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Messages - prokaryotes

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1
Follow up with some more details on gas hydrate pingos

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

2
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.

3
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.

Cheers

4
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

5
Starting in the mid-1980s, the Defense Meteorological Satellite Program (DMSP) constructed eight “F-series” satellites, in bulk, with the plan to launch satellites in succession as each one failed to maintain a continuous record of Arctic sea ice extent.

But in 2016, Congress cut the program, resulting in the dismantling of the last, still not launched, satellite. It is now likely that an impending failure of the last DMSP satellites in orbit will leave the world blind until at least 2022, even as the Arctic shows signs of severe instability and decline.

While international and U.S. monitoring is still being done for ice thickness, the Trump administration has proposed cuts to satellite missions, including NOAA’s next two polar orbiting satellites, NASA’s PACE Satellite (to monitor ocean and atmospheric pollution), and the Orbiting Carbon Observatory 3 (for carbon dioxide atmospheric measurements).

All of these cuts in satellite monitoring come at a time when the world is seeing massive changes due to climate change, development and population growth. One satellite program spared Trump’s budgetary axe so far is Landsat 9, which tracks deforestation and glacial recession. How Congress will deal with Trump’s proposed cuts is unknown.

http://news.mongabay.com/2017/05/as-arctic-sea-ice-shows-record-decline-scientists-prepare-to-go-blind

6
Arctic sea ice / Re: The 2017 melting season
« on: May 27, 2017, 11:41:25 AM »
Alaska's Sea Ice Is Melting Unusually Early, 'Another Sign Arctic Is Unraveling' https://insideclimatenews.org/news/25052017/arctic-sea-ice-disappearing-alaska-climate-change-warm-winter-chukchi-sea

7
Permafrost / Re: Arctic Methane Release
« on: May 23, 2017, 11:50:10 PM »
About doi:10.5194/bg-14-2283-2017  The origin of methane in the East Siberian Arctic Shelf unraveled
with triple isotope analysis

A search of the pdf shows that the word clathrate is never mentioned.
The paper briefly refers to hydrates, basically the same as clathrates.

8
Permafrost / Re: Arctic Methane Release
« on: May 23, 2017, 11:25:37 PM »
Made a video based on recent Shakhova study and the recent review on hydrates (both 2017)

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Feedback is welcome, thanks.

9
Permafrost / Re: Arctic Methane Release
« on: May 23, 2017, 07:42:41 PM »
Possibly OT


Are the seepages off Svalbard possibly of a-biotic origin?


I believe it was near Svalbard where a Swedish team located hydrates in a region where biotic methane was deemed an impossibility. I look at seepage near the Mid-Atlantic Rift as possibly very different from ESAS, continental shelf, or delta seeps.


Terry
Related study NEW SOURCE OF METHANE DISCOVERED IN THE ARCTIC OCEAN
“It is estimated that up to 15 000 gigatonnes of carbon may be stored in the form of hydrates in the ocean floor, but this estimate is not accounting for abiotic methane. So there is probably much more


https://cage.uit.no/news/new-source-methane-discovered-arctic-ocean

The origin, source, and cycling of methane in deep crystalline rock biosphere
My summary, input is welcome...
There are two main routes for geological methane generation, organic (thermogenic), and inorganic (abiotic, meaning non-living). Thermally generated methane, is referred to as thermogenic, originating from deeper sedimentary strata. Thermogenic methane (CH4) formation occurs due to the break-up of organic matter, forced by elevated temperatures and pressures. This type of methane is considered to be the primary methane type in sedimentary basins, and from an economical perspective the most important source of natural gas. Thermogenic methane components are generally considered to be relic (from an earlier time). Generally, formation of thermogenic methane (at depth), can occur through organic matter break-up, or organic synthesis, both ways can involve microorganisms (methanogenesis) but may also occur inorganically. The involved anaerobic and aerobic processes can also consume methane, with and without microorganisms.The more important source of methane at depth (crystalline bedrock) is abiotic. Abiotic means that the methane formation took place involving inorganic compounds, without biological activity, magmatic or created at low temperatures and pressures through water-rock reaction


The abstract
The emerging interest in using stable bedrock formations for industrial purposes, e.g., nuclear waste disposal, has increased the need for understanding microbiological and geochemical processes in deep crystalline rock environments, including the carbon cycle. Considering the origin and evolution of life on Earth, these environments may also serve as windows to the past. Various geological, chemical, and biological processes can influence the deep carbon cycle. Conditions of CH4 formation, available substrates and time scales can be drastically different from surface environments.

This paper reviews the origin, source, and cycling of methane in deep terrestrial crystalline bedrock with an emphasis on microbiology. In addition to potential formation pathways of CH4, microbial consumption of CH4 is also discussed. Recent studies on the origin of CH4 in continental bedrock environments have shown that the traditional separation of biotic and abiotic CH4 by the isotopic composition can be misleading in substrate-limited environments, such as the deep crystalline bedrock.

Despite of similarities between Precambrian continental sites in Fennoscandia, South Africa and North America, where deep methane cycling has been studied, common physicochemical properties which could explain the variation in the amount of CH4 and presence or absence of CH4 cycling microbes were not found. However, based on their preferred carbon metabolism, methanogenic microbes appeared to have similar spatial distribution among the different sites.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4505394/

It is unclear to me what the authors mean with "the more important source of methane" (abiotic). Abiotic seems to originate from deeper in the crust?

10
Permafrost / Re: Arctic Methane Release
« on: May 23, 2017, 06:28:47 PM »
All that was said was the contribution to the releases of methane subjected to microbial oxidation was higher than had been previously suspected...


Can you please quote the part of the study which makes this point? Thanks.

Or is it this:
Shakhova et al. (2010b) have shown that CH4 concentrations in the ESAS water were anomalously high (up to 500 nM) compared to CH4 values generally observed in ocean waters (∼ 5 nM, Damm et al., 2008). Vigorous bubbling events (1.5 to 5.7 bubbles per second) were observed at some sites (Shakhova et al., 2013) as well as seepages of thermogenic CH4 (Cramer and Franke, 2005) indicating that part of the water column supersaturation likely results from a seabed source.

