counteracts the instability. Indeed, when we weaken the parameterized large-scale subsidence by 1 or 3% per Kelvin of tropical SST increase (within the range of GCM responses to warming), the stratocumulus instability occurs at higher CO2 levels: around 1,400 ppm with 1% K–1 subsidence weakening, and around 2,200 ppm with 3% K–1 (Fig. 4). The hysteresis when the CO2 levels drop thereafter remains, but it narrows: stratocumulus decks reform once the CO2 levels drop below 500 ppm for a 1% K–1 subsidence weakening, and once they drop below 1,900 ppm for one of 3% K–1.

For the future, our results suggest that stratocumulus decks may break up if CO2 levels continue to rise. Equivalent CO2 concentrations around 1,300 ppm—the lowest level at which the stratocumulus instability occurred in our simulations—can be reached within a century under high-emission scenarios. However, it remains uncertain at which CO2 level the stratocumulus instability occurs because we had to parameterize rather than resolve the large-scale dynamics that interact with cloud cover. To be able to quantify more precisely at which CO2 level the stratocumulus instability occurs, how it interacts with large-scale dynamics and what its global effects are, it is imperative to improve the parameterizations of clouds and turbulence in climate models."


If nothing else, the findings of the linked reference could be used to better calibrate state-of-the-art ESM climate change projections w.r.t. 'the role of the Southern Ocean in abrupt transitions and hysteresis' in the MOC:

Sophia K.V. Hines, Andrew F. Thompson, Jess F. Adkins (15 March 2019), "The Role of the Southern Ocean in Abrupt Transitions and Hysteresis in Glacial Ocean Circulation", Paleoceanography and Paleoclimatology, https://doi.org/10.1029/2018PA003415

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018PA003415

Abstract: "High‐latitude Northern Hemisphere climate during the last glacial period was characterized by a series of abrupt climate changes, known as Dansgaard‐Oeschger events, which were recorded in Greenland ice cores as shifts in the oxygen isotopic composition of the ice. These shifts in inferred Northern Hemisphere high‐latitude temperature have been linked to changes in Atlantic meridional overturning strength. The response of ocean overturning circulation to forcing is nonlinear and a hierarchy of models have suggested that it may exist in multiple steady state configurations. Here, we use a time‐dependent coarse‐resolution isopycnal model with four density classes and two basins, linked by a Southern Ocean to explore overturning states and their stability to changes in external parameters. The model exhibits hysteresis in both the steady state stratification and overturning strength as a function of the magnitude of North Atlantic Deep Water formation. Hysteresis occurs as a result of two nonlinearities in the model—the surface buoyancy distribution in the Southern Ocean and the vertical diffusivity profile in the Atlantic and Indo‐Pacific basins. We construct a metric to assess circulation configuration in the model, motivated by observations from the Last Glacial Maximum, which show a different circulation structure from the modern. We find that circulation configuration is primarily determined by North Atlantic Deep Water density. The model results are used to suggest how ocean conditions may have influenced the pattern of Dansgaard‐Oeschger events across the last glacial cycle."

&

The linked reference finds that:
"… Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately AD 1850) compared with the preceding 1,500 years.

We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA – sourced from melting glaciers and thickened sea ice that developed earlier in the LIA – weakened Labrador Sea convection and the AMOC.  The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet."

These findings support Hansen's ice-climate feedback mechanism.

Thornalley et al. (2018), "Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years", Nature, doi:10.1038/s41586-018-0007-4

https://www.nature.com/articles/s41586-018-0007-4
&

E. Gasson, R.M. DeConto, D. Pollard, and R.H. Levy (2016), "Dynamic Antarctic ice sheet during the early to mid-Miocene", Proceedings of the National Academy of Sciences, pp. 201516130, doi: 10.1073/pnas.1516130113

http://www.pnas.org/content/early/2016/02/17/1516130113

Significance: "Atmospheric concentrations of carbon dioxide are projected to exceed 500 ppm in the coming decades. It is likely that the last time such levels of atmospheric CO2 were reached was during the Miocene, for which there is geologic data for large-scale advance and retreat of the Antarctic ice sheet. Simulating Antarctic ice sheet retreat is something that ice sheet models have struggled to achieve because of a strong hysteresis effect. Here, a number of developments in our modeling approach mean that we are able to simulate large-scale variability of the Antarctic ice sheet for the first time. Our results are also consistent with a recently recovered sedimentological record from the Ross Sea presented in a companion article."


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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1208 on: June 02, 2019, 10:00:12 AM »
Crossposting this by ivica along with my comments.

An effort to raise public awareness about sea level rise, The Royal Institution, published on 2019-05-29, filmed at the Ri on 2019-02-11:

   Sea Level Rise Can No Longer Be Stopped, What Next? - with John Englander

   Q&A part
Thanks ivica.

Edit; What's not discussed in the future part at the end is sustainability and resource use. Nothing really new around SLR and glaciers (for those who follow this) but other than that, it's all sound and a worthwhile watch. Adding the key messages below.



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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1209 on: June 02, 2019, 10:35:43 AM »
Just to follow-up on my last post on hysteresis and climate change (see Reply #1207); the linked Wikipedia article indicates that mathematically, tipping points are any type of climate bifurcation with hysteresis, such as the abrupt collapse of a marine ice sheet and/or the abrupt slowdown of the MOC:

Title: "Tipping points in the climate system"

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

Extract: "Tipping point behaviour in the climate can also be described in mathematical terms. Tipping points are then seen as any type of bifurcation with hysteresis. Hysteresis is the dependence of the state of a system on its history. For instance, depending on how warm and cold it was in the past, there can be differing amounts of ice present on the poles at the same concentration of greenhouse gases or temperature.

In the context of climate change, an "adaptation tipping point" has been defined as "the threshold value or specific boundary condition where ecological, technical, economic, spatial or socially acceptable limits are exceeded."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1210 on: June 02, 2019, 04:00:28 PM »
Thanks again AbruptSLR for this research.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1211 on: June 02, 2019, 04:50:59 PM »
Thanks again AbruptSLR for this research.

