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Could changing ocean circulation have destabilized methane hydrate at the Paleocene/Eocene boundary?

Could changing ocean circulation have destabilized methane hydrate at the Paleocene/Eocene boundary?
Could changing ocean circulation have destabilized methane hydrate at the Paleocene/Eocene boundary?
During the Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma), marine and terrestrial carbon isotope values exhibit a negative shift of at least 2.5‰, indicative of massive destabilization of marine methane hydrates, releasing ~1100 gigatonnes of methane carbon. The cause of the hydrate destabilization is unknown but has been speculated to be warming due to a change from high-latitude to low-latitude deepwater formation. Here, we present results from a numerical ocean model indicating that a sudden switch of deepwater formation from southern to northern high latitudes caused mid-depth and deep-ocean warming of 3-5°C. The switch is caused by a slow increase in the intensity of the atmospheric hydrologic cycle, as expected under increasing temperatures and consistent with PETM sedimentary evidence. Deepened subduction prior to the thermohaline circulation switch causes warming of 1-4°C in limited areas at thermocline through upper intermediate depths, which could destabilize methane hydrates gradually and at progressively greater depths. The switch itself occurs abruptly, with up to 5°C warming resulting everywhere in the deep ocean.
ocean circulation, methane, carbon isotopes, gas hydrates, mathematical models, palaeoceanography
0883-8305
8.1-8.13
Bice, K.L.
90b0b56f-de2d-49d1-98c4-d111b6bd2914
Marotzke, J.
6047bfd1-68a3-4abe-95ce-e1df9a56ce76
Bice, K.L.
90b0b56f-de2d-49d1-98c4-d111b6bd2914
Marotzke, J.
6047bfd1-68a3-4abe-95ce-e1df9a56ce76

Bice, K.L. and Marotzke, J. (2002) Could changing ocean circulation have destabilized methane hydrate at the Paleocene/Eocene boundary? Paleoceanography, 17 (2), 8.1-8.13. (doi:10.1029/2001PA000678).

Record type: Article

Abstract

During the Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma), marine and terrestrial carbon isotope values exhibit a negative shift of at least 2.5‰, indicative of massive destabilization of marine methane hydrates, releasing ~1100 gigatonnes of methane carbon. The cause of the hydrate destabilization is unknown but has been speculated to be warming due to a change from high-latitude to low-latitude deepwater formation. Here, we present results from a numerical ocean model indicating that a sudden switch of deepwater formation from southern to northern high latitudes caused mid-depth and deep-ocean warming of 3-5°C. The switch is caused by a slow increase in the intensity of the atmospheric hydrologic cycle, as expected under increasing temperatures and consistent with PETM sedimentary evidence. Deepened subduction prior to the thermohaline circulation switch causes warming of 1-4°C in limited areas at thermocline through upper intermediate depths, which could destabilize methane hydrates gradually and at progressively greater depths. The switch itself occurs abruptly, with up to 5°C warming resulting everywhere in the deep ocean.

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Published date: 2002
Keywords: ocean circulation, methane, carbon isotopes, gas hydrates, mathematical models, palaeoceanography

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Local EPrints ID: 231
URI: http://eprints.soton.ac.uk/id/eprint/231
ISSN: 0883-8305
PURE UUID: bed6ebb8-f064-4d1a-820c-3c08cbb0637e

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Date deposited: 18 Nov 2003
Last modified: 02 Dec 2019 19:41

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