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Reassessment of hydrate destabilization mechanisms offshore west Svalbard confirms link to recent ocean warming

Reassessment of hydrate destabilization mechanisms offshore west Svalbard confirms link to recent ocean warming
Reassessment of hydrate destabilization mechanisms offshore west Svalbard confirms link to recent ocean warming
The stability of methane hydrates at the feather edge of hydrate stability on the upper continental slope (UCS) is prone to ocean warming and relative sea level (RSL) change. West of Svalbard, methane seeps on the UCS were initially proposed to result from hydrate destabilization resulting from four decades of warming of Atlantic bottom water. Alternatively, it has been proposed that hydrate dissociation was triggered by RSL fall due to isostatic rebound over the past 8,000 yr rather than recent bottom water temperature (BWT) rise. Here, we address these two contrasting hypotheses by simulating the impact of 11,000 yr of BWT and RSL change on hydrates located at the UCS off west Svalbard. Our numerical simulation considers multiphase fluid and heat flow coupled with hydrate formation and dissociation. We used two reconstructions of local ice history (UiT and ICE-6G_C) that predict contrasting results for the local sea level history. Over the past 8,000 yr, the UiT model predicts a fall in RSL on the UCS, while the ICE-6G_C model, which provides a better fit to nearby coastal RSL observations, predicts a continuous rise. Our modeling shows that whilst long-term RSL fall would progressively thin the region of hydrate stability, the abrupt rise in BWT enhances hydrate dissociation. Even in the model with an RSL rise, the increase in BWT causes hydrate destabilization and pore water freshening that matches observations. We conclude that recent ocean warming plays a critical role in hydrate dissociation west of Svalbard regardless of the longer-term sea level history.
Arctic methane hydrate, hydrate dissociation, isostatic rebound, methane emission, ocean warming, sea level change
2169-9356
Trivedi, Akash
15ec9e24-3495-4623-a442-e5758dffd9e6
Sarkar, Sudipta
53e08952-8fd6-4c90-bb39-15f71baa494d
Marin Moreno, Hector
e466cafd-bd5c-47a1-8522-e6938e7086a4
Minshull, Timothy A.
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Whitehouse, Pippa L.
ff506bf6-5f47-4488-8a68-4622adf0d9e0
Singh, Utpal
59064714-1d6c-4d4e-9f49-0c3380ad1300
Trivedi, Akash
15ec9e24-3495-4623-a442-e5758dffd9e6
Sarkar, Sudipta
53e08952-8fd6-4c90-bb39-15f71baa494d
Marin Moreno, Hector
e466cafd-bd5c-47a1-8522-e6938e7086a4
Minshull, Timothy A.
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Whitehouse, Pippa L.
ff506bf6-5f47-4488-8a68-4622adf0d9e0
Singh, Utpal
59064714-1d6c-4d4e-9f49-0c3380ad1300

Trivedi, Akash, Sarkar, Sudipta, Marin Moreno, Hector, Minshull, Timothy A., Whitehouse, Pippa L. and Singh, Utpal (2022) Reassessment of hydrate destabilization mechanisms offshore west Svalbard confirms link to recent ocean warming. Journal of Geophysical Research: Solid Earth, 127 (11), [e2022JB025231]. (doi:10.1029/2022JB025231).

Record type: Article

Abstract

The stability of methane hydrates at the feather edge of hydrate stability on the upper continental slope (UCS) is prone to ocean warming and relative sea level (RSL) change. West of Svalbard, methane seeps on the UCS were initially proposed to result from hydrate destabilization resulting from four decades of warming of Atlantic bottom water. Alternatively, it has been proposed that hydrate dissociation was triggered by RSL fall due to isostatic rebound over the past 8,000 yr rather than recent bottom water temperature (BWT) rise. Here, we address these two contrasting hypotheses by simulating the impact of 11,000 yr of BWT and RSL change on hydrates located at the UCS off west Svalbard. Our numerical simulation considers multiphase fluid and heat flow coupled with hydrate formation and dissociation. We used two reconstructions of local ice history (UiT and ICE-6G_C) that predict contrasting results for the local sea level history. Over the past 8,000 yr, the UiT model predicts a fall in RSL on the UCS, while the ICE-6G_C model, which provides a better fit to nearby coastal RSL observations, predicts a continuous rise. Our modeling shows that whilst long-term RSL fall would progressively thin the region of hydrate stability, the abrupt rise in BWT enhances hydrate dissociation. Even in the model with an RSL rise, the increase in BWT causes hydrate destabilization and pore water freshening that matches observations. We conclude that recent ocean warming plays a critical role in hydrate dissociation west of Svalbard regardless of the longer-term sea level history.

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2022JB025231 - Accepted Manuscript
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JGR Solid Earth - 2022 - Trivedi - Reassessment of Hydrate Destabilization Mechanisms Offshore West Svalbard Confirms Link - Version of Record
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Accepted/In Press date: 15 October 2022
e-pub ahead of print date: 1 November 2022
Published date: 1 November 2022
Additional Information: Funding Information: SS was supported by the Science and Engineering Research Board (SERB Act 2008) as a part of its Earth and Atmospheric Science program Start-up Research Grant (SRG/2019/001072) and SS also thanks DST FIST (Grant SR/FST/ES-I/2018/25) for infrastructure support. The authors thank Henry Patton for providing information about the UiT Ice sheet modeling. The authors thank the Associate Editor, one anonymous reviewer, and Peter Flemings for their detailed and helpful comments. Funding Information: SS was supported by the Science and Engineering Research Board (SERB Act 2008) as a part of its Earth and Atmospheric Science program Start‐up Research Grant (SRG/2019/001072) and SS also thanks DST FIST (Grant SR/FST/ES‐I/2018/25) for infrastructure support. The authors thank Henry Patton for providing information about the UiT Ice sheet modeling. The authors thank the Associate Editor, one anonymous reviewer, and Peter Flemings for their detailed and helpful comments. Publisher Copyright: © 2022. American Geophysical Union. All Rights Reserved.
Keywords: Arctic methane hydrate, hydrate dissociation, isostatic rebound, methane emission, ocean warming, sea level change

Identifiers

Local EPrints ID: 471750
URI: http://eprints.soton.ac.uk/id/eprint/471750
ISSN: 2169-9356
PURE UUID: c1e557ea-dcbf-479b-bb81-e53d154e129a
ORCID for Hector Marin Moreno: ORCID iD orcid.org/0000-0002-3412-1359
ORCID for Timothy A. Minshull: ORCID iD orcid.org/0000-0002-8202-1379

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Date deposited: 17 Nov 2022 17:44
Last modified: 17 Mar 2024 07:34

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Contributors

Author: Akash Trivedi
Author: Sudipta Sarkar
Author: Hector Marin Moreno ORCID iD
Author: Pippa L. Whitehouse
Author: Utpal Singh

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