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ArcticMelt2

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Re: Arctic Methane Release
« Reply #1100 on: November 01, 2019, 07:57:19 PM »
Apologies for the duplicate post, I'm reposting this here (from the stupid questions thread) as I think it's a more appropriate thread.

I'm looking for recent methane concentration data from the Tiksi weather station, but the most recent data I can find on the NOAA website is over a year old.

Is the station still operational? Is NOAA still collecting this data? Or am I just being impatient?

But there's data from Barrow. This year is really different unprecedented methane emissions in the Arctic for all time observations (after 1984).

https://www.esrl.noaa.gov/gmd/dv/iadv/graph.php?code=BRW&program=ccgg&type=ts
« Last Edit: November 01, 2019, 08:06:07 PM by ArcticMelt2 »

ArcticMelt2

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Re: Arctic Methane Release
« Reply #1101 on: November 01, 2019, 08:03:06 PM »
I note that the summer of 2019 in Barrow was the warmest during observations:



This is further proof that every record in positive temperatures in the Arctic leads to a record of methane emissions.

I noted in a neighboring topic that this area of Alaska has some of the largest coal reserves in the world. Coal is buried in permafrost, and its melting causes methane to be released from the coal. Methane often explodes and kills the miners in the coal mines.

Bugalugs

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Re: Arctic Methane Release
« Reply #1102 on: November 01, 2019, 10:52:08 PM »
The Barrow NOAA methane data is bizarre.

I note that a spike is not appearing at other sites, yet.

A burp, or the beginning of feedback acceleration?

Ken Feldman

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Re: Arctic Methane Release
« Reply #1103 on: November 01, 2019, 11:47:37 PM »
The Barrow NOAA methane data is bizarre.

I note that a spike is not appearing at other sites, yet.

A burp, or the beginning of feedback acceleration?

Or a quality control issue?  Notice that the last few months of data are in orange which means they haven't been validated through quality control yet.

Quote
A smooth curve and long-term trend may be fitted to the representative measurements when sufficient data exist. Data shown in ORANGE are preliminary. All other data have undergone rigorous quality assurance and are freely available from GMD, CDIAC, and WMO WDCGG.

https://www.esrl.noaa.gov/gmd/dv/iadv/help/ccgg_details.html

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Warning: Preliminary data include the this group's most up-to-date data and have not yet been subjected to rigorous quality assurance procedures. Preliminary data viewed from this site are "pre-filtered" using tools designed to identify suspect values. Filtering is performed each time a data set containing preliminary data is requested. Filtering, however, cannot identify systematic experimental errors and will not be used in place of existing data assurance procedures. Thus, there exists the potential to make available preliminary data with systematic biases. In all graphs, preliminary data are clearly identified. Users are strongly encouraged to contact Dr. Pieter Tans, Group Chief (pieter.tans@noaa.gov) before attempting to interpret preliminary data.

kassy

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Re: Arctic Methane Release
« Reply #1104 on: November 02, 2019, 06:25:28 PM »
Basically all the orange is this year so they might only validate per year. If so i hope they do it in January.

I guess it´s a ´local burp´ and since the highest blue dot is only a bit lower then the highest orange dot and the process of measuring is automatic it probably will not change much after validation.

It is a logical progression from the rest of the series with last years conditions.

It´s a pity that we have no Tiksi data as Alumril noted.

PS: Alumril do you have any idea if there are russian sites with this sort of data?
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Lewis

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Re: Arctic Methane Release
« Reply #1105 on: November 04, 2019, 01:03:03 AM »
Igor Semiletov and 65 other scientists on board of a Russian vessel studying the Arctic waters have found that methane in the air over the ESS has up to nine times the global average, research also found that methane jets are shooting up from the seabed to the water’s surface.

https://www.cnn.com/2019/10/12/us/arctic-methane-gas-flare-trnd/index.html?no-st=1572824167

I’ve read some comments on this thread that methane doesn’t come up in the bubbles because due microorganisms eats most of the methane.

Has this understanding changed? Is there more methane being released now than in the past to the point that the microorganism are unable to consume most of the methane before it reaches the surface?

kassy

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Re: Arctic Methane Release
« Reply #1106 on: November 04, 2019, 02:55:23 PM »
I’ve read some comments on this thread that methane doesn’t come up in the bubbles because due microorganisms eats most of the methane.

It depends on the local circumstances. If the water column is very deep the methane will not reach the surface. The ESAS is very shallow so the methane comes up to the surface there. 

The change is not due to methane overwhelming microorganisms.
It is just a result of more warming in the area.

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Eastern Siberian Sea (ESS)
- The average open water for the year in the 1980's was circa 10 %. Since 2007 it has risen to over 20% in nearly all years.
- For the three minimum ice months Aug-Oct the open water percentage has risen from circa 15% for most of the 1980's to a highly variable 70% to 90% since 2007. In 2019 nearly 90%.
See post #2839 in the 2019 sea ice area and extent thread for the full version with graph.

This is a good start point:
Understanding the Permafrost–Hydrate System and Associated Methane Releases in the East Siberian Arctic Shelf
https://www.mdpi.com/2076-3263/9/6/251/htm
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Ken Feldman

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Re: Arctic Methane Release
« Reply #1107 on: November 05, 2019, 08:19:44 PM »
Igor Semiletov and 65 other scientists on board of a Russian vessel studying the Arctic waters have found that methane in the air over the ESS has up to nine times the global average, research also found that methane jets are shooting up from the seabed to the water’s surface.

https://www.cnn.com/2019/10/12/us/arctic-methane-gas-flare-trnd/index.html?no-st=1572824167

I’ve read some comments on this thread that methane doesn’t come up in the bubbles because due microorganisms eats most of the methane.

Has this understanding changed? Is there more methane being released now than in the past to the point that the microorganism are unable to consume most of the methane before it reaches the surface?

Lewis,

The most recent studies still support the fact that most methane is consumed by microbes as it migrates up through the unfrozen sediment that overlays the thawing permafrost layers.  (In some cases, the permafrost is hundreds of meters below the unfrozen sediment, so when you see estimates of huge amounts of methane in permafrost, keep that in mind).  And if the methane is released from areas deeper than 30 meters, it doesn't reach the surface due to chemical reactions with the water.

Here's a link to a pre-published discussion paper from July 2019.  It has a good overview of the current science about methane escape from the ESAS.

https://pdfs.semanticscholar.org/0745/b28231ab3a1a33c47362b03da21d519924ca.pdf

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Assessing the potential for non-turbulent methane escape from the East Siberian Arctic Shelf
Matteo Puglini, Victor Brovkin, Pierre Regnier, and Sandra Arndt

Abstract.

East Siberian Arctic Shelf (ESAS) hosts large, yet poorly quantified reservoirs of subsea permafrost and associated gas  hydrates.  It  has  been  suggested  the  global-warming  induced  thawing  and  dissociation  of  these  reservoirs  is  currently releasing methane to the shallow shelf ocean and ultimately the atmosphere. However, the exact contribution of permafrost thaw  and  methane  gas  hydrate  destabilization  to  benthic  methane  efflux  from  the  warming  shelf  and  ultimately  methane-climate feedbacks remains controversial. A major unknown is the fate of permafrost and/or gas hydrate-derived methane as it migrates towards the sediment-water interface. In marine sediments, (an)aerobic oxidation reactions generally act as extremely efficient biofilters that often consume close to 100% of the upward migrating methane. However, it has been shown that a number of environmental conditions can reduce the efficiency of this biofilter, thus allowing methane to escape to the overlying ocean. Here, we used a reaction-transport model to assess the efficiency of the benthic methane filter and, thus, the potential for permafrost and/or gas hydrate derived methane to escape shelf sediments under a wide range of environmental conditions encountered on East Siberian Arctic Shelf. Results of an extensive sensitivity analysis show that, under steady state conditions, anaerobic oxidation of methane (AOM) acts as an efficient biofilter that prevents the escape of dissolved methane from shelf sediments  for  a  wide  range  of  environmental  conditions.  Yet,  highCH4 escape  comparable  to  fluxes  reported  from  mud-volcanoes is simulated for rapidly accumulating (sedimentation rate>0.7cm yr−1) and/or active (active fluid flow>6cmyr−1) sediments and can be further enhanced by mid-range organic matter reactivity and/or intense local transport processes, such as bioirrigation. In active settings, high non-turbulent methane escape of up to 19μmolCH4cm−2yr−1can also occur during a transient, multi-decadal period following the sudden onset of CH4 flux triggered by, for instance, permafrost thaw or hydrate destabilization. This "window of opportunity" arises due to the time needed by the microbial community to build up an efficient AOM biofilter. In contrast, seasonal variations in environmental conditions (e.g. bottom water SO2−4,CH4 flux) exert a negligible effect on CH4 efflux through the Sediment-Water Interface (SWI). Our results indicate that present and future methane efflux from ESAS sediments is mainly supported by methane gas and non-turbulent CH4 efflux from rapidly accumulating and/or active sediments (e.g. coastal settings, portions close to river mouths or submarine slumps). In particular active sites on the ESAS may release methane in response to the onset or increase of permafrost thawing or CH4 gas hydrate destabilization rates. Model results also reveal that AOM generally acts as an efficient biofilter for upward migrating CH4 under environmental conditions that are representative for the present-day ESAS with potentially important, yet unquantified implications for the Arctic ocean’s alkalinity budget and, thus, CO2 fluxes. The results of the model sensitivity study are used as a quantitative framework to derive first-order estimates of non-turbulent, benthic methane efflux from the Laptev Sea. We find that, under present day conditions, AOM is an efficient biofilter and non-turbulent methane efflux from Laptev Sea sediments does not exceed 1 GgCH4yr−1. As a consequence, we state that previously published estimates of fluxes from ESAS water into atmosphere cannot be supported by non-turbulent methane escape from the sediments, but require the build-up and preferential escape of benthic methane gas from the sediments to the atmosphere that matches or even exceeds such estimated fluxes.

The "methane fountain" reported on in October was a very rare event.

https://siberiantimes.com/other/others/news/first-pictures-and-video-of-the-largest-methane-fountain-so-far-discovered-in-the-arctic-ocean/

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‘It was a needle in a haystack chase, to find an exact place of a methane seep in dark sea waters, but we found it!

Quote
‘This was the most powerful seep I have ever observed. No one has ever recorded anything similar’ said head of the expedition Igor Semiletov, who has participated in 45 Arctic expeditions.

And it was pretty small.

Quote
The area of the fountain covered about five metres,



Lewis

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Re: Arctic Methane Release
« Reply #1108 on: November 06, 2019, 05:25:29 AM »
Thanks Ken for your detailed explanation, appreciate it.
Kassy, thanks for your reply as well.

wdmn

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Re: Arctic Methane Release
« Reply #1109 on: January 14, 2020, 09:13:20 AM »
Climate gas budgets highly overestimate methane discharge from Arctic Ocean

https://phys.org/news/2020-01-climate-gas-highly-overestimate-methane.html

The atmospheric concentration of methane, a potent greenhouse gas, has almost tripled since the beginning of industrialisation. Methane emissions from natural sources are poorly understood. This is especially the case for emissions from the Arctic Ocean.