Bussmann (2013) has investigated the distribution of CH4 in the estuary of the Lena, one of the largest Russian rivers draining into the ESAS. They reported high CH4 concentrations (up to 1500 nM) in the river and in the creeks draining from permafrost soil and a strong decrease in the Buor-Khaya Bay (down to 26–33 nM). They concluded that the CH4 contained in the rich waters of the river was, for the most part, not reaching the marine waters, but that it was released by diffusion into the atmosphere before reaching the bay. A large water source is therefore unlikely to explain the CH4 saturation we observe in the ESAS coastal waters


Related
Predicting the fate of methane emanating from the seafloor using a marine two-phase gas model in one dimension (M2PG1) - Example from a known Arctic methane seep site offshore Svalbard
This work presents the model's first application in an Arctic Ocean environment at the landward limit of the methane-hydrate stability zone west of Svalbard, where we observe substantial methane bubble release over longer time periods.
http://adsabs.harvard.edu/abs/2017EGUGA..19.7004J

Widespread methane seepage along the continental margin off Svalbard - from Bjørnøya to Kongsfjorden
Numerous articles have recently reported on gas seepage offshore Svalbard, because the gas emission from these Arctic sediments was thought to result from gas hydrate dissociation, possibly triggered by anthropogenic ocean warming. We report on findings of a much broader seepage area, extending from 74° to 79°, where more than a thousand gas discharge sites were imaged as acoustic flares. The gas discharge occurs in water depths at and shallower than the upper edge of the gas hydrate stability zone and generates a dissolved methane plume that is hundreds of kilometer in length. Data collected in the summer of 2015 revealed that 0.02–7.7% of the dissolved methane was aerobically oxidized by microbes and a minor fraction (0.07%) was transferred to the atmosphere during periods of low wind speeds. Most flares were detected in the vicinity of the Hornsund Fracture Zone, leading us to postulate that the gas ascends along this fracture zone. The methane discharges on bathymetric highs characterized by sonic hard grounds, whereas glaciomarine and Holocene sediments in the troughs apparently limit seepage. The large scale seepage reported here is not caused by anthropogenic warming.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5322355/

Gas Hydrate Breakdown Unlikely to Cause Massive Greenhouse Gas Release https://www.usgs.gov/news/gas-hydrate-breakdown-unlikely-cause-massive-greenhouse-gas-release

Open access paper, recommended reading http://onlinelibrary.wiley.com/doi/10.1002/2016RG000534/full

This last study does not mean that methane buildup specifically in the unique geological ESAS region under sea-ice and penetrated permafrost, couldn't release larger amounts. Thus, it remains
Our results show that thawing subsea permafrost of the ESAS emits CH4 with an isotopic signature that cannot be easily distinguished from Arctic wetland emissions when looking only at stable isotope data. This similarity might complicate recent efforts to quantify Arctic CH4 source strengths on the basis of isotopic- and back-trajectory analysis of atmospheric CH4. Further in situ work is necessaryspecifically on the isotopic composition of CH4 in gas bubbles that reach the atmosphere – to better quantify the contribution of the ESAS to the global methane budget.

11
Permafrost / Re: Arctic Methane Release
« on: May 23, 2017, 03:29:16 PM »

Also interesting
..anthropogenic nuclear contribution, e.g. from nuclear waste buried in the coastal permafrost, is the most likely explanation for these elevated radiocarbon levels.

12
Arctic Background / Re: Dark Snow
« on: May 22, 2017, 03:55:58 PM »
Funding The Dark Snow Greenland Operation in 2017
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http://darksnow.org/support

13
Greenland and Arctic Circle / Re: Greenland 2017 melt season
« on: May 22, 2017, 03:53:41 PM »
In retrospect (and to give some background information), this was just released last week

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14
Consequences / Re: Seed Bank Vault Flooding
« on: May 20, 2017, 07:06:33 PM »
Made a video

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Consequences / Re: Climate change, the ocean, agriculture, and FOOD
« on: May 20, 2017, 01:12:53 PM »
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16
Permafrost / Re: Arctic Methane Release
« on: May 12, 2017, 03:15:52 PM »
What happens to the algae though? Does it actually sequester the carbon by dying and getting buried by silt at the bottom of the ocean or just die and decompose in the water column? If it does that, then this is just a roundabout way of adding carbon to the carbon cycle.
What appears to be a seasonal negative factor may work to some extent for gradual release, but i doubt this would make a big impact if large scale release occurs, due to continued warming, or if this can be observed in other areas, with different conditions for algae growth. Also, the uptake will affect other organisms, CO2 uptake has detrimental effects for many ocean species https://www.sciencedaily.com/releases/2012/01/120120184233.htm

And then there is this

Blooming Algae Could Accelerate Arctic Warming
Scientists have generally believed that more algae — more specifically, the type known as phytoplankton — would be good for the climate, since they thrive on CO2 while alive, then carry the carbon they’ve absorbed down to the sea bottom when they die. Some experts have even suggested that fertilizing the oceans to encourage algal growth would be one way to counteract global warming.

But Park and his co-authors point out that thicker layers of algae on the sea surface would prevent sunlight from penetrating deeper into the water.

“More heat is trapped in the upper layers of the ocean, where it can be easily released back into the atmosphere,” Park said. He and his team reached this conclusion by marrying computer models of how ocean ecosystems behave to models that simulate the climate. Then they ramped up levels of CO2 to see how the algae would respond to the resulting warming, the extra carbon dioxide itself, and changes in sea ice.

http://www.climatecentral.org/news/algae-accelerate-arctic-warming-18929

If you combine findings on enhanced algae growth, and potential for increased surface layer warming, then you end up with something very much resembling another wildcard.

17
Permafrost / Re: Arctic Methane Release
« on: May 12, 2017, 01:48:11 PM »
Yesterday, professor of Geophysics Vladimir Romanovsky discusses the impact of Arctic permafrost thaw.
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The rest / Re: Human Stupidity (Human Mental Illness)
« on: April 28, 2017, 04:35:01 PM »
This brings us to the topic of how soon might we expect to reach the 2 to 3C GMSTA range cited by DeConto & Pollard (2016) for the WAIS to begin its main stage collapse.


