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Author Topic: Methane in Antarctica  (Read 829 times)

prokaryotes

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Methane in Antarctica
« on: July 22, 2020, 09:19:19 AM »
Related topics
Antarctic Methane Concentrations https://forum.arctic-sea-ice.net/index.php/topic,73.0.html
Antarctic ecosystems https://forum.arctic-sea-ice.net/index.php/topic,906.0.html
Methane emissions, sea levels and temperature https://forum.arctic-sea-ice.net/index.php/topic,3171.msg276128/topicseen.html


Talk by Andrew Thurber with the scope on methane in Antarctica


Quote
Antarctica Cinder Cones in McMurdo Sound: Researchers say potent climate-heating gas almost certainly escaping into atmosphere. Took more than five years for the microbes to begin to show up then there was still methane rapidly escaping from the sea floor
https://www.theguardian.com/environment/2020/jul/22/first-active-leak-of-sea-bed-methane-discovered-in-antarctica

Summary video from above talk and some other footage
« Last Edit: July 23, 2020, 10:01:27 PM by prokaryotes »
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Tom_Mazanec

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Re: Methane in Antarctica
« Reply #1 on: July 22, 2020, 01:46:42 PM »
After all this worrying about NH methane now we have to worry about Antarctica methane.
Sigh...
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kassy

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Re: Methane in Antarctica
« Reply #2 on: July 22, 2020, 05:19:58 PM »
Fascinating presentation.

That graph at 9 minutes is interesting.
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.

AbruptSLR

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Re: Methane in Antarctica
« Reply #3 on: July 22, 2020, 05:45:05 PM »
Fascinating presentation.

That graph at 9 minutes is interesting.

I guess that you mean the attached image, where the red indicates atmospheric methane concentration and the blue means atmospheric CO2 concentrations.

Edit: I note that the GWP for methane is higher than the 25 value cited on this image.
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prokaryotes

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Re: Methane in Antarctica
« Reply #4 on: July 22, 2020, 06:46:52 PM »
...
This is a reminder to readers that if the BSB were to experience an MICI-type of collapse beginning possibly as early as 2030 due to hydrofacturing of the calving front of the Thwaites Ice Tongue due to a Super El Nino event, then it is possible that significant amounts of methane could be emitted into the atmosphere from the associated rapid degradation of seabed methane hydrates in the BSB bed.

The linked open access reference provides more details bout the nature of methane hydrate seeps from the seafloor around Antarctica:

Andrew R. Thurber, Sarah Seabrook and Rory M. Welsh (22 July 2020), "Riddles in the cold: Antarctic endemism and microbial succession impact methane cycling in the Southern Ocean", Proceedings of the Royal Society B, https://doi.org/10.1098/rspb.2020.1134

https://royalsocietypublishing.org/doi/10.1098/rspb.2020.1134

Abstract
Antarctica is estimated to contain as much as a quarter of earth's marine methane, however we have not discovered an active Antarctic methane seep limiting our understanding of the methane cycle. In 2011, an expansive (70 m × 1 m) microbial mat formed at 10 m water depth in the Ross Sea, Antarctica which we identify here to be a high latitude hydrogen sulfide and methane seep. Through 16S rRNA gene analysis on samples collected 1 year and 5 years after the methane seep formed, we identify the taxa involved in the Antarctic methane cycle and quantify the response rate of the microbial community to a novel input of methane. One year after the seep formed, ANaerobic MEthane oxidizing archaea (ANME), the dominant sink of methane globally, were absent. Five years later, ANME were found to make up to 4% of the microbial community, however the dominant member of this group observed (ANME-1) were unexpected considering the cold temperature (−1.8°C) and high sulfate concentrations (greater than 24 mM) present at this site. Additionally, the microbial community had not yet formed a sufficient filter to mitigate the release of methane from the sediment; methane flux from the sediment was still significant at 3.1 mmol CH4 m−2 d−1. We hypothesize that this 5 year time point represents an early successional stage of the microbiota in response to methane input. This study provides the first report of the evolution of a seep system from a non-seep environment, and reveals that the rate of microbial succession may have an unrealized impact on greenhouse gas emission from marine methane reservoirs.

I note that the GWP for methane is higher than the 25 value cited on this image.
Can someone point me to a video with the updated values?
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Ken Feldman

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Re: Methane in Antarctica
« Reply #5 on: July 22, 2020, 08:07:45 PM »
Not a video, but a pretty clear narrative explanation.

