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Author Topic: Arctic Methane Release  (Read 108189 times)

longwalks1

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Re: Arctic Methane Release
« Reply #250 on: August 11, 2016, 12:46:28 AM »
I have gone through the paper once so far. 

 Free on the above site is the supporting information with illos of the land versus sea sector acquisition paths and a small graph with some topography information.  It is worth a glance if you are interested. 

"Near" continuous data.  The site went off line in 2012 after pretty standard gas chromatography was used for decades with one minor change to update and upgrade equipment.  I will have to look up the two latest technologies used, first was  "cavity ring-down spectrometer" and the second was an "off-axis integrated cavity output spectrometer".  So the recent new trend of a longer season of ground outgassing with slightly higher values, especially in the late fall is also accompanied by a gap in data and then different instrumentation and then another different instrumentation.   

The air intake sampling height is 16 meters.  Although the up wind slope of the Land Sector between 150 to 210 degrees is probably slight (via a cursory look at googlemaps) for about 100 km, it probably does rise.  Although my methane sampling experience was very different and much lower tech, using a hydrogen flame - I would not find a small leak of natural gas sampled from below a meter set as fast or reliably as from above.  I do believe that fairly valid data is possible, I will investigate diffusion and rise for methane for my own edification.  A higher sampling stack would probably be hard to maintain in that environment. 

I should look up whether or not they have other papers on emissions from the other directions. The oil and gas input might be tricky as looked at in the map.  However the sea values should be even easier to compile than the land values. 

My quibbles apart, it is good news.  Rare these days. 
 

AbruptSLR

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Re: Arctic Methane Release
« Reply #251 on: August 17, 2016, 11:22:56 AM »
The linked article indicates that more methane leaks from the permafrost during the cold months than previously thought:


http://www.climatechangenews.com/2016/01/06/arctic-methane-emissions-greater-than-previous-estimates/


Extract: “The quantity of methane leaking from the frozen soil during the long Arctic winters is probably much greater than climate models estimate, scientists have found.
They say at least half of annual methane emissions occur in the cold months from September to May, and that drier, upland tundra can emit more methane than wetlands.
The multinational team, led by San Diego State University (SDSU) in the US and including colleagues from the National Oceanic and Atmospheric Administration, and the University of Sheffield and the Open University in the UK, have published their conclusion, which challenges critical assumptions in current global climate models, in the Proceedings of the National Academy of Sciences."
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longwalks1

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Re: Arctic Methane Release
« Reply #252 on: August 18, 2016, 04:16:51 AM »

Here is what appears to be the original article for reply #251 concerning methane release during the cold season. 

http://www.pnas.org/content/113/1/40.abstract?sid=36140e33-589e-4e88-b08c-78fe9db33d7b

Cold season emissions dominate the Arctic tundra methane budget

Arctic ecosystems are major global sources of methane. We report that emissions during the cold season (September to May) contribute ≥50% of annual sources of methane from Alaskan tundra, based on fluxes obtained from eddy covariance sites and from regional fluxes calculated from aircraft data. The largest emissions were observed at the driest site (<5% inundation). Emissions of methane in the cold season are linked to the extended “zero curtain” period, where soil temperatures are poised near 0 °C, indicating that total emissions are very sensitive to soil climate and related factors, such as snow depth. The dominance of late season emissions, sensitivity to soil conditions, and importance of dry tundra are not currently simulated in most global climate models.

Looking at one of the data sets web sites (from CARVE flights) shows a quite similar sample basin as in reply #249's article also about tundra emissions.  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1300  They also used land based methane values from around Barrow including some from reply #249. 

My favourite quote from the article

Microbial consumption of CH4 in the near-surface soil layer (methanotrophy) can be very active in summer (28) but is inhibited by near-surface soil freezing (28, 29). Thus, the fraction of CH4 escaping to the atmosphere likely increases as the soil surface freezes in the fall.
 



