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Author Topic: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)  (Read 80589 times)

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #800 on: March 24, 2019, 03:04:05 PM »
The linked UNEP reference has a lot of nice graphics about the changing Arctic (too many to choose just a few to post in this reply); however, most of the climate change comments focus on the RCP 4.5 pathway; which to my way of thinking is overly optimistic but as indicated by the extract still results in "… winter temperatures over the Arctic Ocean would increase 3 to 5°C by mid-century and 5 to 9°C by late century (relative to 1986–2005 levels) …":

Title: "Global Linkages A graphic look at the changing Arctic"

https://wedocs.unep.org/bitstream/handle/20.500.11822/27687/Arctic_Graphics.pdf?sequence=1&isAllowed=y

Extract: "Continuing global emissions at rates of a medium-emission scenario (RCP4.5) projects global warming of 2.4 ± 0.5°C above pre-industrial levels by 2100 (Collins et al., 2013 (AR5)). At this rate of emissions, winter temperatures over the Arctic Ocean would increase 3 to 5°C by mid-century and 5 to 9°C by late century (relative to 1986–2005 levels) (AMAP, 2017a)."

Edit, per Hausfather, the UNEP document, cited above, got the AMAP (2017) quote slightly in error and it should be as cited in the extract below:

Title: "Factcheck: Is 3-5C of Arctic warming now ‘locked in’?" by Zeke Hausfather

https://www.carbonbrief.org/factcheck-is-three-five-celsius-of-arctic-warming-now-locked-in

Extract: "The reference for these numbers is the 2017 Arctic Monitoring and Assessment Programme (AMAP) report. The 2017 AMAP report states:

“Over the Arctic Ocean, which is ice-free in early winter in some models and covered by thin sea ice during late winter, the warming is 3–5C by mid-century and 5–9C by late century under RCP4.5.”"
« Last Edit: March 24, 2019, 03:20:41 PM by AbruptSLR »
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wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #801 on: March 24, 2019, 04:55:05 PM »
This report doesn't make any sense to me. We've already had 3C of warming in the Arctic over preindustrial, in fact almost 3C rise since 2000.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #802 on: March 24, 2019, 06:44:39 PM »
This report doesn't make any sense to me. We've already had 3C of warming in the Arctic over preindustrial, in fact almost 3C rise since 2000.
Here is the graph of temp change since 1880 derived from NASA data from  https://data.giss.nasa.gov/gistemp/
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wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #803 on: March 24, 2019, 06:50:05 PM »
This report doesn't make any sense to me. We've already had 3C of warming in the Arctic over preindustrial, in fact almost 3C rise since 2000.
Here is the graph of temp change since 1880 derived from NASA data from  https://data.giss.nasa.gov/gistemp/

Thank you!

I was looking at the below graph. But in any case, according to the NASA graph temps are about 4C higher than pre-industrial. So why all this kerfuffle about 3C rise by 2050?

Bruce Steele

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #804 on: March 24, 2019, 09:11:59 PM »
"countries manage to cut GHG emissions to the targets outlined in the 2015 Paris Agreement on climate change, winter temperatures in the Arctic will still be 3 to 5°C higher by 2050 and 5 to 9°C higher by 2080, relative to 1986–2005 levels. In fact, even if we stopped all emissions overnight, winter temperatures in the Arctic will still increase by 4 to 5°C compared to the late twentieth century."

Anthropocene commented #756 in the "Places becoming less livable" thread on the misquote in the Guardian re. Preindustrial when the UN paper says 3-5 C higher is relative to 1986-2005 levels.

https://gridarendal-website-live.s3.amazonaws.com/production/documents/:s_document/465/original/GlobalLinkages.pdf?1552478695



wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #805 on: March 24, 2019, 10:08:54 PM »
I guess my point is that the a mount of warming against the 1981-2010 is (according to some measurements; i.e. Berkeley) already around 2C or more. And yet there's been tremendous push back against this report. There was a critique of it on Carbon Brief that resulted in the UNEP changing the wording of the report.

Moreover, the original text seems to say "winter temperatures." I am quite confident that winter temperatures have already risen by more than 3C against the 1985-2005 baseline.

So what's the controversy? Who thinks that there won't be at least as much warming in the next 30 years as there's already been?

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #806 on: March 24, 2019, 10:43:57 PM »
This report doesn't make any sense to me. We've already had 3C of warming in the Arctic over preindustrial, in fact almost 3C rise since 2000.
Here is the graph of temp change since 1880 derived from NASA data from  https://data.giss.nasa.gov/gistemp/

Just so that readers are not confused, gistemp values are referenced to 1951-1980, and
to convert 1951-1980 temp departures to a late 19th baseline one needs to add + 0.256 Celsius; as Gavin Schmidt has done in the attached image of the Global Mean Surface Temperature Anomaly, GMSTA.  Furthermore, the UNEP document that I quoted was referring to "... winter temperatures over the Arctic Ocean ..."; while the Arctic temperate values that you cited are for both temperatures over land and ocean above 64N; which to two very different things.  I believe that the UNEP document cites the temperatures over the Arctic Ocean (relative to 1986–2005 levels) because it is concern about an albedo flip associated with a loss of Arctic Sea Ice.
« Last Edit: March 25, 2019, 02:36:22 AM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #807 on: March 25, 2019, 07:58:52 AM »
So what's the controversy?

In short, RCP2.6. Graph posted by Zeke Hausfather:


I commented this on a Swedish blog a week ago, my summary was that Zeke Hausfather is correct, UN stumbled on the scenarios and AMAP will probably be closest to reality with Fig 2.13.
Who believes in RCP2.6, certainly not the model itself (~4C annual and ~5C winter warming by 2100 relative to preindustrial) or that the world will follow a path close to it?
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #808 on: March 25, 2019, 01:51:38 PM »
So what's the controversy?


As a short note, wdmn’s plot is linked in the long-term ASI blog graphs of observed data.  However it is for 67 to 90N instead of 60 to 90N.S

See also:

https://sites.uci.edu/zlabe/arctic-temperatures/
« Last Edit: March 25, 2019, 10:48:37 PM by AbruptSLR »
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wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #809 on: March 25, 2019, 06:07:09 PM »
So what's the controversy?


As a short note, wdmn’s plot is linked in the long-term ASI blog graphs of observed data.  However it is for 67 to 90N instead of 60 to 90N.

Thank you for the clarification. Looking at the source of gerontocrat's data, it seems as though his graph covers 64-90N.

Sorry for going slightly off topic, but...

So if I have this straight, the main gripe is with the claim that even if we were to meet the Paris objectives the warming would be locked in, since the projections used were from RCP 4.5, which is less ambitious than the Paris targets. Moreover values were not used for the full arctic (60-90N).

While I agree that accuracy is important, and appreciate Zeke's work on this, it really is obscene to be carrying on this debate as though we're still serious about the possibility of keeping warming well below 2C given what other recent studies have said, and the early results for ECS from CMIP6.

In the U.S. plans for oil extraction surge on. In Canada, where I live, it looks as though the conservatives will be winning in Alberta this year. One conservative commentator from that province was on CBC radio this weekend talking about how it will take 10 years to get the oil and gas industry back to where it was. i.e. there are no plans to leave anything in the ground.

Meanwhile there is this huge terror of admitting that we might be too late to reach 1.5, let alone 2C, to the point where we're likely to get caught with our pants down over the coming decade, and I sometimes wonder if relying on the IPCC and the RCP pathways is the new predominant form of denial.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #810 on: March 25, 2019, 06:22:20 PM »
I think, telling us this, is the whole purpose of this thread, isn't it AbruptSLR?

PS: Sorry AbruptSLR, don't want to put words in your mouth. It's only, this is the impression whenever i read new posts in this thread.

Lennart van der Linde

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #811 on: March 25, 2019, 06:52:03 PM »
I think, telling us this, is the whole purpose of this thread, isn't it AbruptSLR?

It doesn't have to be the purpose, but could be a consequence/conclusion.

wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #812 on: March 25, 2019, 07:05:33 PM »
I think, telling us this, is the whole purpose of this thread, isn't it AbruptSLR?

PS: Sorry AbruptSLR, don't want to put words in your mouth. It's only, this is the impression whenever i read new posts in this thread.

Definitely it has been a consequence for my thinking.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #813 on: March 25, 2019, 10:05:05 PM »
I think, telling us this, is the whole purpose of this thread, isn't it AbruptSLR?

