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Effects of climate change on methane emissions from seafloor sediments in the Arctic

Effects of climate change on methane emissions from seafloor sediments in the Arctic
Effects of climate change on methane emissions from seafloor sediments in the Arctic
Large quantities of methane are stored in hydrates and permafrost within shallow marine sediments in the Arctic Ocean. These reservoirs are highly sensitive to climate warming, but the fate of methane released from sediments is uncertain. Here, we review the principal physical and biogeochemical processes that regulate methane fluxes across the seabed, the fate of this methane in the water column, and potential for its release to the atmosphere. We find that, at present, fluxes of dissolved methane are significantly moderated by anaerobic and aerobic oxidation of methane. If methane fluxes increase then a greater proportion of methane will be transported by advection or in the gas phase, which reduces the efficiency of the methanotrophic sink. Higher freshwater discharge to Arctic shelf seas may increase stratification and inhibit transfer of methane gas to surface waters, although there is some evidence that increased stratification may lead to warming of sub-pycnocline waters, increasing the potential for hydrate dissociation. Loss of sea-ice is likely to increase wind speeds and sea-air exchange of methane will consequently increase. Studies of the distribution and cycling of methane beneath and within sea ice are limited, but it seems likely that the sea-air methane flux is higher during melting in seasonally ice-covered regions. Our review reveals that increased observations around especially the anaerobic and aerobic oxidation of methane, bubble transport, and the effects of ice cover, are required to fully understand the linkages and feedback pathways between climate warming and release of methane from marine sediments.
0024-3590
S283-S299
James, Rachael H.
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Bousquet, Phillipe
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Bussmann, Ingeborg
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Haeckel, Mathias
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Kipfer, Rolf
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Leifer, Ira
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Niemann, Helge
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Ostrovsky, Ilia
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Piskozub, Jacek
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Rehder, Gregor
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Treude, Tina
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Vielstädte, Lisa
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Greinert, Jens
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James, Rachael H.
79aa1d5c-675d-4ba3-85be-fb20798c02f4
Bousquet, Phillipe
6b375d86-46b9-4c27-b6b3-ff1fc474c798
Bussmann, Ingeborg
f8db520e-a9d9-4b80-9fd9-55e30a4c1024
Haeckel, Mathias
75519caf-aae1-4622-a78f-712a99588235
Kipfer, Rolf
4e9c6393-7fb0-49ed-b885-cd8a65dc8962
Leifer, Ira
24e1e6be-9265-4538-b3b1-7c2179456331
Niemann, Helge
51398a14-68cb-46f0-bd02-f90068cf9848
Ostrovsky, Ilia
11b9f2d1-8724-495b-815b-e654a5fa7eea
Piskozub, Jacek
e04ce311-06bb-46be-b669-749e1d0d40dc
Rehder, Gregor
91093308-4975-4930-8ccb-49bc7c95f5ac
Treude, Tina
3166500a-1b9b-41d8-8047-30d47b428e12
Vielstädte, Lisa
ac0a3ae8-b0db-4f76-a788-4c21690a7286
Greinert, Jens
4e3d5578-8e20-402e-bb76-6742df96f8db

James, Rachael H., Bousquet, Phillipe, Bussmann, Ingeborg, Haeckel, Mathias, Kipfer, Rolf, Leifer, Ira, Niemann, Helge, Ostrovsky, Ilia, Piskozub, Jacek, Rehder, Gregor, Treude, Tina, Vielstädte, Lisa and Greinert, Jens (2016) Effects of climate change on methane emissions from seafloor sediments in the Arctic. Limnology and Oceanography, 61 (S1), S283-S299. (doi:10.1002/lno.10307).

Record type: Article

Abstract

Large quantities of methane are stored in hydrates and permafrost within shallow marine sediments in the Arctic Ocean. These reservoirs are highly sensitive to climate warming, but the fate of methane released from sediments is uncertain. Here, we review the principal physical and biogeochemical processes that regulate methane fluxes across the seabed, the fate of this methane in the water column, and potential for its release to the atmosphere. We find that, at present, fluxes of dissolved methane are significantly moderated by anaerobic and aerobic oxidation of methane. If methane fluxes increase then a greater proportion of methane will be transported by advection or in the gas phase, which reduces the efficiency of the methanotrophic sink. Higher freshwater discharge to Arctic shelf seas may increase stratification and inhibit transfer of methane gas to surface waters, although there is some evidence that increased stratification may lead to warming of sub-pycnocline waters, increasing the potential for hydrate dissociation. Loss of sea-ice is likely to increase wind speeds and sea-air exchange of methane will consequently increase. Studies of the distribution and cycling of methane beneath and within sea ice are limited, but it seems likely that the sea-air methane flux is higher during melting in seasonally ice-covered regions. Our review reveals that increased observations around especially the anaerobic and aerobic oxidation of methane, bubble transport, and the effects of ice cover, are required to fully understand the linkages and feedback pathways between climate warming and release of methane from marine sediments.

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Accepted/In Press date: 1 March 2016
e-pub ahead of print date: 17 May 2016
Published date: 18 November 2016
Organisations: Geochemistry

Identifiers

Local EPrints ID: 390650
URI: https://eprints.soton.ac.uk/id/eprint/390650
ISSN: 0024-3590
PURE UUID: 07971dac-d093-4084-b689-347a793a5361

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Date deposited: 01 Apr 2016 13:59
Last modified: 15 Aug 2019 05:33

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Contributors

Author: Phillipe Bousquet
Author: Ingeborg Bussmann
Author: Mathias Haeckel
Author: Rolf Kipfer
Author: Ira Leifer
Author: Helge Niemann
Author: Ilia Ostrovsky
Author: Jacek Piskozub
Author: Gregor Rehder
Author: Tina Treude
Author: Lisa Vielstädte
Author: Jens Greinert

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