AbruptSLR

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Re: Arctic Methane Release
« Reply #253 on: August 22, 2016, 06:18:33 PM »
The linked reference provides field evidence that aquatic plants in arctic tundra wetlands is a major source of methane emissions, and will likely serve as a positive feedback mechanism with continued global warming (the AR5 & CMIP5 projections do not account for this source of methane):

C G Andresen, M J Lara, C E Tweedie & V L Lougheed (19 August 2016) "Rising Plant-mediated Methane Emissions from Arctic Wetlands", Global Change Biology, DOI: 10.1111/gcb.13469

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13469/abstract

Abstract: "Plant-mediated CH4 flux is an important pathway for land-atmosphere CH4 emissions but the magnitude, timing, and environmental controls, spanning scales of space and time, remain poorly understood in arctic tundra wetlands, particularly under the long term effects of climate change. CH4 fluxes were measured in situ during peak growing season for the dominant aquatic emergent plants in the Alaskan arctic coastal plain, Carex aquatilis and Arctophila fulva, to assess the magnitude and species-specific controls on CH4 flux. Plant biomass was a strong predictor of A. fulva CH4 flux while water depth and thaw depth were co-predictors for C. aquatilis CH4 flux. We used plant and environmental data from 1971-72 from the historic International Biological Program (IBP) research site near Barrow, Alaska, which we resampled in 2010-13, to quantify changes in plant biomass and thaw depth, and used these to estimate species-specific decadal-scale changes in CH4 fluxes. A ~60% increase in CH4 flux was estimated from the observed plant biomass and thaw depth increases in tundra ponds over the past 40 years. Despite covering only ~5% of the landscape, we estimate that aquatic C. aquatilis and A. fulva account for two-thirds of the total regional CH4 flux of the Barrow Peninsula. The regionally observed increases in plant biomass and active layer thickening over the past 40 years not only have major implications for energy and water balance, but have significantly altered land-atmosphere CH4 emissions for this region, potentially acting as a positive feedback to climate warming."
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AbruptSLR

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Re: Arctic Methane Release
« Reply #254 on: August 24, 2016, 09:26:09 PM »
The linked refer provides data of methane emissions from Arctic lakes:

Torben R. Christensen (2016), "Permafrost: It's a gas", Nature Geoscience, doi:10.1038/ngeo2803

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2803.html

Summary: "Climate change is causing widespread permafrost thaw in the Arctic. Measurements at 33 Arctic lakes show that old carbon from thawing permafrost is being emitted as methane, though emission rates have not changed during the past 60 years."
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ghoti

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Re: Arctic Methane Release
« Reply #255 on: August 26, 2016, 04:31:11 AM »
Also this paper:
Methane emissions proportional to permafrost carbon thawed in Arctic lakes since the 1950s
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2795.html


prokaryotes

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Re: Arctic Methane Release
« Reply #256 on: September 07, 2016, 12:34:12 AM »
Made a video, about a recent related article

Climate Change, Arctic Security and Methane Risks #3DEdition
https://www.youtube.com/watch?v=L8oFt6KRoBE

Also check this graph

Methane release around Barrow, AK, about 20% higher than recent summers.
https://twitter.com/Climatologist49/status/773263796265553920
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prokaryotes

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Re: Arctic Methane Release
« Reply #257 on: September 25, 2016, 10:49:09 PM »
Not sure if this fits here but it seems this went a bit unnoticed, seabed craters of considerable size have been identified

Giant Seafloor Craters and Thriving Fauna: Methane Seepage in the Arctic
https://www.youtube.com/watch?v=t3JQ9a3apc8
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AbruptSLR

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Re: Arctic Methane Release
« Reply #258 on: December 09, 2016, 11:13:19 PM »
The linked AGU abstract B44D-08 is entitled: "Characterizing Methane Emission Response to the Past 60 Years of Permafrost Thaw in Thermokarst Lakes".  For those attending the AGU the associated talk will be on Dec 15 2016 from 17:36-17:48pm in Moscone West – 2020:


https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/197390
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logicmanPatrick

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Re: Arctic Methane Release
« Reply #259 on: December 19, 2016, 10:06:18 AM »
Cross-posted here from 'stupid questions'

Global Methane Biogeochemistry, W S Reeburgh 2003

www.ess.uci.edu/~reeburgh/WSR%20TOG%202006.pdf

New from UK Met office:

A synthesis study of the global methane budget 2000-2012

http://www.metoffice.gov.uk/research/news/2016/global-carbon-budget-ch4-2016
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frankendoodle

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Re: Arctic Methane Release
« Reply #260 on: December 21, 2016, 07:46:03 PM »
Is under wet or dry conditions that melted permafrost will decay and release methane?
 