DeConto at EGU17 http://meetingorganizer.copernicus.org/EGU2017/sessionprogramme type DeConto into the search, no video available :(

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The rest / Re: Russiagate
« on: April 23, 2017, 05:27:21 PM »
...
...
If you ever want to publish your thoughts to a wider audience, let me know.

20
The rest / Re: Russiagate
« on: April 23, 2017, 04:12:26 PM »
When Donnie is a slob to his wife.......THAT effects RussiaGate
The best arguments are those made based on the major issues, if you write a story about how he leaves a plane without his woman, then this is interference, just not really news. However, people take notice of such subtle details, some things do not have to be communicated. Focus on the major issues, such as a climate denier who sued EPA, leads it now, and what he does, what he said - threatening clean air and water, and climate disruption. Now, you get attention from the average Joe. If you focus too much on the details,  or too vague claims, small slips, you lose credibility, or let's say you over bombard the attention spans with small stuff. Focus on the big picture.

21
The rest / Re: Russiagate
« on: April 23, 2017, 03:07:36 PM »
Or stop dividing in terms of the left and right entirely, and just focus on science based policy

+1


Can you imagine a world where policy is based on the best science and policy changes to meet new data?  Too bad we are prisoners of the lawyers and their cognitive dissonance based system.
I would think that is the way to go, because it eliminates the noise from the facts. The evolution of politics, our future .... how long will it take? It would also possibly mean the best possible environment for prosperity.

22
The rest / Re: Russiagate
« on: April 23, 2017, 02:55:44 PM »
How about we stop running from the labels "liberal" and "progressive", and instead embrace them and let people know that many of the good things they have in life are courtesy of the Left, things which the Right wants to take away?

Or stop dividing in terms of the left and right entirely, and just focus on science based policy :)

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The rest / Re: Russiagate
« on: April 23, 2017, 02:32:03 PM »
While i think it is important to point out flaws in general, regarding everything elections, my impression is that the media has put too much emphasis when discussing Russia's alleged involvement. It appears that this is especially a trust issue with voter base, if you have many from the left political spectrum (Jimmy Dore, Chomsky among many others), and independent security analysts pointing out flaws with that argument. Basically when it comes to digital transmission (who done it, who accessed etc etc), everything can be faked.

On the bottom line, votes, elections, should only be done on paper ballots.   

On the other hand political arguments would be much stronger when you would focus on Trump's business ties and political actions involving Russia.

24
The rest / Re: Human Stupidity (Human Mental Illness)
« on: April 23, 2017, 02:23:27 PM »
My previous post in this thread..

Thanks Abrupt, it will take some time to make a video with the suggested science. Will post it here when ready, cheers.

25
The rest / Re: Human Stupidity (Human Mental Illness)
« on: April 21, 2017, 01:57:48 PM »
To learn more about  large-noise events such as ice-climate feedback due to the collapse of a marine ice sheet (like the WAIS) please review my posts
AbruptSLR, i currently plan a new video production where i want to summarize some of the most worrying research. Is it possible, can you summarize maybe what you think are the top 5 or top 10 findings in those regards? Or what you think should be communicated to a larger audience of laymen?
 Thank you.

26
Greenland and Arctic Circle / Re: The Bølling-Allerød warming
« on: April 20, 2017, 08:25:11 PM »
Made a summary video of the volcanism ice albedo feedback study https://www.youtube.com/watch?v=UZbpC2zoklA

Btw can you embed YT videos here somehow?

27
Antarctica / Re: Rift in Larsen C
« on: April 20, 2017, 08:11:19 PM »
ESA video on Larsen C crack, includes insides into detection with Interferogram (using two radar images) https://www.youtube.com/watch?v=8PvCY7pBd-w

#interferometry

28
Currently Open Access

Paleofluvial and subglacial channel networks beneath Humboldt Glacier, Greenland
We suggest that basal meltwater is actively
being routed down both the paleofluvial and subglacially formed channel networks to the coast.
Inheritance of the preglacial channel network may have influenced the present-day location
and dynamics of Humboldt Glacier and enhanced selective erosion at its down-glacier end.
http://geology.gsapubs.org/content/early/2017/03/27/G38860.1.full.pdf+html

29
The rest / Re: Article links: drop them here!
« on: April 20, 2017, 07:32:34 PM »
The Milo’s logbook of its 1863 voyage is just one of 35 whaling logs that are part of the Old Weather: Whaling project, an online portal that allows volunteers to assist in exploring, marking, and transcribing ship logs, largely from the 19th and early 20th centuries. The initiative, and its sister side Old Weather, were founded by Dr. Philip Brohan at the UK Met Office in 2010 to recover historical marine-meteorological observations that can be used by supercomputers to reconstruct the weather of the past 150 years. Historic ship logs are difficult for computers to transcribe and mark because of their diverse and idiosyncratic handwriting that only humans can read and understand effectively.

Despite their difficulty, ship loggers’ observations on sea ice conditions that whaling ships have sailed through and documented while navigating Arctic waters are vital to informing the foundations of climate science research being done today.

“Old Weather volunteers have recovered millions of new-to-science weather observations,” explains Dr. Kevin Wood, a research scientists at the University of Washington’s Joint Institute for the Study of Atmosphere and the Arctic Lead Investigator for Old Weather.

“For the Arctic, they have also been recovering many thousands of sea-ice observations and other environmental data – the former specifically to validate century-scale sea-ice model hindcast experiments, so we can better know well our models are working, and more fundamentally document what the Arctic sea-ice was like in the past (especially in offshore areas and in some instances in winter).”

http://www.highnorthnews.com/using-old-weather-to-inform-climate-change-work-today

30
Science / The Sciences of Ice Shelf Meltwater (Retention vs Discharge)
« on: April 19, 2017, 07:41:08 PM »
Antarctic ice shelf potentially stabilized by export of meltwater in surface river

Here we present evidence for persistent active drainage networks—interconnected streams, ponds and rivers—on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf’s meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century.