The Arctic Ocean is a harsh working environment. That is why many scientific expeditions are conducted in the summer and early autumn months, when the weather and the waters are more predictable. Most extrapolations regarding the amount of methane discharge from the ocean floor, are thus based on observations made in the warmer months.

"This means that the present climate gas calculations are disregarding the possible seasonal temperature variations. We have found that seasonal differences in bottom water temperatures in the Arctic Ocean vary from 1.7°C in May to 3.5°C in August. The methane seeps in colder conditions decrease emissions by 43 percent in May compared to August." says oceanographer Benedicte Ferré, researcher at CAGE Centre for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway.

"Right now, there is a large overestimation in the methane budget. We cannot just multiply what we find in August by 12 and get a correct annual estimate. Our study clearly shows that the system hibernates during the cold season."

...

How methane will react in future ocean temperature scenarios is still unknown. The Arctic Ocean is expected to become between 3°C and a whopping 13°C warmer in the future, due to climate change. The study in question does not look into the future, but focuses on correcting the existing estimates in the methane emissions budget. However:

"We need to calculate the peculiarities of the system well, because the oceans are warming. The system such as this is bound to be affected by the warming ocean waters in the future," says Benedicte Ferré. A consistently warm bottom water temperature over a 12-month period will have an effect on this system.

"At 400 meters water depth we are already at the limit of the gas hydrate stability. If these waters warm merely by 1.3°C this hydrate lid will permanently lift, and the release will be constant," says Ferré.

kassy

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Re: Arctic Methane Release
« Reply #1110 on: January 14, 2020, 03:41:32 PM »
"This means that the present climate gas calculations are disregarding the possible seasonal temperature variations. We have found that seasonal differences in bottom water temperatures in the Arctic Ocean vary from 1.7°C in May to 3.5°C in August. The methane seeps in colder conditions decrease emissions by 43 percent in May compared to August." says oceanographer Benedicte Ferré, researcher at CAGE Centre for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway.

"Right now, there is a large overestimation in the methane budget. We cannot just multiply what we find in August by 12 and get a correct annual estimate. Our study clearly shows that the system hibernates during the cold season."


This is so blindingly obvious that i don´t think anyone actually working out emissions ever just extrapolates from august.

Read the abstract to compare. They made it overly simple for the journalists or something like that.

Reduced methane seepage from Arctic sediments during cold bottom-water conditions
https://www.nature.com/articles/s41561-019-0515-3
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Re: Arctic Methane Release
« Reply #1111 on: January 14, 2020, 09:06:15 PM »
" We have found that seasonal differences in bottom water temperatures in the Arctic Ocean vary from 1.7°C in May to 3.5°C in August. The methane seeps in colder conditions decrease emissions by 43 percent in May compared to August.""


If I'm suppose to feel relieved that an increase in bottom water temperatures of less than 2C can increase methane emissions by 43%, I must be missing something.

Ken Feldman

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Re: Arctic Methane Release
« Reply #1112 on: January 22, 2020, 01:01:40 AM »
While the initial part of peer-reviewed science is to get your paper published in a peer-reviewed journal, it doesn't end there.  Once your paper is published, other scientists read and evaluate it and if they find mistakes, publish comments in the peer-reviewed journals.  Often, these comments don't get the same attention that the initial paper received.

For example the paper, "Understanding the Permafrost–Hydrate System and Associated Methane Releases in the East Siberian Arctic Shelf" by Shakhova, Semiletov and Chuvilin, (S2019), got a lot of press when it was published.  It's been linked to upthread and there were also several posts linking the video interview that Dr. Shakova gave when the paper was published.

To date, no one has linked to the comment on the paper that corrects several of the mistakes in S2019.  Here it is.

https://www.mdpi.com/2076-3263/9/9/384/htm 

Quote

Geosciences 2019, 9(9), 384; https://doi.org/10.3390/geosciences9090384
Comment
Comment on “Understanding the Permafrost–Hydrate System and Associated Methane Releases in the East Siberian Arctic Shelf”
by Brett F. Thornton 1,2,*, Marc C. Geibel 2,3,*, Patrick M. Crill 1,2, Christoph Humborg 2,3 and Carl-Magnus Mörth 1,2
1 Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden
2 Bolin Centre for Climate Research, 106 91 Stockholm, Sweden
3 Baltic Sea Centre, Stockholm University, 106 91 Stockholm, Sweden
*
Authors to whom correspondence should be addressed.
Received: 12 July 2019 / Accepted: 29 August 2019 / Published: 2 September 2019

  Abstract: The recent paper in Geosciences, “Understanding the Permafrost–Hydrate System and Associated Methane Releases in the East Siberian Arctic Shelf” by Shakhova, Semiletov, and Chuvilin, (henceforth “S2019”), contains a number of false statements about our 2016 paper, “Methane fluxes from the sea to the atmosphere across the Siberian shelf seas”, (henceforth “T2016”). S2019 use three paragraphs of section 5 of their paper to claim methodological errors and issues in T2016. Notably they claim that in T2016, we systematically removed data outliers including data with high methane concentrations; this claim is false. While we appreciate that flawed methodologies can be a problem in any area of science, in this case, the claims made in S2019 are simply false. In this comment, we detail the incorrect claims made in S2019 regarding T2016, and then discuss some additional problematic aspects of S2019.

Quote
Below are some additional concerns we have with S2019, not directly related to their discussion of T2016.

In the introduction, S2019 state: “This vast yet shallow region has recently been shown to be a significant modern source of atmospheric CH4, contributing annually no less than terrestrial Arctic ecosystems [19,20]”. Neither reference being cited here reports an annual emission flux of CH4 greater than that from terrestrial arctic ecosystems—which are dominated by wetlands. Arctic wetland emissions are estimated between 23–31 Tg of CH4 per year [13,14,15,16], exceeding the sea emission estimates provided in S2019’s references 19 and 20. Additionally, terrestrial Arctic ecosystem emissions include other freshwater systems, such that the total terrestrial CH4 emission easily exceeds the fluxes predicted in S2019’s references 19 and 20.

S2019 also state in the introduction that “Releases could potentially increase by 3–5 orders of magnitude, considering the sheer amount of CH4 preserved within the shallow ESAS seabed deposits and the documented thawing rates of subsea permafrost reported recently [22].” Reference 22 of S2019 does not support the assertion that ESAS CH4 releases could increase by 3–5 orders of magnitude, and the claim itself is unsupported and untenable. If we consider the largest “best estimate” of annual ESAS CH4 emission to the atmosphere published from Drs. Shakhova and Semiletov’s work [11], 17 Tg year−1, 3 orders of magnitude more is 17,000 Tg of CH4 per year, and five orders of magnitude is 1,700,000 Tg of CH4 per year, an absurd annual flux value, not only compared to the current annual emissions of CH4 from all sources (~555 Tg CH4 year−1, [17]), but the larger also vastly exceeds estimates of the entire global CH4 hydrate inventory (estimated at 1800 gigatonnes carbon, or ~239,400 Tg CH4) [18]. We also wonder if S2019 are conflating seawater-to-air fluxes with seafloor-to-seawater fluxes in this section. The text in S2019 is also unclear as to whether this postulated massive increase in flux applies to the entire ESAS, or some subsection, which is critical when determining how large future CH4 emissions might be. It may be helpful if S2019 reported their actual predicted flux, instead of a multiplication factor.

kassy

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Re: Arctic Methane Release
« Reply #1113 on: January 22, 2020, 06:13:50 PM »
Sometimes science can be annoying.  :)

Did not look into the first part.

Reference 22 of S2019 does not support the assertion that ESAS CH4 releases could increase by 3–5 orders of magnitude

I did actually miss the numbers for that too on the initial read.

The second bolded part is even more annoying. Because either someone screwed up or there is a severe miscommunication somewhere.

If we are really lazy and read orders of magnitude as doublings we get 68-17 is 51 Tg so nearly 10% extra on the global budget (which would go along with a rise from other sources).

I am not really interested in the maximum numbers (but i would not mind a more budget oriented paper).

Basically we know this methane release happens and it will increase as long as we increase our push.

And it will go together with the CO2 and CH4 wafting of the melting permafrost.

I am not looking toward future scenarios as much as seeing the current damage and thinking we should limit that. The old idea of preventing climate change was save the Arctic Sea Ice so in the long run Greenland would not melt too badly and the permafrost would remain a sink. And Antarctica would not be a thing ever.

So far we probably failed 1 no matter what we do, we will see what Ger reports about Greenland in the long term and probably arctic permafrost is already a net source not a sink.

And there is enough stuff happening in Antarctica.

This is not an isolated problem but just another feedback.
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kassy

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Re: Arctic Methane Release
« Reply #1114 on: February 05, 2020, 11:41:30 AM »
Less methane released from Arctic Ocean than previously believed

A new study, led by researchers at Stockholm university and published in Science Advances, now demonstrates that the amount of methane presently leaking to the atmosphere from the Arctic Ocean is much lower than previously claimed in recent studies.

...

A unique application of an established measurement technique

In their study, the researchers used direct measurements of the methane sea-to-air flux to determine how much methane is leaking from the eastern Arctic Ocean to the atmosphere. They used data from the 2014 SWERUS-C3 project, during which the Swedish icebreaker Oden crossed the eastern Arctic Ocean from Tromsø, Norway.

Although other researchers have calculated the sea-to-air flux before, this study used a unique measurement technique to measure the fluxes directly, and the authors believe their paper is the first to successfully apply this method from a ship. The reason the method has not been used before is that it requires measuring the gas concentration in the atmosphere very rapidly -- 10 times per second -- in addition to even faster measurements of the wind flow in three dimensions around the ship, and the precise location, acceleration and motion of the ship relative to the sea surface. Faster, smaller, accelerometers and inertial navigation units, similar to the chips which let smartphones know when you turn them sideways or upside down, as well as faster spectrometers for the methane measurement, and a detailed model of airflow around Oden, made this measurement possible.

"By understanding the airflow over the sea surface, and simultaneously measuring methane concentrations, we can determine how much methane is coming out of the ocean," explains researcher Brett Thornton at the Department of Geological Sciences, Stockholm University.

...

This new study shows that "hotspots" of methane emission from the sea can be up to 25 times higher than emissions from on-shore wetlands. These emissions are driven by bubbles coming from the seafloor and reaching the sea surface. This study directly observed very high peak emissions and, for the first time, was able to map their spatial extent.

"The peak emissions are indeed large but at the same time they are also extremely limited in area," says Brett Thornton.

Across the Laptev, East Siberian, and Chukchi seas the authors saw no evidence of widespread emissions at the magnitude of the "hotspots." In fact, their estimates for total methane emission from the eastern Arctic Ocean did not substantially increase even when they included these "hotspots" in the budget calculations.

"What this means is that -- at least at the time of our measurements -- the shallow eastern Arctic Ocean was not a huge source of methane to the atmosphere, and our understanding of Arctic sea emissions in the methane cycle is still reasonably correct.

https://www.sciencedaily.com/releases/2020/01/200130115433.htm


Shipborne eddy covariance observations of methane fluxes constrain Arctic sea emissions
https://advances.sciencemag.org/content/6/5/eaay7934

The Sverus data is from 2014.
I would like to see the same sort of measures taken again this year or sometime soon.
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vox_mundi

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Re: Arctic Methane Release
« Reply #1115 on: February 14, 2020, 05:08:09 PM »
NASA Flights Detect Millions of Arctic Methane Hotspots
https://www.jpl.nasa.gov/news/news.php?feature=7598

... In a new study, scientists with NASA's Arctic Boreal Vulnerability Experiment (ABoVE) used planes equipped with the Airborne Visible Infrared Imaging Spectrometer—Next Generation (AVIRIS—NG), a highly specialized instrument, to fly over some 20,000 square miles (30,000 square kilometers) of the Arctic landscape in the hope of detecting methane hotspots. The instrument did not disappoint.