As a service, I provide a link to a pdf of Vakulenko and Sudakov (2019) "Complex bifurcations in fast-slow climate dynamics"

https://arxiv.org/pdf/1902.07936.pdf

Extract: "Then, we consider the dynamic model with random parameters for the climate-biospher coupling to explain why the climate may stay stable over long-time intervals.  The model shows that climate stability can be explained by mutual annihilation of many independent factors.  One of the important consequences is that if biodiversity decreases then the random evolution of the biosphere can lead to global climate changes."

Also, of Dortmans et al (2018) "An Energy Balance Model for Paleoclimate Transitions", first cited in Reply #349:

https://www.clim-past.net/15/493/2019/cp-15-493-2019.pdf

Caption for the attached image: "Figure 7. Pliocene Arctic EBM (36)(37). Parameter values δ = 0.67, FA = 115; other parameters as in Table 1. Subfigure a): CO2 takes valuesµ = 1200, 1000, 800, 600, 400, 200ppm,from top to bottom on the blue curves, with fixed FO = 50 Wm−2. The warm equilibrium state disappears as µ decreases. Subfigure b): Bifurcation Diagram for the Pliocene Paradox. Here, CO2 concentration µ and ocean heat transport FO decrease simultaneously, with increasing ν, (0≤ν ≤1), as given by equations (42). As ν increases, the warm equilibrium solution (τS > 1) disappears in a saddlenode bifurcation, at approximately ν = 0.9, corresponding to forcing parameter µ = 343 ppm and FO = 51 Wm2. To the right of this point, only the frozen equilibrium state exists. To the left of this point, the frozen and warm equilibrium states coexist, separated by the unstable intermediate state."
« Last Edit: June 03, 2019, 04:20:21 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1212 on: June 03, 2019, 04:20:42 PM »
Just to be clear species extinction is a real, and accelerating, problem; and is a positive feedback for the acceleration of climate change:

Title: "Rise of the Extinction Deniers"

https://therevelator.org/extinction-deniers/

Extract: "Extinction’s not a problem, right?

That’s actually a point made quite a bit lately by a group of “extinction deniers” — people who use the relatively low number of confirmed extinctions to say there’s no such thing as an extinction crisis. These industry shills came out of the woodwork in the wake of the recent Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services report that predicts the world faces up to one million extinctions in the coming decades due to human activity."
« Last Edit: June 03, 2019, 07:12:02 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1213 on: June 03, 2019, 05:03:42 PM »
With a hat-tip to bligh8, the linked articles present paleo-evidence that the WAIS likely collapsed during the Eemian.  Such findings indicate that the WAIS contribution to SLR during the Eemian was much more significant than that of the GIS.  Furthermore, since some records indicate that for periods of the Eemain, sea level rose at a rate of 2.5 m per century, these new findings provide support that an MICI-type of collapse may have occurred in at least portion of the WAIS during the Eemian (I note that we are currently headed towards Mid-Pliocene conditions):

Title: "Discovery of recent Antarctic ice sheet collapse raises fears of a new global flood"

https://www.sciencemag.org/news/2018/12/discovery-recent-antarctic-ice-sheet-collapse-raises-fears-new-global-flood

Extract: "Some 125,000 years ago, during the last brief warm period between ice ages, Earth was awash. Temperatures during this time, called the Eemian, were barely higher than in today’s greenhouse-warmed world. Yet proxy records show sea levels were 6 to 9 meters higher than they are today, drowning huge swaths of what is now dry land.

Scientists have now identified the source of all that water: a collapse of the West Antarctic Ice Sheet. Glaciologists worry about the present-day stability of this formidable ice mass. Its base lies below sea level, at risk of being undermined by warming ocean waters, and glaciers fringing it are retreating fast. The discovery, teased out of a sediment core and reported last week at a meeting of the American Geophysical Union in Washington, D.C., validates those concerns, providing evidence that the ice sheet disappeared in the recent geological past under climate conditions similar to today’s. “We had an absence of evidence,” says Anders Carlson, a glacial geologist at Oregon State University in Corvallis, who led the work. “I think we have evidence of absence now.”

If it holds up, the finding would confirm that “the West Antarctic Ice Sheet might not need a huge nudge to budge,” says Jeremy Shakun, a paleoclimatologist at Boston College. That, in turn, suggests “the big uptick in mass loss observed there in the past decade or two is perhaps the start of that process rather than a short-term blip.” If so, the world may need to prepare for sea level to rise farther and faster than expected: Once the ancient ice sheet collapse got going, some records suggest, ocean waters rose as fast as some 2.5 meters per century."

See also:

Title: "PP11A-05: Absence of the West Antarctic ice sheet during the last interglaciation" Carlson et al (2018)

https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/421418

Summary: "During the last interglaciation (LIG; ~129-116 ka), global mean sea level (GMSL) was >6 m above present. Based on evidence of only modest LIG Greenland ice-sheet retreat, Antarctic ice sheets may also have contributed to LIG GMSL, but direct data for a contribution is lacking. Here we investigate the LIG extent of the West Antarctic (WAIS) and Antarctic Peninsula (APIS) ice sheets using Sr-Nd-Pb isotopes of silt from ODP Site 1096 in the Bellingshausen Sea. Based on our shelf Sr-Nd-Pb provenance data and a stable-isotope age model, we document WAIS-APIS erosion of all radiogenically-discernable terranes from the latter part of marine isotope stage (MIS) 5 up through the Holocene, consistent with independent ice-margin chronologies showing ice presence on all of these terranes from MIS 2 through the Holocene. For the LIG/early MIS 5, we only find evidence of silt sourced from the erosion of the APIS and the mountain ranges that rim the northern modern WAIS, with an absence of silt from Pine Island glacier. Ice-sheet models link Pine Island glacier absence to full WAIS collapse into ice caps on mountains. Our record thus provides the first direct indication of a much smaller LIG WAIS, providing paleo-context for the susceptibility of the WAIS to collapse."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1214 on: June 03, 2019, 05:13:48 PM »
As a follow-on to my last post, the linked articles discuss how the International Ocean Discovery Program, spent January to March 2019 in the Amundsen Sea collection seabed sediment cores to better evaluate the stability of the WAIS.  The cores extend back to at least 6 million years and thus include the Mid-Pliocene period.  While the cores will take 2 years to fully evaluate.  Preliminary x-rays of the cores taken on the drill ship showed layers of abundant stones/pebbles that could only have been deposited by iceberg leaving the ASE (i.e. ice-rafted debris); which supports the possibility/probability of MICI-types of WAIS collapse during multiple periods over the past 6 million years:

