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Alumril

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Re: Arctic Methane Release
« Reply #1200 on: December 02, 2020, 03:52:35 AM »
Kassy, so I had a think about this, and tried to come up with sites that are more likely to have increased in methane faster than the global average.
I tried Niwot Ridge, Colorado, United States (NWR) due to the local fracking activity and Mt. Waliguan, Peoples Republic of China (WLG) due to increased rice production and increased industrial activity. I don't have any local knowledge of these places, so it was a bit of a guess.

There is a slight increased trend on both sites vs south pole data. While the trend for Barrow  (BRW) is flat.

Now I did deliberately pick these sites because I thought would have the largest increase in emissions. But then I originally expected to see the same trend in Barrow and Tiksi and didn't find it.

I'm no expert on this, so I'm happy for any challenge of these methods.

morganism

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ArgonneForest

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Re: Arctic Methane Release
« Reply #1202 on: December 02, 2020, 06:51:20 AM »
Kassy, so I had a think about this, and tried to come up with sites that are more likely to have increased in methane faster than the global average.
I tried Niwot Ridge, Colorado, United States (NWR) due to the local fracking activity and Mt. Waliguan, Peoples Republic of China (WLG) due to increased rice production and increased industrial activity. I don't have any local knowledge of these places, so it was a bit of a guess.

There is a slight increased trend on both sites vs south pole data. While the trend for Barrow  (BRW) is flat.

Now I did deliberately pick these sites because I thought would have the largest increase in emissions. But then I originally expected to see the same trend in Barrow and Tiksi and didn't find it.

I'm no expert on this, so I'm happy for any challenge of these methods.
Great data! I've asked around on Twitter for a couple of scientists about what happened to the Tiksi station. I'll let you guys know if they get back to me

kassy

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Re: Arctic Methane Release
« Reply #1203 on: December 02, 2020, 11:00:52 AM »
Finding out more about Tiksi would be great.

Sentinel-5 might help but it will be a couple of years before it launches.

When i looked at the arctic stations the big problem is that there are so little stations.
If there were a lot more stations then you could look at other details. IIRC there was a specific error code for measures removed because of some local source made the readings too high.

If there had been more stations with a good spatial distribution it would be interesting to see if  dates with those codes relate to local sea ice break up for example but with the amount of stations we have now that does not work. 
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

vox_mundi

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Re: Arctic Methane Release
« Reply #1204 on: December 14, 2020, 08:05:35 PM »
The Moon Controls the Release of Methane in Arctic Ocean
https://phys.org/news/2020-12-moon-methane-arctic-ocean.html

Small pressure changes affect methane release. A recent paper in Nature Communications even implies that the moon has a role to play.

The moon controls one of the most formidable forces in nature—the tides that shape our coastlines. Tides, in turn, significantly affect the intensity of methane emissions from the Arctic Ocean seafloor.

"We noticed that gas accumulations, which are in the sediments within a meter from the seafloor, are vulnerable to even slight pressure changes in the water column. Low tide means less of such hydrostatic pressure and higher intensity of methane release. High tide equals high pressure and lower intensity of the release," says co-author of the paper Andreia Plaza Faverola.

"It is the first time that this observation has been made in the Arctic Ocean. It means that slight pressure changes can release significant amounts of methane.

Plaza Faverola points out that the observations were made by placing a tool called a piezometer in the sediments and leaving it there for four days.

It measured the pressure and temperature of the water inside the pores of the sediment. Hourly changes in the measured pressure and temperature revealed the presence of gas close to the seafloor that ascends and descends as the tides change. The measurements were made in an area of the Arctic Ocean where no methane release has previously been observed but where massive gas hydrate concentrations have been sampled.

"This tells us that gas release from the seafloor is more widespread than we can see using traditional sonar surveys. We saw no bubbles or columns of gas in the water. Gas burps that have a periodicity of several hours won't be identified unless there is a permanent monitoring tool in place, such as the piezometer," says Plaza Faverola

These observations imply that the quantification of present-day gas emissions in the Arctic may be underestimated. High tides, however, seem to influence gas emissions by reducing their height and volume.

"What we found was unexpected and the implications are big. This is a deep-water site. Small changes in pressure can increase the gas emissions but the methane will still stay in the ocean due to the water depth. But what happens in shallower sites? This approach needs to be done in shallow Arctic waters as well, over a longer period. In shallow water, the possibility that methane will reach the atmosphere is greater," says Knies

... The question remains whether sea-level rise due to global warming might partially counterbalance the effect of temperature on submarine methane emissions.