"We consider hotspots to be areas showing an excess of 3,000 parts per million of methane between the airborne sensor and the ground," said lead author Clayton Elder of NASA's Jet Propulsion Laboratory in Pasadena, California. "And we detected 2 million of these hotspots over the land that we covered."

The paper, titled "Airborne Mapping Reveals Emergent Power Law of Arctic Methane Emissions," was published Feb. 10 in Geophysical Research Letters.

... Within the dataset, the team also discovered a pattern: On average, the methane hotspots were mostly concentrated within about 44 yards (40 meters) of standing bodies of water, like lakes and streams. After the 44-yard mark, the presence of hotspots gradually became sparser, and at about 330 yards (300 meters) from the water source, they dropped off almost completely.

The scientists working on this study don't have a complete answer as to why 44 yards is the "magic number" for the whole survey region yet, but additional studies they've conducted on the ground provide some insight.

"After two years of ground field studies that began in 2018 at an Alaskan lake site with a methane hotspot, we found abrupt thawing of the permafrost right underneath the hotspot," said Elder. "It's that additional contribution of permafrost carbon—carbon that's been frozen for thousands of years—that's essentially contributing food for the microbes to chew up and turn into methane as the permafrost continues to thaw."



Clayton D. Elder et al. Airborne Mapping Reveals Emergent Power Law of Arctic Methane Emissions, Geophysical Research Letters (2020)
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kassy

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Re: Arctic Methane Release
« Reply #1116 on: March 31, 2020, 09:12:39 AM »
Intensity of past methane release measured with new, groundbreaking methods

A novel approach to geochemical measurements helps scientists reconstruct the past intensity of the methane seeps in the Arctic Ocean. Recent studies show that methane emissions fluctuated, strongly, in response to known periods of abrupt climate change at the end of the last glacial cycle.

"Previously, when dating the natural release of methane, we used to measure mostly carbon isotopes. But now we know that carbon isotopes alone can't tell us the full story of past emissions of this greenhouse gas." says professor Giuliana Panieri, from CAGE Centre for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway.

...

The study in Scientific Reports highlights the potential of sulfur isotopic signature (δ34S) in foraminifera, as a novel tool for reconstructing the intensity of CH4 emissions in geological records. This can also, indirectly, help date the release.

"This is the first time that sulfur isotopes are measured in foraminiferal shells from methane seeps. The samples were collected from a well-known site of present-day methane release, Vestnesa Ridge. Here, gas has been seeping into the ocean at least from the Last Glacial Maximum: some 20,000 to 5,000 years ago." says Panieri.

"How did methane in the sub-seabed respond to previous global warmings? Was it merely bubbling up, or was it released in a constant and abrupt jet, strongly emitted into the water column?"

These questions are important in the provinces of large gas hydrate accumulations, such as Vestnesa Ridge.

...

"The combination of carbon, oxygen, and sulfur isotopes found in foraminifera allows us to reconstruct the flux of methane released in the geological past. This represents a fundamental advancement in studies of past climate. It offers the opportunity to study the connection between methane seepage, climate, and underlying tectonic processes with a new degree of confidence." Says Chiara Borrelli, first author of the study and researcher at Department of Earth and Environmental Sciences, University of Rochester, USA.

"Our study shows that there was a strong methane fluctuation at the sampling site, responding to known periods of abrupt cooling and warming, at the end of the last glacial cycle."

...

 However, the traces of oxygen isotopic signature δ18O in benthic foraminifera can, as shown in a newly published study by Dessandier et al. in Geo-Marine letters.

"If we have a large amount of δ18O in the foraminiferal shells, we can say that the source of methane is the gas hydrate dissociation," says Panieri, who also co-authored this paper.

"We found a significant enrichment of δ18Oin all foraminifera samples characterized by depleted δ13C. These results mainly come from the precipitation of authigenic carbonates around the foraminiferal shells, so-called secondary overgrowth. These methane-derived carbonates are characterized by a heavy oxygen isotopic signature. This signature can only be explained by dissociation of gas hydrates because gas hydrates are naturally enriched in 18O due to their ice-like physical properties." according to Pierre-Antoine Dessandier, a postdoc at CAGE and first author of the study.

...

"Consider secondary overgrowth on foraminiferal shells: It is a minuscule carbonate deposit. Before CAGE it was considered to be a contaminant in the samples. But new technology opens new doors. We have discovered that the presence of the secondary overgrowth in itself is an indicator of methane release. Something that previously was considered an interference, and caused samples to be thrown out with the thrash, is, in reality, an unknown book, containing enormous amounts of information in itself." says Panieri.

https://www.sciencedaily.com/releases/2020/03/200330093427.htm

The benthic foraminiferal δ34S records flux and timing of paleo methane emissions (OA)
https://www.nature.com/articles/s41598-020-58353-4
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kassy

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Re: Arctic Methane Release
« Reply #1117 on: April 18, 2020, 02:07:33 PM »
A repost from ASLR followed by some more quotes from the article.

As the topic is highly controversial, I tend not to post very often in this thread about the risk of potential methane bursts from the East Siberian Arctic Shelf, ESAS.  Nevertheless, I provide the following hyperlink (& short extract) to a Counterpunch article on this topic:

Title: "The Rumbling Methane Enigma"

https://www.counterpunch.org/2020/01/17/the-rumbling-methane-enigma/

Extract: "The northern continental shelves of Russia, inclusive of the Barents Sea, Kara Sea, Laptev Sea and East Siberian Sea (ESAS) are some of the least researched yet most controversial subjects in climate science today. It’s the one region that has the biggest potential to trigger runaway global warming because of sizeable subsea methane deposits, thereby taking civilization down to its knees. But, that prospect is also extremely controversial within the scientific community.

Scientific opinion runs the gamut: (1) high risk- methane bursts will bury civilization with runaway global warming – a dreadful, deadly risk (2) not to worry, it’s low risk because almost all of the massive deposits of undersea methane will stay put (3) not to worry, low risk because any methane seepage via undersea permafrost is oxidized and dissolves within the seawater and not a threat to runaway global warming.

By and large, climate scientists dismiss the ESAS and some go so far as to vilify published research. In fact, the Intergovernmental Panel on Climate Change (IPCC) dismisses its near-term/intermediate-term risks. The reasons are manifold (more on that later).

Unfortunately, recent events in the high Arctic lean towards option number one as the more likely outcome. In that regard, I recently met with Dr. Peter Wadhams, world-renowned Arctic expert, to discuss the issue (more on that follows)."

As it happens, only recently, inordinately high levels of methane emissions have been reported, to wit:

(1) Methane Observation – October 2019 -“This is the most powerful seep I have ever been able to observe… No one has ever recorded anything similar.” (Source: Research Vessel Encounters Giant Methane Seep in Arctic Waters, The Maritime Executive, Oct. 10, 2019) The quote is from Igor Semiletov, professor Tomsk Polytechnic University on the research vessel Academic M.A. Lavrentyev on a 40-day Arctic mission.

(2) Methane Observation – December 2019 – Three months later at COP25 in Madrid, Dr. Peter Carter, an IPCC expert reviewer, in an interview d/d December 10th, 2019, referenced an ongoing eruption of methane above Barrow, Alaska, saying: “We’ve never seen anything like it. And, it has stayed at elevated levels to the present week. Looking at the 2.2 million year ice core, the maximum methane concentration ever was 800 ppb. In Barrow, Alaska it is 2,050 ppb and staying there. It’s been up there for 4 months.”

A note about the Barrow observation – Dr. Peter Carter believes the origin may be permafrost decay from land. However, according to Dr. Wadhams, he’s not so sure of Carter’s explanation and even though the waters offshore Barrow are not known to contain subsea methane, it is theorized the 4-month extremely high CH4 reading may have originated at ESAS and drifted, a theory with forceful negative ramifications.

The Barrow Atmospheric Baseline Observatory was established in 1973 by NOAA (National Oceanic and Atmospheric Administration) Earth System Research Laboratory to track hourly methane readings.

According to initial reports by NOAA re the sharp uptick in CH4 readings to 2050 ppb: “To spot methane levels breaking the 2000ppb mark so sharply in this fragile region is unprecedented.” (Source: Arctic Methane Levels Reach New Heights, The Institution of Engineering and Technology, September 16, 2019)

(3) Methane Observation – Dahr Jamail’s book The End of Ice (The New Press, 2019) relates an ominous story of methane bubbling at Barents Sea. In Barrow, Alaska, he met Ira Leifer, a scientist who studies the shallow seas of the Arctic and works with NASA on methane data. Leifer discovered wicked SOS signals coming from a 620 square mile area of the Barents Sea jam-packed with methane bubbles at the rate of 60 million plumes, which is almost impossible to fathom as the normal background rate should be thousands, not 60 million.

...

When the subject of methane and the Siberian continental shelves came up, I recalled his cautionary statement in A Farewell to Ice:

“We must remember— many scientists, alas, forget—that it is only since 2005 that substantial summer open water has existed on Arctic shelves, so we are in an entirely new situation with a new melt phenomenon taking place.” (Wadhams, pg. 123)

Read the whole thing on:

https://www.counterpunch.org/2020/01/17/the-rumbling-methane-enigma/
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Freegrass

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Re: Arctic Methane Release
« Reply #1118 on: April 18, 2020, 04:15:32 PM »
Hi Kassy. I thinks that's one of the best articles about arctic methane I read in a long time. Thanks for that! It's probably the most important question for the world that few are asking... What about the methane?

Quote
Postscript: “First, the probability of this pulse happening is high, at least 50 percent according to the analysis of sediment composition by those best placed to know what is going on, Natalia Shakhova and Igor Semiletov. Moreover, if it happens, the detrimental effects are gigantic… the risk of an Arctic seabed methane pulse is one of the greatest immediate risks facing the human race… Why then are we doing nothing about it? Why is this risks ignored by climate scientists, and scarcely mentioned in the latest IPCC assessment? It seems to be not just climate change deniers who wish to conceal the Arctic methane threat, but also many Arctic scientists, including so-called ‘methane experts.” (Wadhams, pg. 127-28)
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Re: Arctic Methane Release
« Reply #1119 on: April 18, 2020, 05:48:40 PM »
A repost from ASLR followed by some more quotes from the article.


Scientific opinion runs the gamut: (1) high risk- methane bursts will bury civilization with runaway global warming – a dreadful, deadly risk (2) not to worry, it’s low risk because almost all of the massive deposits of undersea methane will stay put (3) not to worry, low risk because any methane seepage via undersea permafrost is oxidized and dissolves within the seawater and not a threat to runaway global warming.
No #3 is rubbish.
The ESAS is so shallow that methane bubbles are largely intact when reaching the surface.