Title: "Newly drilled sediment cores could reveal how fast the Antarctic ice sheet will melt" by Erik Stokstad (April 2019)

https://www.sciencemag.org/news/2019/04/newly-drilled-sediment-cores-could-reveal-how-fast-antarctic-ice-sheet-will-melt

Extract: "The West Antarctic Ice Sheet is particularly vulnerable to melting from warming ocean waters because its base lies below sea level. Computer models vary in their predictions of how quickly it will disappear, but some predict it will be responsible for driving up global sea levels by a meter or more over the next century. To improve those models, scientists want to learn about the behavior of the ice sheet during the mid-Pliocene, 3 million to 4 million years ago, when temperatures were like today’s, says Rob DeConto, a glaciologist at the University of Massachusetts in Amherst who studies the ice sheet. The new cores, he says “will have a lot to bring to the table.”

The JOIDES Resolution, a research ship operated by the International Ocean Discovery Program, spent January to March in the Amundsen Sea, off the coast of West Antarctica. The hope was to drill sediment cores in five places, ranging from the continental rise toward the shallower waters of the continental shelf. Unfortunately, the ship could not reach the drill sites closer to Antarctica because it is not equipped to travel through ice and sea ice (which grows and retreats each year) extended farther out than usual. Even in the open water, avoiding the many icebergs meant less time to drill in other places. “We simply had bad luck this year,” says Karsten Gohl, a geophysicist at the Alfred Wegener Institute in Bremerhaven, Germany, and a leader of the cruise. “Despite the icebergs, we still got fantastic cores.”

Crucially, the sediment cores preserve a complete history: The Amundsen Sea at that site is 4000 meters deep, so the seafloor dune was safe from storms that can erode sediment in shallower water. “The fact that you have a continuous record from this margin is really exceptional,” Colleoni says. Tiny fossils indicate that the oldest parts of the core date back to the late Miocene, about 6 million years ago, dates that were confirmed by the patterns of magnetism recorded in the sediments.

The other site, which yielded cores from four holes, is some 60 kilometers away from the first one and close to a submarine channel. When deep currents travel down such channels, they often carry and deposit sediment that was eroded from nearby land. (The currents passing over the drift, in contrast, are thought to carry sediment from much farther away.) Researchers can trace the origin of sediment by studying the mineralogy and chemistry of individual grains, comparing them to rocks on land. By combining various lines of evidence, the team hopes to infer when the ice sheet retreated.

The cores from both sites also contain pebbles or larger stones that were transported from the continent by icebergs. An abundance of such stones is another, more straightforward sign of a retreating ice sheet that is calving many icebergs.

A key question is how the waxing and waning of the ice sheet correlates with records of ocean temperatures, which the researchers can estimate from the abundance of certain chemical isotopes in the fossilized shells of tiny organisms called foraminifera.

The research team expects to spend the next 2 years coaxing this history out of the cores.:

See also:

Title: "The sensitive Achilles heel of the white continent" by Dagmar Rohrlich (March 2019)

https://translate.google.com/translate?sl=de&tl=en&u=https%3A%2F%2Fwww.deutschlandfunk.de%2Fwestantarktischer-eisschild-die-sensible-achillesferse-des.676.de.html%3Fdram%3Aarticle_id%3D446200

Extract: " To do this, one would have to know how much the ice sheet has melted off in the warm phases – and this can be seen in the deep-sea sediments of the Amundsen Sea. …
"We can already say that in the past millions of years the central part of the West Antarctic Ice Sheet has repeatedly extended far out to the sea before retreating, …

How long these cycles last exactly, the evaluations have yet to show.  Then the researchers hope, it will also prove where the ice sheet could completely collapse during warm periods. If man triggered it, he would cause sea level rise of three to six meters."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1215 on: June 04, 2019, 03:19:05 AM »
The linked website provides a number of downloadable reports from the Australian 'Breakthrough National Centre for Climate Rehabilitation', including its latest report entitled: "What Lies Beneath - The Understatement of Existential Climate Risk" by Spratt & Dunlop (2019)

https://www.breakthroughonline.org.au/publications

Extract: "This latest Breakthrough report argues for an urgent risk reframing of climate research and the IPCC reports. What Lies Beneath is the inside story of how climate policy-making has become embedded in a culture of failure and scientific reticence. The report brings together the voices of some of the world’s leading scientists."

Edit: Unfortunately, none of these reports appropriately address the risks of positive ice-climate feedback mechanisms.
« Last Edit: June 04, 2019, 04:18:24 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1216 on: June 04, 2019, 03:59:55 AM »
That's a valuable report which I agree with. I also think the IPCC SR 1.5 was a good step in the right direction in terms of being more forthcoming about risk.

Unfortunately, I think this report is correctly diagnosing something (scientific reticence) much later than optimal. The consequences baked in as a result of past reticence are now enormous.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1217 on: June 04, 2019, 07:58:42 AM »
Roughly twelve years late or so... Remember beeing highly annoyed a decade ago about scientific reticence. Still someone told me just a few days ago, that I can't say that RCP2.6 is dead. A trip down memory lane:

Hansen on scientific reticence and sea level rise. (2007)
https://pubs.giss.nasa.gov/abs/ha01210n.html

Van Vuuren from 2007 (a paper preceeding the RCP2.6 one from 2011...).
Stabilizing greenhouse gas concentrations at low levels: an assessment of reduction strategies and costs
https://link.springer.com/article/10.1007%2Fs10584-006-9172-9

Adding Fig. 3:  Global CO 2 -eq. emissions (all sources) for the B2 baseline emission and pathways to stabilization at a concentration of 650, 550 and 450 ppm CO 2 -eq.

