Methane HydratesDuane Castaldi3.28.03What are Methane Hydrates? A type of clathrate, a complex formed when molecules are trapped inside a lattice structure of another type of molecule. Water molecules form the latticestructure that traps methane molecules inside the structure. Located either in marine sediments or in permafrost regions.Methane Hydrate ReservesSource: http://www.giss.nasa.gov/research/intro/schmidt_02/Importance of Methane Hydrates A new source of energy. Methane/Natural Gas is considered to be a cleaner burning fossil fuel The effect methane hydrates may have on climate change.Methane Hydrates and Climate Methane is a “greenhouse gas.” 10 times more effective than CO2 at warming. 3000 times the amount of methane in hydrate form than in the atmosphere currently.Paleocene-Eocene Thermal Maximum A very abrupt event in terms of geologic time. Late Paleocene- Early Eocene or about 55 million years ago. Climate was already relatively warm. The pole-equatorial temperature gradient was smaller at this time.Paleocene-Eocene Thermal Maximum Intermediate to deep ocean water temperatures increased between 6 and 8 C. It all occurred with in 20,000 years. Sediment cores indicate: -2.5 13C in marine environments and at least a –5 13C shift in terrestrial environments.Why such a decrease in Carbon Isotopes at the PETM Approximately 2000gigatons of isotopically depleted Carbon was released into the ocean atmosphere system. Possibly due to the melting of methane hydrates trapped in the ocean Hydrates tend to be highly unstable, a concern to mining for natural gas.Ocean Temperatures Warmed Bottom ocean water could have warmed due to deep water formation at low latitudes. This is a possibility as the thermal forcing of the THC was reduced by the fact that the pole-equator temperature gradient was small. Not all data/models agree. Either way a changing THC seems a likely cause of global water temperature change.The PETM Feedback The abruptness of bottom warming was thought to indicate THC as changing. A possible change would have been from the high southern regions to the high northern regions. This switch from sinking in the south to sinking in the north may represent a climatic threshold.Positive Feedback Loop Occurs when one factor leads to an increase in another. Rare in nature. Common with human alterations. Can become dangerous.The PETM Positive FeedbackIncreased VolcanismIncreasedHydrologic cycleSubduction WarmingHydrate DestabilizationMethaneReleasedMethaneOxidized to CO2+More Evidence Testing the PETM Hypothesis has been difficult as proxy records have been unable to definitively lay out a time scale and put the initial events into a sequence. Planktonic and Benthic Foramnifera shells have been analyzed giving key information. These findings support the thermal dissociation of Methane Hydrates.Current Methane Hydrate Research USGS Hydrate formation Hydrate breakdown Hydrate evolution Hydrate effects In cooperation with National Oceanic and Atmospheric Administration, US Navy, and Department of EnergyReview Questions Why are Methane Hydrates important? What is the effect of Methane Hydrates on Global Climate?References http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html http://wpc.prenhall.com/esm_abel_issuesocean_2/0,6649,22819-,00.htm Bice, K. and Marotzke J. Paleoceanography. Could Changing ocean circulation have destablized methane hydrate at the Paleocene/Eocene boundary? Volume 17. June 2002. Pages 8-1 to 8-13. Chiras D. Environmental Science- Creating a Sustainable Future. Jones and Bartlett. Sudbury, Ma. 2001. Thomas DJ, Zachos JC, Bralower TJ, Thomas E, Bohaty S. Geology. Warming the fuel for the fire: Evidence for the thermal dissociation of methane hydrate during the Paleocene-Eocene thermal maximum. Volume 30. December