Even in deeper water the statement is not always true. The stronger the seepage, the bigger the bubbles. Oxidation attacks the surface of the bubble. The bigger the bubble, the greater the ratio of volume to surface area (V = 4/3 πr³.  A=4πr2). So the bigger the bubble, the less gets oxidised on its way to the surface.

Also an awful lot of the studies related to seepage a considerable ocean depths, and from that conclude that methane release from the oceans is not a problem. Some time ago I seem to remember A-Team getting hot under the collar about this bias.

No #2 will become more likely to be rubbish as the Arctic coastal fringes (e.g. the shores of the ESS) are open water for longer and warmth (even direct solar radiation) attacks the frozen sea bed.
« Last Edit: April 19, 2020, 12:38:11 AM by gerontocrat »
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Ken Feldman

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Re: Arctic Methane Release
« Reply #1120 on: April 20, 2020, 09:03:28 PM »
A repost from ASLR followed by some more quotes from the article.


Scientific opinion runs the gamut: (1) high risk- methane bursts will bury civilization with runaway global warming – a dreadful, deadly risk (2) not to worry, it’s low risk because almost all of the massive deposits of undersea methane will stay put (3) not to worry, low risk because any methane seepage via undersea permafrost is oxidized and dissolves within the seawater and not a threat to runaway global warming.
No #3 is rubbish.
The ESAS is so shallow that methane bubbles are largely intact when reaching the surface.

Even in deeper water the statement is not always true. The stronger the seepage, the bigger the bubbles. Oxidation attacks the surface of the bubble. The bigger the bubble, the greater the ratio of volume to surface area (V = 4/3 πr³.  A=4πr2). So the bigger the bubble, the less gets oxidised on its way to the surface.

Also an awful lot of the studies related to seepage a considerable ocean depths, and from that conclude that methane release from the oceans is not a problem. Some time ago I seem to remember A-Team getting hot under the collar about this bias.

No #2 will become more likely to be rubbish as the Arctic coastal fringes (e.g. the shores of the ESS) are open water for longer and warmth (even direct solar radiation) attacks the frozen sea bed.

Bubbles that reach the surface are constrained to a relatively small area.

https://advances.sciencemag.org/content/advances/6/5/eaay7934.full.pdf

Quote
Shipborne eddy covariance observations ofmethane fluxes constrain Arctic sea emissions
Thornton et al., Sci. Adv. 2020; 6 : eaay7934     29 January 2020

We  demonstrate  direct  eddy  covariance  (EC)  observations  of  methane  (CH4)  fluxes  between  the  sea  and  atmo-sphere from an icebreaker in the eastern Arctic Ocean. EC-derived CH4 emissions averaged 4.58, 1.74, and 0.14mg m−2day−1 in the Laptev, East Siberian, and Chukchi seas, respectively, corresponding to annual sea-wide fluxes of 0.83, 0.62, and 0.03 Tg year−1. These EC results answer concerns that previous diffusive emission estimates, which ex-cluded bubbling, may underestimate total emissions. We assert that bubbling dominates sea-air CH4 fluxes in only small constrained areas: A ~100-m2 area of the East Siberian Sea showed sea-air CH4 fluxes exceeding 600mg m−2day−1; in a similarly sized area of the Laptev Sea, peak CH4 fluxes were ~170mg m−2 day−1. Calculating additional emissions below the noise level of our EC system suggests total ESAS CH4 emissions of 3.02 Tg year−1, closely matching an earlier diffusive emission estimate of 2.9 Tg year

Freegrass

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Re: Arctic Methane Release
« Reply #1121 on: April 20, 2020, 09:12:23 PM »
When methane dissolves in the water, doesn't that cause the ocean water to become more acidic?
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Ken Feldman

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Re: Arctic Methane Release
« Reply #1122 on: April 20, 2020, 10:12:59 PM »
When methane dissolves in the water, doesn't that cause the ocean water to become more acidic?

Absorption of carbon dioxide from the atmosphere is responsible for much more of the acidification.  Recent measurements have CO2 at about 415 ppm whereas methane's concentration is less than 2 ppm.

Here's a recent paper on Arctic Ocean acidification.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL086421

Quote
Two Decades of Ocean Acidification in the Surface Waters of the Beaufort Gyre, Arctic Ocean: Effects of Sea Ice Melt and Retreat From 1997–2016
Y. Zhang, M. Yamamoto‐Kawai, W.J. Williams
First published: 15 January 2020

 Abstract

Anthropogenic CO2 uptake drives ocean acidification and so decreases the calcium carbonate (CaCO3) saturation state (Ω). Undersaturation of surface water with respect to aragonite‐type CaCO3 was first reported for 2008 in the Canada Basin, preceding other open ocean basins. This study reveals interannual variation of Ω in the surface Canada Basin before and after 2008. A rapid decrease of Ω occurred during 2003–2007 at a rate of −0.09 year−1, 10 times faster than other open oceans. This was due to melting and retreat of sea ice, which diluted surface water and enhanced air‐sea CO2 exchange. After 2007, Ω did not further decrease, despite increasing atmospheric CO2 and continued sea ice retreat. A weakened dilution effect from sea ice melt and stabilized air‐sea CO2 disequilibrium state is the main reason for this stabilization of Ω. Aragonite undersaturation has been observed for the last 11 years, and aragonite‐shelled organisms may be threatened.


Ken Feldman

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Re: Arctic Methane Release
« Reply #1123 on: April 20, 2020, 10:37:21 PM »
Hi Kassy. I thinks that's one of the best articles about arctic methane I read in a long time. Thanks for that! It's probably the most important question for the world that few are asking... What about the methane?

Quote
Postscript: “First, the probability of this pulse happening is high, at least 50 percent according to the analysis of sediment composition by those best placed to know what is going on, Natalia Shakhova and Igor Semiletov. Moreover, if it happens, the detrimental effects are gigantic… the risk of an Arctic seabed methane pulse is one of the greatest immediate risks facing the human race… Why then are we doing nothing about it? Why is this risks ignored by climate scientists, and scarcely mentioned in the latest IPCC assessment? It seems to be not just climate change deniers who wish to conceal the Arctic methane threat, but also many Arctic scientists, including so-called ‘methane experts.” (Wadhams, pg. 127-28)

The "information" in this article has been debunked repeatedly over the years.  Skeptical science, an excellent source for information on climate change, addressed this topic in a video at this link:

https://skepticalscience.com/methane-time-bomb-how-big-concern.html

And here is a recent Popular Science article explaining that relatively recent episodes of warming released very little methane from permafrost.

Quote
But there’s more to understanding methane, as another recent study points out. In a paper published mid-February in Science, researchers analyzed Antarctic ice cores from between 18,000 and 8,000 years ago—the period in which the Earth was warming back up after the last ice age. Using pockets of air in the ice, they could quantify the gases present in the atmosphere during that period. They looked for methane free of the radioactive carbon-14 isotope, which is naturally present in living and recently decayed material, but is lost as that organic matter ages. Because permafrost contains very old carbon, methane formed from it typically has virtually no carbon-14. If the air bubbles contained this type of methane, that would indicate that the deglaciation period experienced a permafrost-caused methane boom.

But most of the methane in the ice core samples did contain C-14, which means it came from sources other than permafrost and other old carbon stores. From that period of warming, in which the Arctic got to be a little warmer than it is today, the researchers concluded that very little methane from permafrost was released.

Isaac Vimont, a carbon cycle researcher at NOAA’s Earth System Research Laboratory and co-author of the study, says the results suggest that we might not see the global warming-caused methane explosion that other studies have pointed to. “To a certain extent, we can say that these old carbon reservoirs [like permafrost] will stay stable,” says Vimont. “Going forward, we don’t know.” If temperatures keep rising past those observed in the last deglaciation, we might still have methane surprises in store.

Vimont and his colleagues offer one explanation for how their assessment landed at a different conclusion. While some microbes essentially breathe out methane in waterlogged environments, other organisms eat methane and breathe out carbon dioxide. In this way, not all of the methane that gets released actually ends up in the atmosphere. Some studies have documented this process in seeps of methane from the Arctic seafloor. “Old methane release occurs much slower than the pace of modern climate change,” writes Joshua Dean, biogeochemist at the University of Liverpool, in an article accompanying the Science study. “This is because methane is a rich source of energy within ecosystem food webs.”

Certainly, there will be—and currently is—some methane release. But it might not be significant compared to other sources of methane, like the production and burning of natural gas.

It will be interesting to see if the current shut ins of oil and gas wells has an impact on methane emissions.


kassy

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Re: Arctic Methane Release
« Reply #1124 on: April 20, 2020, 11:01:48 PM »
When methane dissolves in the water, doesn't that cause the ocean water to become more acidic?

No.

It is the CO2 which does that and actually gets added to the oceans over time since we dump so much into the atmosphere. CO2 makes more H+ when it reacts with water and methane does not react in that way.

With the methane the issue is how much escapes the water. Methane from deep non arctic sinks does not make it to the atmosphere but i think it mainly gets used up by all kinds of ocean critters.

For acidification see post #527 and follow up posts:
https://forum.arctic-sea-ice.net/index.php/topic,77.500.html

PS: Ken i would say it is an ongoing debate. The Barrow data is not that comforting.

In the grand scheme of things this does not matter because if you want to minimize the methane effect (whatever the scale) you need to address our CO2 output. Putting extra pressure on your local government to regulate methane emissions from unprofitable and environment destroying industries might help too because every little bit helps.

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Re: Arctic Methane Release
« Reply #1125 on: April 20, 2020, 11:46:20 PM »
The linked article discusses NASA's new 3D visualization tool for better understanding methane sources (both anthropogenic and natural).  In our current non-stationary climate change situation, I am not comforted by the fact that high-latitude regions are currently only responsible for about 20% of global methane emissions (with 70% of this 20% coming from natural sources); because this percentage will likely increase in the future:

Title: "New 3D View of Methane Tracks Sources and Movement around the Globe"

https://www.nasa.gov/feature/goddard/2020/new-3d-view-of-methane-tracks-sources-and-movement-around-the-globe

Extract: "The Arctic and high-latitude regions are responsible for about 20% of global methane emissions. “What happens in the Arctic, doesn’t always stay in the Arctic,” Ott said. “There’s a massive amount of carbon that’s stored in the northern high latitudes. One of the things scientists are really concerned about is whether or not, as the soils warm, more of that carbon could be released to the atmosphere. Right now, what you’re seeing in this visualization is not very strong pulses of methane, but we’re watching that very closely because we know that’s a place that is changing rapidly and that could change dramatically over time.”"
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Freegrass

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Re: Arctic Methane Release
« Reply #1126 on: April 20, 2020, 11:55:54 PM »
When methane dissolves in the water, doesn't that cause the ocean water to become more acidic?

No.

It is the CO2 which does that and actually gets added to the oceans over time since we dump so much into the atmosphere. CO2 makes more H+ when it reacts with water and methane does not react in that way.

With the methane the issue is how much escapes the water. Methane from deep non arctic sinks does not make it to the atmosphere but i think it mainly gets used up by all kinds of ocean critters.
Thanks for the reply Kassy. I just used the Google Machine and found this article from 2010, and it confirms that "ocean critters" do consume the methane, but the waste they produce is CO2, and this causes acidification.


