Modeling the global carbon cycle with a gas hydrate capacitor: significance for the latest Paleocene Thermal Maximum

Dickens, Gerald R. (2001) Modeling the global carbon cycle with a gas hydrate capacitor: significance for the latest Paleocene Thermal Maximum. Geophysical Monograph Series, 124. pp. 19-38.

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The "Latest Paleocene Thermal Maximum" (or LPTM) ca. 55 Ma was characterized by a 4 to 6 °C rise in deep ocean water temperature and an extraordinary injection of ¹²C-rich carbon into the exogenic carbon cycle. The best explanation for the carbon cycle perturbation is that the bottom water warming converted massive amounts of marine gas hydrate to free CH4 gas, and this CH4 was added to the ocean. If correct, basic models for the global carbon cycle must be reconstructed with a gas hydrate "capacitor" so that large quantities of ¹²C-rich carbon can be stored and released over time. Although recent work has discussed CH4 release from gas hydrate, the first operational model of the global carbon cycle including CH4 storage is presented here both conceptually and mathematically. Using the Blake Ridge gas hydrate deposit as an example, the capacitor contains three internal reservoirs: dissolved gas, gas hydrate and free gas. Carbon enters dissolved gas through methanogenesis of organic matter. Upon saturation of pore waters, carbon is transferred to gas hydrate and then free gas at appropriate temperature and pressure conditions. Carbon leaves free gas to the exogenic carbon cycle through anaerobic CH4 oxidation or, if there is no overlying gas hydrate, direct injection to the water column. Because the amount and location of free gas depends on temperature, the capacitor can suddenly release massive amounts of ¹²C-rich carbon with abrupt bottom water warming. When the "gas hydrate" capacitor is connected to a Paleogene exogenic carbon cycle and subjected to a SOC warming, the response is similar to that observed for the LPTM.

Item ID: 14320
Item Type: Article (Research - C1)
ISBN: 0-87590-982-5
ISSN: 0065-8448
Additional Information:

[Monograph Title] Natural gas hydrates: occurrence, distribution, and detection

Date Deposited: 06 Feb 2013 02:04
FoR Codes: 04 EARTH SCIENCES > 0405 Oceanography > 040502 Chemical Oceanography @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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