Edit; also adding Fig. 12 from the Van Vuuren 2011 paper. Emissions for the IMAGE (IM) alternative RCP scenarios.
« Last Edit: June 04, 2019, 09:06:06 AM by Sleepy »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1218 on: June 05, 2019, 08:05:01 AM »
If you want to have a serious exchange with a scientist, I would not recommend twitter.  Use email. For example, Mann's email address is on the penn state web site. And please ask permission before reposting replies on the web. It would help to read his recent papers first as well, so you can address his position.

Twitter is for people who cannot develop an argument or a thesis beyond a couple hundred characters.  It lends itself to epigram and epithet, not science discussion.

sidd
 

wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1219 on: June 05, 2019, 08:28:50 AM »
I appreciate that very well Sidd thank you. Twitter is a horrible platform for dialogue. I have in the past talked to James Hansen over email.

I was not expecting MM to reply to me. I was replying to his sort of cavalier attitude as to how easy it would be to limit warming to 2.5C.


Cheers

Sleepy

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1220 on: June 06, 2019, 06:51:40 AM »
Knowing how and knowing when: unpacking public understanding of atmospheric CO2 accumulation
https://link.springer.com/article/10.1007%2Fs10584-019-02423-8

One image split in two (snipped out the top and bottom parts) says it all (although current numbers are higher).
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Tom_Mazanec

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1221 on: June 06, 2019, 01:50:22 PM »
My father, decades ago, mused that the Netherlands would be the first to be hit by SLR:
https://www.vn.nl/rising-sea-levels-netherlands/
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Lennart van der Linde

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1222 on: June 06, 2019, 02:00:44 PM »
Maybe not the first, being rich enough to postpone being hit before some poorer parts of the world. But we'll be hit eventually, or that risk seems substantial, at least.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1223 on: June 06, 2019, 04:48:37 PM »
As global warming leads to the retreat of more Arctic (terrestrial) glaciers, the associated high-latitude aeolian dusts may well contribute to an Arctic albedo flip due to both reduced Arctic cloud reflectivity and reduced life of Arctic clouds.  This is another climate risk that is under appreciated by consensus climate science:

Title: "How Dust From Receding Glaciers Is Affecting the Climate"

http://glacierhub.org/2019/06/05/how-dust-from-receding-glaciers-is-affecting-the-climate/

Extract: "Though the study focused on the effect of glacier dust on cloud properties and lifetime, the results suggest larger questions about the impact of glacier dust on cloud reflectivity.
A decline in the reflective capability of clouds could degrade the Earth’s ability to moderate its temperature. Paul DeMott, one of the study’s co-authors, told GlacierHub that he was careful not make conclusions about the role of glacier dust in cloud reflectivity, though he acknowledged that it is “a natural, if simplistic, way of thinking about it.”

Whether or not a cloud contains ice particles is a primary determinant of its reflective capacity, as well as heat-trapping ability. Ice crystals allow more light to pass through clouds, while effectively absorbing outgoing infrared radiation.

As warming from the human-driven climate crisis accelerates, glacier dust is expected to become more abundant, with consequences for Arctic cloud cover and the Earth’s temperature, which depends on the reflectivity and heat-trapping ability of clouds. The study’s conclusion, that ice nucleating particles in glacier dust affect cloud properties, underscores the interconnectedness of natural systems, and their sensitivities."

See also:

Yutaka Tobo  et al (2019), "Glacially sourced dust as a potentially significant source of ice nucleating particles", Nature Geoscience,  12, 253–258, DOI: https://doi.org/10.1038/s41561-019-0314-x

https://www.nature.com/articles/s41561-019-0314-x

Abstract: "Aeolian dusts serve as ice nucleating particles in mixed-phase clouds, and thereby alter the cloud properties and lifetime. Glacial outwash plains are thought to be a major dust source in cold, high latitudes. Due to the recent rapid and widespread retreat of glaciers, high-latitude dust emissions are projected to increase, especially in the Arctic region; which is highly sensitive to climate change. However, the potential contribution of high-latitude dusts to ice nucleation in Arctic low-level clouds is not well acknowledged. Here we show that glacial outwash sediments in Svalbard (a proxy for glacially sourced dusts) have a remarkably high ice nucleating ability under conditions relevant for mixed-phase cloud formation, as compared with typical mineral dusts. The high ice nucleating ability of the sediments is probably governed by the presence of small amounts of organic matter (<1 wt% organic carbon) rather than mineral components. In addition, our results from intensive field measurements and model simulations indicate that the concentrations of atmospheric ice nucleating particles over the Svalbard region are expected to be enhanced in the summertime under the influence of dust emissions from Svalbard and its surroundings. We suggest that high-latitude dust sources have the potential to significantly influence glaciation of Arctic low-level clouds."
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kassy

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1224 on: June 07, 2019, 02:56:14 PM »
Maybe not the first, being rich enough to postpone being hit before some poorer parts of the world. But we'll be hit eventually, or that risk seems substantial, at least.

I am pretty sure that Bangladesh will suffer before us. The thing that frightens me most is Antarctica. In the article they already use a wcs of 292 cm SLR by 2100 which gives us some margin but i am not sure how much contribution they figure for Antarctica (and more importantly how much we will actually get).
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Tor Bejnar

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1225 on: June 07, 2019, 05:44:42 PM »
Subglacial hydrological control on flow of an Antarctic Peninsula palaeo-ice stream
Robert D. Larter, et al., The Cryosphere, 13, 1583-1596, https://doi.org/10.5194/tc-13-1583-2019, 2019.
Quote
Introduction
There is growing evidence that basal hydrology is a critical factor controlling the dynamic behaviour of ice streams, which account for most of the mass loss from large ice sheets. Understanding ice stream dynamics, including basal hydrology, is thus essential for quantifying ice sheet contributions to sea level change. Subglacial lakes and areas of elevated geothermal heat flux have been discovered in the onset regions of several large ice streams. Obtaining high resolution topographic data from modern ice stream beds that can reveal features associated with subglacial water flow is, however, logistically difficult and time consuming. In contrast, modern ship-mounted sonar systems can be used to obtain such data efficiently over extensive areas of former ice stream beds on continental shelves that ice has retreated from since the Last Glacial Maximum.
 …
Here we present extensive new multibeam bathymetry data from the Anvers-Hugo Trough (AHT) west of the Antarctic Peninsula …