Quote
During anaerobic oxidation of methane in the sediment the microbes use sulphate (SO42–), the salt of sulphuric acid that is present in large quantities in sea water, for the methane decomposition. In this process methane is converted to bicarbonate (HCO3–). If the bicarbonate reacts further with calcium ions (Ca2+) in the seawater, calcium carbonate (CaCO3) precipitates, which remains stored in the sea floor over long periods of time. That would be the ideal situation, because it would make the potent greenhouse gas methane (CH4) harmless. At the same time, hydrogen sulphide (H2S) is produced from the sulphate, which provides energy to chemosynthetic communities, including symbiotic clams and tubeworms. During aerobic oxidation in the water column, however, bacteria break down methane with the help of oxygen (O2). In this process, carbon dioxide is produced, which dissolves in the water. Carbon dioxide contributes to ocean acidification. Furthermore, aerobic oxidation of methane consumes oxygen. The depletion of oxygen in the water column could create or expand oxygen minimum zones in the ocean, which are a threat for fishes and other sensitive organisms. Rough estimates suggest that anaerobic and aerobic oxidation of methane together currently convert around 90 per cent of the methane produced in the sea floor before it can reach the atmosphere. The more slowly methane migrates through the sea floor or through the water column, the more effective the microbes are in converting it.


https://worldoceanreview.com/en/wor-1/ocean-chemistry/climate-change-and-methane-hydrates/
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Ken Feldman

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Re: Arctic Methane Release
« Reply #1127 on: April 20, 2020, 11:57:44 PM »
Recent research (the linked articles were published in February and March this year) indicates that bacterial consumption and peatland growth will offset expected methane release from permafrost.

http://www.eaps.purdue.edu/ebdl/pdfs/Oh2020NCC.pdf

Quote
Reduced net methane emissions due to microbial methane oxidation in a warmer Arctic
Oh, Y., Zhuang, Q., Liu, L. et al.
Nat. Clim. Chang. 10, 317–321 (2020). https://doi.org/10.1038/s41558-020-0734-z

Methane emissions from organic-rich soils in the Arctic have been  extensively  studied  due  to  their  potential  to  increase  the   atmospheric   methane   burden   as   permafrost   thaws1–3. However, this methane source might have been overestimated without   considering   high-affinity   methanotrophs   (HAMs;   methane-oxidizing bacteria) recently identified in Arctic min-eral  soils4–7.  Herein  we  find  that  integrating  the  dynamics  of  HAMs  and  methanogens  into  a  biogeochemistry  model8–10that includes permafrost soil organic carbon dynamics3 leads to the upland methane sink doubling (~5.5 Tg CH4 yr−1) north of 50 °N in simulations from 2000–2016. The increase is equiva-lent to at least half of the difference in net methane emissions estimated  between  process-based  models  and  observation-based  inversions11,12,  and  the  revised  estimates  better  match  site-level   and   regional   observations5,  7,13–15.   The   new   model   projects doubled wetland methane emissions between 2017–2100 due to more accessible permafrost carbon16–18. However, most of the increase in wetland emissions is offset by a con-cordant  increase  in  the  upland  sink,  leading  to  only  an  18%  increase in net methane emission (from 29 to 35 Tg CH4 yr−1). The  projected  net  methane  emissions  may  decrease  further  due  to  different  physiological  responses  between  HAMs  and  methanogens in response to increasing temperature19,20

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG005501

Quote
Long‐term Impacts of Permafrost Thaw on Carbon Storage in Peatlands: Deep Losses Offset by Surficial Accumulation
Liam Heffernan, Cristian Estop‐Aragonés, Klaus‐Holger Knorr, Julie Talbot, David Olefeldt
First published: 19 February 2020

 Abstract

Peatlands in northern permafrost regions store a significant proportion of global soil carbon. Recent warming is accelerating peatland permafrost thaw and thermokarst collapse, exposing previously frozen peat to microbial decomposition and potential mineralization into greenhouse gases. Here, we show from a site in the sporadic‐discontinuous permafrost zone of western Canada that thermokarst collapse leads to neither large losses nor gains following thaw, as deep carbon losses are offset by surficial accumulation. We collected peat cores along two thaw chronosequences, from peat plateau, through young (~30 years since thaw), intermediate (~70 years), and mature (~200 years) thermokarst bog locations. Macrofossil and 14C analysis showed synchronicity of peatland development until recent thaw, with wetland initiation ~8,500 cal yr BP followed by succession through peatland stages prior to permafrost aggradation ~1,800 cal yr BP. Analysis and modeling of soil carbon stocks indicated 8.7 ± 12.4 kg C m−2 of carbon accumulated prior to thaw was lost in ~200 years post‐thaw. Despite these losses, there was no observed increase in peat humification as assessed by Fourier transform infrared and C:N ratios. Rapid peat accumulation post‐thaw (9.8 ± 1.6 kg C m−2 over 200 years) offset deeper losses. Our approach constrains the net carbon balance to be between uptake of 27.3 g C m−2 yr−1 and loss of 106.6 g C m−2 yr−1 over 200 years post‐thaw. While our approach cannot determine whether thermokarst bogs in the sporadic‐discontinuous permafrost zone act as long‐term carbon sinks or sources post‐thaw, our study better constrains post‐thaw C losses and gains.

Freegrass

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Re: Arctic Methane Release
« Reply #1128 on: April 21, 2020, 12:14:56 AM »
I think this could be a more serious problem for the Arctic Ocean, no?
Quote
The depletion of oxygen in the water column could create or expand oxygen minimum zones in the ocean, which are a threat for fishes and other sensitive organisms.
Have there been studies on this? Could increased methane release create dead zones in the Arctic ocean?
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Re: Arctic Methane Release
« Reply #1129 on: April 21, 2020, 12:42:03 AM »
I think this could be a more serious problem for the Arctic Ocean, no?
Quote
The depletion of oxygen in the water column could create or expand oxygen minimum zones in the ocean, which are a threat for fishes and other sensitive organisms.
Have there been studies on this? Could increased methane release create dead zones in the Arctic ocean?

https://phys.org/news/2010-12-undersea-methane-contributor-ocean-acidity.html
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Ken Feldman

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Re: Arctic Methane Release
« Reply #1130 on: April 21, 2020, 12:49:44 AM »
I think this could be a more serious problem for the Arctic Ocean, no?
Quote
The depletion of oxygen in the water column could create or expand oxygen minimum zones in the ocean, which are a threat for fishes and other sensitive organisms.
Have there been studies on this? Could increased methane release create dead zones in the Arctic ocean?

The studies that have been done show that sub-sea methane seeps increase biological productivity and act as overall carbon sinks. Here's a recent study from February 2020.  It references several other studies in the sections I've quoted below.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JG005387

Quote
Development, Productivity, and Seasonality of Living Planktonic Foraminiferal Faunas and Limacinahelicinain an Area of Intense Methane Seepage in the Barents Sea
Siri Ofstad, Julie Meilland, Katarzyna Zamelczyk, Melissa Chierici, Agneta Fransson, Friederike Gründger, Tine L. Rasmussen
First published: 09 February 2020

Although the plankton communities in the Barents Sea have been intensely studied for decades, little is known about the living planktonic foraminiferal (LPF) and pteropod faunas, especially those found at methane seep sites. Along a repeated transect in the “crater area” (northern Barents Sea, 74.9°N, 27.7°E) in spring and summer 2016 the flux of LPF and of the pteropod species Limacina helicina showed a high degree of variability. The LPF had low concentration (0–6 individuals m−3) and small tests (x̄ = 103.3 μm) in spring and a 53‐fold increase (43–436 individuals m−3) and larger tests (x̄ = 188.6 μm) in summer. Similarly, the concentration of L. helicina showed a tenfold increase between spring and summer. The LPF species composition remained stable with the exception of the appearance of subtropical species in summer. No relationship was observed between the spatial distribution of LPF, L. helicina, and methane concentrations in the area. The methane plumes in April coincided with elevated dissolved inorganic carbon, low pH, and calcium carbonate saturation states, and the methane concentration seemed to be controlled by lateral advection. The δ13C and δ18O of Neogloboquadrina pachyderma and Turborotalita quinqueloba are comparable to previous observations in the Arctic and do not show any influence of methane in the isotopic signals of the shells. Although no evidence of direct impact of high methane concentrations on the LPF (size and concentration) were found, we speculate that methane could indirectly enhance primary productivity, and thus biomass, through several potential pathways.

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In the Arctic, gas hydrate provinces are widespread on the continental shelves (Damm et al., 2005; Graves et al., 2015; Mau et al., 2017; Pisso et al., 2016; Sapart et al., 2017; Shakhova et al., 2010; Westbrook et al., 2009) and are stable under low temperature and high pressure, this stability is threatened under the current climate warming trend. At present, little of the methane (CH4) from the gas hydrate provinces reach the atmosphere (Graves et al., 2015; Pisso et al., 2016; Silyakova et al., 2015). Instead, the CH4 from Arctic subsurface marine hydrate reserves is either anaerobically or aerobically oxidized in the upper layers of the sediments or in the water column by microbial activity (Boetius & Wenzhöfer, 2013; Ruppel & Kessler, 2017). In the water column, microbial aerobic oxidation (MOX) and the less common AOM (anaerobic oxidation of methane) are sinks for CH4; both processes remain poorly understood (Reeburgh, 2013). Following the release of CH4 from the seafloor, these water column processes can change the manner of impact of the CH4 release. For example, model studies have shown that, through the MOX reaction, CH4 seepage is a potential source of CO2, which can increase ocean acidification (Biastoch et al., 2011; Archer et al., 2008). It has also been hypothesized that CH4 seepage can cause an increase in photosynthetic primary production (Pohlman et al., 2017), making CH4 seepage areas CO2 sinks. There have been several studies in the Arctic focusing on the effects of CH4 seepage on the living benthic communities (Åström et al., 2016, 2018, 2019; Sen, Duperron, et al., 2018, Sen et al., 2019), including living benthic foraminifera, although not exclusive to the Arctic region (Heinz et al., 2005; Herguera et al., 2014; Hill et al., 2004; Rathburn et al., 2000). However, no studies from the Arctic exist that examine the effects of CH4 seepage on the pelagic ecosystem.

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5.4 The Effect of Methane on Productivity and LPF Biomass

Methane seep ecosystems are unique, because they host chemosynthesis‐based communities resulting in an “oasis effect” on the seafloor, due to enhanced macrofaunal biomass and diversity in comparison to nearby nonseep environments (Åström et al., 2018; Levin, 2005; Levin et al., 2016; Sibuet & Olu, 1998; Sibuet & Olu‐Le Roy, 2002; Thomsen et al., 2019). At the crater area, numerous frenulate siboglinid worms, the dominant chemosymbiotrophic megafauna in high latitude seeps, and chemosynthetic bacterial mats are recorded (Sen, Duperron, et al., 2018). The impact of CH4 seepage on benthic productivity and biomass in the Arctic is clear (Åström et al., 2018, 2019), but an effect on the ecosystem in the overlying water column is unknown. Aggregations of various demersal fish have been found at CH4 seeps around the world, although the cause of this remains unclear (Åström et al., 2019; Bowden et al., 2013; Grupe et al., 2015; Sellanes et al., 2008; Sen, Aström, et al., 2018). We hypothesize that planktonic organisms may behave in the same manner in that they aggregate above seeps.

