Introduction to Methane Hydrate “Methane Hydrates and Contemporary Climate Change” (2011)

IDENTIFICATION

This post “A Mechanism for Shallow Methane Hydrate Dissociation”, explores possible mechanism which could release vast quantities of shallow Methane Hydrate into the ocean and atmosphere.

CH4 Release

The following studies explore the release of CH4 emissions in the Arctic region.

OBSERVATION STUDIES

Overall, the δ¹³C_DIC values confirm recent suggestions of substantial degradation of OC_ter over the ESAS, and further show that a large part of the CO₂ produced from degradation has been outgassed to the atmosphere. Source

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
On the basis of the analysis of published data and in the course of the authors’ long-term geochemical and acoustic surveys performed in 1995–2011 on the East Siberian shelf (ESS) and aimed to research the role of the Arctic shelf in the processes of massive methane outbursts into the Earth’s atmosphere, some crucially new results were obtained. A number of hypotheses were proposed concerning the qualitative and quantitative characterization of the scale of this phenomenon. The ESS is a powerful supplier of methane to the atmosphere owing to the continued degradation of the submarine permafrost, which causes the destruction of gas hydrates. The emission of methane in several areas of the ESS is massive to the extent that growth in the methane concentrations in the atmosphere to values capable of causing a considerable and even catastrophic warning on the Earth is possible. The seismic data were compared to those of the drilling from ice performed first by the authors in 2011 in the southeastern part of the Laptev Sea to a depth of 65 m from the ice surface. This made it possible to reveal some new factors explaining the observed massive methane bursts out of the bottom sediments.(Ref 1.2)

CO2 Release

The following studies explore the release of CO2 emissions in the Arctic region.

OBSERVATION 2012

SWERUS-C3 scientists lead study in Nature on carbon release from collapsing coastal permafrost in Arctic Siberia

Release to the atmosphere of carbon dioxide from thawing permafrost in the Arctic is identified as a positive feedback mechanism to climate warming. About half of the carbon pool in soils globally is held in frozen surficial permafrost in the Arctic (twice as much as in atmospheric CO2); the region is experiencing twice the global average of climate warming.

– Coastal Yedoma is likely more vulnerable towards carbon release than other permafrost bodies as it is not only subject to thermal collapse from above but also to enhanced wave and wind erosion of the Yedoma-dominated coast brought on by sea-level rise and longer ice-free seasons”, explains Örjan Gustafsson, professor of biogeochemistry at the Department of Applied Environmental Science and the Bert Bolin Centre for Climate Research.

The carbon-rich Ice-Complex permafrost structures (Yedoma) – rising along this Arctic coast are relict soils from the latest Ice Age, covering ~1 million km² (twice the area of Sweden). While satellite images reveal 1000s of kilometers of muddy-turbid waters along the Arctic coast, the Yedoma has remained understudied largely due to the region’s inaccessibility.

Detailed chemical characterization of thaw-eroding Yedoma slopes of a disappearing island in SE Laptev Sea suggested rapid conversion of the old soils to carbon dioxide even before being washed into the sea. The compositional fingerprint of old organic carbon ( 7,000 to 10,000 years) found in marine bottom sediments revealed that erosional input from ancient coastal Yedoma was the dominant source of carbon, overwhelming input from marine sources and river-carried debris from inland vegetation and soils, on this, the World’s largest coastal shelf sea.

While the present rate of carbon release from the NE Siberian coast is not substantially affecting the CO2 levels in the global atmosphere, the study demonstrates that the process is firmly underway.

This study adds to previous reports on extensive methane releases from collapsing subsea permafrost on the East Siberian Arctic Shelf (ESAS) published by the team. In order to project the future trajectory of greenhouse gases in the atmosphere, it is important to study the interaction of a warming climate and releases from the enormous carbon pools held in coastal and subsea permafrost, as well as in methane hydrates, on the ESAS. Source

Thermal collapse and erosion of old permafrost masses along the 20–30 m steep and desolate Arctic coastline is an impressive phenomenon. credit: Igor Semiletov

Thaw-remobilization of carbon and GHG emissions from sub-sea and coastal eroded permafrost

The East Siberian Arctic Ocean (ESAO) is our focus area since it is experiencing the fastest rate of climate warming and holds vast stores of potentially vulnerable carbon. The severely understudied ESAO system hosts 80% of the World’s subsea permafrost, receives massive amounts of thawed old permafrost carbon from land with a poorly constrained fate in the marine system and, finally, also holds large deposits of CH4 in unknown proportions as hydrates and free gas, just below the subsea permafrost. There is thus a potential for – partly climate-induced – mobilization of these carbon pools into the atmosphere in form of CO2 and CH4.

On carbon transport and fate in the East Siberian Arctic land–shelf–atmosphere system

REFERENCES

2012

Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia
J. E. Vonk, L. Sánchez-García, B. E. van Dongen, V. Alling, D. Kosmach, A. Charkin, I. P. Semiletov, O. V. Dudarev, N. Shakhova, P. Roos, T. I. Eglinton, A. Andersson & Ö. Gustafsson  doi:10.1038/nature11392 |  http://www.nature.com/nature/journal/v489/n7414/full/nature11392.html

Degradation of terrestrial organic carbon, primary production and out-gassing of CO2 in the Laptev and East Siberian Seas as inferred from d 13C values of DIC
V. Allinga, , D. Porcelli, C.-M. Morth, L.G. Anderson, L. Sanchez-Garcia, O. Gustafsson, P.S. Andersson, C. Humborga | doi: dx.doi.org/10.1016/j.gca.2012.07.028

1.2) 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, L. I. Lobkovskii, I. P. Semiletov, O. V. Dudarev, N. N. Dmitrievskii, N. E. Shakhova, N. N. Romanovskii, D. A. Kosmach, D. N. Nikol’skii, S. L. Nikiforov, A. S. Salomatin, R. A. Anan’ev, A. G. Roslyakov, A. N. Salyuk, V. V. Karnaukh, D. B. Chernykh, V. E. Tumskoi, V. I. Yusupov, A. V. Kurilenko, E. M. Chuvilin, B. A. Bukhanov http://link.springer.com/article/10.1134/S1028334X12080144