The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present.

The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica—contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.
https://www.nature.com/nature/journal/v544/n7650/full/nature22048.html

Clip of Nansen Ice Shelf waterfall https://www.youtube.com/watch?v=55hhWq8W9hY

I did not read the study paper, but it seems plausible that surface discharge is less of an issue when compared to moulin/fracturing discharge to bottom with potential for lubricating effects, and concerning stability.

31
Greenland and Arctic Circle / Re: North Atlantic Cold Spot
« on: April 18, 2017, 12:04:37 AM »
Abrupt cooling over the North Atlantic https://www.nature.com/articles/ncomms14375
Summary of the new study and earlier findings
https://www.youtube.com/watch?v=Li3-JdXIjc4

32
Greenland and Arctic Circle / Re: North Atlantic Cold Spot
« on: April 16, 2017, 06:13:15 PM »
Abrupt cooling over the North Atlantic https://www.nature.com/articles/ncomms14375


33
Greenland and Arctic Circle / Re: Meltwater & Run-off
« on: April 16, 2017, 06:01:36 PM »
Great !
I find this fascinating, and I think under-represented in the literature on ice-melt and the ecosystem it is unavoidably entangled with.

Indeed fascinating, also this, life might have evolved first in Greenland ...

From the study you initially posted above

The researchers say that additional studies are needed to refine the picture of whether the balance of carbon produced by glaciers is weighted more to release of ancient carbon or production by microorganisms.


Hints of oldest fossil life found in Greenland rocks http://www.sciencemag.org/news/2016/08/hints-oldest-fossil-life-found-greenland-rocks

34
Greenland and Arctic Circle / Re: Meltwater & Run-off
« on: April 16, 2017, 05:20:49 PM »
Related study (from Greenland)

Molecular and biogeochemical evidence for methane cycling beneath the western margin of the Greenland Ice Sheet http://www.nature.com/ismej/journal/v8/n11/full/ismej201459a.html

And Antarctic permafrost highlights the history of biogeochemical activity in some Antarctic regions. Coastal Antarctic Permafrost Melting Faster Than Expected https://news.utexas.edu/2013/07/24/coastal-antarctic-permafrost-melting-faster-than-expected

35
Greenland and Arctic Circle / Re: Greenland ice sheet retreat
« on: April 16, 2017, 02:38:16 PM »
A new study pinpoints the year ca 1997 as a tipping point for GICs mass balance.

..we identify 1997 (±5 years) as the year after which the GICs refreezing regime starts to decrease and diverges significantly from the GrIS refreezing regime (black point in Fig. 3c). This marked reduction in refreezing capacity is representative of a deteriorating firn layer, the porous, multiyear snow layer between surface fresh snow (∼350 kg m−3) and the underlying ice (∼900 kg m−3). Decades of increased melt have reduced pore space to such a degree that enhanced refreezing can no longer compensate for increased meltwater production. Because it would take decades to regrow a healthy firn layer, we interpret 1997 as a tipping point in the mass balance of Greenland’s GICs.


Covering a total area of ∼90,000 km2, Greenland’s peripheral glaciers and ice caps (GICs) represent ∼12% of the world’s glacierized area outside of the Antarctic and Greenland ice sheets1. Greenland’s GICs account for 14 to 20% of total current Greenland glacial mass loss2, although they only represent ∼5% of the area and ∼0.5% (∼39 mm SLE) of the volume of the Greenland ice sheet (GrIS). In a scenario of continued global warming, Greenland’s GICs may lose 19–28% (7.5–11 mm) of their volume by 2100 (ref. 3).




Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote sensing data, to identify 1997 (±5 years) as a tipping point for GICs mass balance. That year marks the onset of a rapid deterioration in the capacity of the GICs firn to refreeze meltwater. Consequently, GICs runoff increases 65% faster than meltwater production, tripling the post-1997 mass loss to 36±16 Gt−1, or ∼14% of the Greenland total. In sharp contrast, the extensive inland firn of the GrIS retains most of its refreezing capacity for now, buffering 22% of the increased meltwater production. This underlines the very different response of the GICs and GrIS to atmospheric warming. 


A tipping point in refreezing accelerates mass loss of Greenland’s glaciers and ice caps https://www.nature.com/articles/ncomms14730

Slice of Greenland ice melts into oblivion http://climatenewsnetwork.net/slice-greenland-ice-melts-oblivion/

36
The rest / Re: Human Stupidity (Human Mental Illness)
« on: April 16, 2017, 12:15:12 AM »
..decision makers are fully aware that our combined societal behavior will likely lead to climate catastrophe; which is an example of our stupid collective  behavior due to the mental illness of the decision makers

“One does not play games, or take chances, when essentially the whole of civilization and humanity MAY be in peril.”
http://climatestate.com/2013/05/03/false-climate-change-data-a-crime-against-humanity-ecocide/

37
The rest / Re: Human Stupidity (Human Mental Illness)
« on: April 15, 2017, 11:15:27 PM »
Since the topic title includes Human Mental Illness, which seems a bit off-topic, you might find this read interesting.

Neanderthal genes' effects on gene expression likely contribute to traits such as height and susceptibility to schizophrenia or lupus, the researchers found.
"Even 50,000 years after the last human-Neanderthal mating, we can still see measurable impacts on gene expression," says geneticist and study co-author Joshua Akey of the University of Washington School of Medicine. "And those variations in gene expression contribute to human phenotypic variation and disease susceptibility."


Read more at: https://phys.org/news/2017-02-neanderthal-dna-contributes-human-gene.html#jCp

38
The rest / Re: Human Stupidity (Human Mental Illness)
« on: April 15, 2017, 11:02:40 PM »
When it is human stupidity that has caused climate change, why do so many think that humans will be able to avoid exceeding the 2C target?
Humans have not caused climate change per se, more like unknowingly - at least to some degree. Something every evolving species on a habitable planet in the Universe encounters, burning fossil fuels at one point.