The hypothesis that CH4 seepage enhances primary production and hence biomass in the water column has been discussed previously in the literature (e.g., D'Souza et al., 2016; Pohlman et al., 2017; Rakowski et al., 2015). Enhanced primary production and CO2 uptake has been reported at a site off the west coast of Spitsbergen, which is also characterized by high CH4 flux from the seafloor (Pohlman et al., 2017). The mechanism, which causes this enhancement, is, however, unknown. One of the hypotheses is that the physical bubbling of CH4 gas from the seafloor may cause an upwelling of nutrient rich waters. This mechanism may be present even at depths exceeding 1,000 m, particularly if gas plumes are strong and extend high into the water column (D'souza et al., 2016; Leifer et al., 2009). It is feasible that this upwelling effect of nutrient‐rich water, and therefore an enhancement of photosynthetic primary production, also occurs at the crater area where the water depth is only 370 m and intense gas seepage with CH4 bubble streams up to 200 m height were observed (Andreassen et al., 2017).

In addition to the physical bubbling mechanism, potential chemical pathways that could link CH4 seepage and photosynthetic primary production exist as well. Further evidence to support the links between CH4 and planktonic biomass was found in a subterranean estuary ecosystem. It was shown that shrimps were feeding on CH4‐derived carbon (Brankovits et al., 2017). Methane‐derived carbon could be added to the water column by two mechanisms; first through bubble stripping, which entails gas exchange of CO2 from CH4 bubbles (Vielstädte et al., 2015), and second by CO2 production as a result of active microbial MOX (equation 1). An addition of CO2 into the water column may lead to an increase in primary production if nutrient levels are sufficient (Engel et al., 2013). The hypothesis that CO2 is added to the water column by gas exchange from CH4 bubbles is supported by the elevated DIC and AT in the CH4 plumes in April, relative to the surrounding water (Figures 2d and 2e). In April, the pH, ΩAr, and ΩCa are lower in the plumes than in the surrounding water, likely due to a net CO2 addition from the CH4 plumes (Figures 2f and 2g). In June, the high DIC values in waters just above the seafloor are no longer confined in plumes and has likely been accumulating and dispersing since April (Figure 3d). Since AT is relatively constant between the seasons, CO2 has most likely caused the elevated DIC. MOX data from June (Figure 4c) show 14 times higher rates compared to rates measured at another Arctic CH4 seepage location at Storfjorden, east of Spitzbergen (Mau et al., 2013). It could therefore be possible that plankton are feeding on carbon sourced from methanotrophic bacteria.

Freegrass

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Re: Arctic Methane Release
« Reply #1131 on: April 21, 2020, 01:30:55 AM »

Defusing the Methane Greenhouse Time Bomb

Could methane-digesting bacteria and an Arctic cap of fresh water prevent a climate catastrophe?
By Christopher Mims on February 5, 2010

Methane trapped in Arctic ice (and elsewhere) could be rapidly released into the atmosphere as a result of global warming in a possible doomsday scenario for climate change, some scientists worry. After all, methane is 72 times more powerful as a greenhouse gas than carbon dioxide over a 20-year timescale. But research announced at the annual meeting of the American Geophysical Union this December suggests that marine microbes could at least partially defeat the methane "time bomb" sitting at the bottom of the world's oceans.

The conventional wisdom for decades has been that methane emanating from the seafloor could be consumed by a special class of bacteria called methanotrophs. It has long been known, for instance, that these organisms at the bottom of the Black Sea consume methane produced in its deep oxygen-free waters.

What has not been clear is whether these bacteria would be of any use in the event that a special class of ice at the bottom of the ocean is destabilized by a warmer climate. This ice, known as clathrates, or methane hydrates, consists of a cage of water molecules surrounding individual molecules of methane, and it exists under conditions of low temperature and high pressure. These conditions can be found on the continental shelf the world over, but there is an extra large quantity of seafloor suitable for methane hydrates in the Arctic because of its low temperatures and a seafloor plateau that happens to be at the optimum depth for clathrate formation. The Arctic also happens to be more vulnerable to climate change because parts of the poles are warming at least twice as fast as the rest of the world.

To investigate this Arctic ice more carefully, Scott Elliott, a biogeochemist at Los Alamos National Laboratory, used the Coyote supercomputer to model the complex interplay of physical and biological systems that govern the fate of methane released from Arctic clathrates during the first few decades of projected future global warming.

Elliott's model includes the activity of methanotrophs. In accordance with conventional wisdom, his virtual bacteria can keep up with small to medium-size failures of the clathrates and subsequent releases of methane gas. As the "burps" of methane increase in size in response to warming seas, however, his model also shows that in some areas of the Arctic, the methanotrophs could potentially run out of the nutrients required to metabolize methane, including oxygen, nitrate, iron and copper.

But, even if the methanotrophs in the Arctic run out of the nutrients required to digest methane—especially if the waters in which they normally live become anoxic (low in the oxygen modern life-forms need to survive)—a second phenomenon demonstrated in Elliott's models may yet prevent methane from percolating all the way to the surface of the ocean, and then into the atmosphere.

"It happens that the Arctic Ocean is capped with a relatively fresh layer of seawater," Elliott says. Freshwater from the many rivers that empty into the Arctic float atop the denser ocean brine. In Elliott's simulations, methane hits this fresh water "cap" and cannot escape into the atmosphere. Instead, it "hangs out in the Arctic Ocean until it flows out into the deep, abyssal Atlantic Ocean," Elliott says. "The time constants in deep oceans are many hundreds of years—that's long enough for methanotrophs to consume all the methane. The model says that right now we have multiple layers of security."

Elliot cautions that there is a large degree of uncertainty in the results generated by his model, which is the first attempt ever made to incorporate the biological activity of methanotrophs into a regional climate model.

Vincent Gauci, lecturer in Earth systems and ecosystem science at The Open University in England, agrees that the uncertainties in the model prevent it from being used to conclude whether or not the methane released from deep-sea clathrates will enter the atmosphere, especially in the event of a "catastrophic submarine slope failure," in which large volumes of clathrate spontaneously collapse and release their stored methane. This is an outrageously complex problem," Elliott says.

Dave Valentine, associate professor of microbial geochemistry at the University of California, Santa Barbara, who heard Elliott's talk, notes that paleoclimatologists have yet to definitively answer whether or not there is evidence that methane from clathrates ever reached the atmosphere in the past, which would support the conclusions of Elliott's model. University of Chicago geophysicist David Archer's The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate (Princeton University Press, 2008), notes that the "jury is still out" on what the role was, if any, of destabilizing methane hydrates in past global warming events and mass extinctions.

Even if methane doesn't reach the atmosphere, Elliott's model suggests it could still have dire effects on the Arctic environment: As it is oxidized by methanotrophs, it will acidify the Arctic Ocean and turn the water into a anoxic "dead zone" analogous to the oxygen-free dead zones that show up in the Gulf of Mexico every year as a result of farmland fertilizer runoff carried by the Mississippi River. "It would mean those nutrients [oxygen] are not available to other organisms," Elliott says. "In other words, maybe we're safe, but other organisms are not."

On a local level these changes would be equal to or even greater than the acidification of the ocean that is already occurring because of rising levels of atmospheric carbon dioxide. "It would be a very serious environmental issue—but regional, not global," Elliott says.

Future iterations of Elliott's model will have to include a class of methane-digesting bacteria not included in its first version, says Rick Colwell, an Oregon State University marine microbiologist specializing in methanotrophs who attended a recent presentation by Elliott. These yet-to-be-modeled bacteria operate only in anaerobic conditions that are usually found only in ocean sediments. If conventional, oxygen-dependent methanotrophs deplete the water column of oxygen, it could create conditions favorable for anaerobic methane-digesting bacteria to carry on the work of digesting the methane—flopping these parts of the ocean back to conditions that last prevailed 250 million years ago, during the most devastating mass extinction ever to befall life on Earth.

University of Washington in Seattle paleontologist Peter Ward has hypothesized that this event, known as the Great Dying, was the result of runaway global warming that turned the majority of the world's oceans anoxic throughout their entire depths, leading to a large release of hydrogen sulfide gas, a by-product of the metabolism of anaerobic bacteria. Elliott would not speculate whether or not the phenomena he modeled could have been part of that event, which in Ward's hypothesis was most likely caused by a different source of carbon all together: CO2 vented from massive volcanic eruptions in a region that is now part of Siberia.

"You could refer to these [anaerobic methane-eating bacteria] as a 'biofilter'—they would consume some of the methane that is moving into the water," Colwell says. Already, he adds, these bacteria perform this role in anoxic environments like the depths of the Black Sea.

Also, recent results from the Svalbard Islands north of Norway suggest that methane may not always rise from the water column in the way that Elliott's model assumes. In most models, including Elliott's, methanotrophs in the water were able to digest methane because it diffused into the water. Around Spitsbergen, however, 250 plumes rising from the bottom of the ocean included large bubbles which could ascend much higher up the water column before dispersing, increasing the danger that they could reach the atmosphere intact.

Ultimately, Elliott says, he and his team cannot eliminate the possibility that methanotrophs in the Arctic could be overwhelmed by large burps of methane gas from clathrates. Valentine speculates that the limiting nutrient will be oxygen, but Elliott's model raises some other potentially interesting possibilities.

When asked whether or not fertilizing the Arctic Ocean with some of the missing nutrients that could enhance the productivity of methanotrophs, such as iron, Elliott speculates that "I would bet that someone will very soon discuss the potential for engineering this situation. This becomes an opportunity for the geoengineering types to become creative."

https://www.scientificamerican.com/article/defusing-the-methane-time-bomb/
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Ken Feldman

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Re: Arctic Methane Release
« Reply #1132 on: April 21, 2020, 08:00:24 PM »
There was a lot of speculation about a potential "methane time bomb" or "methane clathrate gun" in the mid-2000s and early 2010s.  Both of the alarmist articles posted here recently are from 2010.

Additional research this decade showed that a potential massive release of methane clathrates is physically impossible based on the thermodynamic properties of hydrates and the physical location of methane hydrates in permafrost zones.  Here's a review paper from 2016 summarizing many studies of methane hydrate dissociation.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016RG000534

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The interaction of climate change and methane hydrates
Carolyn D. Ruppel, John D. Kessler
First published: 14 December 2016
https://doi.org/10.1002/2016RG000534

 Abstract

Gas hydrate, a frozen, naturally‐occurring, and highly‐concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low‐temperature and moderate‐pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane and methane‐derived carbon that escape from sediments and soils and reach the atmosphere could exacerbate greenhouse warming. The synergy between warming climate and gas hydrate dissociation feeds a popular perception that global warming could drive catastrophic methane releases from the contemporary gas hydrate reservoir. Appropriate evaluation of the two sides of the climate‐methane hydrate synergy requires assessing direct and indirect observational data related to gas hydrate dissociation phenomena and numerical models that track the interaction of gas hydrates/methane with the ocean and/or atmosphere. Methane hydrate is likely undergoing dissociation now on global upper continental slopes and on continental shelves that ring the Arctic Ocean. Many factors—the depth of the gas hydrates in sediments, strong sediment and water column sinks, and the inability of bubbles emitted at the seafloor to deliver methane to the sea‐air interface in most cases—mitigate the impact of gas hydrate dissociation on atmospheric greenhouse gas concentrations though. There is no conclusive proof that hydrate‐derived methane is reaching the atmosphere now, but more observational data and improved numerical models will better characterize the climate‐hydrate synergy in the future.