Nabil Sultan et al, Impact of tides and sea-level on deep-sea Arctic methane emissions, Nature Communications (2020).
https://www.nature.com/articles/s41467-020-18899-3
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salbers

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Re: Arctic Methane Release
« Reply #1205 on: February 21, 2021, 08:46:47 PM »
I think we may have liftoff of the CH4 rocket. The annual cycle didn't really have a low point this year.

I think this is an incorrect conclusion

It does seem like an attenuated seasonal minimum and the overall acceleration in the past few years looks somewhat significant? We'll see if this is partially a kink in the curve as in 2015, within the still notable rising trend.
« Last Edit: February 21, 2021, 08:58:13 PM by salbers »

ArgonneForest

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Re: Arctic Methane Release
« Reply #1206 on: February 23, 2021, 07:30:19 PM »
It is somewhat significant, but I doubt it has mainly to do with Arctic sources. Probably a combination of different sources

salbers

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Re: Arctic Methane Release
« Reply #1207 on: February 28, 2021, 09:51:25 PM »
It will be interesting to see the growth rate.

The fact that it's not affecting the atmospheric concentrations and most is getting dissolved in the water column leads me to think there will be an increase in methane emissions from the region, but far from the level of a "bomb"

To clarify, there were local increases in atmospheric concentration of around 15x (during 2020). Hopefully this can be better monitored in a spatial and temporal context to see if (or how much) it is growing.

ESAS emissions have been small between 2012-2017 (around 0.6 Tg/yr) if I'm reading this Tohjima et al. paper correctly. The analysis in this paper suggests there had been a regional enhancement of atmospheric CH4 during that period. What is the potential for the 1-2 orders of magnitude of subsequent growth to have a more global impact?

https://www.sciencedirect.com/science/article/pii/S1873965220300803

The ship in the above paper sailed near the ESAS (to its east) though not really in the ESAS itself.
« Last Edit: February 28, 2021, 11:23:28 PM by salbers »

vox_mundi

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Re: Arctic Methane Release
« Reply #1208 on: March 02, 2021, 04:47:05 PM »
Testing Waters of East Siberian Arctic Ocean Suggests Origin of Elevated Methane Is Reservoir Located In Laptev Sea
https://phys.org/news/2021-03-east-siberian-arctic-ocean-elevated.html



An international team of researchers has found evidence implicating a deep underground reservoir as the source of high levels of methane in the waters of the East Siberian Arctic Ocean. In their paper published in Proceedings of the National Academy of Sciences, the group describes testing three isotopic forms of dissolved methane in the waters.

The work involved first obtaining water samples from regions of the East Siberian Arctic Ocean. Each of the samples then underwent triple-isotope-based fingerprinting. Doing so showed that only a small amount of the methane was coming from shallow microbial sources—the rest was coming from what the team believes is a very large, deep thermogenic reservoir. The researchers also believe the reservoir is located beneath the Laptev Sea; a portion of the East Siberian Arctic Ocean situated north of the eastern part of Russia.

Researchers have found that such releases can sometimes result in pressure building up as the gas makes its way into unstable parts of the ocean floor. And that can lead to seepage or sometimes explosive events as the gas is suddenly released up through the water and to the surface.

Julia Steinbach et al. Source apportionment of methane escaping the subsea permafrost system in the outer Eurasian Arctic Shelf, Proceedings of the National Academy of Sciences (2021).
https://www.pnas.org/content/118/10/e2019672118

... The results consistently point to the presence of an old, predominantly radiocarbon-depleted source of thermogenic origin or a mixture of thermogenic and old microbial sources. The stable isotope source signatures for station 13 fall into a range typical for thermogenic/natural gas origin, whereas the slightly more depleted signal at station 14 indicates additional input from another, potentially microbial origin (Fig. 6A). Both the old radiocarbon signatures (Fig. 6B) and the ebullitive nature of methane at these stations, characterized by abrupt releases and strong spatial gradients in the water column, suggest a deep, advective methane pool as an important contributor to the observed water column methane signal.

... The presence of a thermogenic source pool beneath our study area is consistent with results by Cramer and Franke (24), based on their observations of hydrocarbon concentrations and their δ13C in adsorbed gases in the sediment. The existence of pathways to transport methane from these deep sources to the water column in our study area is also consistent with recent seismic data (25), which show ∼500-m wide gas conduits in the sediment, correlating with a fault zone and cuts through the Neogene succession to the basement.