Then the fact that our Society is primarily driven by decisions made at the top, via elected officials, or people who influence power over them. We are well aware of climate change and that it means problems since at least the 80s, theoretically enough time to act. But it seems that we as individuals for the most part are too busy with everyday life, our work, with newly obtained technologies in the information age, to understand the gravity of what future temperature rise entails.

So on the one side you have the concerned educated guy who understands the science, or at least is cautious enough about the looming fundamental changes, and on the other side the influencers who make the rules. And in some progressive countries this seems to work actually, for example Denmark or Scotland with their 100% renewable energy generation targets. Germany also has a great commitment to solar and wind power, but most cars on the street are still spewing fossil fuel exhaust, and coal power plants are still running.

To better understand our actions we can go back into the past and see many civilizations failed before us, even today as we speak many nations have collapsed or are on the bring to it, because of war, or economic mismanagement, sometimes enhanced by climatic factors, a trend very likely to become more pronounced, hence more strain for weaker nations in the years ahead.

Recently, i came across the theory that our overly optimistic attitude toward the future, the idea that everything will be better, is partially responsible for the situation today, or the lack of actions taken today. While i long regarded myself as an optimist, i think to be more of a pessimist now, or maybe just a pragmatic realist.

If we can draw any conclusion from the past, at large, simplified, then it almost seems as if our species unknowingly only learns from collapse.
 
Joseph Tainter talks Energy, Collapse, and Society (2015)
https://www.youtube.com/watch?v=0KeY1dIPi8k

Walter Scheidel on Society, Collapse and Equality
https://www.youtube.com/watch?v=pQ0_oj_V64Q

However, if you want big change, sometimes it is good if you have exactly the opposite direction taken, which apparently will make more and more people uncomfortable. And then the overly optimistic attitude that human imagination, research and inventions will somehow come up at a later time with a fix. Happened quite often actually, but first all other options were exhausted. But those problems are very small in comparison to altering the chemistry of the atmosphere and oceans. The question is, will it be too late by then to avert more serious harm, harm on an extinction level, for our and the other species on the planet.

Basically large scale catastrophes are required to change the behavior of our species at large, but the catastrophes which come with a much warmer world have the power to destroy our civilization. And then factor into that equation the nuclear power capabilities of many nations. A 2 degree and beyond world, disrupted by climate chaos makes people even more trigger happy.  This means that there will likely be an exponential rise of various sorts of catastrophes (Flooded coastlines, flooded agricultural land, flooded power plants, flooded dumb sites, heatwaves overwhelming the energy grid, food shortages, plagues, diseases,  financial loses because beach property becomes worthless, contamination of the water and food chain related to flooding, precipitation events damaging infrastructure, properties, the toll on the psyche of individuals affected, warmer temperatures result in more violent tendencies, and so on)

No, i do not think that we will avoid 2 degree temperature rise, because i have yet to see an emission chart and the required actions to make this miracle happen.

39
Science / Re: Earthquakes and climate change
« on: April 15, 2017, 04:19:15 PM »
Is there a sub-thread at CS where all the relevant pieces would be stored together? What would be the best terms to use to do a search on this topic?

You need to use the search and seek keywords, but there are not many updates, the last post was a 2014 interview, this http://climatestate.com/2014/10/16/methane-hydrate-destabilisation-is-clearly-a-real-worry-particularly-in-the-context-of-warming-ocean-waters-in-the-east-siberian-continental-shelf/

And then i recommend this lecture, Waking the Giant: Climate Force and Geological Hazards
 https://www.youtube.com/watch?v=xndhx7KpSU0

Recently
This study paper

Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation https://www.researchgate.net/publication/306418361_Interaction_between_climate_volcanism_and_isostatic_rebound_in_Southeast_Alaska_during_the_last_deglaciation Summary posted here http://forum.arctic-sea-ice.net/index.php/topic,1952.0.html

Climate change may prevent volcanoes from cooling the planet
November 16, 2016 https://phys.org/news/2016-11-climate-volcanoes-cooling-planet.html

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The rest / Re: 2017 open thread
« on: April 15, 2017, 02:24:38 PM »
I was curious about this conversation in PIOMAS, and was hoping you all would continue it here.
Ofc, would be nice to get some expert opinions on this years projected melt rates and the data.

41
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: April 14, 2017, 08:31:20 PM »
Will there be impact on the Greenland surface melt, like we had in 2012? So far not much? (tick 2017 to compare 2012 with 2017 in NSIDC interactive graph)
http://nsidc.org/greenland-today/greenland-surface-melt-extent-interactive-chart

Notice NSIDC stated April 3, 2017
Daily updates have resumed for the 2017 melt season. Bit puzzling, according to the data not a single melt day so far?

In recent decades, the Greenland ice sheet has experienced increased surface melt. However, the underlying cause of this increased surface melting and how it relates to cryospheric changes across the Arctic remain unclear. Here it is shown that an important contributing factor is the decreasing Arctic sea ice. Reduced summer sea ice favors stronger and more frequent occurrences of blocking-high pressure events over Greenland. Blocking highs enhance the transport of warm, moist air over Greenland, which increases downwelling infrared radiation, contributes to increased extreme heat events, and accounts for the majority of the observed warming trends. These findings are supported by analyses of observations and reanalysis data, as well as by independent atmospheric model simulations using a state-of-the-art atmospheric model that is forced by varying only the sea ice conditions. Reduced sea ice conditions in the model favor more extensive Greenland surface melting. The authors find a positive feedback between the variability in the extent of summer Arctic sea ice and melt area of the summer Greenland ice sheet, which affects the Greenland ice sheet mass balance. This linkage may improve the projections of changes in the global sea level and thermohaline circulation.
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0391.1

42
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: April 14, 2017, 07:02:25 PM »
You won't find much of that in the Cryosphere part of the forum...

Thanks, was just mentioning it because of what appears to be FOOW's excellent blog -
 and thought it was worth mentioning because of the interconnections http://www.dailykos.com/blog/FishOutofWater

43
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: April 14, 2017, 06:20:40 PM »
And then there is the Arctic air intrusion into lower latitudes, ie. The highs of 25 ºC last week will seem like a distant memory as it turns colder this #EasterWeekend, as cooler air comes down from the north https://twitter.com/metoffice/status/852902667064102912 Like to read a bit more updates on the historical perspective on this, and frequency and such, and in relation to the Polar Vortex pressure.