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The remaining ~1% or more of global gas hydrates occurs in high northern latitude permafrost areas [McIver, 1981; Ruppel, 2015], both onshore beneath tundra (e.g., Russia, Canada, and the U.S.) and on continental shelves on circum‐Arctic Ocean margins whose permafrost has been inundated by sea level rise since ~15 ka [e.g., Kvenvolden, 1993; Lachenbruch et al., 1982; Rachold et al., 2007]. The shallowest permafrost‐associated gas hydrates (PAGH) are predicted to lie a few hundred meters deep but still within the permafrost zone (Figure 4a). For permafrost that is several hundreds of meters thick, gas hydrate should also be stable beneath the base of permafrost, depending on the prevailing geothermal gradient. Many PAGH formed by a process that can be described in the vernacular as “freezing in place” of gaseous CH4 that has presumably migrated to shallower depths from underlying conventional gas reservoirs containing thermogenic gas [Collett et al., 2011; Judge and Majorowicz, 1992; Ruppel, 2015].

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The fundamental impact of climate‐related changes on the gas hydrate reservoir is relatively straightforward, but several points bear mentioning: First, the gas hydrate reservoir tends to be viewed as relatively static during periods of climate stability or in certain settings (e.g., deep oceans). In fact, gas hydrates near the BGHS are nearly always undergoing dissociation due to normal sedimentation, small perturbations in pressure, and propagation of past temperature changes to depth [e.g., Dickens, 2001a]. Second, the impact of past climate change events is often used to frame how the gas hydrate reservoir may respond to future climate change. As noted by Archer and Buffett [2005], the predicted changes associated with anthropogenically‐driven global warming may be far larger than those of many past climate events, affecting even the stability of deep ocean hydrates. Finally, just as snow piles do not instantaneously melt on a hot day, gas hydrate dissociation is also not instantaneous merely because pressure or temperature conditions in the sediments lie outside those required for hydrate stability. The endothermic heat of reaction (~439 J g−1 of methane hydrate) [Gupta et al., 2008] hinders rapid dissociation and makes the dissociation process self‐regulating [Circone et al., 2005]. Without the delivery of additional heat to the hydrate deposits, a scenario of runaway dissociation (dissociation that self‐perpetuates once initiated) is unlikely.

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In the shallow marine sedimentary section, the strongest biochemical sink is the anaerobic oxidation of methane (AOM) [Barnes and Goldberg, 1976; Martens and Berner, 1977; Reeburgh, 1976], which is carried out by a consortium of microbes [Knittel and Boetius, 2009] and is strongly coupled to sulfate reduction [e.g., Malinverno and Pohlman, 2011], particularly in diffusion‐dominated provinces lacking additional hydrocarbon sources [Joye et al., 2004]. The sulfate reduction zone (SRZ) occupies the centimeters to meters just below the seafloor, with a thicker SRZ corresponding to areas of lower upward methane flux [Borowski et al., 1997]. The microbial consortium that carries out AOM [Boetius et al., 2000] has been termed a biofilter that prevents upwardly‐migrating CH4 from reaching the seafloor, where it could be emitted to the ocean. A summary by Reeburgh [2007] concluded that up to 80% to 90% of the estimated 400 Tg yr−1 CH4 that reaches the SRZ via upward migration through the sediments is consumed by AOM [Hinrichs and Boetius, 2003]. At sites with vigorous seepage, AOM has sometimes been found to be highly efficient [Joye et al., 2004], while only about 20% of the CH4 is consumed by AOM at other locations [Boetius and Wenzhofer, 2013]. The reduced efficiency of AOM in some higher flux settings leads to the possibility that rapidly ascending gas in the form of bubbles may bypass the sediment biofilter [e.g., Martens and Klump, 1980] and be injected into the overlying ocean without major alteration by the AOM sediment sink.

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The physical characteristics of marine sediments also constitute a type of sink for CH4 released from dissociating gas hydrates. These physical sinks do not transform CH4 in the way that AOM does, but they can prevent it from interacting with the ocean‐atmosphere system for thousands of years. The most important physical factors are those that impede the migration of methane through the sedimentary section. Examples include low‐permeability sediments, structural traps, and hydrate‐ and/or gas‐saturated sediments that impede fluid advection [e.g., Bhatnagar et al., 2007; Chatterjee et al., 2014; Davies and Clarke, 2010; Davies et al., 2014; Garg et al., 2008; Liu and Flemings, 2007; Nimblett and Ruppel, 2003].

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Once CH4 is emitted at the seafloor, two major factors may prevent its reaching the atmosphere. First, despite methane's low solubility in seawater [Wiesenburg and Guinasso, 1979], the concentrations of CH4 in most ocean waters are still so low that the gas diffuses rapidly from rising CH4‐filled bubbles following emission at the seafloor. During this bubble‐stripping process, CH4 is replaced by oxygen and nitrogen [McGinnis et al., 2006; Vielstädte et al., 2015]. Bubbles emitted deeper than the shallowest extent of gas hydrate stability in the water column may develop an armor of gas hydrate [Chen et al., 2014, 2016; Graves et al., 2015; Rehder et al., 2002, 2009; Sauter et al., 2006; Topham, 1984; Wang et al., 2016; Warzinski et al., 2014; Zhang, 2003], but such armoring may or may not reduce the rate at which CH4 leaves the rising bubbles [Rehder et al., 2002; Wang et al., 2016]. Overall, most CH4 emitted from the seafloor either above or below the top of the GHSZ and whether originating with gas hydrate dissociation or other processes will be dissolved relatively deep in the water column.

As an example, for 50% of the CH4 contained in the bubble at the seafloor to reach the atmosphere requires 14 and 20 mm diameter bubbles to be emitted at 50 and 100 m water depths, respectively, and even larger bubbles at greater water depths. (Figure 8a). While quantification of bubble sizes at marine seeps is in its infancy, the bubble sizes measured to date are far smaller than would be necessary to ensure that CH4 reaches the atmosphere [e.g., Römer et al., 2012; Skarke et al., 2014; Wang et al., 2016]. Once dissolved in ocean waters, CH4 can eventually be emitted to the atmosphere by gas exchange, which can be enhanced by certain conditions (e.g., high winds and storminess [Shakhova et al., 2014; Wanninkhof, 1992]). In deeper waters, CH4 could remain in the oceans for centuries, depending on the nature of ocean circulation and the depth below the surface mixed layer at which the CH4 is dissolved.

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Bubble stripping and the water column oxidation sink may prevent much of the CH4 emitted at the seafloor from reaching the sea‐air interface, but these processes could still potentially have an important impact on ocean chemistry and habitats. As noted above, aggressive oxidation following massive CH4 releases can deoxygenate waters and deplete certain chemical species while also increasing dissolved CO2 that could enhance acidification [e.g., Archer et al., 2009; Biastoch et al., 2011; Dickens, 2001a; Elliott et al., 2011; Kessler et al., 2011]. Outside of semienclosed anoxic basins, typical CH4 concentrations range from 2 to 300 nM [Heintz et al., 2012; Mau et al., 2013; Rona et al., 2015], while the background concentrations of dissolved CO2 and dissolved inorganic carbon (DIC) are approximately 30 μM and 2260 μM, respectively. The 4 to 6 orders of magnitude difference between dissolved methane concentration and DIC concentration suggests that even complete oxidation of CH4 emitted at the seafloor from natural seeps will have an insignificant influence on inorganic carbon chemistry and, by extension, seawater pH, unless CH4 and CH4‐derived DIC can substantially accumulate in seawater.

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Gas hydrates associated with subsea permafrost lie in water‐covered areas, but they have some characteristics that distinguish them from both marine gas hydrates and their terrestrial PAGH counterparts. As noted above, marine gas hydrates cannot form in the contemporary ocean beneath waters shallower than ~300 to 600 m. However, PAGH that now lie offshore on high‐latitude continental shelves are in sediments covered by a maximum of 100 to 120 m of water. This adds up to ~1 MPa of additional hydrostatic pressure, may cause formation of new gas hydrate near the top of the stability zone, and serves as a slightly stabilizing influence offsetting the profound destabilization caused by warming of the sedimentary section during and after inundation. Dissociating gas hydrates associated with subsea permafrost liberate CH4 that is subject to the full suite of marine sedimentary and water column sinks that affect marine gas hydrates [Overduin et al., 2015; Thornton and Crill, 2015]. However, sulfate, which is necessary for marine sedimentary AOM sink processes, may not fully intrude sediments inundated only since ~15 ka, and the shallow water depths mean that gas emitted at the seafloor is more likely to reach the sea surface before bubble stripping [McGinnis et al., 2006], CH4 dissolution, and/or microbial oxidation can have a large mitigating impact. As in other settings, CH4 liberated from dissociating gas hydrates at depth must also navigate overlying sediments to reach the seafloor. In addition, ice‐related processes have contributed to the widespread development of indurated (low‐permeability) sediments that could be particularly effective at trapping CH4 beneath some Arctic Ocean shelves.

Like other PAGH, those that ended up within submerged shelves are unlikely to be widely distributed or sequester large amounts of CH4 [Ruppel, 2015]. Some researchers do infer large amounts of PAGH beneath arctic continental shelves (e.g., 35 Gt C in hydrate beneath the Laptev Sea shelf) [Shakhova et al., 2010a], but several assumptions used in making this estimate may not fully account for the complexity of PAGH systems. Shakhova et al. [2010a] also invoked anomalous shallow gas hydrates beneath the East Siberian Arctic shelf as a potential CH4 source and to explain elevated estimates of CH4 sequestered in gas hydrates. This area was not glaciated at the LGM, as is usually required for shallow gas hydrates to occur, and the origin and existence of possible anomalous gas hydrate deposits remain controversial and require further examination.

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On the contemporary Earth, gas hydrate is dissociating in specific terrains in response to post‐LGM climate change and probably also due to warming since the onset of the Industrial Age. Nevertheless, there is no conclusive proof that the released methane is entering the atmosphere at a level that is detectable against the background of ~555 Tg yr−1 CH4 emissions. The IPCC estimates are not based on direct measurements of methane fluxes from dissociating gas hydrates, and many numerical models adopt simplifications that do not fully account for sinks, the actual distribution of gas hydrates, or other factors, resulting in probable overestimation of emissions to the ocean‐atmosphere system. The new generation of models based on ocean circulation dynamics holds the greatest promise for robustly predicting the fate of gas hydrates under climate change scenarios [Kretschmer et al., 2015] and could be improved further with better incorporation of sinks.

At high latitudes, the key factors contributing to overestimation of the contribution of gas hydrate dissociation to atmospheric CH4 concentrations are the assumption that permafrost‐associated gas hydrates are more abundant and widely distributed than is probably the case [Ruppel, 2015] and the extrapolation to the entire Arctic Ocean of CH4 emissions measured in one area. Appealing to gas hydrates as the source for CH4 emissions on high‐latitude continental shelves lends a certain exoticism to the results but also feeds catastrophic scenarios. Since there is no proof that gas hydrate dissociation plays a role in shelfal CH4 emissions and several widespread and shallower sources of CH4 could drive most releases, greater caution is necessary.


