Talk:Clathrate gun hypothesis

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REMOVED IMAGES[edit source]

Specific structure of a gas hydrate piece, from the subduction zone off Oregon
Gas hydrate-bearing sediment, from the subduction zone off Oregon
Shows how the hydrates decompose as temperatures rise. The amount of methane gas released into the surrounding water column or soils increases as the ambient temperature increases, figure based on graphic from Osegovic et al[1]
Solid gas hydrate from a sediment 6 meters below the sea floor near Vancouver island in Canada[2]
Shows how the hydrates decompose as temperatures rise. The amount of methane gas released into the surrounding water column or soils increases as the ambient temperature increases, figure based on graphic from Osegovic et al[3]

REMOVED SECTIONS[edit source]

This covers primary research from 2012 and earlier and is likely out of date.

Would be good to have a section on "the original Clathrate Gun Hypothesis" and use some of this material there, but as it is, risks confusing the reader by suggesting this material is still valid, contradicting the rest of hte article.

Don't have time to rewrite it just now so have removed it and will look into writing that section later. Thought better to remove than to leave it in place and potentially mislead the reader with out of date findings.

Editor's note: This article needs attention. The lede and first section and the #Current outlook sections are fixed and the #Videos section consists of videos by Carolyn Ruppel of the USGS / CAGE so do check that out too. The rest needs more work - imported from Wikipedia and mid edit to fix various errors in it

Metastable methane clathrates[edit source]

Another kind of exception is in clathrates associated with the Arctic ocean, where clathrates can exist in shallower water stabilized by lower temperatures rather than higher pressures; these may potentially be marginally stable much closer to the surface of the sea-bed, stabilized by a frozen 'lid' of permafrost preventing methane escape.

The so-called self-preservation phenomenon has been studied by Russian geologists starting in the late 1980s.[4] This metastable clathrate state can be a basis for release events of methane excursions, such as during the interval of the Last Glacial Maximum.[5] A study from 2010 concluded with the possibility for a trigger of abrupt climate warming based on metastable methane clathrates in the East Siberian Arctic Shelf (ESAS) region.[6]

Ocean anoxia[edit source]

Euxinic (i.e. sulfidic) and anoxic events happened in the past on different time scales ranging from decades to centuries (from impact events) or through climate change within tens of thousands of years or a few million years. According to Gregory Ryskin, such a scenario could lead to the release of methane and other gases (e.g., CO2, Template:Chem/atomTemplate:Chem/atomTemplate:Chem/atom) into the atmosphere, from the ocean. Following atmospheric methane excursions he postulates explosions and burning of methane would produce lots of smoke and dust, which would first lead to global cooling.[7] And likely after a relatively short geological period following stratospheric cooling, global warming would take over.

Model simulations[edit source]

A study of the effects for the original hypothesis, based on a coupled climate–carbon cycle model (GCM) assessed a 1000-fold (from <1 to 1000 ppmv) methane increase—within a single pulse, from methane hydrates (based on carbon amount estimates for the PETM, with ~2000 GtC), and concluded it would increase atmospheric temperatures by more than 6 °C within 80 years. Further, carbon stored in the land biosphere would decrease by less than 25%, suggesting a critical situation for ecosystems and farming, especially in the tropics.[8]


Continental slopes[edit source]

Template:Expand section

Profile illustrating the continental shelf, slope and rise

A trapped gas deposit on the continental slope off Canada in the Beaufort Sea, located in an area of small conical hills on the ocean floor is just 290 meters below sea level and considered the shallowest known deposit of methane hydrate.[9]

Seismic observation (in 2012) of destabilizing methane hydrate along the continental slope of the eastern United States, following the intrusion of warmer ocean currents, suggests that underwater landslides could release methane. The estimated amount of methane hydrate in this slope is 2.5 gigatonnes (about 0.2% of the amount required to cause the PETM), and it is unclear if the methane could reach the atmosphere. However, the authors of the study caution: "It is unlikely that the western North Atlantic margin is the only area experiencing changing ocean currents; our estimate of 2.5 gigatonnes of destabilizing methane hydrate may therefore represent only a fraction of the methane hydrate currently destabilizing globally." [10]

  1. Osegovic, J.P., Tatro, S.R. and Holman, S.A., 2006. Physical chemical characteristics of natural gas hydrate. In Economic Geology of Natural Gas Hydrate (pp. 45-104). Springer, Dordrecht.
  2. Cite error: Invalid <ref> tag; no text was provided for refs named Ruppel
  3. Osegovic, J.P., Tatro, S.R. and Holman, S.A., 2006. Physical chemical characteristics of natural gas hydrate. In Economic Geology of Natural Gas Hydrate (pp. 45-104). Springer, Dordrecht.
  4. Istomin, V. A.; Yakushev, V. S.; Makhonina, N. A.; Kwon, V. G.; Chuvilin, E. M. (2006). "Self-preservation phenomenon of gas hydrates". Gas Industry of Russia (4). 
  5. Buffett, Bruce A.; Zatsepina, Olga Y. (1999), "Metastability of gas hydrate", GRL, 26: 2981–2984, Bibcode:1999GeoRL..26.2981B, doi:10.1029/1999GL002339 
  6. Shakhova, Natalia; Semiletov, Igor; Salyuk, Anatoly; Yusupov, Vladimir; Kosmach, Denis; Gustafsson, Örjan (2010), "Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf", Science, 327 (5970): 1246–50, Bibcode:2010Sci...327.1246S, doi:10.1126/science.1182221, PMID 20203047 
  7. Ryskin, Gregory (September 2003). "Methane-driven oceanic eruptions and mass extinctions". Geology. 31 (9): 741–744. Bibcode:2003Geo....31..741R. doi:10.1130/G19518.1. 
  8. Atsushi Obata; Kiyotaka Shibata (June 20, 2012). "Damage of Land Biosphere due to Intense Warming by 1000-Fold Rapid Increase in Atmospheric Methane: Estimation with a Climate–Carbon Cycle Model". J Climate. 25: 8524–8541. Bibcode:2012JCli...25.8524O. doi:10.1175/JCLI-D-11-00533.1. Retrieved January 17, 2015. 
  9. Corbyn, Zoë (December 7, 2012). "Locked greenhouse gas in Arctic sea may be 'climate canary'". Nature. doi:10.1038/nature.2012.11988. Retrieved April 12, 2014. 
  10. Phrampus, B. J.; Hornbach, M. J. (December 24, 2012). "Recent changes to the Gulf Stream causing widespread gas hydrate destabilization". Nature. 490: 527–530. doi:10.1038/nature.2012.11652. Retrieved April 12, 2014.