It doesn't have to be the purpose, but could be a consequence/conclusion.

Yes, my input to this thread is a consequence of what I have observed is happening.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #814 on: March 26, 2019, 07:09:36 AM »
The linked reference finds that Fennoscandian cloud cover is changing now in response to anthropogenic global warming (in recent decades) in the same manner that it has changed in past periods of climate change.  Such findings may help to explain why so many CMIP6 programs are exhibiting relatively high values of TCR/ECS; because net cloud feedback may well have become markedly more positive in recent decades:

Young, Giles H. F.., Gagen, Mary H.., Loader, Neil J.., McCarroll, Danny., Grudd, Håkan., Jalkanen, Risto., Kirchhefer, Andreas. & Robertson, Iain. (2019). Cloud cover feedback moderates Fennoscandian summer temperature changes over the past 1000 years. Geophysical Research Letters, https://cronfa.swan.ac.uk/Record/cronfa48822, doi:10.1029/2018GL081046

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL081046

Abstract: "Northern Fennoscandia has experienced little summer warming over recent decades, in stark contrast to the hemispheric trend, which is strongly linked to greenhouse gas emissions. A likely explanation is the feedback between cloud cover and temperature. We establish the long‐ and short‐term relationships between summer cloud cover and temperature over Northern Fennoscandia, by analyzing meteorological and proxy climate data. We identify opposing feedbacks operating at different timescales. At short timescales, dominated by internal variability, the cloud cover‐temperature feedback is negative; summers with increased cloud cover are cooler and sunny summers are warmer. However, over longer timescales, at which forced climate changes operate, this feedback is positive, rising temperatures causing increased regional cloud cover and vice versa. This has occurred both during warm (Medieval Climate Anomaly and at present) and cool (Little Ice Age) periods. This two‐way feedback relationship therefore moderates Northern Fennoscandian temperatures during both warm and cool hemispheric periods."

Plain Language Summary: "Temperatures have increased globally over recent decades, strongly linked to increases in greenhouse gases. However, over Northern Fennoscandia summer temperatures have increased little over this period, although this region should be strongly affected by global warming. We suggest that changes in summer cloud cover, driven by global temperature changes, are responsible for this moderation of temperatures. This is happening now and during past episodes of climate change. We produce a new reconstruction of summer cloud cover for this region and compare it to existing temperature reconstruction to establish the relationship between temperature and cloud cover. We find that over short timescales, increased cloud cover leads to cooler temperatures and vice versa. However, over longer timescales (decades to centuries), we find that increased global temperature leads to increased northern cloud cover, which reduces local temperatures (the medieval period and at present). The opposite being true in globally cool periods, such as the Little Ice Age. These finding are important as they help to explain the feedback relationship between cloud cover and temperature, which is one of the major uncertainties in modeling future climate. Our data also confirm models of climate that suggest a poleward movement of storm tracks during recent warming."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #815 on: March 26, 2019, 07:23:50 AM »
At least last year, increasing sustainable energy production has just allowed the world to use more energy; thus still maintaining high CO₂ emissions:

Title: "Global carbon dioxide emissions reached record high in 2018"

https://www.axios.com/global-co2-emissions-rose-again-2018-aceffb3b-0f5c-42e9-80b0-238ab397d6c8.html

Extract: "Global carbon dioxide emissions from energy generation climbed for the second straight year in 2018 and reached a record high as global energy demand surged, a new International Energy Agency (IEA) report shows."
&

See also, "Global Energy & CO2 Status Report
The latest trends in energy and emissions in 2018"

https://www.iea.org/geco/

Extract: "Global energy consumption in 2018 increased at nearly twice the average rate of growth since 2010, driven by a robust global economy and higher heating and cooling needs in some parts of the world. Demand for all fuels increased, led by natural gas, even as solar and wind posted double digit growth. Higher electricity demand was responsible for over half of the growth in energy needs. Energy efficiency saw lacklustre improvement. As a result of higher energy consumption, CO2 emissions rose 1.7% last year and hit a new record."

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #816 on: March 26, 2019, 02:56:24 PM »

...
Moreover values were not used for the full arctic (60-90N).

While I agree that accuracy is important, and appreciate Zeke's work on this, it really is obscene to be carrying on this debate as though we're still serious about the possibility of keeping warming well below 2C given what other recent studies have said, and the early results for ECS from CMIP6.

...

wdmn,

I generally do not have time to address most of the assumptions that work their way into various posts in this thread, but I thought that I would clarify my position on some of the matters that you raise.

First, the Arctic Circle is from 66° 33' 39" N. to 90oN, so the plot you referenced is more relevant than Zeke Hausfather's; and I was merely pointing out that different posts were comparing apples to oranges.

Second, in Zeke Hausfather's following linked article on the SSP scenarios, he notes that SSP2 is most comparable to the relatively new RCP 7.0, and he claims that these scenarios are more likely to be more representative of future anthropogenic forcing than either SSP5 baseline or RCP 8.5.  However, before the end of April 2019 global population will be at 7.7 billion people, which is above all of the SSPs estimated global populations in 2019 as shown in the first image from Hausfather's article, and I note that in 2100 RCP 8.5 assumed a world population of about 12 billion while SSP5-baseline assumes a world population of about 7.38 billion people (indicating that SSP5-baseline was rigged to match the radiative forcing of RCP 8.5, significantly by ignoring global population projections).  Thus SSP5-baseline seriously underestimates global population, which means to me that even if the people ignored by SSP5-baseline were to only use sustainable energy (see the second attached image for the year 2018) then we would still be following SSP5-baseline and not SSP2.

Title: "Explainer: How ‘Shared Socioeconomic Pathways’ explore future climate change"

https://www.carbonbrief.org/explainer-how-shared-socioeconomic-pathways-explore-future-climate-change

Extract: "While RCP8.5 lives on in the form of the SSP5 baseline, it is now just one of many possible no-new-policy futures. The fact that only one of the SSPs, SSP5, can reach the level of emissions found in RCP8.5 suggests that it may not now be best suited for use as the sole baseline scenario in future research.

If any SSP can be said to be characteristic of current conditions it is SSP2, where social, economic and technological trends do not shift markedly from historical patterns. Greenhouse gas concentrations in the SSP2 baseline roughly correspond to the new RCP7.0, which shows lower emissions and nearly 1C less warming than RCP8.5 – though still 3.8-4.2C of warming above pre-industrial levels."

The second image comes from the IEA report on global energy use thru 2018 at:

https://www.iea.org/geco/

Finally, I remind readers that I think that we will only follow SSP5-baseline through circa 2060 when I expect global socio-economic collapse will drop anthropogenic GHG emissions down to something like SSP1.

Best,
ASLR
« Last Edit: March 26, 2019, 04:45:28 PM by AbruptSLR »
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wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #817 on: March 26, 2019, 04:11:29 PM »
Thank you ASLR for taking the time to reply.

I had been taught that Arctic was 66 to 90, but thought that maybe there was some unusual convention amongst climate scientists for using a larger area, kind of like using 1985-2005 as a pre-industrial baseline...

I greatly appreciate all your posts here. Thanks again.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #818 on: March 26, 2019, 04:56:45 PM »
I estimate that by about 2028 the Jakobshavn grounding line will be upstream of location A15 shown in the attached image; at which point I expect ice cliff instability will supersede ocean water temperature as the key parameter for grounding line retreat of the Jakobshavn Glacier.  Therefore, the fact that the linked source indicate that the ice thickness of Jakobshavn has been increasing in recent years implies that after circa 2028 the ice cliff instability will proceed faster than previously estimated:

Title: "The fastest-melting Greenland glacier has made a temporary U-turn"

https://www.axios.com/fastest-melting-greenland-glacier-abruptly-slows-melt-rate-b616aa1e-7e71-4d6a-94e2-0abbb2840fd0.html

Extract: "The Jakobshavn Glacier in west-central Greenland, which has been the fastest-flowing and thinning glacier on the vast ice island during the past 20 years, has temporarily slowed its retreat and thickened in the past few years, scientists say."

See also:

https://www.nature.com/articles/s41561-019-0329-3

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #819 on: March 26, 2019, 06:36:48 PM »
So what's the controversy?