Wet and dry conditions; one will release CO2 and the other CH4 but I cannot remember which is which.

logicmanPatrick

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Re: Arctic Methane Release
« Reply #261 on: January 03, 2017, 01:11:32 AM »
Frankendoodle

Dry conditions promote CO2 release.  Wet conditions promote methane release.

As organic matter decays, it gets eaten up and digested by microbes. The bacteria that eat it produce either carbon dioxide or methane as waste. If there is oxygen available, the microbes make carbon dioxide. But if there is no oxygen available, they make methane. Most of the places where methane would form are the swamps and wetlands. And there are many miles of wetlands in the Arctic. When you walk around in the Arctic tundra, it's like sloshing through a giant sponge.

Kevin Schaefer  NSIDC

https://nsidc.org/cryosphere/frozenground/methane.html


hth.
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longwalks1

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Re: Arctic Methane Release
« Reply #262 on: February 12, 2017, 05:34:46 PM »
A new study from the USGS on ocean bed methane release.  Study was received Aug 2016 and is online now. 

The Physorg version
https://phys.org/news/2017-02-gas-hydrate-breakdown-massive-greenhouse.html

Gas hydrate breakdown unlikely to cause massive greenhouse gas release

From towards the end

"Our review is the culmination of nearly a decade of original research by the USGS, my coauthor Professor John Kessler at the University of Rochester, and many other groups in the community," said USGS geophysicist Carolyn Ruppel, who is the paper's lead author and oversees the USGS Gas Hydrates Project. "After so many years spent determining where gas hydrates are breaking down and measuring methane flux at the sea-air interface, we suggest that conclusive evidence for release of hydrate-related methane to the atmosphere is lacking."


The source study online at AGU "Review of Geophysics" - non paywalled. 

http://onlinelibrary.wiley.com/doi/10.1002/2016RG000534/full

I am not sure, but I believe this is the first time I have seen the 84 times more potent than CO2 in the 20 year time frame (IPCC 2013) in a refereed journal.  Read in the first paragraph of the introduction. 

It is really large, large  and my shortest quick take away is that it is not disputing methane emissions from the ocean and especially the Arctic Ocean.  It ls laying some of the emissions onto submerged permafrost  - more research needed.

From the second paragraph of Conclusions.

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.


From 6.3 Gas Hydrates in Glaciated areas. 

Figure 11 shows nominal conditions for permafrost evolution and gas hydrate stability beneath cold and warm-base ice sheets. Even where permafrost is lacking beneath warm-base ice, gas hydrate is stable at shallow depths in the sedimentary section for ice sheets a mere 500 m thick. Such shallow hydrates could form from microbial gas instead of the thermogenic gas thought to be sourcing many contemporary PAGH [Ruppel, 2015]. Anomalously shallow gas hydrates have been postulated for the Yamal Peninsula [Chuvilin et al., 2002] and invoked to explain some observations on the East Siberian Arctic Shelf [Shakhova et al., 2010a], as discussed above. Neither area was glaciated at the LGM, and the shallow gas releases on which the anomalous hydrate interpretation is based [Chuvilin et al., 2002] are common in permafrost areas during drilling and thought to be unrelated to gas hydrate dynamics. Even if proof for anomalous gas hydrates is eventually found, it remains uncertain how the pressure and temperature conditions at shallow depths (e.g., less than 100 m) could have been within the gas hydrate stability field absent recent glacial loading or a highly unusual mixture of hydrocarbons.


Intact arctic continental shelf gas hydrate certainly remains today within or beneath subsea permafrost, but distinguishing hydrate- from ice-bearing sediments based on geophysical data is nearly impossible without direct sampling.


Some will read this and think that the USGS is severely underestimating the methane emissions from the oceans and others will read the "conclusive evidence for release of hydrate-related methane to the atmosphere is lacking" and mentally black out "hydrate-related" and mentally scrub out methane impacts to CO2Equiv.  But for a quick read, my opinion is not a bad distillation. 

For me - it is not a counterpoint to the possibility of spiking methane emissions, but a caveat specific to methane hydrate emissions via the clathrate gun scenario.  Must read more..