[references removed]

Quote
Abstract
Basal hydrological systems play an important role in controlling the dynamic behaviour of ice streams. Data showing their morphology and relationship to geological substrates beneath modern ice streams are, however, sparse and difficult to collect. We present new multibeam bathymetry data that make the Anvers-Hugo Trough west of the Antarctic Peninsula the most completely surveyed palaeo-ice stream pathway in Antarctica. The data reveal a diverse range of landforms, including streamlined features where there was fast flow in the palaeo-ice stream, channels eroded by flow of subglacial water, and compelling evidence of palaeo-ice stream shear margin locations. We interpret landforms as indicating that subglacial water availability played an important role in facilitating ice stream flow and controlling shear margin positions. Water was likely supplied to the ice stream bed episodically as a result of outbursts from a subglacial lake located in the Palmer Deep basin on the inner continental shelf. These interpretations have implications for controls on the onset of fast ice flow, the dynamic behaviour of palaeo-ice streams on the Antarctic continental shelf, and potentially also for behaviour of modern ice streams.
« Last Edit: June 08, 2019, 08:54:33 PM by Tor Bejnar »
Arctic ice is healthy for children and other living things.

prokaryotes

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1226 on: June 08, 2019, 07:46:52 PM »
"While glaciovolcanism (defined as “the interactions of magma with ice in all its forms, including snow, firn and any meltwater”), may still be in its infancy; nevertheless, I provide the following links to relevant information (& two images about geomagnetism), and I note that there is more information in the 'Antarctic Tectonics' thread in the Antarctic folder; for those who are interested in learning more about this topic:

J.L. Smellie (2018), "Chapter 10 – Glaciovolcanism: A 21st Century Proxy for Palaeo-Ice",
Past Glacial Environments (Second Edition), Pages 335–375, https://doi.org/10.1016/B978-0-08-100524-8.00010-5

https://www.sciencedirect.com/science/article/pii/B9780081005248000105

Abstract: "Glaciovolcanism is a young science that has undergone a major transformation during the last 15 years. It is important for a variety of reasons but it is set to play a major role in deriving critical parameters of past ice sheets and thus greatly improve the accuracy of their reconstruction. Glaciovolcanic studies can deduce a wider range of parameters than any other methodology currently existing, including: establishing the presence of ice, its age, ice thickness, ice surface elevation, and basal thermal regime. These attributes can be acquired routinely for many glaciovolcanic sequences and, uniquely, several are quantifiable. Most glaciovolcanic terrains provide punctuated rather than continuous records of the coeval ice sheet, i.e., with numerous time gaps. Despite the gaps, glaciovolcanic studies of ice sheets have been completed successfully in the three major glaciovolcanic regions of the Earth: mainly Antarctica, but also Iceland and British Columbia (Canada). Future studies in these and other glaciovolcanic regions will considerably improve our knowledge of Earth’s water inventory and contribute to a better understanding of past ice dynamics and the impact of the cryosphere on global climate."

&

Title: "Antarctic Glaciovolcanism:

https://www2.le.ac.uk/departments/geology/people/smellie-jl/personal/ant-glaciovolc
A dedicated topic would be great, but where would it fit in?

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

See attached image for potential glaciovolcanism hot spots, via 2018 REVIEW by Cooper etal. http://eprints.whiterose.ac.uk/124024/ . However, active faults possibly with submarine landslides could become apparent too, hence not only about volcanoes.

See my recent blog here with related studies Study: Enhanced Seismic Activity Observed in Alaska Due To Climate Change http://climatestate.com/2019/06/06/enhanced-seismic-activity-observed-due-to-climate-change/

Attempt to capture this topic in video format, for sources see http://climatestate.com/2019/06/08/video-enhanced-seismic-activity-observed-in-alaska-due-to-climate-change/


Maybe this terminology should be dubbed

Glacioseismicity.

« Last Edit: June 08, 2019, 08:41:20 PM by prokaryotes »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1227 on: June 09, 2019, 12:13:11 PM »
Mt. Erebus has played a key role in the WAIS past and if it is activated again (possibly by the loss of sufficient WAIS ice mass) it could play an important part in the WAIS's future, as it is an alkaline volcano.

From the following summary and image are from:

 http://erebus.nmt.edu/index.php/volcanology/51-volcanological-evolution

"Prior to the early 1990's, much was known about the geochemical evolution of lavas from Mt. Erebus. Clearly, the stratigraphically oldest lavas were of a primitive basanitic composition, while the current activity is a more chemically evolved tephriphonolite. However, only a few age dates existed for the whole of Mt. Erebus and these were limited to imprecise conventional K/Ar dates. Beginning in 1993, Dr. Philip Kyle and two of his students (Chris Harpel and Richard Esser) began utilizing the more advanced, high precision 40Ar/39Ar dating technique to determine the ages of many of the exposed lava flows on Mt. Erebus. Prior to the use of 40Ar/39Ar geochronology on Mt. Erebus, what little age data existed suggested that the volcano was several million years old, including the young-looking summit area. We now know that the entire volcano is just slightly older than 1 million years old and that the summit is significantly younger than 100,000 years old.

By combining the new geochronologic data with the existing database of geochemical data, we can better confirm an evolutionary model for the development of Mt. Erebus. Below are the summarized results from several researchers working on the evolution of the volcano.

Mt. Erebus is one of several volcanoes in the McMurdo Volcanic Group which itself consists of Late Cenozoic intraplate alkaline volcanoes."