In short, RCP2.6. Graph posted by Zeke Hausfather:




zeke's work was a total hack job as the AMAP report shows direct observations that are ALREADY higher than what he projects under RCP 2.6.  Note that he is also looking at 2100 values not peak warming under 2.6  (he is counting on significant cooling after 2040 with no loss of sea ice (in fact recovery).

we had an exchange here:  https://twitter.com/hausfath/status/1108068566689996800
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #820 on: March 27, 2019, 07:03:02 AM »
It's a shame he never responded, John.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #821 on: March 27, 2019, 08:46:16 PM »
Sounds like Zeke has gone off the deep end in modelling. Even Encyclopedia Britannica admitted 20+years ago that Arctic is about +65N. Today we might discount the Bering and Ohotsk seas all together and use the Arctic Circle.
https://www.britannica.com/science/polar-ecosystem
« Last Edit: March 28, 2019, 10:51:11 AM by Pmt111500 »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #822 on: March 29, 2019, 05:07:13 PM »
When one considers the implications of the combined influences of both a MICI-type abrupt sea level rise (beginning circa 2040), with the associated greater storm activity (ala Hansen's 'Storms of My Grandchildren), on infragravity (IG) waves (see the linked reference); one realizes that the impacts on coastal regions will be significantly greater than current assumed by planners.

As indicated in the linked article oceanic IG waves are primarily produced in shallow (or shoaling) water from the gravitational energy released from the shorter period wind-generated waves as the wind waves enter the shallow water. IG waves have long periods (on the order of 20 seconds) and thus they can damage coastlines more than wind-driven waves (think hurricanes, typhoons & cyclones) as indicated in the linked reference.  Furthermore, reflected IG waves (say off-of a beach) can form soliton waves that do not dissipate with distance traveled, as is currently the case where IG soliton wave travel from the south coast of Alaska all the wave to Western Antarctica; where their long-period energy can reach underneath ice shelves and cause them to flex.

Finally, I note that there are many relatively flat coastal plains around the world that would be inundated by abrupt sea level rise (and/or inundated by storm related rainfall); which would create a large number of new shallow/shoaling water zones that would create many more IG waves than currently occur today; which would be accelerate the collapse of more Antarctic ice shelves (which would be a positive feedback on both abrupt SLR & on ice-climate feedback mechanisms) and would cause more coastal damage around the world.

Xavier Bertin et al. (February 2018), "Infragravity waves: From driving mechanisms to impacts", Earth-Science Reviews, Volume 177, Pages 774-799, https://doi.org/10.1016/j.earscirev.2018.01.002

https://www.sciencedirect.com/science/article/pii/S0012825217303239

Abstract
Infragravity (hereafter IG) waves are surface ocean waves with frequencies below those of wind-generated “short waves” (typically below 0.04 Hz). Here we focus on the most common type of IG waves, those induced by the presence of groups in incident short waves. Three related mechanisms explain their generation: (1) the development, shoaling and release of waves bound to the short-wave group envelopes (2) the modulation by these envelopes of the location where short waves break, and (3) the merging of bores (breaking wave front, resembling to a hydraulic jump) inside the surfzone. When reaching shallow water (O(1–10 m)), IG waves can transfer part of their energy back to higher frequencies, a process which is highly dependent on beach slope. On gently sloping beaches, IG waves can dissipate a substantial amount of energy through depth-limited breaking. When the bottom is very rough, such as in coral reef environments, a substantial amount of energy can be dissipated through bottom friction. IG wave energy that is not dissipated is reflected seaward, predominantly for the lowest IG frequencies and on steep bottom slopes. This reflection of the lowest IG frequencies can result in the development of standing (also known as stationary) waves. Reflected IG waves can be refractively trapped so that quasi-periodic along-shore patterns, also referred to as edge waves, can develop. IG waves have a large range of implications in the hydro-sedimentary dynamics of coastal zones. For example, they can modulate current velocities in rip channels and strongly influence cross-shore and longshore mixing. On sandy beaches, IG waves can strongly impact the water table and associated groundwater flows. On gently sloping beaches and especially under storm conditions, IG waves can dominate cross-shore sediment transport, generally promoting offshore transport inside the surfzone. Under storm conditions, IG waves can also induce overwash and eventually promote dune erosion and barrier breaching. In tidal inlets, IG waves can propagate into the back-barrier lagoon during the flood phase and induce large modulations of currents and sediment transport. Their effect appears to be smaller during the ebb phase, due to blocking by countercurrents, particularly in shallow systems. On coral and rocky reefs, IG waves can dominate over short-waves and control the hydro-sedimentary dynamics over the reef flat and in the lagoon. In harbors and semi-enclosed basins, free IG waves can be amplified by resonance and induce large seiches (resonant oscillations). Lastly, free IG waves that are generated in the nearshore can cross oceans and they can also explain the development of the Earth's “hum” (background free oscillations of the solid earth).

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #823 on: March 29, 2019, 05:36:41 PM »
The late Cretaceous period ended about 66 million years ago, and thus is relatively close to the often discuss PETM period, and is thus relevant to the possible future conditions that Earth may be headed towards.  The linked reference offers new paleo-information that can used to better calibrate advanced ESM projects, particularly those associated with potential sea ice losses in the Arctic Ocean:

I. Niezgodzk et al. (20 March 2019), "Was the Arctic Ocean ice free during the latest Cretaceous? The role of CO2 and gateway configurations", Global and Planetary Change, https://doi.org/10.1016/j.gloplacha.2019.03.011

https://www.sciencedirect.com/science/article/pii/S0921818118306775

Abstract
The Arctic region is thought to play a key role in unraveling Mesozoic climate evolution. However, Late Cretaceous climate reconstructions in the high latitudes suffer from contradicting paleoclimatic interpretations. Toward the end of the Cretaceous hot-house, atmospheric CO2 concentration declined potentially enabling the formation of sea-ice in the Arctic Ocean. We use a coupled atmosphere-ocean climate model to investigate possible effects of different atmospheric CO2 levels and gateway configurations between the North proto-Atlantic Basin and the Arctic Ocean on the formation of Arctic sea-ice in the latest Cretaceous. Sensitivity tests were run with two atmospheric CO2 levels (840 and 1120 ppm, representing 3× and 4× pre-industrial concentrations, respectively) with six paleogeographic configurations. In the experiment with 840 ppm CO2, seasonal Arctic sea-ice is observed in each gateway configuration in December–June, while for 1120 ppm sea-ice in the central Arctic is either limited or absent, depending on gateway configuration. This suggests the existence of a CO2 threshold, estimated between 3× and 4× pre-industrial (PI) CO2 levels. For higher atmospheric CO2 levels sea-ice formation can only occur by the combined effect of cold winds blowing over the Arctic from continental North America during boreal winter and seawater freshening. The latter can be caused by either very limited or an absence of gateway connections between the Arctic and the open ocean. Such a configuration likely developed in the latest Cretaceous, i.e. close to the Cretaceous/Paleogene boundary interval.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #824 on: March 30, 2019, 04:23:26 PM »
Now that the field phase of the International Thwaites Glacier Collaboration is complete, I can recommend periodically monitoring the linked websites in the coming weeks & months for updates as the field data is analyzed from the eight associated projects (see the attached image):

Title: "The International Thwaites Glacier Collaboration"

https://thwaitesglacier.org/
&
https://thwaitesglacier.org/projects

Extract: "UK and US scientists are collaborating to investigate one of the most unstable glaciers in Antarctica, the Thwaites Glacier, roughly the same size as Florida or Britain."

See also:

For the project Twitter site, see:

https://twitter.com/GlacierThwaites?ref_src=twsrc%5Etfw%7Ctwcamp%5Eembeddedtimeline%7Ctwterm%5Eprofile%3AGlacierThwaites&ref_url=https%3A%2F%2Fthwaitesglacier.org%2F

Also, I note that both Jeremy Bassis & Doug Benn are involved in the DOMINOS project & thus this hierarchical approach to computer modeling will certainly include ice-cliff failure mechanisms.

Title: "Disintegration of Marine Ice-sheets Using Novel Optimised Simulations (DOMINOS)"

https://thwaitesglacier.org/projects/dominos

Extract: "Currently, it is difficult to model calving and its complex interactions with atmospheric and oceanic conditions. The DOMINOS team will use a novel ice-dynamic model suite coupled with an ocean forcing model suite. This model suite includes a discrete element model capable of simulating coupled fracture and ice-flow processes, a 3D full Stokes continuum model, and the continental scale ice-dynamics model BISICLES. Ice dynamics models will be coupled to an ocean forcing model suite including simple plume models, intermediate complexity 2-layer ocean models and fully 3D regional ocean models. This hierarchical approach will use high-fidelity process models to inform and constrain the sequence of lower-order models needed to extrapolate improved understanding to larger scales and has the potential to radically reduce uncertainty of rates of marine ice sheet collapse and associated sea level rise."
&

Furthermore, I note that the Thwaites Drainage Basin can merge together with the Pine Island Drainage Basin as the Thwaites Glacier Eastern Shear Margin migrates outward (& I note that this outward migration has been accelerated by the recent reduction in ice shelf buttressing on the Southwest Tributary Glacier.