44
Antarctica / Re: Rift in Larsen C
« on: April 14, 2017, 05:05:41 PM »
The Making of an Iceberg
April 14, 2017

In 2014, a crack began opening in the Larsen C Ice Shelf—a huge slab of floating ice along the Antarctic Peninsula. By April 2017, only 16 kilometers (10 miles) of ice separated the tip of that crack from the open sea.
Predicting when the cracking shelf will set loose an iceberg is a challenge because ice fracturing depends on several factors, some of which are poorly understood. The iceberg, which is likely to be the size of Rhode Island, could break off any time from days to years from now, according to scientists from Project MIDAS, a United Kingdom-based group that is monitoring the event.
https://earthobservatory.nasa.gov/IOTD/view.php?id=90021

46
Hydrofracturing???

Eric Rignot, a NASA and University of California-Irvine scientist who has studied Petermann up close, commented:

The ice shelf is slowly but surely falling apart. It has been stable from 1901 till the 2000s, then started to break up, especially in 2010-2012. We have seen the glacier speed up for the first time around 2014-2015. Whether this new crack is significant or not is hard to tell as of now. It is unusual to see cracks forming from the center, they usually start from the sides. This could indicate that the ice shelf has gotten too thin in the middle.

Since a meltwater river runs in the middle, hydrofracturing might cause the thinning?

48
Greenland and Arctic Circle / Re: The Bølling-Allerød warming
« on: April 14, 2017, 02:15:05 PM »
Since all the primary forcings initiating these events were occurring at 'natural' rates (eg over Milankovitch cycles) then I would imagine that the comparatively high rate of human-caused change could see a correspondingly higher rate of response by those same mechanisms today.


I would think this is true for some fundamental systems like Arctic sea ice, the most visible and sensitive(?), but too difficult yet to say for ie. seismic response times. See below quote from a 2014 Bill McGuire interview.

Today the discussion evolves more around, to how much we commit ourself and future generations to the amount of sea level rise, and temperature increase. If you look at current several meters of sea level rise possible by the end of the century projections, then we are already in a realm comparable to the BA, but on a global scale.

Chris Machens: Since a lot of discussions evolve around the amount of CO2 in the atmosphere, is it yet possible to quantify projected seismic uptake in relation to particular emission scenarios, based on past events or modelling, or is this easier when comparing sea level heights?

Bill McGuire: It is not possible to link the level of seismic response to particular emissions scenarios in any meaningful way. This is because each active fault is in a different state of strain at any given time, so will respond in a different manner to stress and strain changes that accompany the loss of ice cover or increase in sea level. Where a fault is primed, however, its rupture may be triggered by a pressure change that is literally comparable to that exerted by a handshake. In such circumstances, the environmental changes promoted by climate change could be expected to provide such a trigger.
http://climatestate.com/2014/10/16/methane-hydrate-destabilisation-is-clearly-a-real-worry-particularly-in-the-context-of-warming-ocean-waters-in-the-east-siberian-continental-shelf/


49
Greenland and Arctic Circle / The Bølling-Allerød warming
« on: April 13, 2017, 11:05:26 PM »
I thought to open a discussion on the science related to the Bølling-Allerød warming, a period with exceptional rate of changes, as recorded in ice core records from Greenland/Northern Greenland. Then there is science related to the AMOC, and Volcanism.

Bølling–Allerød Interstade (BA), is a widespread abrupt warming event in the Northern Hemisphere during the deglacial transition, essentially synchronous in Alaska and Greenland (Praetorius and Mix, 2014).

The sea-surface warming of ∼3 ◦C in the Gulf of Alaska (GOA) record occurs abruptly (in <90 yrs), consistent with ice-core records that register this transition as occurring within decades (Steffensen et al., 2008).
https://www.researchgate.net/publication/306418361_Interaction_between_climate_volcanism_and_isostatic_rebound_in_Southeast_Alaska_during_the_last_deglaciation
 

The question is what causes the abrupt warming at the onset of the Bølling as seen in the Greenland ice cores. There is a clear antiphasing seen in the deglaciation interval between 20 and 10 ka. During the first half of this period, Antarctica steadily warmed, but little change occurred in Greenland. Then, at the time when Greenland’s climate underwent an abrupt warming, the warming in Antarctica stopped. A possible hypothesis can be that a sudden increase of the northward heat transport draws more heat from the south, and leads to a strong warming in the north. This “heat piracy” from the South Atlantic has been formulated by Crowley (1992). A logical consequence of this heat piracy is the Antarctic Cold Reversal (ACR) during the Northern Hemisphere warm Bølling/Allerød.
http://epic.awi.de/41137/1/polfor_2016_013.pdf

The bottom line seems to me, to identify involved mechanisms, but to be careful to draw conclusions as analog for today's climate, with different configurations, loading, and rates or warming. However, responsible mechanism are very likely to take part this time around as well, but might act differently, ie. AMOC, response times, regional differences.

Below a link to an excerpt by Jim White with a brief comment on the event, and a couple of related studies.



Abrupt Climate Change explained by Jim White, 12 Minutes excerpt (@AGU 2014)
https://www.youtube.com/watch?v=siWCXOypJh4&feature=youtu.be&t=3m15s

July 16, 2009 BOULDER—By simulating 8,000 years of climate with unprecedented detail and accuracy, a team led by scientists from the University of Wisconsin–Madison and the National Center for Atmospheric Research (NCAR) has found a new explanation for the last major period of global warming, which occurred about 14,500 years ago.

