Methane Hydrate and Climate Change
By: Kolter Hartman
Methane hydrate occurs abundantly in nature in marine sediments and polar terrestrial permafrost environments. It is most commonly found in marine sediments all over the world under favorable conditions of temperature and pressure. Methane hydrate is stable in ocean floor sediments at water depths greater than 300 meters, and where it occurs, it is known to cement loose sediments in a surface layer several hundred meters thick.
Methane hydrate is a crystalline solid consisting of methane gas molecules, each surrounded by a cage of water molecules. It looks very much like water ice. The picture at the left shows a methane gas molecule (yellow) surrounded by a matrix of frozen water molecules. The picture at the right shows methane hydrate burning readily in air with a blue, luminous flame.
Methane bound in hydrates amounts to approximately 3,000 times the volume of methane in the atmosphere. As a greenhouse gas, methane is 10 times more effective than carbon dioxide in causing climate warming. The worldwide amounts of carbon bound in methane hydrate is conservatively estimated to total twice the amount of carbon to be found in all known fossil fuels on Earth. Methane released as a result of landslides caused by a sea-level fall would warm the Earth, as would methane released from methane hydrate in Arctic sediments as they become warmed during a sea-level rise. This global warming might counteract cooling trends and thereby stabilize climatic fluctuation, or it could exacerbate climatic warming and thereby destabilize the climate. My seminar will provide evidence for and against methane hydrate as a mechanism for global climate change.
Behl, Richard J. Cannariato, Kevin G. Hendy, Ingrid L. Kennett, James P. Carbon Isotopic Evidence for
Methane Hydrate Instability During Quaternary Interstadials. Science. April 7, 2000. v288 i5463. p128.
Bratton, John F. Clathrate eustasy: Methane hydrate melting as a mechanism for geologically rapid sea-level fall.
v27 i10. p915(4).
Castillo, Maria M. Dickens, Gerald R. Walker, James C.G. A blast of gas in the latest Paleocene: simulating
first-order effects of massive dislocation of oceanic methane hydrate. Geology. March 1997. v25 n3. p259(4).
Geological Survey of Canada. Fact Sheet: Climate Change Science: Gas Hydrates in Permafrost.
http://sts.gsc.nrcan.gc.ca/page1/clim/new/E-GHP-ES.HTM Natural Resources Canada. March 1, 1997.
Hydrates and Climate Change. http://www.hydrate.org/about/climate.cfm Feb 2001.
Simpson, Sarah. Gas Blasts - Methane once frozen under the seafloor may help heat up the climate.
http://www.sciam.com/explorations/1999/122099hydrate/index.html Scientific American. Dec 20, 1999.
Sassen, Roger. Gas Hydrate Gardens of the Gulf of Mexico. Texas A&M University, Dept.of Oceanography, Quarterdeck.
Vol 5. Issue 3. Dec 1997.
Sources. http://www.hydrate.org/sources.cfm Feb 2001.