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/global-warming-potential

Quote
Because CO2 has a very long residence time in the atmosphere, its emissions cause increases in atmospheric concentrations of CO2 that will last thousands of years [8]. Methane’s average atmospheric residence time is about a decade. However, its capacity to absorb substantially more energy than CO2 gives it a GWP ranging from 28 to 36. The GWP also accounts for some indirect effects; for example, CH4 is a precursor to another greenhouse gas, ozone.

Quote
What happens to the methane GWP if a 20-year averaging time is used?

A 20-year GWP is sometimes used as an alternative to the 100-year GWP. The 20-year GWP is based on the energy absorbed over 20 years, which prioritizes gases with shorter lifetimes, since it ignores any impacts that occur after 20 years from the emission. The GWPs are calculated relative to CO2, so the GWPs are based on an 80% shorter time frame that will be larger for gases with atmospheric residence times shorter than that of CO2 and smaller for gases with residence times greater than CO2.

Since CH4 has a shorter atmospheric residence time than CO2, the 100-year GWP is much less than the 20-year GWP. The CH4 20-year GWP has been estimated [8] to be 84–87, compared with the 100-year GWP of 28–36.

A new metric, GWP*, has been developed to address the confusion between the short term and long term GWPs of short lived greenhouse gases like methane.  Here's a link to a study about GWP*.

https://iopscience.iop.org/article/10.1088/1748-9326/ab6d7e/pdf

Quote
Demonstrating GWP*: a means of reporting warming-equivalentemissions that captures the contrasting impacts of short- and long-lived climate pollutants
John Lynch, Michelle Cain, Raymond Pierrehumbert and Myles Allen

Abstract
The atmospheric lifetime and radiative impacts of different climate pollutants can both differ markedly, so metrics that equate emissions using a single scaling factor, such as the 100-year Global Warming Potential (GWP100), can be misleading. An alternative approach is to report emissions as ‘warming-equivalents’ that result in similar warming impacts without requiring a like-for-like weighting per emission. GWP*, an alternative application of GWPs where the CO2-equivalence of short-lived climate pollutant emissions is predominantly determined by changes in their emission rate, provides a straightforward means of generating warming-equivalent emissions. In this letter we illustrate the contrasting climate impacts resulting from emissions of methane, a short-lived greenhouse gas, and CO2, and compare GWP100 and GWP* CO2-equivalents for a number of simple emissions scenarios. We demonstrate that GWP* provides a useful indication of warming, while conventional application of GWP100 falls short in many scenarios and particularly when methane emissions are stable or declining, with important implications for how we consider ‘zero emission’ or ‘climate neutral’ targets for sectors emitting different compositions of gases. We then illustrate how GWP* can provide an improved means of assessing alternative mitigation strategies. GWP* allows warming-equivalent emissions to be calculated directly from CO2-equivalent emissions reported using GWP100, consistent with the Paris Rulebook agreed by the UNFCCC, on condition that short-lived and cumulative climate pollutants are aggregated separately, which is essential for transparency. It provides a direct link between emissions and anticipated warming impacts, supporting stock takes of progress towards a long-term temperature goal and compatible with cumulative emissions budgets.




prokaryotes

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Re: Methane in Antarctica
« Reply #6 on: July 22, 2020, 08:20:04 PM »
Not a video, but a pretty clear narrative explanation.
Thanks, currently working on a summary video and will add the info.
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uniquorn

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Re: Methane in Antarctica
« Reply #7 on: July 22, 2020, 11:03:45 PM »
Probably old news here but it turned up in a daily newspaper
https://www.theguardian.com/environment/2020/jul/22/first-active-leak-of-sea-bed-methane-discovered-in-antarctica
Quote
The first active leak of methane from the sea floor in Antarctica has been revealed by scientists.

The researchers also found microbes that normally consume the potent greenhouse gas before it reaches the atmosphere had only arrived in small numbers after five years, allowing the gas to escape.

Vast quantities of methane are thought to be stored under the sea floor around Antarctica. The gas could start to leak as the climate crisis warms the oceans, a prospect the researchers said was “incredibly concerning”.

The reason for the emergence of the new seep remains a mystery, but it is probably not global heating, as the Ross Sea where it was found has yet to warm significantly. The research also has significance for climate models, which currently do not account for a delay in the microbial consumption of escaping methane.

The active seep was first spotted by chance by divers in 2011, but it took scientists until 2016 to return to the site and study it in detail, before beginning laboratory work.

prokaryotes

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Re: Methane in Antarctica
« Reply #8 on: July 23, 2020, 10:02:06 PM »
Made a summary video on the recent discovery - what we know so far
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