In a period called the Bølling-Allerød warming, global sea level rose by 16 feet and temperatures in Greenland soared by up to 27 degrees Fahrenheit over several hundred years. The new study shows how increased carbon dioxide, strengthening ocean currents, and a release of ocean-stored heat could have combined to trigger the warming.
https://www2.ucar.edu/atmosnews/news/809/new-cause-past-global-warming-revealed-massive-modeling-project

2016 On the Abruptness of Bølling–Allerød Warming
Using a high-resolution TCC-resolved regional model, it is found that this decadal-scale accumulation of OCAPE ultimately overshoots its intrinsic threshold and is released abruptly (~1 month) into kinetic energy of TCC, with further intensification from cabbeling. TCC has convective plumes with approximately 0.2–1-km horizontal scales and large vertical displacements (~1 km), which make TCC difficult to be resolved or parameterized by current general circulation models. The simulation herein indicates that these local TCC events are spread quickly throughout the OCAPE-contained basin by internal wave perturbations. Their convective plumes have large vertical velocities (~8–15 cm s−1) and bring the WSW to the surface, causing an approximate 2°C sea surface warming for the whole basin (~700 km) within a month. This exposes a huge heat reservoir to the atmosphere, which helps to explain the abrupt Bølling–Allerød warming.
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0675.1

Related talk from AGU 2014 Thermobaric instability / and modelling of warm salty water getting to the surface. The role of the ocean in the last deglaciation https://www.youtube.com/watch?v=F1VcOHS0kGA

2017 The Atlantic Meridional Overturning Circulation and Abrupt Climate Change
Abrupt changes in climate have occurred in many locations around the globe over the last glacial cycle, with pronounced temperature swings on timescales of decades or less in the North Atlantic. The global pattern of these changes suggests that they reflect variability in the Atlantic meridional overturning circulation (AMOC). This review examines the evidence from ocean sediments for ocean circulation change over these abrupt events. The evidence for changes in the strength and structure of the AMOC associated with the Younger Dryas and many of the Heinrich events is strong. Although it has been difficult to directly document changes in the AMOC over the relatively short Dansgaard-Oeschger events, there is recent evidence supporting AMOC changes over most of these oscillations as well. The lack of direct evidence for circulation changes over the shortest events leaves open the possibility of other driving mechanisms for millennial-scale climate variability.
http://annualreviews.org/doi/abs/10.1146/annurev-marine-010816-060415

2016 Abrupt Bølling warming and ice saddle collapse contributions to the Meltwater Pulse 1a rapid sea level rise
Elucidating the source(s) of Meltwater Pulse 1a, the largest rapid sea level rise caused by ice melt (14–18 m in less than 340 years, 14,600 years ago), is important for understanding mechanisms of rapid ice melt and the links with abrupt climate change. Here we quantify how much and by what mechanisms the North American ice sheet could have contributed to Meltwater Pulse 1a, by driving an ice sheet model with two transient climate simulations of the last 21,000 years. Ice sheet perturbed physics ensembles were run to account for model uncertainties, constraining ice extent and volume with reconstructions of 21,000 years ago to present. We determine that the North American ice sheet produced 3–4 m global mean sea level rise in 340 years due to the abrupt Bølling warming, but this response is amplified to 5–6 m when it triggers the ice sheet saddle collapse.
http://onlinelibrary.wiley.com/doi/10.1002/2016GL070356/full


2014 An ice core record of near-synchronous global climate changes at the Bølling transition http://www.nature.com/ngeo/journal/v7/n6/abs/ngeo2147.html

2014 Abrupt pre-Bølling–Allerød warming and circulation changes in the deep ocean http://www.nature.com/nature/journal/v511/n7507/abs/nature13472.html

https://en.wikipedia.org/wiki/B%C3%B8lling-Aller%C3%B8d

Volcanism linked to BA

Related Modelling suggests with ice cap melt, an increase in volcanic activity http://climatestate.com/2014/10/16/methane-hydrate-destabilisation-is-clearly-a-real-worry-particularly-in-the-context-of-warming-ocean-waters-in-the-east-siberian-continental-shelf/

2016 Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation
We evaluate the timing and climate context of a deglacial volcanic sequence from Southeast Alaska.
We document an increase in volcanism in response to deglacial ice loss and isostatic rebound.
These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity.
An increase in regional climate variability is associated with the interval of intense volcanism.
This study illustrates a two-way coupling of climate and volcanism across time scales.

The sudden increase in volcanic activity from the MEVF coincides with the onset of Bølling–Allerød interstadial warmth, the disappearance of ice-rafted detritus, and rapid vertical land motion associated with modeled regional isostatic rebound in response to glacier retreat. These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity. Rapid sea surface temperature fluctuations and an increase in local salinity (i.e., δ18Osw) variability are associated with the interval of intense volcanic activity, consistent with a two-way interaction between climate and volcanism in which rapid volcanic response to ice unloading may in turn enhance short-term melting of the glaciers, plausibly via albedo effects on glacier ablation zones.
http://www.sciencedirect.com/science/article/pii/S0012821X16303892 https://www.researchgate.net/publication/306418361_Interaction_between_climate_volcanism_and_isostatic_rebound_in_Southeast_Alaska_during_the_last_deglaciation

Two plausible mechanisms could have linked the interval of isostatic adjustment with enhanced volcanism: 1) increased melt production generated through decompression in the shallow mantle (Maclennan et al., 2002), or 2) reduced storage time of crustal magmas through regional adjustment in crustal stress and enhanced dike formation (Rawson et al., 2016). The near-zero timelag between regional isostatic adjustment and an abrupt increase in volcanic eruptive frequency in Southeast Alaska suggests the latter scenario is more plausible, or at least the dominant mechanism.

Supporting this supposition is the rapid mobilization of differentiated magma through multiple vents. Decompression melting would not likely have produced differentiated magmas on the time-frames observed, while previous work by others has shown that the Mount Edgecumbe magma chamber likely contained cupolas above the main basaltic chamber that already contained the more siliceous material (e.g. Myers and Sinha, 1985; Riehle et al., 1992b).

The rapid response of the Southeast Alaska system contrasts with inferred lags of volcanism several thousand years behind sealevel rise in global compilations (Kutteroff et al., 2013; Watt et al., 2013). It is plausible to think that some volcanic systems may have longer lag times behind local unloading; for example, arc systems in thicker continental crust may have longer response times (Rawson et al., 2016) than relatively isolated volcanic systems with shallow magma chambers, such as in Southeast Alaska (Riehle et al., 1994). Nevertheless, our findings highlight the importance of well-constrained regional studies to understand the rates and sensitivity of interactions between surface processes and volcanic activity.