The caption for the attached figure is:  Cross-section of the crust and upper mantle below Ross Island, Antarctica. A "hot spot" or mantle plume is theorized as the mechanism to account for the origin of Mt. Erebus and Ross Island

See also:

Title: "Antarctica's sleeping dragon: Lava lake steams amid coldest place on Earth"

https://www.mnn.com/earth-matters/wilderness-resources/stories/antarcticas-sleeping-dragon-lava-lake-steams-amid-coldest
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1228 on: June 10, 2019, 08:15:39 PM »
The first linked reference indicates the relatively unique relationship between the African rift valley and the West Antarctic Rift, WAR, established about 180 million years ago as Gondwana (Pangaea) split apart (see first and second images).

http://www.luomus.fi/en/largest-lava-eruptions-earth

Caption for the second image: " Schematic cross-section of the Karoo continental flood basalt province c. 180 million years ago. 1) Mantle melts extensively and the 2) melts intrude the lithosphere (=crust + brittle upper mantle), where they form large magma chambers and mix with it. 3) The contaminated melts proceed upwards and 4) erupt from shield volcanoes or fissures. 5) Some rare melts do not assimilate lithosphere and preserve the original mantle-derived geochemical signature. Image: Luomus / Jussi Heinonen"

Quote: "Our latest findings indicate that the enormous melt generation was caused by at least two processes: 1) Gondwana supercontinent functioned like a "lid on a cooking pot" and prevented the cooling of the sublithospheric mantle. High amount of accumulated heat caused more efficient melting of the mantle (Heinonen et al., 2010). 2) Some portions of the sublithospheric mantle were relatively Fe-rich and melted more efficiently than ambient mantle materials. Such portions were formed by mixing with ancient parts of oceanic crust that sank in to the mantle at subduction zones (Heinonen et al., 2013, 2014)."

Furthermore, the second linked reference shows how the sub-lithospheric interconnection between Africa's rift valley and WAR may have changed with some interconnection possibly being maintained via mantle plumes, such as beneath the Erebus volcano (see the third and fourth images).  Thus as the WAIS loses ice mass, we may witness changes in mantle dynamics as far away as Central Africa and South America:

Philip J. Heron (19 November 2018), "Mantle plumes and mantle dynamics in the Wilson cycle",
Geological Society, London, Special Publications, 470, https://doi.org/10.1144/SP470.18

https://sp.lyellcollection.org/content/early/2018/11/16/SP470.18

Caption for third image: "A cartoon of a simple supercontinent, the starting point for this review. Step 1, a supercontinent is amassed through a super-downwelling. Step 2, subduction then forms on the margins of the continent, generating sub-continental plumes due to mantle return flow and warming of the mantle through continental insulation (step 3). Step 4, the continental plumes facilitate the dispersal of the supercontinent."

Edit, see also Replies #: 101, 102, 103, 113, 115, 117, 147, 167, 168, 170, 172, 178, 442, 900 & 1,149.
« Last Edit: June 11, 2019, 04:46:48 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1229 on: June 11, 2019, 04:49:13 PM »
For what it is worth, the attached BoM Nino 3.4 Outlook forecast was issued today based on models runs from June 8, 2019; which projects the current mild El Nino event to last throughout 2019 (which will increase GMSTA this year).
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jai mitchell

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1230 on: June 11, 2019, 05:36:09 PM »

Title: "PP11A-05: Absence of the West Antarctic ice sheet during the last interglaciation" Carlson et al (2018)

https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/421418

Summary: "During the last interglaciation (LIG; ~129-116 ka), global mean sea level (GMSL) was >6 m above present. Based on evidence of only modest LIG Greenland ice-sheet retreat, Antarctic ice sheets may also have contributed to LIG GMSL, but direct data for a contribution is lacking. Here we investigate the LIG extent of the West Antarctic (WAIS) and Antarctic Peninsula (APIS) ice sheets using Sr-Nd-Pb isotopes of silt from ODP Site 1096 in the Bellingshausen Sea. Based on our shelf Sr-Nd-Pb provenance data and a stable-isotope age model, we document WAIS-APIS erosion of all radiogenically-discernable terranes from the latter part of marine isotope stage (MIS) 5 up through the Holocene, consistent with independent ice-margin chronologies showing ice presence on all of these terranes from MIS 2 through the Holocene. For the LIG/early MIS 5, we only find evidence of silt sourced from the erosion of the APIS and the mountain ranges that rim the northern modern WAIS, with an absence of silt from Pine Island glacier. Ice-sheet models link Pine Island glacier absence to full WAIS collapse into ice caps on mountains. Our record thus provides the first direct indication of a much smaller LIG WAIS, providing paleo-context for the susceptibility of the WAIS to collapse."

Some direct evidence of the collapse that is shown by the genetic distribution of octopi found in 2012.  At the time this was a primary indication that WAIS will collapse sooner under global warming than was thought at the time. 

https://www.sciencedaily.com/releases/2012/05/120509111453.htm
Scientists at the University have found that genetic information on the Antarctic octopus supports studies indicating that the West Antarctic Ice Sheet could have collapsed during its history, possibly as recently as 200,000 years ago.


Quote
Dr Phill Watts, from the University's Institute of Integrative Biology, explains: "We looked at information gathered by the Census of Antarctic Marine Life, which allowed us to examine genetic data on a scale that had not been done before in this area of the world. We expected to find a marked difference between Turguet's octopuses living in different regions of the ocean, particularly between areas that are currently separated by approximately 10,000km of sea. These creatures don't like to travel and so breeding between the populations in the Ross and Weddell Seas would have been highly unusual.

"We found, however, that they were genetically similar, suggesting that at some point in their past these populations would have been in contact with each other, perhaps at a time when the oceans were connected and not separated by the West Antarctic Ice Sheet. These findings agree with climate models indicating repeated periods in history when the climate was warmer, which would have released water from the ice and increased the sea levels, allowing dispersal of creatures between the Ross and Weddell Seas."
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Tom_Mazanec

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1231 on: June 11, 2019, 06:06:48 PM »
I suspect it is the EAIS that will get us.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1232 on: June 12, 2019, 08:59:49 PM »
The attached image shows that primary energy consumptions is growing even faster than CO2 emissions, while the linked article indicates that this is significantly due to the recent rapid growth in natural gas as a primary energy fuel.  However, it would be better if media articles reported CO2-equivalent emissions and used a GWP-100 value of 35 for methane rather than the 25 value unscientifically used by NOAA:

Title: "In-depth: BP data reveals record CO2 emissions in 2018 driven by surging use of gas"

https://www.carbonbrief.org/in-depth-bp-data-reveals-record-co2-emissions-in-2018-driven-by-surging-use-of-gas

Extract: "Gas was the largest driver of energy-use growth in 2018, responsible for more than 40% of the increase. This, along with increased use of oil and coal, led to global CO2 emissions rising by 2% in 2018, the largest year-on-year increase in seven years."