Title: "Thwaites Interdisciplinary Margin Evolution - The Role of Shear Margin Dynamics in the Future Evolution of Thwaites Drainage Basin (TIME)"

https://thwaitesglacier.org/projects/time

Extract: "If the Thwaites Glacier Eastern Shear Margin migrates outwards it could join the Pine Island Glacier, connecting the two glaciers which are already making large contributions to sea-level rise."

See also:
Title: "Melting at Thwaites grounding zone and its control on sea level (MELT)"

https://thwaitesglacier.org/projects/melt

Extract: "MELT is an ice-based project to understand how warm waters are affecting the Thwaites Glacier at the grounding line – the point where the glacier goes afloat to become ice shelf. This will allow the glacier’s potential sea-level contribution to be more accurately predicted."
&

Title: "Thwaites Offshore Research (THOR)"

https://thwaitesglacier.org/projects/thor

Extract: "Thwaites Offshore Research (THOR) is a ship-based and ice-based project that will examine the sedimentary records both offshore from the glacier and beneath the ice shelf, together with glacial landforms on the sea bed, to reconstruct past changes in ocean conditions and the glaciers response to these changes."
&

Title: "Geophysical Habitat of Subglacial Thwaites (GHOST)"

https://thwaitesglacier.org/projects/ghost

Extract: "GHOST is an ice-based project which will examine the bed beneath the Thwaites Glacier, to assess whether conditions are likely to allow rapid retreat, or if the retreat may slow or stop due to a ridge 70 km inland."
&

Title: "Geological History Constraints on the Magnitude of Grounding-Line Retreat in the Thwaites Glacier System (GHC)"

https://thwaitesglacier.org/projects/ghc

Extract: "GHC will gather information about past ice sheet behavior and relative sea level change in the Thwaites Glacier system. Determining the timing and magnitude of past episodes of thinning and retreat and subsequent re-advance is important to provide a context for the current and future behavior of Thwaites Glacier and its influence on global sea level."
&

Title: "Thwaites-Amundsen Regional Survey and Network Integrating Atmosphere-Ice-Ocean Processes (TARSAN)"

https://thwaitesglacier.org/projects/tarsan

Extract: "TARSAN is a ship-based project studying how atmospheric and oceanic processes are influencing the behavior of the Thwaites and Dotson Ice Shelves – neighboring ice shelves which are behaving differently."
&

Title: "Processes, drivers, Prediction: modeling the History and Evolution of Thwaites (PROPHET)"

https://thwaitesglacier.org/projects/prophet

Extract: "PROPHET is a computer modelling based project which aims to improve the representation of several key processes (calving, ice damage and basal conditions), which are not currently characterized well in large scale ice-flow models."
&

Title: "The Future of Thwaites Glacier and its Contribution to Sea-level Rise Science Coordination Office Proposal (SCO)"

https://thwaitesglacier.org/projects/sco

Extract: "The ITGC Science Coordination Office coordinates the eight funded research projects to deliver the best possible science for the funding agencies and the public of both the US and UK."

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #825 on: March 30, 2019, 04:36:49 PM »
Just as a general comment (without a lot of back-up), in my last post I noted that the Thwaites and the Pine Island Drainage Basins could link-up into one single drainage basin, and I note that if the worst case ice-cliff failure scenarios were to occur for these two combined drainage basins, then per the fingerprint effect (see the attached image of the fingerprint effect is the entire WAIS were to collapse), the sea level at the Ross Ice Shelf (RIS) might drop abruptly which might cause flexural fissures near the grounding line of the RIS; which might contribute to a potential abrupt collapse of the RIS.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #826 on: March 30, 2019, 04:58:23 PM »
As a follow-on to my last post & again without much back-up, the attached image shows the extent of the Arctic Coastal Plain (particularly in Alaska but also in Siberia & Canada) that are subject to inundation if the WAIS were to collapse abruptly.  Furthermore, I note that such inundated Arctic Coastal Plains contain extensive reserves of methane (natural gas) hydrates that could be destabilized by heat transferred from the relatively warm, inundating ocean water.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #827 on: March 30, 2019, 07:16:40 PM »
Ice-climate feedback mechanisms are numerous, interacting, complex and already happening, as demonstrated by the linked open access reference, that demonstrates how freshening of local Antarctic surface water (due significantly from the basal ice melting of local Antarctic ice shelves, largely driven by changes in wind patterns due largely to the formation of the Antarctic ozone hole and subsequent increase in local GHG concentrations), reduces the full-depth convection and formation of Dense Shelf Water (DSW).  This in turn slows the formation of Antarctic Bottom Water, AABW; which then slows the MOC as well as acceleration the retreat of the grounding lines of key Antarctic marine glaciers.  These ice-climate feedback mechanisms are self-reinforcing:

Alessandro Silvano et al. (2018), "Freshening by glacial meltwater enhances melting of ice shelves and reduces formation of Antarctic Bottom Water", Science Advances, Vol. 4, no. 4, eaap9467, DOI: 10.1126/sciadv.aap9467

http://advances.sciencemag.org/content/4/4/eaap9467.full

Abstract
Strong heat loss and brine release during sea ice formation in coastal polynyas act to cool and salinify waters on the Antarctic continental shelf. Polynya activity thus both limits the ocean heat flux to the Antarctic Ice Sheet and promotes formation of Dense Shelf Water (DSW), the precursor to Antarctic Bottom Water. However, despite the presence of strong polynyas, DSW is not formed on the Sabrina Coast in East Antarctica and in the Amundsen Sea in West Antarctica. Using a simple ocean model driven by observed forcing, we show that freshwater input from basal melt of ice shelves partially offsets the salt flux by sea ice formation in polynyas found in both regions, preventing full-depth convection and formation of DSW. In the absence of deep convection, warm water that reaches the continental shelf in the bottom layer does not lose much heat to the atmosphere and is thus available to drive the rapid basal melt observed at the Totten Ice Shelf on the Sabrina Coast and at the Dotson and Getz ice shelves in the Amundsen Sea. Our results suggest that increased glacial meltwater input in a warming climate will both reduce Antarctic Bottom Water formation and trigger increased mass loss from the Antarctic Ice Sheet, with consequences for the global overturning circulation and sea level rise.

See also:

Title: "Study Reveals Dangerous Antarctic Feedback Loop"

https://www.ecowatch.com/antarctic-climate-change-study-2562971817.html

Extract: "... Silvano's research backs up a study co-authored by early climate change alarm-sounder Dr. James Hansen in 2016, which used computer models to predict that melting ice in Antarctica and Greenland would warm the oceans below the surface and increase the rate of melting, increasing storms and leading to sea level rise of "several meters over a timescale of 50 to 150 years," according to the abstract.

"Our study shows for the first time actual evidence of this mechanism. Our study shows that it is already happening," Silvano told The Washington Post."


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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #828 on: March 30, 2019, 09:22:30 PM »
In active inference, action selection is driven by an objective function that evaluates possible future actions with respect to current, inferred beliefs about the world.  Furthermore, adaptive active inference results in 'autonomous organization' or self-reinforcing echo chambers within modern society.

With this background, I note that in adaptive active inference one can either accept the external conditions and adapt to them, or one can draw upon preconceived inferences and seek to adapt by changing the external conditions.

While there a numerous papers that I could link to about elaborations of Karl Friston's basic theory about active inference and adaptive active inference, I have selected the linked reference that accounts for human hallucinations using active interference as I believe it is relevant to both climate change denialism and to consensus climate science.  Finally, I note that it is a hallucination of both climate change denialism and consensus climate science to believe that Mother Nature will adapt to their preconditioned inferences about the nature of the world.

