High Methane Levels over Laptev Sea

A major fault line crosses the Arctic Ocean, forming the boundery between two tectonic plates, the North American Plate and the Eurasian Plate. These plates slowly diverge, creating seismic tension along the fault line.

From where the Mid-Atlantic ridge enters the Arctic Ocean, it is called the Gakkel Ridge. The fault continues as the Laptev Sea Rift, on to a transitional deformation zone in the Chersky Range in Siberia, then the Ulakhan Fault between the North American Plate and the Okhotsk Plate, and then continues as the Aleutian Trench to the end of the Queen Charlotte Fault system.

Above map shows the location of some of the main points of interest, i.e. the Laptev Sea Rift and the Gakkel Ridge, where high methane readings have been recorded recently, as shown in the image below. Indicated in yellow are all methane readings of 1950 ppb and over, for a period of just over one day, October 19 - 20, 2013.  

To pointpoint more closely where methane is venting along the Laptev Sea Rift, the image below gives readings for October 20, 2013, pm, at just three altitudes (607 - 650 mb). 

This is a very dangerous situation, since high levels of methane have been recorded over the Arctic Ocean for more than a month now. Furthermore, large amounts of methane have vented in the Laptev Sea area in previous years. Added below is an edited part of a previous post, Unfolding Climate Catastrophe. 

In September 2005, extremely high concentrations of methane (over 8000 ppb, see image on the right) were measured in the atmospheric layer above the sea surface of the East Siberian Shelf, along with anomalously high concentrations of dissolved methane in the water column (up to 560 nM, or 12000% of super saturation).

The authors conclude: "Since the area of geological disjunctives (fault zones, tectonically and seismically active areas) within the Siberian Arctic shelf composes not less than 1-2% of the total area and area of open taliks (area of melt through permafrost), acting as a pathway for methane escape within the Siberian Arctic shelf reaches up to 5-10% of the total area, we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time".

In 2007, concentrations of dissolved methane in the water column reached a level of over 5141 nM at a location in the Laptev Sea. For more background, see the previous post, Unfolding Climate Catastrophe. 

Satellite measurements show methane readings of up to 2411 ppb on October 20, 2013. Sadly, no current data are available from measurements in the Laptev Sea, neither methane levels in the water, nor atmospheric methane levels just above sea level. Perhaps in time, some data will become available from expeditions.

Methane presence over Arctic Ocean continues

The image on the right, created with IPCC data, shows that methane levels have risen even stronger than levels of two other greenhouse gases, i.e. carbon doxide (CO2) and nitrous oxide (N2O).

Methane levels have risen strongly over the past few years, especially over the Arctic.

Previous posts at this blog have illustrated that, from early October 2013, high methane readings have shown up persistently over the depths of the Arctic Ocean.

The persistence of these readings indicates that this methane wasn't blown there from elsewhere. Furthermore, the presence of methane appears to line up closely with the fault line that crosses the Arctic Ocean and extends into Siberia and further into the Sea of Okhotsk.

The latest data show a continuation of this worrying methane presence over the Arctic Ocean.

On October 18, 2013, readings of up to 2426 ppb were recorded. As the above image shows, high peak readings have occurred over the past few months. Currently, however, high readings can be more clearly attributed to methane venting from the depths of the Arctic Ocean. On the image below, methane shows up very prominently over the Arctic Ocean.

For more background, see posts below.

Related

- The Unfolding Methane Catastrophe
http://arctic-news.blogspot.com/2013/10/unfolding-methane-catastrophe.html

- Methane hydrates
http://methane-hydrates.blogspot.com/2013/04/methane-hydrates.html

- Myths about methane hydrates
http://methane-hydrates.blogspot.com/p/myths.html

Post by Sam Carana.

Unfolding Methane Catastrophe

The above image shows that, over a period of less than two days, huge amounts of methane show up over the depth of the Arctic Ocean, especially along the fault line that crosses the Arctic Ocean and extends into Siberia and further into the Sea of Okhotsk. On October 17, 2013, readings of up to 2351 ppb were recorded.

The above image shows that such high readings have occurred before over the past few months. This time, however, this high reading can be more clearly attributed to methane escaping from the depth of the Arctic Ocean, as also indicated by the image below that shows that at 469 mb (i.e. the altitude at which this high reading was recorded on the afternoon of October 17) methane was predominantly present at higher northern latitudes.

The methane that appears over the depth of the Arctic Ocean is likely have traveled a long path through the vertical water column before entering the atmosphere. Clearly, some of the methane must have oxidized in the ocean. Therefore, methane must be escaping from the seabed in amounts far higher than what is visible in the air.

Below follows some history regarding this unfolding methane catastrophe. Note that methane concentrations in the water are measured in nM, while methane concentrations in the atmosphere are typically measured in parts per billion (ppb).

