Clathrate gun hypothesis 5069503 219030486 2008-06-13T07:09:42Z 24.46.164.83 /* In fiction - The Far Shore of Time */ {{annotated image/Extinction}} The '''clathrate gun hypothesis''' states that as sea temperatures rise the sudden release of [[methane]] from [[methane clathrate]] compounds buried in the [[seabed]]s will cause a drastic alteration of the ocean environment and the atmosphere of earth, as [http://www.bbc.co.uk/science/horizon/2002/dayearthdied.shtml recent analysis] concerning the [[Permian-Triassic extinction event|Permian extinction event]] indicates may have happened in the past. ==Mechanism== Methane clathrate, also called methane hydrate, is a form of water ice that contains a large amount of methane within its crystal structure. Extremely large deposits of methane clathrate have been found under sediments on the ocean floors of the Earth. The sudden release of large amounts of natural gas from methane clathrate deposits in a [[runaway greenhouse effect#Positive_feedback_and_runaway_greenhouse_effect|runaway greenhouse effect]] could be a cause of past and future climate changes. The release of this trapped methane is a potential major outcome of a rise in temperature; it is thought that this is a main factor in the global warming of 6°C that happened during the end-Permian extinction[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VJ1-48HY72J-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=af2525d974a4efe58fcd7b8cc3a52ea3], as methane is much more powerful as a greenhouse gas than carbon dioxide (despite its atmospheric lifetime of around 12 years, it has a [[global warming potential]] of 62 over 20 years and 23 over 100 years). The theory also predicts this will greatly affect available oxygen content of the atmosphere. ==Recent findings== In 2002, a BBC2 'Horizon' documentary, '[http://www.bbc.co.uk/science/horizon/2002/dayearthdied.shtml The Day the Earth Nearly Died],' summarized some recent findings and speculation concerning the [[Permian-Triassic extinction event|Permian extinction event]]. Paul Wignall examined Permian strata in Greenland, where the rock layers devoid of marine life are tens of meters thick. With such an expanded scale, he could judge the timing of deposition more accurately and ascertained that the entire extinction lasted merely 80,000 years and showed three distinctive phases in the plant and animal fossils they contained. The extinction appeared to kill land and marine life selectively at different times. Two periods of extinctions of terrestrial life were separated by a brief, sharp, almost total extinction of marine life. Such a process seemed too long, however, to be accounted for by a meteorite strike. His best clue was the carbon isotope balance in the rock, which showed an increase in [[carbon-12]] over time. The standard explanation for such a spike – rotting vegetation – seemed insufficient. Geologist Gerry Dickens suggested that the increased carbon-12 could have been rapidly released by up-swellings of frozen methane hydrate from the seabed. Experiments to assess how large a rise in deep sea temperature would be required to sublimate solid methane hydrate suggested that a rise of 5°C (9 F) would be sufficient. ==Possible release events== Two events possibly linked in this way are the Permian-Triassic extinction event and the [[Paleocene-Eocene Thermal Maximum]]. However, warming at the end of the last [[ice age]] is thought not to be due to methane release. ==Related mechanism: dissolved methane release== Focusing on the Permian-Triassic boundary, Gregory Ryskin [http://pangea.stanford.edu/Oceans/GES205/methaneGeology.pdf] explores the possibility that mass extinction can be caused by an extremely fast, explosive release of dissolved methane (and other dissolved gases such as carbon dioxide and hydrogen sulfide) that accumulated in the oceanic water masses prone to stagnation and anoxia (e.g., in silled basins). As today's global CO<sub>2</sub> levels head towards 400 ppm, the destabilisation of methane clathrates could become an