The δ18Osw reconstruction reveals low values, implying freshening of surface waters, between 14.6 and 14.0 ka. Although the rapid freshening of surface waters coincides with abrupt warming, the interval of freshening is not uniquely linked to the warmest temperatures, as there are intervals within the BA with equivalently high SSTs that do not show an apparent decrease in δ18Osw.

The interval with greatest apparent freshening and high variance in δ18Osw coincides with the interval of deposition of basaltic tephra, which is coeval with the rapid warming and disappearance of ice-rafted debris (IRD) at the onset of the Bølling Interstade (Fig. 5, Fig. S5). Although these initial tephra layers are thin (0.5 cm), the deposition of dark tephra in the ablation zone of glaciers could have reduced albedo of the snow and ice surfaces (Conway et al., 1996), thereby promoting rapid melting and accelerated local meltwater output along with deglaciation. This mechanism would likely have enhanced freshwater runoff into the Alaskan coastal currents during deglaciation, and this influx of low δ18O water would in turn have influenced the isotopic composition of near-surface waters.


Although firm attribution of specific causal relationships is difficult with only a few events, it is plausible that both hemispheric and regional forcings contribute to climate variability in the GOA region. While direct radiative-forcing effects from individual eruptions are unlikely to lead to long-term cooling due to the relatively short residence time of volcanic aerosols in the upper atmosphere (1–3 yrs), a prolonged increase in the frequency of eruptions could lead to either warming or cooling perturbations through ice-albedo, sea-ice, or CO2 feedbacks.

Modeling studies suggest that hemispheric cooling of decades to centuries can be initiated by the effects of multiple eruptions (McGregor et al., 2015; Pollack et al., 1993), or sea-ice feedbacks (Miller et al., 2012).


Sustained intervals of volcanism during the deglaciation may also have contributed to warming through increased CO2 emissions (Huybers and Langmuir, 2009), and ice-albedo feedbacks. Tephra deposited in the ablation zone of glaciers accelerates melting because the tephra (>5 μm) tends to remain at the ice surface as the glacier retreats (Conway et al., 1996).

Tephra that was once covered in the accumulation zone will at some point be uncovered in the ablation zone, where its growing concentration at the ice surface may provide a feedback for glacial melting in models (Peltier and Marshall, 1995).

In some instances thick ash (>10 mm) can act as a short-term insulating layer on glaciers (Dragosics et al., 2016), delaying melting in areas proximal to the vent, but the wider dispersal of finer ash particles will likely more than compensate this localize insulating effect through a greater surface area over which thin tephra layers will act to increase ablation rates.

Given the evidence for rapid retreat of marine terminating glaciers preceding/coinciding with the interval of frequent volcanic tephra deposition from the MEVF, it is plausible that tephra deposited on these regional glaciers would have an nearly immediate impact on melt rates in the already-expanding ablation zones. Thus, rapid responses of Alaskan volcanic systems to initial deglaciation may have accelerated ice losses in the region.

The large number of volcanoes in the Pacific “Ring of Fire”, coupled with the prevailing westerly winds, make deposition of tephra on the Laurentide and Cordilleran ice sheets (Fig. 1) a potential contributor to glacial wasting and ice-sheet instability


Greenhouse gases are considered one of the powerful feedback mechanisms in the ice age cycle. Might deglacial volcanism contribute to this effect? The rise of atmospheric CO2 during the first half of the deglaciation (18–15 ka) was likely sourced primarily from processes related to organic matter, as shown by δ13C (Schmitt et al., 2012; Bauska et al., 2016), plausibly through a decrease in the net strength of the ocean’s biological pump, which yields CO2 depleted in 13C relative to the atmosphere.

Later in the deglaciation (<15 ka), further trends of rising CO2 are not associated with long-term 13C depletion, and therefore could include contributions from either ocean warming or volcanic CO2, which both yield CO2 rise not depleted in 13C relative the background atmospheric values. Superimposed in these larger trends are abrupt (∼10 ppm) rises in atmospheric CO2 near 16–16.5 ka, 14.5–14.7 ka, and 11.5–12 ka (Marcott et al., 2014).

Carbon isotope data from ice core CO2 constrain the youngest and oldest of these abrupt rises to be sourced primarily from organic carbon reservoirs, most likely on land (Bauska et al., 2016), but could allow partial contributions from other sources including volcanic CO2.

The abrupt rise in atmospheric CO2 near 14.7–14.5 ka, however, has no discernable change in atmospheric δ13C (Bauska et al., 2016) implying that it cannot be sourced from oxidation of organic matter and therefore may be consistent with volcanic sources that responded relatively quickly to deglacial unloading.


This finding is consistent with the hypothesis that ice-unloading can trigger volcanism. We find no significant lag between the timing of major ice retreat and the onset of volcanism, suggesting that the volcanic response to deglaciation is rapid in this region. Between 14.6–13.1 ka, the MEVF exhibited an eruption recurrence interval of ∼1.5 events/century based on the macroscopic tephra-fall units identified in this study.

Early in the eruptive sequence, basaltic tephra is associated with surface water freshening (implied by anomalously low δ18Osw), suggesting that in this region, volcanism triggered by deglacial unloading may plausibly accelerate melting and water runoff through an albedo effect of dark tephra on snow and ice. With this insight from a well constrained regional study, re-examination of the integrated sulfate record from the Greenland ice core suggests that sustained early deglacial volcanism could accelerate rapid melting of some northern hemisphere glaciers through a reduction in surface albedo. Regional volcanism may thus play a significant role in century-to millennial scale climate change during the deglaciation.


BA and AMOC
2016 Abrupt Climate Change Experiments: The Role of Freshwater, Ice Sheets and Deglacial Warming for the Atlantic Meridional Overturning Circulation http://epic.awi.de/41137/1/polfor_2016_013.pdf

50
In regards to melting and temperature, Rignot 2017 has some explanation in regards to the freezing point https://youtu.be/AAPPq43iRLs?t=15m04s

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