There are vast amounts of methane in sediments underneath the Arctic Ocean.  Natalia Shakhova et al. (2010) estimate the accumulated potential for the East Siberian Arctic Shelf (ESAS) region alone (image on the right) as follows:

• organic carbon in permafrost of about 500 Gt
• about 1000 Gt in hydrate deposits
• about 700 Gt in free gas beneath the gas hydrate stability zone.⁸

Natalia Shakhova et al. (2008) consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time. By comparison, the total amount of methane currently in the atmosphere is about 5 Gt.³

The danger that volcanic and earthquake activity along the Gakkel Ridge could lead to destabilization and abrupt methane release into the atmosphere was highlighted by Light and Sorana back in 2002.¹

Measurements taken in September 2003 and September 2004 show that the surface layer of shelf water in the East-Siberian Sea and Laptev Sea was supersaturated up to 2500% relative to the present average atmospheric methane content of 1.85 ppm. Anomalously high concentrations (up to 154 nM or 4400% supersaturation) of dissolved methane in the bottom layer of shelf water suggest that the bottom layer is somehow affected by near-bottom sources. Considering the possible formation mechanisms of such plumes, we favor thermo-abrasion and the effects of shallow gas or gas hydrates release, conclude the authors of this study, published in 2005.²

In September 2005, extremely high concentrations of methane (up to 8 ppm) were measured in the atmospheric layer above the sea surface of the East Siberian Shelf, along with anomalously high concentrations of dissolved methane in the water column (up to 560 nM, or 12000% of super saturation).³

The authors conclude: "Since the area of geological disjunctives (fault zones, tectonically and seismically active areas) within the Siberian Arctic shelf composes not less than 1-2% of the total area and area of open taliks (area of melt through permafrost), acting as a pathway for methane escape within the Siberian Arctic shelf reaches up to 5-10% of the total area, we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time. That may cause ∼12-times increase of modern atmospheric methane burden with consequent catastrophic greenhouse warming".³

In 2007, concentrations of dissolved methane in the water column reached a level of over 5141 nM at a location in the Laptev Sea.⁴

A study published in 2008 found volcanoes up to 2,000 m in diameter and a few hundred metres high at the bottom of the Arctic Ocean, at Gakkel Ridge.⁵

End September 2011, a cluster of methane plumes, over one km in diameter, appeared in the Laptev Sea, as shown on the image below, from a paper on the unfolding "Methane Catastrophe".⁶

In early October 2013, high atmospheric levels of methane started to appear over the depth of the Arctic Ocean.⁹  See image at top for most recent readings.


References

1. Arctic Methane Hydrates: A Potential Greenhouse Gas Hazard. - Light, M.P.R. and Solana, C. (2002)
http://adsabs.harvard.edu/abs/2002EGSGA..27.4077L
For more details, see also
http://arctic-news.blogspot.com/p/seismic-activity.html

2. The distribution of methane on the Siberian Arctic shelves: Implications for the marine methane cycle. - Natalia Shakhova, Igor Semiletov and Gleb Panteleev (2005)
http://onlinelibrary.wiley.com/doi/10.1029/2005GL022751/abstract

3. Anomalies of methane in the atmosphere over the East Siberian shelf: Is there any sign of methane leakage from shallow shelf hydrates? - N. Shakhova, I. Semiletov, A. Salyuk and D. Kosmach (2008)
http://meetings.copernicus.org/www.cosis.net/abstracts/EGU2008/01526/EGU2008-A-01526.pdf

4. Siberian Sea Shelf Study, International Arctic Research Center, University of Alaska Fairbanks
http://research.iarc.uaf.edu/SSSS/data2010.php

5. Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean. - Sohn RA et al. (2008)
http://www.ncbi.nlm.nih.gov/pubmed/18580949

6. The Degradation of Submarine Permafrost and the Destruction of Hydrates on the Shelf of East Arctic Seas as a Potential Cause of the “Methane Catastrophe”: Some Results of Integrated Studies in 2011. - V. I. Sergienko et al., in Oceanology (Sept. 2012)
http://link.springer.com/article/10.1134/S102833

7. On carbon transport and fate in the East Siberian Arctic land–shelf–atmosphere system. - Semiletov et al. (2012)
http://iopscience.iop.org/1748-9326/7/1/015201

8. Methane release from the East Siberian Arctic Shelf and the Potential for Abrupt Climate Change. - Natalia Shakhova and Igor Semiletov (2010), Presentation at Symposium, November 30, 2010
http://symposium2010.serdp-estcp.org/content/download/8914/107496/version/3/file/1A_Shakhova_Final.pdf

9. High Methane Readings continue over Depth of Arctic Ocean
http://arctic-news.blogspot.com/2013/10/high-methane-readings-continue-over-depth-of-arctic-ocean.html

Post by Sam Carana.

High Methane Readings continue over Depth of Arctic Ocean

The image below contains 12 frames, with methane readings recorded over 12 days in the first half of October 2013.

[ click on image to enlarge ]

As discussed in earlier posts at this blog, high methane readings have been recorded recently over the depth of Arctic Ocean. Above image shows that these high readings are continuing. The image below shows that at 469 mb, the altitude at which the highest reading was recorded on the afternoon of October 13, methane shows up very prominently over the Arctic Ocean.

The fact that little methane shows up elsewhere indicates that methane is present at high levels, at times over 2200 ppb, over the depth of the Arctic Ocean, and that these high levels result from methane that originates from hydrates under the seabed.

The image below, with methane readings over the past few days (from October 12 10:00 pm to October 14 11:23 pm), shows high levels of methane over the depth of the Arctic Ocean.

The image below shows methane readings at 586 mb, the altitude at which the highest methane reading was recorded on the afternoon of October 14 (a reading of 2248 ppb). Again, methane is present very prominently over the depth of the Arctic Ocean.

Post by Sam Carana.