Further support for a migratory inflow of petroleum hydrocarbons from below is also given by a recent biomarker study in the studied seep area (26): Excess amounts of two molecular markers typical of a petrogenic source have been found in the surface sediment of the studied seep area, with significant differences between the seepage area and the “background areas” without apparent seeps. Taken together, the triple isotopes and these other ancillary data are consistent with a deep thermogenic source of methane.

...Taken together, the triple-isotope data presented here, in combination with other system data and indications from earlier studies, suggest that deep thermogenic reservoirs are key sources of the elevated methane concentrations in the outer Laptev Sea. This finding is essential in several ways: The occurrence of elevated levels of radiocarbon-depleted methane in the water column may be an indication of thawing subsea permafrost in the study area (see also ref. 8). The triple-isotope fingerprinting suggests, however, that methane may not primarily originate directly from the subsea permafrost; the continuous leakage of an old geological reservoir to the water column suggests the existence of perforations in the subsea permafrost, serving as conduits of deeper methane to gas-charged shallow sediments.

Second, the finding that methane is released from a large pool of preformed methane, as opposed to methane from slow decomposition of thawing subsea permafrost organic matter, suggests that these releases may be more eruptive in nature, which provides a larger potential for abrupt future releases.

.... More triple-isotope data, also temporally resolved, covering a wide range of the inner, mid, and outer shelf in the Laptev, East Siberian, and Chukchi Seas are strongly warranted.
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ArgonneForest

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Re: Arctic Methane Release
« Reply #1209 on: March 02, 2021, 11:28:38 PM »
Two things about this:
1. The research was conducted on the Oden expedition from 2014, so this is not new research per se.
2. Most of the methane was dissolved in the water column since the depths were greater than 50m.

vox_mundi

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Re: Arctic Methane Release
« Reply #1210 on: March 22, 2021, 11:47:30 PM »
Arctic Methane Release Due to Melting Ice Is Likely to Happen Again
https://phys.org/news/2021-03-arctic-methane-due-ice.html

New research, published on today in Geology, indicates that during the last two global periods of sea-ice melt, the decrease in pressure triggered methane release from buried reserves. Their results demonstrate that as Arctic ice, such as the Greenland ice sheet, melts, similar methane release is likely and should be included in climate models.

Pierre-Antoine Dessandier, a postdoctoral scientist at the Arctic University of Norway, and his co-authors were interested in two periods around 20 thousand years ago (ka), known as the Last Glacial Maximum (LGM), and 130 ka, known as the Eemian deglaciation. Because the Eemian had less ice and was warmer than the LGM, it is more similar to what the Arctic is experiencing today, serving as a good analogue for future climate change.

... The team collected two cores: a 60-meter reference core off the western coast of Svalbard, which they used to date and correlate stratigraphy, and a 22-meter core spanning the LGM and the Eemian deglaciations. The site for the 22-meter core was chosen based on its "pockmark" feature, marking where the gas escaped violently in the past, and massive carbonate rocks that form where methane is still leaking out today.

Carbon isotopes of microscopic shells in the long core revealed multiple episodes of methane release, which geochemists recognize from their distinct spikes in the record. Because methane is still seeping from the sediments, Dessandier needed to to make sure the signal wasn't from modern interference. He compared the shells' carbon isotope values to measurements his colleagues made on carbonate minerals that formed outside the shells, after the foraminifera had died, when methane emission was at its most intense.

The isotopic record showed that as ice melted and pressure on the seafloor lessened, methane was released in violent spurts, slow seeps, or—most likely—a combination of both. By the time the ice disappeared completely, some thousands of years later, methane emissions had stabilized.

Despite modern complications, the team has pinpointed two methane releases associated with ice retreat, like they hypothesize could happen today. The best part for Dessandier was discovering layers of massive bivalves in the cores which, based on modern observations from remotely operated vehicles, can indicate a methane leak. "It was super interesting for us to observe these same sorts of layers at the LGM and the Eemian," he said. "It confirmed what we thought at the beginning, with a methane-rich seafloor allowing this community to develop... We can say that these events are very similar, with similar processes happening during both periods of warming. So this is something to consider for our current warming. It could happen again."