David Benrimoh, Thomas Parr, Rick A. Adams, and Karl Friston (2019), "Hallucinations both in and out of context: An Active Inference Account", doi: http://dx.doi.org/10.1101/540419.

https://www.biorxiv.org/content/biorxiv/early/2019/02/04/540419.full.pdf

ABSTRACT: Hallucinations, including auditory verbal hallucinations (AVH), occur in both the healthy population and in psychotic conditions such as schizophrenia (often developing after a prodromal period). In addition, hallucinations can be in-context (they can be consistent with the environment, such as when one hallucinates the end of a sentence that has been repeated many times), or out-of-context (such as the bizarre hallucinations associated with schizophrenia). In previous work, we introduced a model of hallucinations as false (positive) inferences based on a (Markov decision process) formulation of active inference. In this work, we extend this model to include content – to disclose the computational mechanisms behind in- and out-of-context hallucinations. In active inference, sensory information is used to disambiguate alternative hypotheses about the causes of sensations. Sensory information is balanced against prior beliefs, and when this balance is tipped in the favor of prior beliefs, hallucinations can occur. We show that in-context hallucinations arise when (simulated) subjects cannot use sensory information to correct prior beliefs about hearing a voice, but beliefs about content (i.e. the sequential order of a sentence) remain accurate. When hallucinating subjects also have inaccurate beliefs about state transitions, out-of-context hallucinations occur; i.e. their hallucinated speech content is disordered. Furthermore, subjects with inaccurate beliefs about state transitions but an intact ability to use sensory information do not hallucinate and are reminiscent of prodromal patients. This work demonstrates the different computational mechanisms that may underlie the spectrum of hallucinatory experience – from the healthy population to psychotic states. 

For more on extensions to the theory of active inference see also:

Title: "Expanding the Active Inference Landscape: More Intrinsic Motivations in the Perception-Action Loop"

https://www.frontiersin.org/articles/10.3389/fnbot.2018.00045/full
&

Title: "The Active Inference Approach to Ecological Perception: General Information Dynamics for Natural and Artificial Embodied Cognition"

https://www.frontiersin.org/articles/10.3389/frobt.2018.00021/full
&

Title: "The Markov blankets of life: autonomy, acitve inference and the free energy principle"

https://royalsocietypublishing.org/doi/full/10.1098/rsif.2017.0792
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #829 on: March 31, 2019, 07:56:38 PM »
Perhaps some readers think that I am being overly harsh when I implied in my last post (Reply #828) that consensus climate scientist may well be hallucinating with regards to their collective expectations of how Mother Nature is most like going to respond to anthropogenic radiative forcing in the coming several decades (say from 2040 to 2060).  Therefore, I provide this follow-on post in order to briefly discuss why the concept of carbon budgets (which consensus climate scientists began formulating circa 2009 and cited explicitly in AR5 and then revised upward in SR15, see the first linked article), actually provides dangerous guidance to policymakers, as is lightly touched upon by the second linked article.

In addition to the discussion provided in the two linked articles, I raise the following points, that help to clarify why I believe that the carbon budget guidance provided relatively recently by SR15 is actually quite dangerous:

1. SR15 assumes that the values of TCR estimated by CMIP5 were too high and thus SR15 expanded the AR5 carbon budget to stay below 1.5C; while preliminary results from CMIP6 indicates that actually CMIP5 under estimated TCR and thus the carbon budget should have been decreased.  In the way of explaining the differences between CMIP5 and the preliminary CMIP6 projections, I note that the more advanced CMIP6 models: a) estimate that aerosol interactions in recent decades have been more negative than CMIP5 assumed (which means that TCR was higher than CMIP5 assumed); b) estimate that cloud interaction feedback mechanism are progressively becoming more positive (which means that TCR is progressively increasing in magnitude); and c) estimate that some ice-climate mechanisms are already being activated.

2. SR15 assumes that world governments will aggressively implement negative emissions technology (like BECCS); while recent studies of food supply clearly indicate that in coming decades there will be insufficient land for food production let alone for BECCS.

3. SR15 underestimates the global warming potential of future methane emissions, and totally ignore ice-climate feedback mechanisms (including those that are already occurring).

4. SR15 ignores the fact that anthropogenic radiative forcing has been occurring since at least 1750 and thus numerous slow-response positive feedback mechanisms are already being activated, and thus it may be advisable to use ECS, rather than TCR, when calculating the remaining carbon budget.

5.  If Hawkins et al. (2017) is correct that one needs to add about 0.675C (or at least 0.6C) to the consensus science GMSTA values; then not only are we closer to Mid-Pliocene conditions than most people assume, but also that ECS is higher than AR5 assumes.

6. If DeConto & Pollard (2018)'s estimates of how the WAIS will respond to Mid-Pliocene conditions is correct, then we are currently at risk of triggering an irreversible abrupt collapse of the WAIS; which is not considered by any consensus science carbon budget.

If reader wants more reasons that consensus climate science estimates of our remaining carbon budget (including that from SR15), may be dangerous; just scroll be through this thread:

Title: "Analysis: Why the IPCC 1.5C report expanded the carbon budget"

https://www.carbonbrief.org/analysis-why-the-ipcc-1-5c-report-expanded-the-carbon-budget

Extract: "The newly published Intergovernmental Panel on Climate Change’s (IPCC) special report on 1.5C (SR15) significantly expands the budget for a 66% chance of avoiding 1.5C to the equivalent of 10 years of current emissions. This compares to the IPCC’s fifth assessment report (AR5), which put it at around three years.

Based on estimates made in the IPCC’s fifth assessment report (AR5), there would be around 120 gigatonnes of CO2 (GtCO2) remaining from the beginning of 2018 – or around three years of current emissions – for a 66% chance of avoiding 1.5C warming. For a 50/50 chance of exceeding 1.5C, the remaining budget was a modestly larger 268GtCO2 – or around seven years of current emissions.

The IPCC’s new SR15 significantly revises these numbers. It raises the budget for a 66% of avoiding 1.5C to 420GtCO2 – or 10 years of current emissions. Similarly, the budget for a 50/50 chance of exceeding 1.5C is increased to 580GtCO2 – 14 years of current emissions.

Even the revised 1.5C carbon budget is unlikely to be the end of the debate, however, given a number of large remaining uncertainties. These include:
•   The precise meaning of the 1.5C target.
•   Disagreement about what “surface temperature” actually refers to.
•   The definition of the “pre-industrial” period.
•   What observational temperature datasets should be used.
•   What happens to non-CO2 factors that influencing the climate.
•   Whether Earth-system feedbacks like melting permafrost are taken into account.

Finally, the emission scenarios considered in the new SR15 also tend to emit far more than the budget would allow, but make up for it with the large-scale use of negative emissions in the future. The large carbon budget uncertainty and reliance on negative emissions – basically, sucking CO2 from the atmosphere and permanently storing it – suggest that the idea of a carbon budget may be of limited use for strict mitigation targets such as 1.5C."
&

Title: "How the “Carbon Budget” Is Causing Problems"

https://www.scientificamerican.com/article/how-the-carbon-budget-is-causing-problems/

Extract: "Confusion over how much CO2 can be emitted could undermine global climate action

Uncertainties about the value make it difficult to develop policies based around a single budget, they suggest. And the debate about the exact number may actually provide a kind of political flexibility for world leaders, enabling them to endlessly argue that there’s still time for action, even while time is actually running out.

“Instead of oversimplifying, the scientific community should seek to discuss and emphasize the persistent uncertainties,” he wrote—making it clear, instead, that any given estimate includes a wide range of assumptions about all kinds of factors, and that these are all part and parcel of any given budget."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #830 on: April 01, 2019, 02:42:20 PM »
I agree that the IPCC has mishandled uncertainty and the carbon budgets are based on false confidence. The IPCC has ignored processes that have been identified but not well quantified. There may be processes not yet discovered. What we have learned between each iteration of the IPCC reports has tended to discover that the climate is more sensitive to GHGs than previously estimated.

A better handling of uncertainty would lead to less confidence in budgets and more urgency for action because the uncertainties skew towards higher impacts of GHGs on climate change.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #831 on: April 01, 2019, 11:04:06 PM »
The UNFCCC and IPCC have turned into a device to enable growth while keeping the pressure for more fundamental change at bay by creating a mirage of real progress. Every time there is a clash between the need to reduce GHG emissions and growth another rabbit is pulled out of the hat - such things as the inclusion of BECCS and DACS, the manipulation of confidence intervals, and the usage of low estimates for climate sensitivity.

It does look like the science is starting to remove some of the rabbits (e.g. low estimates of climate sensitivity) and the confidence interval cant be messed with any more (the 50% for 1.5 degrees was the lowest that I think they can get away with). The continued increase in atmospheric CH4 is also adding pressure. So the new rabbits for the 2022 IPCC report may be even greater use of BECCS/DACS, plus maybe rock weathering and SRM?

Reading some of Radoslav Dimitrov's articles on the UN FCCC processes (he was a delegate at Copenhagen and Paris) helps show what a political circus it is. He calls the Copenhagen Accord and Paris Agreement "decoy institutions" meant to hide the reality of a lack of any real progress.

« Last Edit: April 02, 2019, 05:05:45 AM by rboyd »

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #832 on: April 02, 2019, 07:43:39 AM »
Reading some of Radoslav Dimitrov's articles on the UN FCCC processes (he was a delegate at Copenhagen and Paris) helps show what a political circus it is. He calls the Copenhagen Accord and Paris Agreement "decoy institutions" meant to hide the reality of a lack of any real progress.

Thanks for the reference to Dimitrov. It seems he indeed calls the Copenhagen Accord a decoy institution, but leaves the question open on the Paris Agreement (Dimitrov 2018):
https://www.researchgate.net/profile/Radoslav_Dimitrov/project/Decoy-institutions-in-world-politics/attachment/5ba286483843b006753a259a/AS:672625667887109@1537377864774/download/+Decoy+Institutions+-R.+Dimitrov.pdf?context=ProjectUpdatesLog

"Is the Paris Agreement on Climate Change, for instance, a decoy institution? The agreement is characterized by remarkable complexity and is not a conventional treaty that conforms easily to the traditional model of international law. It relies on a complex mix between legally binding obligations and voluntary provisions that give full discretion to governments. This ambiguity leads to various interpretations and vigorous debates but, mostly, genuine uncertainty in academic circles. Some observers claim there are no legal obligations for action, and even decry it as a misleading nonbinding agreement that is camouflaged as a treaty. Others disagree and insist the Paris Agreement is a treaty with real policy obligations. Even veteran IR scholars of global governance appear at a loss and state cautiously that the vagueness of the Paris Agreement creates uncertainty about its effectiveness. The possibility that this treaty is actually an elaborate decoy institution that allows governments to hide behind a weak international arrangement could clarify the situation and deserves investigation."

In 2016 he did seem to think the Paris Agreement was a genuine diplomatic success:
http://politicalscience.uwo.ca/people/faculty/full-time_faculty/GEP%20Paris%20Agreement.pdf

"The Paris Agreement constitutes a political success in climate negotiations and traditional state diplomacy, and offers important implications for academic research. Based on participatory research, the article examines the political dynamics in Paris and highlights features of the process that help us understand the outcome. It describes battles on key contentious issues behind closed doors, provides a summary and evaluation of the new agreement, identifies political winners and losers, and offers theoretical explanations of the outcome. The analysis emphasizes process variables and underscores the role of persuasion, argumentation, and organizational strategy. Climate diplomacy succeeded because the international conversation during negotiations induced cognitive change. Persuasive arguments about the economic benefits of climate action altered preferences in favor of policy commitments at both national and international levels."

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #833 on: April 02, 2019, 04:34:23 PM »
Per the linked reference, stratospheric water vapor is an important positive climate feedback mechanism that has been previously underestimated in earlier projections:

Banerjee et al. (2019), "Stratospheric water vapor: an important climate feedback",
Climate Dynamics, pp 1–14, DOI https://doi.org/10.1007/s00382-019-04721-4

https://link.springer.com/article/10.1007%2Fs00382-019-04721-4

Abstract: "The role of stratospheric water vapor (SWV) changes, in response to increasing CO2CO2, as a feedback component of quantitative significance for climate sensitivity has remained controversial. Here, we calculate the SWV climate feedback under abrupt CO2CO2 quadrupling in the CMIP5 ensemble of models. All models robustly show a moistening of the stratosphere, causing a global mean net stratosphere adjusted radiative perturbation of 0.89±0.27Wm−20.89±0.27Wm−2 at the reference tropopause. The stratospheric temperature adjustment is a crucial component of this radiative perturbation. The associated climate feedback is 0.17±0.05Wm−2K−10.17±0.05Wm−2K−1, with a considerable inter-model range of 0.12–0.28 Wm−2K−1Wm−2K−1. Taking into account the rise in tropopause height under 4×CO24×CO2 slightly reduces the feedback to 0.15±0.04Wm−2K−10.15±0.04Wm−2K−1, with a range of 0.10–0.26Wm−2K−10.26Wm−2K−1. The SWV radiative perturbation peaks in the midlatitudes and not the tropics: this is due primarily to increases in SWV in the extratropical lowermost stratosphere, which cause the majority (over three quarters) of the global mean feedback. Based on these results, we suggest an increased focus on understanding drivers of water vapor trends in the extratropical lowermost stratosphere. We conclude that the SWV feedback is important, being on the same order of magnitude as the global mean surface albedo and cloud feedbacks in the multi-model mean."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #834 on: April 02, 2019, 04:53:36 PM »
Reading some of Radoslav Dimitrov's articles on the UN FCCC processes (he was a delegate at Copenhagen and Paris) helps show what a political circus it is. He calls the Copenhagen Accord and Paris Agreement "decoy institutions" meant to hide the reality of a lack of any real progress.

Thanks for the reference to Dimitrov. It seems he indeed calls the Copenhagen Accord a decoy institution, but leaves the question open on the Paris Agreement (Dimitrov 2018):
...

This thread opened by discussing the article "Ice Apocalypse" by Eric Holthaus, November 2017; which was critiqued by Tamsin Edwards in an article entitled: "How soon will the 'ice apocalypse' come?".  Furthermore, Edwards et al. (2019) proceeded to critique DeConto's, Pollard's (and sometimes Alley's) work on MICI.

In this regards, I note that not only are UN reports likely to under represent our current climate risks, but individual consensus climate change scientists like Tamsin Edwards feel free to ignore uncertain high impact climate risks (such as early collapse of key WAIS ice shelves, near-term increases in methane emissions [say from thermokarst lakes], etc.) in their projection, merely because there might be another uncertain lower impact climate scenario.  Thus while government influenced reports from the UN might have ulterior motives, many consensus climate change scientist may simply be self-deluding themselves with happy thoughts:

Title: "Ice Apocalypse" by Eric Holthaus, November 21, 2017

https://grist.org/article/antarctica-doomsday-glaciers-could-flood-coastal-cities/

Extract: "Rapid collapse of Antarctic glaciers could flood coastal cities by the end of this century."
&

Title: "How soon will the 'ice apocalypse' come?" by Tamsin Edwards November 23, 2017.

https://www.theguardian.com/science/head-quarters/2017/nov/23/climate-change-how-soon-will-the-ice-apocalypse-come-antarctica

Extract: "An emotive article on the ‘ice apocalypse’ by Eric Holthaus describes a terrifying vision of catastrophic sea level rise this century caused by climate change and the collapse of the Antarctic ice sheet. But how likely is this – and how soon could such a future be here?"
&

Edwards, T. L. et al. (2019) Revisiting Antarctic ice loss due to marine ice-cliff instability, Nature, doi:10.1038/s41586-019-0901-4

https://www.nature.com/articles/s41586-019-0901-4


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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #835 on: April 02, 2019, 06:22:07 PM »
The linked reference discusses a more accurate computer model for calculating ice shelf basal ice melt rates, that indicate higher melt rates for key Antarctic ice shelves than earlier models.  This implies that such key Antarctic ice shelves are less stable than earlier consensus climate models projected:

Pelle, T., Morlighem, M., and Bondzio, J. H.: Brief communication: PICOP, a new ocean melt parameterization under ice shelves combining PICO and a plume model, The Cryosphere, 13, 1043-1049, https://doi.org/10.5194/tc-13-1043-2019, 2019.

https://www.the-cryosphere.net/13/1043/2019/

Abstract: "Basal melting at the bottom of Antarctic ice shelves is a major control on glacier dynamics, as it modulates the amount of buttressing that floating ice shelves exert onto the ice streams feeding them. Three-dimensional ocean circulation numerical models provide reliable estimates of basal melt rates but remain too computationally expensive for century-scale projections. Ice sheet modelers therefore routinely rely on simplified parameterizations based on either ice shelf depth or more sophisticated box models. However, existing parameterizations do not accurately resolve the complex spatial patterns of sub-shelf melt rates that have been observed over Antarctica's ice shelves, especially in the vicinity of the grounding line, where basal melting is one of the primary drivers of grounding line migration. In this study, we couple the Potsdam Ice-shelf Cavity mOdel (PICO, Reese et al., 2018) to a buoyant plume melt rate parameterization (Lazeroms et al., 2018) to create PICOP, a novel basal melt rate parameterization that is easy to implement in transient ice sheet numerical models and produces a melt rate field that is in excellent agreement with the spatial distribution and magnitude of observations for several ocean basins. We test PICOP on the Amundsen Sea sector of West Antarctica, Totten, and Moscow University ice shelves in East Antarctica and the Filchner-Ronne Ice Shelf and compare the results to PICO. We find that PICOP is able to reproduce inferred high melt rates beneath Pine Island, Thwaites, and Totten glaciers (on the order of 100 m yr−1) and removes the “banding” pattern observed in melt rates produced by PICO over the Filchner-Ronne Ice Shelf. PICOP resolves many of the issues contemporary basal melt rate parameterizations face and is therefore a valuable tool for those looking to make future projections of Antarctic glaciers."

Extract: "… we see that modeled melt rates produced by PICOP reach approximately 100 and 70 m yr−1 near the grounding line of Pine Island and Thwaites glaciers, respectively, compared to approximately 20 m yr−1 by PICO. These high melt rates are a product of the deeply entrenched bed that both Pine Island and Thwaites glaciers are grounded to."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #836 on: April 02, 2019, 08:20:52 PM »
The linked article (and associated linked report) indicates that since 1948 not only has Canada's mean surface warming been more than twice the global average, but also that the Arctic has warmed almost three times faster than the global average.  This indirectly implies that climate sensitivity is relatively high:

Title: "Canada warming at twice the global rate, climate report finds"

https://www.theguardian.com/world/2019/apr/02/canada-climate-change-warming-twice-as-fast-report

Extract: "While global temperatures have increased 0.8C since 1948, Canada has seen an increase of 1.7C – more than double the global average.

And in the Arctic, the warming is happening at a much faster rate of 2.3C, the report says."

See also:

Title: "Canada in a Changing Climate"
https://changingclimate.ca/
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Tor Bejnar

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #837 on: April 02, 2019, 09:02:29 PM »
The consequence of that warming is seen in Banks Island thaw slumps:  Extremes of summer climate trigger thousands of thermokarst landslides in a High Arctic environment
  Antoni G. Lewkowicz & Robert G. Way  -  Nature Communications volume 10, Article number: 1329 (2019)

Abstract:
Quote
Retrogressive thaw slumps (RTS) – landslides caused by the melt of ground ice in permafrost – have become more common in the Arctic, but the timing of this recent increase and its links to climate have not been fully established. Here we annually resolve RTS formation and longevity for Banks Island, Canada (70,000 km2) using the Google Earth Engine Timelapse dataset. We describe a 60-fold increase in numbers between 1984 and 2015 as more than 4000 RTS were initiated, primarily following four particularly warm summers. Colour change due to increased turbidity occurred in 288 lakes affected by RTS outflows and sediment accumulated in many valley floors. Modelled RTS initiation rates increased by an order of magnitude between 1906–1985 and 2006–2015, and are projected under RCP4.5 to rise to >10,000 decade−1 after 2075. These results provide additional evidence that ice-rich continuous permafrost terrain can be highly vulnerable to changing summer climate.

paper and pictures at link


« Last Edit: April 02, 2019, 11:15:19 PM by Tor Bejnar »
Arctic ice is healthy for children and other living things.

Stephan

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #838 on: April 02, 2019, 10:07:48 PM »
Very interesting article. Thanks for sharing this information with us.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #839 on: April 03, 2019, 04:34:06 PM »
The linked reference makes it clear as to how important it is for consensus climate change models to include the impacts of glacial algae in their calculation of albedo (particularly in Greenland).  This is not only important for projecting future SLR but also for projecting ice-climate feedback:

Cook, J. M., Tedstone, A. J., Williamson, C., McCutcheon, J., Hodson, A. J., Dayal, A., Skiles, M., Hofer, S., Bryant, R., McAree, O., McGonigle, A., Ryan, J., Anesio, A. M., Irvine-Fynn, T. D. L., Hubbard, A., Hanna, E., Flanner, M., Mayanna, S., Benning, L. G., van As, D., Yallop, M., McQuaid, J., Gribbin, T., and Tranter, M.: Glacier algae accelerate melt rates on the western Greenland Ice Sheet, The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-58, in review, 2019.

https://www.the-cryosphere-discuss.net/tc-2019-58/

Abstract. Melting of the Greenland Ice Sheet (GrIS) is the largest single contributor to eustatic sea level and is amplified by the growth of pigmented algae on the ice surface that increase solar radiation absorption. This biological albedo reducing effect and its impact upon sea level rise has not previously been quantified. Here, we combine field spectroscopy with a novel radiative transfer model, supervised classification of UAV and satellite remote sensing data and runoff modelling to calculate biologically-driven ice surface ablation and compare it to the albedo reducing effects of local mineral dust. We demonstrate that algal growth led to an additional 5.5–8.0 Gt of runoff from the western sector of the GrIS in summer 2016, representing 6–9 % of the total. Our analysis confirms the importance of the biological albedo feedback and that its omission from predictive models leads to the systematic underestimation of Greenland’s future sea level contribution, especially because both the bare ice zones available for algal colonization and the length of the active growth season are set to expand in the future.
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gerontocrat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #840 on: April 03, 2019, 05:03:05 PM »
The consequence of that warming is seen in Banks Island thaw slumps:  Extremes of summer climate trigger thousands of thermokarst landslides in a High Arctic environment
  Antoni G. Lewkowicz & Robert G. Way  -  Nature Communications volume 10, Article number: 1329 (2019)

Abstract:
Quote
Retrogressive thaw slumps (RTS) – landslides caused by the melt of ground ice in permafrost – have become more common in the Arctic, but the timing of this recent increase and its links to climate have not been fully established. Here we annually resolve RTS formation and longevity for Banks Island, Canada (70,000 km2) using the Google Earth Engine Timelapse dataset. We describe a 60-fold increase in numbers between 1984 and 2015 as more than 4000 RTS were initiated, primarily following four particularly warm summers. Colour change due to increased turbidity occurred in 288 lakes affected by RTS outflows and sediment accumulated in many valley floors. Modelled RTS initiation rates increased by an order of magnitude between 1906–1985 and 2006–2015, and are projected under RCP4.5 to rise to >10,000 decade−1 after 2075. These results provide additional evidence that ice-rich continuous permafrost terrain can be highly vulnerable to changing summer climate.

paper and pictures at link
If this is happening on this scale on Banks Island - area 70 k km2, are there a few million km2 of Tundra elsewhere where the same is happening? I know one does not extrapolate from the particular to the general, but......
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #841 on: April 03, 2019, 05:08:21 PM »
The linked reference provides paleo data indicating that climate change induced coastal erosion can accelerate GHG emissions from coastal permafrost regions, and that consensus climate models should be re-calibrated to account for this positive feedback mechanism:

Jannik Martens et al. (13 December 2018), "Remobilization of Old Permafrost Carbon to Chukchi Sea Sediments During the End of the Last Deglaciation", Global Biogeochemical Cycles, https://doi.org/10.1029/2018GB005969

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB005969

Abstract: "Climate warming is expected to destabilize permafrost carbon (PF‐C) by thaw‐erosion and deepening of the seasonally thawed active layer and thereby promote PF‐C mineralization to CO2 and CH4. A similar PF‐C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Δ14C, δ13C, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS‐L2‐4‐PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Allerød warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual‐carbon‐isotope‐based source apportionment demonstrates that Ice Complex Deposit—ice‐ and carbon‐rich permafrost from the late Pleistocene (also referred to as Yedoma)—was the dominant source of organic carbon (66 ± 8%; mean ± standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 ± 4.6 g·m−2·year−1) as in the late Holocene (3.1 ± 1.0 g·m−2·year−1). These results are consistent with late deglacial PF‐C remobilization observed in a Laptev Sea record, yet in contrast with PF‐C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF‐C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #842 on: April 03, 2019, 05:17:21 PM »
If this is happening on this scale on Banks Island - area 70 k km2, are there a few million km2 of Tundra elsewhere where the same is happening? I know one does not extrapolate from the particular to the general, but......

While not directly addressing your question, the last panel in the attached image showing a burst of methane emissions from Arctic thermokarst lakes (TKL) circa 2060 when following RCP 8.5 to that date, which is a serious problem as CH4 emission have about 35 times more global warming potential than do CO2 emissions.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #843 on: April 03, 2019, 05:25:06 PM »
The linked reference indicates that historically anthropogenic aerosol emissions have increased terrestrial sequestration of carbon.  This indicates that as future anthropogenic aerosols are decreased, global warming will accelerate faster than considered by current consensus climate model projections:

Yuan Zhang et al. (07 February 2019), " Increased Global Land Carbon Sink Due to Aerosol‐Induced Cooling", Global Biogeochemical Cycles,
https://doi.org/10.1029/2018GB006051

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GB006051

Abstract: "Anthropogenic aerosols have contributed to historical climate change through their interactions with radiation and clouds. In turn, climate change due to aerosols has impacted the C cycle. Here we use a set of offline simulations made with the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model driven by bias‐corrected climate fields from simulations of three Coupled Model Intercomparison Project Phase 5 (CMIP5) Earth system models (ESMs; IPSL‐CM5A‐LR, CSIRO‐Mk3.6.0, and GISS‐E2‐R) to quantify the climate‐related impacts of aerosols on land carbon fluxes during 1860–2005. We found that climate change from anthropogenic aerosols (CCAA) globally cooled the climate, and increased land carbon storage, or cumulative net biome production (NBP), by 11.6–41.8 PgC between 1860 and 2005. The increase in NBP from CCAA mainly occurs in the tropics and northern midlatitudes, primarily due to aerosol‐induced cooling. At high latitudes, cooling caused stronger decrease in gross primary production (GPP) than in total ecosystem respiration (TER), leading to lower NBP. At midlatitudes, cooling‐induced decrease in TER is stronger than that of GPP, resulting in NBP increase. At low latitudes, NBP was also enhanced due to the cooling‐induced GPP increase, but precipitation decline from CCAA may negate the effect of temperature. The three ESMs show large divergence in low‐latitude CCAA precipitation response to aerosols, which results in considerable uncertainties in regional estimations of CCAA effects on carbon fluxes. Our results suggest that better understanding and simulation of how anthropogenic aerosols affect precipitation in ESMs is required for a more accurate attribution of aerosol effects on the terrestrial carbon cycle."
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gerontocrat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #844 on: April 03, 2019, 05:31:10 PM »
If this is happening on this scale on Banks Island - area 70 k km2, are there a few million km2 of Tundra elsewhere where the same is happening? I know one does not extrapolate from the particular to the general, but......

While not directly addressing your question, the last panel in the attached image showing a burst of methane emissions from Arctic thermokarst lakes (TKL) circa 2060 when following RCP 8.5 to that date, which is a serious problem as CH4 emission have about 35 times more global warming potential than do CO2 emissions.
Abrupt SLR,

Cheer me up. Are there any significant -ve feedbacks that do not require active input by us humans that could at least slow Armageddon for a day or two?
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #845 on: April 03, 2019, 05:44:09 PM »
While the information/recommendations contained in linked website on the Club of Rome Climate Emergency Plan, is admirable, I am less than certain that global governments, business leaders and other global decision makers will act with sufficient alacrity to prevent the initiation of a MICI-type of collapse of the WAIS circa 2040:

Title: "The Club of Rome Climate Emergency Plan"

https://www.clubofrome.org/project/the-club-of-rome-climate-emergency-plan/
&
https://www.clubofrome.org/wp-content/uploads/2018/12/COR_Climate-Emergency-Plan-.pdf

“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 #846 on: April 03, 2019, 05:55:08 PM »
...

Abrupt SLR,

Cheer me up. Are there any significant -ve feedbacks that do not require active input by us humans that could at least slow Armageddon for a day or two?

While there are many negative climate change feedback mechanisms (see the linked article), some people feel comforted by that fact that currently global warming is increasing Net Primary Productivity of plants; which might be beneficial if society can some how follow a SSP1-type of pathway (see the attached image) sooner rather than later:

Title: "Climate change feedback"

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

Extract: "Net Primary Productivity
Net primary productivity changes in response to increased CO2, as plants photosynthesis increased in response to increasing concentrations. However, this effect is swamped by other changes in the biosphere due to global warming."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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gerontocrat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #847 on: April 03, 2019, 06:07:11 PM »
...

Abrupt SLR,

Cheer me up. Are there any significant -ve feedbacks that do not require active input by us humans that could at least slow Armageddon for a day or two?

While there are many negative climate change feedback mechanisms (see the linked article), some people feel comforted by that fact that currently global warming is increasing Net Primary Productivity of plants; which might be beneficial if society can some how follow a SSP1-type of pathway (see the attached image) sooner rather than later:

Title: "Climate change feedback"

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

Extract: "Net Primary Productivity
Net primary productivity changes in response to increased CO2, as plants photosynthesis increased in response to increasing concentrations. However, this effect is swamped by other changes in the biosphere due to global warming."
Thanks AbruptSLR for trying.

The link shown by you is the one I found last week. I have to say it felt like being on a bicycle playing chicken against a Mack Truck. I guess it was a forlorn hope.

As the cliché has it - "It is what it is".

"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #848 on: April 03, 2019, 07:04:53 PM »
...

Abrupt SLR,

Cheer me up. Are there any significant -ve feedbacks that do not require active input by us humans that could at least slow Armageddon for a day or two?

While there are many negative climate change feedback mechanisms (see the linked article), some people feel comforted by that fact that currently global warming is increasing Net Primary Productivity of plants; which might be beneficial if society can some how follow a SSP1-type of pathway (see the attached image) sooner rather than later:

Title: "Climate change feedback"

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

Extract: "Net Primary Productivity
Net primary productivity changes in response to increased CO2, as plants photosynthesis increased in response to increasing concentrations. However, this effect is swamped by other changes in the biosphere due to global warming."
Thanks AbruptSLR for trying.

The link shown by you is the one I found last week. I have to say it felt like being on a bicycle playing chicken against a Mack Truck. I guess it was a forlorn hope.

As the cliché has it - "It is what it is".

While AbruptSLR is doing a great job in highlighting potential dangers of climate change, he is focusing on the very low-probability extreme climate change scenarios.  If you read the articles he links to, they often focus on hypothetical extreme model runs to show what could happen in the case of runaway carbon emissions.  He has recently posted papers with 4 times increases in CO2 concentrations and 5 or 11 times increases in methane concentrations.  Those are scenarios well beyond even the extremes of RCP 8.5.

Also, many posters on this site assume that if we stop burning fossil fuels, aerosol emissions will be so reduced that increased shortwave radiation will overwhelm any benefit we gain from reducing carbon emissions.  This is false.  The effects of aerosols are still being debated in the scientific literature, and AbruptSLR is focused on the ones that show more warming if aerosols are reduced.  There are scientific articles that show the opposite, such as this one published in Nature Communications in 2018:

https://www.nature.com/articles/s41467-019-08407-7

Quote
Decrease in radiative forcing by organic aerosol nucleation, climate, and land use change
Jialei Zhu,
Joyce E. Penner,
Fangqun Yu,
Sanford Sillman,
Meinrat O. Andreae &

Hugh Coe

Nature Communicationsvolume 10, Article number: 423 (2019)  |  Download Citation

Abstract

Organic nucleation is an important source of atmospheric aerosol number concentration, especially in pristine continental regions and during the preindustrial period. Here, we improve on previous simulations that overestimate boundary layer nucleation in the tropics and add changes to climate and land use to evaluate climate forcing. Our model includes both pure organic nucleation and heteromolecular nucleation of sulfuric acid and organics and reproduces the profile of aerosol number concentration measured in the Amazon. Organic nucleation decreases the sum of the total aerosol direct and indirect radiative forcing by 12.5%. The addition of climate and land use change decreases the direct radiative forcing (−0.38 W m−2) by 6.3% and the indirect radiative forcing (−1.68 W m−2) by 3.5% due to the size distribution and number concentration change of secondary organic aerosol and sulfate. Overall, the total radiative forcing associated with anthropogenic aerosols is decreased by 16%.

Also, renewable energy is now cheaper than coal and is quickly becoming cheaper than natural gas and EVs are poised to outsell ICEs in the coming decade.  As a result, we're probably going to end up on an emissions path between RCP 2.6 and 4.5. 

So there are many reasons to hope.  I agree with AbruptSLR and many posters on this site that we need to get off of fossil fuels as quickly as possible and I also agree with the consensus climate scientists that it's not too late.  Don't give up hope.

FrostKing70

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #849 on: April 03, 2019, 07:25:53 PM »