See also:

Title: "The world goes the wrong way on carbon emissions"

https://www.axios.com/carbon-emissions-energy-consumption-bp-report-2fd9a2dc-b905-433d-b347-115a132a2933.html


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KiwiGriff

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1233 on: June 12, 2019, 09:49:21 PM »
With sea level rise it will be higher storm surge that has significant impacts first.
We have already seen New York badly impacted with tropical cyclone  sandy.
It will not be the slow  rise of sea level that causes eventual retreat it will be weather events causing catastrophic damage and sane evaluation of the costs and futility of repeated repair. The developed world is far more susceptible to such costly events than the poor regions of Bangladesh.

Seeing as I have commented on this thread.
Thanks ASLR I have been reading your output for years and appreciate the immense amount of effort  your do in constructing your well supported narrative.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1234 on: June 13, 2019, 09:16:21 PM »
With sea level rise it will be higher storm surge that has significant impacts first.
We have already seen New York badly impacted with tropical cyclone  sandy.
It will not be the slow  rise of sea level that causes eventual retreat it will be weather events causing catastrophic damage and sane evaluation of the costs and futility of repeated repair. The developed world is far more susceptible to such costly events than the poor regions of Bangladesh.

Seeing as I have commented on this thread.
Thanks ASLR I have been reading your output for years and appreciate the immense amount of effort  your do in constructing your well supported narrative.

There are many factors contributing to inundation risks besides eustatic SLR, and storm surge, as illustrated by the attached three images.

Edit: I also note that recent research finds that for Hurricane/Typhoon cases, wave run-up is worse than previously assumed due to larger (than previously assumed) infragravity waves.
« Last Edit: June 13, 2019, 09:45:08 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1235 on: June 13, 2019, 09:58:28 PM »
AR5 reports ECS values calculated using a large variety of assumptions and methodologies, and the linked reference recommends that in the future (e.g. AR6): "… that researchers should present their analysis in an explicitly Bayesian manner as we have done here, as this allows the influence of the prior and other uncertain inputs to be transparently tested."

Annan, J. and Hargreaves, J.: Bayesian deconstruction of climate sensitivity estimates using simple models: implicit priors, and the confusion of the inverse, Earth Syst. Dynam. Discuss., https://doi.org/10.5194/esd-2019-33, in review, 2019

https://www.earth-syst-dynam-discuss.net/esd-2019-33/

Abstract. Observational constraints on the equilibrium climate sensitivity have been generated in a variety of ways, but the epistemic basis of these calculations have not always been clearly presented and a number of results have been calculated which appear to be based on somewhat informal heuristics. This causes a lack of clarity about the status of such results and how they compare to other analyses, in particular whether the differences between them may be due to differences in unstated assumptions rather than observational evidence.
In this paper, we show how these problems can be resolved. We demonstrate that many of these estimates can be reinterpreted within the standard subjective Bayesian framework in which a prior over the uncertain parameters is updated through a likelihood arising from observational evidence. In many of these cases, the prior which was (under this interpretation) implicitly used exhibits some unconventional and possibly undesirable properties. We present alternative calculations which use the same observational information to update a range of explicitly presented priors.
Our calculations suggest that the heuristic methods do often generate reasonable results, in that they agree fairly well with the explicitly Bayesian approach using a reasonable prior. However, we also find some significant differences and argue that the explicitly Bayesian approach is preferred, as it both clarifies the role of the prior, and allows researchers to transparently test the sensitivity of their results to it.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1236 on: June 15, 2019, 10:28:11 PM »
The linked pdf of a PowerPoint presentation on recent progress in E3SMv2's cryosphere modeling effort, indicate that they believe that their model is biased because it indicates abrupt ice mass loss from the Filchner-Ronne and Avery ice shelves beginning circa 2060 (see images) just as was projected by Hellmer et al. (2012).  To me this indicates not only how difficult it is to model non-linear ice mass loss from Antarctica but also how difficult it is to get decision makers to accept the risks associated with such potential abrupt ice mass loss phenomena:

Title: "Recent Findings from the E3SM Cryosphere Science Campaign" by Comeau et al. (May 2019)

https://e3sm.org/wp-content/uploads/2019/05/Comeau-Asay-Davis-Veneziani-All-Hands-May-2019_opt.pdf

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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1237 on: June 15, 2019, 11:08:30 PM »
The difficulty is that the high melt rate occurs "high melt rates, inconsistent with the preindustrial climate "
(first line, last page)

this is impossible since Amery for example, is still around, didnt melt out in preindustrial ...

I do worry about Amery, tho.

sidd

Rich

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1238 on: June 15, 2019, 11:48:47 PM »
With sea level rise it will be higher storm surge that has significant impacts first.
We have already seen New York badly impacted with tropical cyclone  sandy.
It will not be the slow  rise of sea level that causes eventual retreat it will be weather events causing catastrophic damage and sane evaluation of the costs and futility of repeated repair. The developed world is far more susceptible to such costly events than the poor regions of Bangladesh.

Seeing as I have commented on this thread.
Thanks ASLR I have been reading your output for years and appreciate the immense amount of effort  your do in constructing your well supported narrative.

There are many factors contributing to inundation risks besides eustatic SLR, and storm surge, as illustrated by the attached three images.

Edit: I also note that recent research finds that for Hurricane/Typhoon cases, wave run-up is worse than previously assumed due to larger (than previously assumed) infragravity waves.

I would propose one small change to that first chart. Under tidal range, it suggests a "daily-yearly" cycle. Maximum tidal values occur during along an 18.6 year orbital cycle.  The cycle last peaked in 2015 and is declining. The next peak will be in 2034. King tides then in places like Miami Beach and Norfolk will be epic.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1239 on: June 17, 2019, 01:35:05 AM »
Notice anything unusual in this year data in the attached plot of Greenland Surface Ice Melt Extent Area thru the second week of June 2019?
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Rod

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1240 on: June 17, 2019, 01:51:49 AM »
Notice anything unusual in this year data in the attached plot of Greenland Surface Ice Melt Extent Area thru the second week of June 2019?