P.-A. Dessandier et al. Ice-sheet melt drove methane emissions in the Arctic during the last two interglacials, Geology (2021).
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48580.1/595627/Ice-sheet-melt-drove-methane-emissions-in-the?redirectedFrom=fulltext
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ArgonneForest

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Re: Arctic Methane Release
« Reply #1211 on: March 23, 2021, 03:18:35 AM »
This was also included in the phys.org article:
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Arctic methane release due to melting ice is likely to happen again
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Arctic methane release due to melting ice is likely to happen again
Massive lumps of carbonate litter the seafloor where large quantities of methane are leaking from the sediments and rocks below, marking the spot Dessandier and colleagues targeted to drill deep sediment cores. (Scale bar added by GSA.) Credit:G. Panieri.

Beneath the cold, dark depths of the Arctic ocean sit vast reserves of methane. These stores rest in a delicate balance, stable as a solid called methane hydrates, at very specific pressures and temperatures. If that balance gets tipped, the methane can get released into the water above and eventually make its way to the atmosphere. In its gaseous form, methane is one of the most potent greenhouse gases, warming the Earth about 30 times more efficiently than carbon dioxide. Understanding possible sources of atmospheric methane is critical for accurately predicting future climate change.


 
In the Arctic Ocean today, ice sheets exert pressure on the ground below them. That pressure diffuses all the way to the seafloor, controlling the precarious stability in seafloor sediments. But what happens when the ice sheets melt?

New research, published on today in Geology, indicates that during the last two global periods of sea-ice melt, the decrease in pressure triggered methane release from buried reserves. Their results demonstrate that as Arctic ice, such as the Greenland ice sheet, melts, similar methane release is likely and should be included in climate models.

Pierre-Antoine Dessandier, a postdoctoral scientist at the Arctic University of Norway, and his co-authors were interested in two periods around 20 thousand years ago (ka), known as the Last Glacial Maximum (LGM), and 130 ka, known as the Eemian deglaciation. Because the Eemian had less ice and was warmer than the LGM, it is more similar to what the Arctic is experiencing today, serving as a good analogue for future climate change.

"The oldest episode recorded (Eemian) is very important because it was a strong interglacial in the Arctic, with very similar climate characteristics to what is happening today," Dessandier said. "The idea with the Eemian interglacial is to... compare that with what could happen in the future. Seafloor methane emission is important to consider for modeling spatial estimations of future climate."

To track past methane release, Dessandier measured isotopes of carbon (carbon molecules with slightly different compositions) in the shells of tiny ocean-dwellers called foraminifera. Because the foraminifera build their shells using ingredients from the water around them, the carbon signal in the shells reflects the chemistry of the ocean while they were alive. After they die, those shells are preserved in seafloor sediments, slowly building a record spanning tens of thousands of years.


 
To reach that record, Dessandier and the team needed to drill a deep core off the western coast of Svalbard, a Norwegian archipelago in the Arctic Ocean. The team collected two cores: a 60-meter reference core, which they used to date and correlate stratigraphy, and a 22-meter core spanning the LGM and the Eemian deglaciations. The site for the 22-meter core was chosen based on its "pockmark" feature, marking where the gas escaped violently in the past, and massive carbonate rocks that form where methane is still leaking out today.

Carbon isotopes of microscopic shells in the long core revealed multiple episodes of methane release, which geochemists recognize from their distinct spikes in the record. Because methane is still seeping from the sediments, Dessandier needed to to make sure the signal wasn't from modern interference. He compared the shells' carbon isotope values to measurements his colleagues made on carbonate minerals that formed outside the shells, after the foraminifera had died, when methane emission was at its most intense.

The isotopic record showed that as ice melted and pressure on the seafloor lessened, methane was released in violent spurts, slow seeps, or—most likely—a combination of both. By the time the ice disappeared completely, some thousands of years later, methane emissions had stabilized.

How much methane eventually made it to the atmosphere, which is what would contribute to the greenhouse effect, remains uncertain. Part of the problem in quantifying this is the microbial communities that live on the seafloor and in the water, and that use methane to survive.

"For the microbes, it's an oasis. It's fantastic," Dessandier said. "So they grow like crazy, and some species produce methane and others consume it." That activity complicates the core's detailed carbon record. In sediments, a bustling community with lots of methane recycling could overprint the original signal; in the water column, where nutrients may be less plentiful, methane could get gobbled up or transformed into carbon dioxide before it reaches the atmosphere.