uncontrollable feedback mechanism taking temperatures up alarmingly. Re-assuringly, most are in sediments too deep to respond rapidly, and modelling by Archer (2007) suggests the methane forcing should remain a minor component of the overall GHE. ==References== * {{cite journal |last=Benton |first=Michael J. |coauthors=Richard J. Twitchett |year=2003 |month=July |title=How to kill (almost) all life: the end-Permian extinction event |journal=TRENDS in Ecology and Evolution |volume=18 |issue=7 |pages=358–365|doi=10.1016/S0169-5347(03)00093-4|url=http://palaeo.gly.bris.ac.uk/Benton/reprints/2003TREEPTr.pdf}}, cited by [http://scholar.google.com/scholar?num=100&hl=en&lr=&ie=ISO-8859-1&q=permian+extinction+%22positive+feedback%22&btnG=Search 21 other articles]. *[http://www.nature.com/nature/journal/v429/n6991/abs/nature02566.html Release of methane from a volcanic basin as a mechanism for initial Eocene global warming], Henrik Svensen1, Sverre Planke1,2, Anders Malthe-Sørenssen1, Bjørn Jamtveit1, Reidun Myklebust3, Torfinn Rasmussen Eidem2 and Sebastian S. Rey2; Nature 429, 542-545 (3 June 2004) *[http://www.es.ucsc.edu/~jzachos/pubs/TZBTB_02.pdf Warming the fuel for the fire: Evidence for the thermal dissociation of methane hydrate during the Paleocene-Eocene thermal maximum], Deborah J. Thomas1, James C. Zachos2, Timothy J. Bralower3, Ellen Thomas4 and Steven Bohaty5 ; Geology; December 2002; v. 30; no. 12; p. 1067-1070 *[http://pangea.stanford.edu/Oceans/GES205/methaneGeology.pdf Methane-driven oceanic eruptions and mass extinctions], Gregory Ryskin, Northwestern University. Geology; September 2003; v. 31; no. 9; p. 741-744 * [http://adsabs.harvard.edu/abs/2004AGUFMGC51D1069A Temperature sensitivity and time dependence of the global ocean clathrate reservoir], Archer, D.; Buffett, B., Department of Geophysics, University of Chicago IL, American Geophysical Union, Fall Meeting 2004 *Methane hydrate stability and anthropogenic climate change, Archer D, Department of Geophysics, University of Chicago IL. Biogeosciences v. 4; n 4; 2007; p. 521-544 ==In fiction== *The book ''[[Mother of Storms]]'' by [[John Barnes (author)|John Barnes]] offers a fictional example of catastrophic climate change caused by methane clathrate release. *In ''[[The Life Lottery]]'' by [[Ian Irvine]] unprecedented seismic activity triggers a release of methane hydrate, reversing global cooling. *The hypothesis is the basis of an experiment in [[Death By Degrees]]. *In ''[[Transcendent (novel)|Transcendent]]'' by [[Stephen Baxter]], averting such a crisis is a major plotline. *The novel ''[[The Black Silent]]'' by author [[David Dun]] features this idea as a key scientific point. *In the anime ''[[Ergo Proxy]]'', a string of explosions in the methane hydrate reserves wipes out 85% of human life on Earth. *The novel ''[[The Far Shore of Time]]'' by [[Frederik Pohl]] features an alien race attempting to destroy humanity by bombing the methane clathrate reserves, thus releasing the gas into the atmosphere. ==See also== *[[Clathrate compound]] *[[Extinction event]] *[[Bermuda Triangle]] *[[abiogenic petroleum origin]] ==External links== * [http://www.palaeobiology.org.uk/profiles/wignall_r.htm Homepage of Dr. Paul Wignal, Reader in Palaeoenvironments, University of Leeds.] * [http://www-esd.lbl.gov/seminar_series/abstracts/kennett.html (Abstract) Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis] * [http://www.minsocam.org/MSA/AmMin/TOC/Abstracts/2004_Abstracts/AS04_Abstracts/Chakoumakos_p1153_04.pdf Preface to the Clathrate Hydrates special issue] ===Historical events=== * [http://www.bioedonline.org/news/news.cfm?art=2334 Biology News: Gassy emissions no longer in suspect dock for melting the last ice age] * [http://www.geog.ucl.ac.uk/~mmaslin/publications/Maslin1.pdf Linking continental-slope failures and climate change: Testing the clathrate gun hypothesis] {{Global warming}} [[Category:Climate change]] [[Category:Global warming]] [[Category:Clathrates]] [[ca:Hipòtesi del fusell de clatrats]] [[es:Hipótesis del fusil de clatratos]]