SteveMDFP

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Re: Arctic Methane Release
« Reply #1133 on: April 21, 2020, 09:07:22 PM »
Future iterations of Elliott's model will have to include a class of methane-digesting bacteria not included in its first version, says Rick Colwell, an Oregon State University marine microbiologist specializing in methanotrophs who attended a recent presentation by Elliott. These yet-to-be-modeled bacteria operate only in anaerobic conditions that are usually found only in ocean sediments. If conventional, oxygen-dependent methanotrophs deplete the water column of oxygen, it could create conditions favorable for anaerobic methane-digesting bacteria to carry on the work of digesting the methane—flopping these parts of the ocean back to conditions that last prevailed 250 million years ago, during the most devastating mass extinction ever to befall life on Earth.

University of Washington in Seattle paleontologist Peter Ward has hypothesized that this event, known as the Great Dying, was the result of runaway global warming that turned the majority of the world's oceans anoxic throughout their entire depths, leading to a large release of hydrogen sulfide gas, a by-product of the metabolism of anaerobic bacteria. Elliott would not speculate whether or not the phenomena he modeled could have been part of that event, which in Ward's hypothesis was most likely caused by a different source of carbon all together: CO2 vented from massive volcanic eruptions in a region that is now part of Siberia.

I think this is the real problem with increasing amounts of methane seep from the sea floor.  The trouble only starts with the methane dissolving in the water column.  Aerobic bacteria consume both the methane and oxygen to produce CO2.  This CO2 acidification is probably minor in comparison to the effects of elevated atmospheric CO2, but it doesn't help.

Consumption of oxygen by this route only adds to increasing ocean hypoxia from other causes.  In regions where the water is devoid of oxygen, anaerobic bacteria continue to oxidize methane, using sulfate as an oxygen donor.  The sulfate is thus transformed to hydrogen sulfide, highly toxic to fish.  Yes, this is a leading contender for the cause of the "Great Dying."  See "Canfield ocean."

If large amounts of hydrogen sulfide are released into the atmosphere, terrestrial animals and plants start dying.  I think this will be how humanity ends, along with most sea life and mammalian life globally.  We may already be degraded to a stone age existence by then, from other environmental destruction.

This could be a reasonable problem for geoengineering to solve.  Use wind turbine power to pump air into the ocean depths.  This has been done in hypoxic fresh water lakes, to some apparent benefit.    I can probably find again a research article or two.  Lake aeration, as I recall.

All this could easily happen without any methane seeps.  But increased methane seeps could greatly accelerate the mass extinction.

Freegrass

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Re: Arctic Methane Release
« Reply #1134 on: April 21, 2020, 11:25:49 PM »
If large amounts of hydrogen sulfide are released into the atmosphere, terrestrial animals and plants start dying.  I think this will be how humanity ends, along with most sea life and mammalian life globally.
Dude... By then we'll all be living in space, and no human will care about whats going on on the planet...  ;)
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Re: Arctic Methane Release
« Reply #1135 on: May 14, 2020, 02:56:35 PM »
Igor Semiletov and 65 other scientists on board of a Russian vessel studying the Arctic waters have found that methane in the air over the ESS has up to nine times the global average, research also found that methane jets are shooting up from the seabed to the water’s surface.

https://www.cnn.com/2019/10/12/us/arctic-methane-gas-flare-trnd/index.html?no-st=1572824167

I’ve read some comments on this thread that methane doesn’t come up in the bubbles because due microorganisms eats most of the methane.

Has this understanding changed? Is there more methane being released now than in the past to the point that the microorganism are unable to consume most of the methane before it reaches the surface?

Crazy and right now the ESS is being cooked way way way early with melt ponds already forming and the weather forecast calls for wall to wall sun for another week.

This is also with the thinnest ice on record over the entirety of the ESS.

April thickness was between 1.75-2M while historically it's typically 2.5-3M.

On top of that all of May as a final month for ice thickening is already not only lost but the start of melting at the surface (snow) has started.

If June sees warm sun the ESS will likely melt out completely before August 1st leaving unprecedented open water for insolation to hammer.

When the seabed is mostly 7/8-20M in depth even the 30-35° solar attitude can warm down to the sea bed.
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Alumril

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Re: Arctic Methane Release
« Reply #1136 on: June 01, 2020, 01:03:32 PM »
interesting update on methane release from Arctic permafrost


vox_mundi

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Re: Arctic Methane Release
« Reply #1137 on: June 05, 2020, 04:20:55 PM »
New Study Reveals Cracks Beneath Giant, Methane Gushing Craters
https://cage.uit.no/2020/06/03/new-study-reveals-cracks-beneath-giant-methane-gushing-craters/


Craters found on the seafloor of the Barents Sea are up to a kilometer wide and 35 meters deep. They are still leaking methane

A paper published in Science in 2017 described hundreds of massive, kilometer-wide craters on the ocean floor in the Barents Sea. Today, more than 600 gas flares have been identified in and around these craters, releasing the greenhouse gas steadily into the water column. Another study, published the same year in PNAS, mapped several methane mounds, some 500 meters wide, in the Barents Sea. The mounds were considered to be signs of impending methane expulsions that created the craters.

The most recent study in Scientific Reports looks into the depths far beneath these craters in the ocean floor and reveals the geological structures that have made the area prone to crater formation and subsequent methane expulsions.

"It turns out that this area has a very old fault system—essentially, cracks in bedrock that likely formed 250 million years ago," says Malin Waage, a postdoc at CAGE, Centre for Arctic Gas Hydrate, Environment and Climate, and the first author of the study. "Craters and mounds appear along different fault structures in this system. "These structures control the size, placement and shape of the craters. The methane that is leaking through the seafloor originates from these deep structures and is coming up through these cracks."



"Our previous studies in the area hypothesized that climate warming and the retreat of the ice sheet some 20,000 years ago caused the gas hydrates beneath the ice to melt, leading to abrupt methane release and creating craters," said Waage.

"This study, however, adds several layers to that picture, as we now see that there has been a structural weakness beneath these giant craters for much longer than the last 20,000 years. Deep below the seafloor, the expansion of gas and release of water built up a muddy slurry that eventually erupted through the fractures and caused seafloor collapses and craters in the hard bedrock. Think of it as a building: The roof of a building can cave in if the ground structure is weak. We believe that this is what happened in the crater area after the last glaciation," says Waage.



Some of the questions that scientists pursue: Will these weak structures lead to unpredictable and explosive methane release? Can such release and related geohazards be triggered by drilling? And can the gas reach the atmosphere in the case of abrupt blow-outs, adding to the greenhouse gas budget?

Waage, M. et.al. Geological controls of giant crater development on the Arctic seafloor, Scientific Reports, May 2020.
https://www.nature.com/articles/s41598-020-65018-9
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longwalks1

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Re: Arctic Methane Release
« Reply #1138 on: June 05, 2020, 09:34:40 PM »
Ms. Waage had a very nicepresentation on the pingos with several other young Norsk presenters previously.  I was impressed.  For the life of me I can not find it via the web.  However a search of her name here and voila,  a post by AbruptSLR from 2016 and then in 2017

https://forum.arctic-sea-ice.net/index.php/topic,2067.msg116187.html#msg116187    post 11. 

Their faces gave me a pause, but possibly stage fright and English is a second language played a part.  Sadly the video has been removed and I did not store  via youtube-dl.   

Gray-Wolf

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Re: Arctic Methane Release
« Reply #1139 on: June 12, 2020, 04:43:09 PM »
New Study Reveals Cracks Beneath Giant, Methane Gushing Craters
https://cage.uit.no/2020/06/03/new-study-reveals-cracks-beneath-giant-methane-gushing-craters/




These 'pre-existing Faults' have always had me a tad concerned esp. as the complex moves inland into the permafrost?

If 'free Methane' is finding 'previously blocked' pathways through the complex of faults then areas can be becoming pressurised by the added migration?

If permafrost degradation is leading to the weakening of 'caps' over free methane reserves then this methane could surely take only 2 main pathways? One, via leakage directly into the layers above and Two, migration into existing reserves via interconnecting fault lines?
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morganism

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Re: Arctic Methane Release
« Reply #1140 on: July 27, 2020, 03:29:29 AM »

Discovery Of First Active Seep In Antarctica Provides New Understanding Of Methane Cycle

http://astrobiology.com/2020/07/discovery-of-first-active-seep-in-antarctica-provides-new-understanding-of-methane-cycle.html

"Antarctica is believed to contain as much as 25 percent of Earth's marine methane. Having an active seep to study gives researchers new understanding of the methane cycle and how that process might differ in Antarctica compared to other places on the planet, Thurber said.

For example, researchers have found that the most common type of microbe that consumes methane took five years to show up at the seep site and even then those microbes were not consuming all of the methane, Thurber said. That means some methane is being released and is likely working its way into the atmosphere. "

An expansive microbial mat, about 70 meters long by a meter across, formed on the sea floor about 10 meters below the frozen ocean surface. These mats, which are produced by bacteria that exist in a symbiotic relationship with methane consumers, are a telltale indication of the presence of a seep, said Thurber.

"The microbial mat is the road sign that there's a methane seep here," Thurber said. "We don't know what caused these seeps to turn on. We needed some dumb luck to find an active one, and we got it."

glennbuck

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Re: Arctic Methane Release
« Reply #1141 on: July 28, 2020, 01:55:06 PM »
This raised the possibility that the source of the methane was the cyanobacteria themselves. To find out, Bizic and colleagues collected and cultured cyanobacterial strains from the lake and a variety of other natural sources, and monitored methane production of each culture via mass spectrometry for several days. The team showed that, of the five freshwater strains, two soil strains, and six marine strains of cyanobacteria they analyzed, all produced methane.

https://www.the-scientist.com/news-opinion/blue-green-algae-produce-methane-66971

Is there large amounts of algae in the Arctic Summer and has it been growing more in recent years?

morganism

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Re: Arctic Methane Release
« Reply #1142 on: July 29, 2020, 03:51:00 AM »

morganism

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Re: Arctic Methane Release
« Reply #1143 on: August 01, 2020, 11:07:13 PM »
Oceanic and atmospheric methane cycling in the cGENIE Earth system model

"we find that simulated atmospheric methane levels and marine dissolved methane distributions are generally in good agreement with empirical constraints for the modern and recent Earth. Finally, we illustrate the model's utility in understanding the time-dependent behavior of the methane cycle resulting from transient carbon injection into the atmosphere, and present model ensembles that examine the effects of oceanic chemistry and the thermodynamics of microbial metabolism on steady-state atmospheric methane abundance."

https://arxiv.org/abs/2007.15053


morganism

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Re: Arctic Methane Release
« Reply #1144 on: August 01, 2020, 11:49:56 PM »
New study confirms extensive gas leaks in the North Sea

"The positions of the boreholes and the location and extent of the gas pockets indicate that this area of the North Sea alone has the potential to emit 900 to 3700 tonnes of methane every year. 'However, more than 15,000 boreholes have been drilled in the entire North Sea,'

"In the North Sea, about half of the boreholes are at such shallow water depths that part of the emitted methane can escape into the atmosphere."

https://www.geomar.de/en/news/article/neue-studie-bestaetigt-umfangreiche-gasleckagen-in-der-nordsee