This is very bad and I am very concerned too.  But, when certain alarmist media people started trying to to turn this into an “unprecedented” event, Dr. Robert Rohde, Berkeley Earth, put it into perspective.

We are ahead of schedule, but just like with the sea ice, we have a long way to go to beat 2012. I’m not saying it won’t happen, in fact I’m on the fence leaning towards it will, but it is still early. 

With that said, even if we don’t beat 2012, this should be a wake up call that things are fucked up! 

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1241 on: June 17, 2019, 03:56:35 AM »
Why is it that consensus climate scientist say that we still have time to cut GHG emissions, but a growing number of climate scientists now think that geoengineering may be essential?

Title: "More Scientists Now Think Geoengineering May Be Essential"

https://www.wired.com/story/more-scientists-now-think-geoengineering-may-be-essential/
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Tor Bejnar

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1242 on: June 17, 2019, 05:02:50 AM »
Jason Box is one scientist who believes some sort of geoengineering is required.  He said so in a video I watched a few weeks ago. But rather than hearsay, two references:  (one from 2012)(another from a few days ago-2019-we have to develop technologies to draw down CO2 [semi-quote]- last 30 seconds of video)
« Last Edit: June 18, 2019, 12:55:26 AM by Tor Bejnar »
Arctic ice is healthy for children and other living things.

wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1243 on: June 17, 2019, 05:15:10 AM »
James Hansen gave us an initial target of 350ppm for atmospheric CO2... Carbon capture is required and has been for well over a decade.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1244 on: June 17, 2019, 05:22:40 AM »
I tend to agree with Prof. Box. Carbon capture and storage is required but the scale is quite daunting. It will be an industry as large as the combined coal, oil and gas sectors who have enthusiastically injected fossil carbon into atmosphere in the first place for a century and a half or more.

I look at mountaintop removal coal operations, and am hard put to imagine a similar carbon burial scheme. But perhaps it will put all the coalminers back to work, except in the other direction.

sidd

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1245 on: June 17, 2019, 11:48:19 PM »
The attached image shows the 2019 UN projection of world population through 2100.

https://population.un.org/wpp/Graphs/Probabilistic/900

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

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1246 on: June 18, 2019, 03:45:04 AM »
Boaty McBoatface has identified a mechanism that enables the Southern Ocean's Westerly winds '... to increase turbulence deep in the Southern Ocean, causing warm water a mid depths to mix with cold, dense water in the abyss.' 
Unfortunately, current models do not simulate this newly identified mechanism; which in my book increases our collective risk of potential future abrupt sea level rise:

Title: "Boaty McBoatface mission gives new insight into warming ocean abyss"

https://phys.org/news/2019-06-boaty-mcboatface-mission-insight-ocean.html

Extract: "In recent decades, winds blowing over the Southern Ocean have been getting stronger due to the hole in the ozone layer above Antarctica and increasing greenhouse gases. The data collected by Boaty, along with other ocean measurements collected from research vessel RRS James Clark Ross, have revealed a mechanism that enables these winds to increase turbulence deep in the Southern Ocean, causing warm water at mid depths to mix with cold, dense water in the abyss.

The resulting warming of the water on the sea bed is a significant contributor to rising sea levels. However, the mechanism uncovered by Boaty is not built into current models for predicting the impact of increasing global temperatures on our oceans."

Edit: I note that the new mechanism identified by Boaty McBoatface works to slow-down the velocity of the global meridional overturning current; which, then causes tropical ocean surface temperatures to increase; which, is a positive ice-climate feedback mechanism.
« Last Edit: June 18, 2019, 06:53:15 PM by AbruptSLR »
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KiwiGriff

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1247 on: June 18, 2019, 09:04:03 AM »
Which of course goes alongside this.

https://science.sciencemag.org/content/364/6440/548
Ocean winds blowing harder
Quote
Two frequently asked questions about how climate warming will affect the environment are whether windiness might change and what effects that might have on ocean waves. Young and Ribal analyzed global satellite data over the period from 1985 to 2018 to determine if there are any trends in oceanic wind speed and wave height. They found small increases in both quantities, with the strongest increases in extreme conditions and in the Southern Ocean. These findings are important for understanding air-sea exchange of energy and carbon dioxide and for projecting sea levels during storms.

Science, this issue p. 548
Abstract

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

The higher sea states are  already impacting on west coast erosion rates here in NZ along with the anomalous regional rise in sea level.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1248 on: June 18, 2019, 01:37:28 PM »
Good book on SLR is The Water Will Come by Jeff Goodell.
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1249 on: June 18, 2019, 09:14:47 PM »
It looks like accelerating methane emissions may thwart efforts to meet the Paris Agreement goal of staying well below a 2C GMSTA.  The attached image shows atmospheric methane concentration values from NOAA's South Pole facility from the beginning of 2005 until June 18, 2019:

Title: "Rising methane may thwart efforts to avoid catastrophic climate change"

https://phys.org/news/2019-06-methane-thwart-efforts-catastrophic-climate.html

Extract: "If the world were on track to meet the Paris Agreement goal of less than 2 degrees Celsius of global warming, methane levels in the atmosphere would theoretically be dropping. Instead, they have been rising since 2007, and shooting up even faster since 2014. A perspective published in the journal Science discusses the potential causes and consequences of our planet's out-of-control methane.

The emissions targets in the Paris Agreement were based largely on data from the 1990s and early 2000s, when methane levels were flatter, said Sara Mikaloff Fletcher, a climate scientist with New Zealand's National Institute of Water and Atmospheric Research in Wellington and first author of the new article. The only emissions scenario that achieves Paris Agreement goals in climate models assumes that methane levels have been declining since 2010, when in fact they have been rising since 2007, she said. There may be other ways of keeping climate change under 2 degrees Celsius, but they would involve compensating for rising methane with more drastic cuts to other greenhouse gases."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson