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Author Topic: Ocean crater formation due to Methane Hydrate destabilization  (Read 1274 times)

prokaryotes

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A new study in Science shows that hundreds of massive, kilometre –wide, craters on the ocean floor in the Arctic were formed by substantial methane expulsions https://cage.uit.no/news/massive-craters-formed-methane-blow-outs-arctic-sea-floor


The massive craters were formed around 12,000 years ago, but are still seeping methane and other gases. Illustration: Andreia Plaza Faverola

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Video transcript http://climatestate.com/2017/06/04/like-champagne-opened-methane-explosions-resulted-in-ocean-craters

Related press conference from 2016
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There are several hundred of craters in the area. Over one hundred of them are up to one kilometer wide. Illustration: K. Andreassen/CAGE

The craters are connected to deeper gas chimneys, showing gas flow from deeper hydrocarbon reservoirs. Hundreds of gas flares are seen in the water above. Illustration: M. Winsborrow

Related Links
Massive Craters Formed By Methane Blow-outs From The Arctic Sea Floor https://cage.uit.no/news/massive-craters-formed-methane-blow-outs-arctic-sea-floor

Like ‘champagne bottles being opened’: Scientists document an ancient Arctic methane explosion https://www.washingtonpost.com/news/energy-environment/wp/2017/06/01/like-champagne-bottles-being-opened-scientists-document-an-ancient-arctic-methane-explosion

Methane GWP, How Bad of a Greenhouse Gas Is Methane? https://www.scientificamerican.com/article/how-bad-of-a-greenhouse-gas-is-methane/

Massive craters formed by methane blow-outs from the Arctic sea floor https://phys.org/news/2017-06-massive-craters-methane-blow-outs-arctic.html

Methane exploded from Arctic sea-floor as Ice Age ended https://www.nature.com/news/methane-exploded-from-arctic-sea-floor-as-ice-age-ended-1.22095

View of the methane seeps in the Arctic https://www.youtube.com/watch?v=6oTFjWBiP4E

Massive craters on Arctic Ocean floor caused by methane blow out https://www.youtube.com/watch?v=oNg0z-bYsmY

Scientists just found telltale evidence of an ancient methane explosion in the Arctic
/ A methane mound in the Canadian High Arctic, Stephen Grasby https://www.washingtonpost.com/news/energy-environment/wp/2017/04/21/scientists-just-found-telltale-evidence-of-an-ancient-methane-explosion-in-the-arctic-ocean

Blow-out craters on the Arctic seafloor https://www.youtube.com/watch?v=VQdr0GhoDAc

Animation: From Glaciation to Global Warming – A Story of Sea Level Change (Titanic Belfast) https://www.youtube.com/watch?v=AKT610NxG3s

Methane clathrate https://en.wikipedia.org/wiki/Methane_clathrate

Images Methane bubbles collect under the ice (Natalia Shakhova) https://news.uaf.edu/ESAS2013

TerryM

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #1 on: June 05, 2017, 12:01:31 AM »
Prok
Wonder if the above would be easier to find in the Methane thread?
Terry

prokaryotes

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #2 on: June 05, 2017, 12:09:43 AM »
Prok
Wonder if the above would be easier to find in the Methane thread?
Terry
I really don't mind, but to me it appears significant enough, its kind of different to permafrost/soil methane sources. The search gave 3 entries for methane crater, all not really in scope of a focused discussion for ocean craters. But if the moderation feels we should move this topic, go ahead, please.

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jai mitchell

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #3 on: June 05, 2017, 12:38:21 AM »
Were the craters dated definitively or is the dating arising from a working hypothesis?  How did they date the craters exactly?
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #4 on: June 05, 2017, 01:07:25 AM »
Might want to check CONSEQUENCES: Conservative Scientists & it's Consequences ??

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #5 on: June 05, 2017, 01:50:28 AM »
Worth another subcategory: "Holocene prehistory" or "Arctic methane".
Somehow it makes me worry a little less about a Methane bomb: The comparison scale to back then is logarithmic and it looks there could have been a pretty huge release...
Is there any data (spike in proxy record? Model anomaly?) on any impact?

https://cage.uit.no/news/massive-craters-formed-methane-blow-outs-arctic-sea-floor/
“Despite their infrequency, the impact of such blow-outs may still be greater than impact from slow and gradual seepage. It remains to be seen whether such abrupt and massive methane release could have reached the atmosphere. We do estimate that an area of hydrocarbon reserves twice the size of Russia was directly influenced by ice sheets during past glaciations. This means that a much larger area may have had similar abrupt gas releases in the overlapping time period “ says Andreassen
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prokaryotes

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #6 on: June 05, 2017, 10:58:15 AM »
Worth another subcategory: "Holocene prehistory" or "Arctic methane".
Somehow it makes me worry a little less about a Methane bomb: The comparison scale to back then is logarithmic and it looks there could have been a pretty huge release...
Is there any data (spike in proxy record? Model anomaly?) on any impact?
The events are linked to the Meltwater Pulse 1A


Meltwater pulse 1A occurred in a period of rising sea level and rapid climate change, known as Termination I, when the retreat of continental ice sheets was going on during the end of the last ice age. Several researchers have narrowed the period of the pulse to between 13,500 and 14,700 calendar years ago with its peak at about 13,800 calendar years ago.[3] The start of this meltwater event coincides with or closely follows the abrupt onset of the Bølling-Allerød (B-A) interstadial and warming in the NorthGRIP ice core in Greenland at 14,600 calendar years ago.[4] During meltwater pulse 1A, sea level is estimated to have risen at a rate of 40–60 mm (0.13–0.20 ft)/yr.
https://en.wikipedia.org/wiki/Meltwater_pulse_1A

This means that there was warming/deglaciation going on, and then about 2.5 thousand years later the craters appeared in the Barents Sea region, once the thick ice sheets there retreated enough. The region was likely rather shallow at the time, other than that is it unclear how these deposits compare to today's coastal ice-sheet topography and methane deposits configuration, around Greenland and Antarctica.

Despite their infrequency, the impact of such blow-outs may still be greater than impact from slow and gradual seepage

That's a good point, forgot to mention this.

AbruptSLR

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #7 on: June 05, 2017, 04:11:49 PM »
First, there are lots of papers showing that abrupt sea level rise contributions came from Antarctic marine glaciers during Meltwater Pulse – 1A, including the following physical evidence cited by Deschamps et al 2012:

Pierre Deschamps, Nicolas Durand, Edouard Bard, Bruno Hamelin, Gilbert Camoin, Alexander L. Thomas, Gideon M. Henderson, Jun'ichi Okuno & Yusuke Yokoyama, (2012), "Ice-sheet collapse and sea-level rise at the Bølling warming 14,600 years ago", Nature, Volume: 483, Pages: 559–564, doi:10.1038/nature10902

http://www.nature.com/nature/journal/v483/n7391/full/nature10902.html

Abstract: "Past sea-level records provide invaluable information about the response of ice sheets to climate forcing. Some such records suggest that the last deglaciation was punctuated by a dramatic period of sea-level rise, of about 20 metres, in less than 500 years. Controversy about the amplitude and timing of this meltwater pulse (MWP-1A) has, however, led to uncertainty about the source of the melt water and its temporal and causal relationships with the abrupt climate changes of the deglaciation. Here we show that MWP-1A started no earlier than 14,650 years ago and ended before 14,310 years ago, making it coeval with the Bølling warming. Our results, based on corals drilled offshore from Tahiti during Integrated Ocean Drilling Project Expedition 310, reveal that the increase in sea level at Tahiti was between 12 and 22 metres, with a most probable value between 14 and 18 metres, establishing a significant meltwater contribution from the Southern Hemisphere. This implies that the rate of eustatic sea-level rise exceeded 40 millimetres per year during MWP-1A."

Second, the linked thread entitled: "Potential Collapse Scenario for the WAIS" contain relevant information on this topic (including the attached selected images):

http://forum.arctic-sea-ice.net/index.php/topic,31.0.html
« Last Edit: June 05, 2017, 04:48:21 PM by AbruptSLR »
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A-Team

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #8 on: June 05, 2017, 05:26:12 PM »
Were the craters dated definitively or is the dating arising from a working hypothesis?  How did they date the craters exactly?

We need to up our game on methane. An ice blowout this September will necessitate the rehabilitation of Peter Wadhams who saw it all coming years ago. That is tricky for the CO2-only Narrative Minders to do without validating Wadhams' equally reasonable views on ESS methane.

The new article is blocked but they would have used the well-established technique of alpha decay of uranium-234 into thorium-230 rather than beta decay of carbon-14. The objects dated at the five sites were authigenic carbonates [formed in situ] from methane oxidation at the sedimentary sulphate–methane transition zone (where sulfate takes the place of exhausted molecular oxygen as terminal electron acceptor). The uranium is incidental, present in sedimentary pore water below the sea floor.

The stability zone for gas hydrates near Svalbard is quite sensitive to overhead pressure (ie sea level) and seasonal bottom water temperatures. Here they are concerned with a thick grounded ice sheet rather than floating ice.

We report a methane efflux chronology from five sites, at depths of 220–400 m, in the southwest Barents and Norwegian seas where grounded ice sheets led to thickening of the gas hydrate stability zone during the last glaciation. The onset of methane release was coincident with deglaciation-induced pressure release and thinning of the hydrate stability zone.

Methane efflux continued for 7–10 kyr, tracking hydrate stability changes controlled by relative sea-level rise, bottom water warming and fluid pathway evolution in response to changing stress fields. The protracted nature of seafloor methane emissions probably attenuated the impact of hydrate dissociation on the climate system.

Note that methane emissions (reaching the atmosphere, that is) from the Barents were so gradual that they left no mark in nearby Greenland ice cores:

The radiocarbon and hydrogen isotopic composition of methane from Greenland ice cores suggests that atmospheric methane rise at 11.6 and 38 ka can be predominantly accounted for through wetland emissions.

Methane is consumed at a variety of stages during transport through the sediment and overlying water column. On a global scale, >80% of methane migrating within the sedimentary package can be microbially consumed at the sedimentary sulphate–methane transition zone by the anaerobic oxidation of methane (AOM). However, where gas supply is high and flow through the sediment is advective, the capacity of this benthic microbial filter can be outstripped, resulting in release of methane into the overlying water column.

A proportion (up to 100%) of methane within the water column is consumed via dissolution of free gas bubbles and methanotrophic microbial activity before it reaches the ocean surface and escapes into the atmosphere.

Consequently, the short residence time of methane in the oceans and atmosphere (∼10 years), combined with the processes that control consumption in the sediment and water column, requires a rapid (decadal) release and transfer of large volumes of methane to achieve a significant impact on ocean/atmosphere chemistry.


https://www.nature.com/articles/ncomms11509 (blocked)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865861/ (free full, best read)

http://www.sciencedirect.com/science/article/pii/S0016703703001285 (geeky)

AbruptSLR

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #9 on: June 05, 2017, 05:56:43 PM »
As a follow-on to my Reply #7, I provide the following information related to the DeConto & Pollard's collective 2016 findings related to the implications of cliff failures and hydrofracting on marine glaciers.

The first linked refer indicates that to ensure that cliff failures and hydrofracturing (calving) of marine glaciers do not occur that the GMST departure above pre-industrial could be as low as 1C, but is not higher than 3C (and at the EGU conference DeConto said that the most likely range was between 2 and 2.7C, assuming the current consensus climate sensitivity).

Robert DeConto and David Pollard (2016), "Commitments to future retreat of Antarctic and Greenland ice sheets",  EGU General Assembly, Geophysical Research Abstracts, Vol. 18, EGU2016-10930


http://meetingorganizer.copernicus.org/EGU2016/EGU2016-10930.pdf

Abstract: "The agreement reached at the COP21 United Nations Conference on Climate Change is aimed at limiting future increases in global mean temperature below 2ºC. Here, we use a continental ice sheet/shelf model with new treatments of meltwater-enhanced calving (hydrofracturing) and marine terminating ice-cliffs, to explore future commitments to sea-level rise given limits of global mean warming between 1 and 3ºC. In this case, ice-sheet model physics are calibrated against past ice-sheet response to temperatures warmer than today. The ice-sheet model is coupled to highly resolved atmosphere and ocean-model components, with imposed limits on future warming designed to mimic the idealized limits discussed at COP21. Both the short and long-term potential rise in global mean sea level are discussed in light of the range of allowances agreed in Paris. We also explore the sensitivity of Greenland and Antarctic ice sheets to plausible ranges of atmospheric versus ocean warming consistent with global mean temperatures between 1 and 3ºC; and the resulting long-term commitments to sea-level rise over the coming centuries and millennia."

Also see:

"At an EGU press conference DeConto said this work implied tipping points for major sea level rise occur between 2 and 2.7C above pre-industrial.

http://client.cntv.at/egu2016/press-conference-8 (DeConto starts about 22:10) "

While the entire video is worth watching I provide the four attached screenshots from the video.  The first two images are from the second (MIT EGU) speaker with:
(a) The first image showing the impact of the faux hiatus on both effective ECS (top panel) and effective oceanic diffusion (bottom panel), and the blue lines showing PDF values using observations until 2000 and the black lines showing PDF values using observations until 2010 (including part of the faux hiatus).  Further the lower panel clearly indicates that the faux hiatus (in GMST departures) was due to more heat content temporarily being sequestered into the oceans during the faux hiatus (some of which heat is now being released from the oceans).  Thus I believe that the blue line climate parameter distributions (with observations to 2000) is more "Realistic" (and indicates a mean ECS value of about 4C) and the black line climate parameter distributions is more "Pollyannaish" (and is best ignored).
(b) The second image shows the implications of both MIT's more "Realistic" climate parameters (left panel, which is good to consider) and "Pollyannaish" climate parameters (right panel, which is best ignored) for different carbon emission scenarios described in the video but with the current Paris pledges indicated by the red lines for which the more "Realistic" climate parameters indicate that we will reach 2C by about 2050 and 2.7C by about 2060.
The last two images are from the DeConto & Pollard EGU presentation with:
(c) The third image showing different carbon concentration pathways with the upper left panel showing the RCP scenarios used by DeConto & Pollard (2016) for their SLR projections; and the bottom left panel showing three new pathways postulated by DeConto where we follow the RCP 8.5 50%CL scenario until we reach 2C (by about 2040), 2.7C (by about 2065) and 3.6C (by about 2090), respectively for the blue, green and red lines.
(d) The fourth image shows DeConto & Pollard's (2016 EGU) projections of Antarctic contributions to changes in global mean sea level, GMSL, by the 2C (blue line), 2.7C (green line) and 3.6C (red line) forcing scenarios.  I believe that DeConto & Pollard's 2C scenario is not achievable in the real world (as confirmed by the second attached MIT analysis), and that by 2100 the 2.7C and the 3.6C forcing scenario produce essentially the same amount of increase in GMSL.  Taken together with the more "Realistic" MIT analysis the DeConto & Pollard (2016 EGU) findings indicate it likely that the WAIS collapse will begin about 2050 following the current Paris Pact pledges (and also ignoring the increase in carbon emissions associated with increasing agricultural growth).

Also I note that the indicated DeConto & Pollard (2016) findings do not include considerations that I plan to address in subsequent posts such as Hansen et al (2016)'s ice-climate feedback, nor the current positive PDO phase, nor higher ECS values, nor the activation/acceleration of non-linear positive feedback mechanisms and thus errs on the side of least drama.

Also see:
Robert M. DeConto & David Pollard (31 March 2016), "Contribution of Antarctica to past and future sea-level rise", Nature, Volume: 531, Pages: 591–597, doi:10.1038/nature17145

http://www.nature.com/articles/nature17145.epdf?referrer_access_token=px-zRubs4M6aBBPl42_1GdRgN0jAjWel9jnR3ZoTv0M-pvJMg7VLINRa2mnTNsvXfjbAFNU4M9sSVFBNmnefzinIWT5DIW6fVmmjzqPkWPG0EWAexculA_Dh1H0gVAzIYAUjdsj8uznmBvFk8_blNOM5-opyiSaKMyaJis4af48A0kgec2kZ8QcJLEQ0CKHzo1BxzQZ7aHlC6ggm5qLKPX8C4yz0OZ4SKpsmFZlbgUA%3D&tracking_referrer=www.nature.com
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jai mitchell

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #10 on: June 05, 2017, 08:18:21 PM »
A-Team,

thanks that makes sense, however is it reasonable to suggest that all or some of these craters were formed during previous interglacials and that their dating mechanism only brought about the most recent transition?  I suppose that the existence of ice sheets could be reasonably expected to smooth out these craters between interglacials.  This is interesting to me that it shows the combined pressure/temperature shift in-situ during the ice sheet transition.  This is not anywhere near the conditional changes that happen under a gradual warming of the ESS during sea ice loss.

However, ASLR is right this could have significant implications for Antarctica, say in the next 500 years or so.
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jai mitchell

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #11 on: June 05, 2017, 10:08:56 PM »
very nice presentation on the subject from 8 months ago by the authors https://www.youtube.com/watch?v=t3JQ9a3apc8
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #12 on: June 06, 2017, 12:22:58 AM »
Domes of frozen methane may be warning ch for new blow-outs

Several methane domes, some 500m wide, have been mapped on the Arctic Ocean floor. They may be signs of soon-to-happen methane expulsions that have previously created massive craters in a near-by area...

"Every year we go back to the dome area with our research vessel, and every year I am anxious to see if one of these domes has become a crater," says lead author of the study Pavel Serov, PhD candidate at CAGE at UiT The Arctic University of Norway.

These domes are the present-day analogue to what scientists think preceded the craters found in the near-by area, which were recently reported in Science. The craters were formed as the ice sheet retreated from the Barents Sea during the deglaciation some 12.000 years ago.


More information: Pavel Serov el al., "Postglacial response of Arctic Ocean gas hydrates to climatic amelioration," PNAS (2017). www.pnas.org/cgi/doi/10.1073/pnas.1619288114
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AbruptSLR

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #13 on: June 06, 2017, 12:29:06 AM »
However, ASLR is right this could have significant implications for Antarctica, say in the next 500 years or so.

jai,

The 2016 EGU DeConto analysis of the potential WAIS collapse does not assume that hydrofacturing and cliff failures will begin before GMSTA equals/exceeds 2.7C (from pre-industrial); which they assume will happen circa 2070.  When do you estimate that GMSTA will exceed 2.7C?

Best,
ASLR
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #14 on: June 06, 2017, 07:52:57 AM »
very nice presentation on the subject from 8 months ago by the authors https://www.youtube.com/watch?v=t3JQ9a3apc8

Already seen this....especially their obviously depressed mood during their presentation speaks a lot of words.  :'(
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #15 on: June 06, 2017, 04:58:58 PM »
...

Note that methane emissions (reaching the atmosphere, that is) from the Barents were so gradual that they left no mark in nearby Greenland ice cores:

The radiocarbon and hydrogen isotopic composition of methane from Greenland ice cores suggests that atmospheric methane rise at 11.6 and 38 ka can be predominantly accounted for through wetland emissions.
...
...
Thanks! This I was looking for.

What struck me is that these craters are in hard rock, unlike the famous Siberian craters, as shown in the video:
very nice presentation on the subject from 8 months ago by the authors https://www.youtube.com/watch?v=t3JQ9a3apc8

Already seen this....especially their obviously depressed mood during their presentation speaks a lot of words.  :'(
Methinks it is young scientist stage fright, esp. Malin Waage. Plus, speaking in a foreign language. Rarely have I heard so many "äh"s. I can feel with her, been there myself. She should practise more speaking to intimidating audiences. :)
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #16 on: June 06, 2017, 05:04:31 PM »
However, ASLR is right this could have significant implications for Antarctica, say in the next 500 years or so.

jai,

The 2016 EGU DeConto analysis of the potential WAIS collapse does not assume that hydrofacturing and cliff failures will begin before GMSTA equals/exceeds 2.7C (from pre-industrial); which they assume will happen circa 2070.  When do you estimate that GMSTA will exceed 2.7C?

Best,
ASLR

ASLR,

2038

but the flow of land based Antarctica glaciers toward the sea will continue to press down on potential methane pockets for several hundreds of years, even with sea level rise.

(note: my GMST projection includes early Arctic sea ice loss and albedo feedbacks which has different temp impacts - lower - than theirs on Antarctica, so the equivalent may be up to 20 years later)
« Last Edit: June 06, 2017, 05:11:31 PM by jai mitchell »
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #17 on: June 06, 2017, 05:29:54 PM »
When do you estimate that GMSTA will exceed 2.7C?

ASLR,

2038

but the flow of land based Antarctica glaciers toward the sea will continue to press down on potential methane pockets for several hundreds of years, even with sea level rise.

(note: my GMST projection includes early Arctic sea ice loss and albedo feedbacks which has different temp impacts - lower - than theirs on Antarctica, so the equivalent may be up to 20 years later)
[/quote]
jai,

Thanks.

Per the previously posted attached DeConto 2016 EGU figure, large portions of the WAIS may well become free from marine glaciers much faster than you are assuming; thus potentially exposing methane reserves faster than you are assuming.

Best,
ASLR
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jai mitchell

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #18 on: June 06, 2017, 06:32:31 PM »
indeed,

especially if their model looks at not exceeding +2.7C
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #19 on: June 07, 2017, 03:46:30 PM »
Follow up with some more details on gas hydrate pingos

! No longer available


Press release https://cage.uit.no/news/domes-of-frozen-methane-may-be-warning-signs-for-new-blow-outs

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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #20 on: June 07, 2017, 06:10:32 PM »
indeed,

especially if their model looks at not exceeding +2.7C

jai,

I have provided a link to a video of Pollard & DeConto's 2016 projection including RCP 8.5's impacts on the Antarctic Ice Sheet, AIS; together with screen captures for the years 2070 (the year that they assume we will pass a GMSTA of 2.7C), 2100 (as a common reference), 2135 (if we take your estimate of reaching a GMSTA of 2.7C as 2038 instead of 2070 then extrapolating your estimate this is what the AIS might look like in 2100) and 2170 (which is approximately what I extrapolate the AIS will look like circa 2090 if one were to consider factors that Pollard & DeConto 2016 have ignored).

https://www.washingtonpost.com/video/national/health-science/watch-antactica-melt-in-these-alarming-projection-models/2016/03/30/720314a4-f671-11e5-958d-d038dac6e718_video.html

A partial list of reasons that Pollard & DeConto (2016) likely errs on the side of least drama include:
1. Ice sheet models with resolutions higher than that used by P&D (2016) almost always project more ice mass loss than WAIS models using relatively low resolution models.
2. P&D (2016) do not include the bipolar seesaw interaction between the GIS & the AIS.
3. P&D (2016) assume an effective ECS (this century) of about 3C; while in reality it is likely closer to 4.5C.
4. P&D (2016) do not consider that the Southwest Tributary Glacier that feeds into the PIG could lose much of its ice shelf buttressing before 2040.
5. P&D (2016) do not consider that icebergs could float out from the Thwaites Ice Tongue gateway area within a few years, which could subject a key portion of the Thwaites Glacier to cliff failures before 2040.
6. P&D (2016) ignore local WAIS impacts from: (a) atmospheric river events; (b) ice mass loss triggers seismic & volcanic events; and (c) methane emissions from hydrates.

I could list more consideration as to why Pollard & DeConto's projection for 2170 may be more appropriate for circa 2090, but they are already cited in various threads in the Antarctic folder (& in the Human Stupidity thread).

Very best,
ASLR
« Last Edit: June 07, 2017, 06:17:41 PM by AbruptSLR »
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Re: Ocean crater formation due to Methane Hydrate destabilization
« Reply #21 on: June 28, 2017, 02:24:48 PM »
ASLR,

those are reasonable images, I have not seen such clear maps of projected melt before!  Thinking about it, what does 5m/a of melt actually look like?  Knowing that most of the melt would occur during the austral summer.

The implications are that the long-term warming trend is pretty much locked in now,  however, please remember that the models should show a much greater arctic amplification going forward than they do, so the GMST value is slightly overestimating the Antarctic warming. 

Of course, a shift into a permanent/semi-permanent El Nino regime would easily compensate for this, especially on the West Antarctic Peninsula.

 
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today