Ocean methane hydrates as a slow tipping point in the global carbon cycle
We present a model of the global methane inventory as hydrate and bubbles below the sea floor. The model predicts the inventory of CH4 in the ocean today to be ≈1600-2,000 Pg of C. Most of the hydrate in the model is in the Pacific, in large part because lower oxygen levels enhance the preservation...
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ftpubman:oai:pure.mpg.de:item_993876 2023-08-27T04:06:04+02:00 Ocean methane hydrates as a slow tipping point in the global carbon cycle Archer, D. Buffet, B. Brovkin, V. 2009-12 application/pdf http://hdl.handle.net/11858/00-001M-0000-0011-F76F-7 http://hdl.handle.net/11858/00-001M-0000-0011-F76E-9 eng eng info:eu-repo/semantics/altIdentifier/doi/10.1073/pnas.0800885105 http://hdl.handle.net/11858/00-001M-0000-0011-F76F-7 http://hdl.handle.net/11858/00-001M-0000-0011-F76E-9 info:eu-repo/semantics/openAccess Proceedings of the National Academy of Sciences of the United States of America info:eu-repo/semantics/article 2009 ftpubman https://doi.org/10.1073/pnas.0800885105 2023-08-02T01:13:09Z We present a model of the global methane inventory as hydrate and bubbles below the sea floor. The model predicts the inventory of CH4 in the ocean today to be ≈1600-2,000 Pg of C. Most of the hydrate in the model is in the Pacific, in large part because lower oxygen levels enhance the preservation of organic carbon. Because the oxygen concentration today may be different from the longterm average, the sensitivity of the model to O2 is a source of uncertainty in predicting hydrate inventories. Cold water column temperatures in the high latitudes lead to buildup of hydrates in the Arctic and Antarctic at shallower depths than is possible in low latitudes. A critical bubble volume fraction threshold has been proposed as a critical threshold at which gas migrates all through the sediment column. Our model lacks many factors that lead to heterogeneity in the real hydrate reservoir in the ocean, such as preferential hydrate formation in sandy sediments and subsurface gas migration, and is therefore conservative in its prediction of releasable methane, finding only 35 Pg of C released after 3 ° C of uniform warming by using a 10% critical bubble volume. If 2.5% bubble volume is taken as critical, then 940 Pg of C might escape in response to 3 ° C warming. This hydrate model embedded into a global climate model predicts ≈0.4-0.5 ° C additional warming from the hydrate response to fossil fuel CO2 release, initially because of methane, but persisting through the 10-kyr duration of the simulations because of the CO2 oxidation product of methane. Article in Journal/Newspaper Antarc* Antarctic Arctic Max Planck Society: MPG.PuRe Antarctic Arctic Pacific Proceedings of the National Academy of Sciences 106 49 20596 20601 |
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Max Planck Society: MPG.PuRe |
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ftpubman |
language |
English |
description |
We present a model of the global methane inventory as hydrate and bubbles below the sea floor. The model predicts the inventory of CH4 in the ocean today to be ≈1600-2,000 Pg of C. Most of the hydrate in the model is in the Pacific, in large part because lower oxygen levels enhance the preservation of organic carbon. Because the oxygen concentration today may be different from the longterm average, the sensitivity of the model to O2 is a source of uncertainty in predicting hydrate inventories. Cold water column temperatures in the high latitudes lead to buildup of hydrates in the Arctic and Antarctic at shallower depths than is possible in low latitudes. A critical bubble volume fraction threshold has been proposed as a critical threshold at which gas migrates all through the sediment column. Our model lacks many factors that lead to heterogeneity in the real hydrate reservoir in the ocean, such as preferential hydrate formation in sandy sediments and subsurface gas migration, and is therefore conservative in its prediction of releasable methane, finding only 35 Pg of C released after 3 ° C of uniform warming by using a 10% critical bubble volume. If 2.5% bubble volume is taken as critical, then 940 Pg of C might escape in response to 3 ° C warming. This hydrate model embedded into a global climate model predicts ≈0.4-0.5 ° C additional warming from the hydrate response to fossil fuel CO2 release, initially because of methane, but persisting through the 10-kyr duration of the simulations because of the CO2 oxidation product of methane. |
format |
Article in Journal/Newspaper |
author |
Archer, D. Buffet, B. Brovkin, V. |
spellingShingle |
Archer, D. Buffet, B. Brovkin, V. Ocean methane hydrates as a slow tipping point in the global carbon cycle |
author_facet |
Archer, D. Buffet, B. Brovkin, V. |
author_sort |
Archer, D. |
title |
Ocean methane hydrates as a slow tipping point in the global carbon cycle |
title_short |
Ocean methane hydrates as a slow tipping point in the global carbon cycle |
title_full |
Ocean methane hydrates as a slow tipping point in the global carbon cycle |
title_fullStr |
Ocean methane hydrates as a slow tipping point in the global carbon cycle |
title_full_unstemmed |
Ocean methane hydrates as a slow tipping point in the global carbon cycle |
title_sort |
ocean methane hydrates as a slow tipping point in the global carbon cycle |
publishDate |
2009 |
url |
http://hdl.handle.net/11858/00-001M-0000-0011-F76F-7 http://hdl.handle.net/11858/00-001M-0000-0011-F76E-9 |
geographic |
Antarctic Arctic Pacific |
geographic_facet |
Antarctic Arctic Pacific |
genre |
Antarc* Antarctic Arctic |
genre_facet |
Antarc* Antarctic Arctic |
op_source |
Proceedings of the National Academy of Sciences of the United States of America |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1073/pnas.0800885105 http://hdl.handle.net/11858/00-001M-0000-0011-F76F-7 http://hdl.handle.net/11858/00-001M-0000-0011-F76E-9 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1073/pnas.0800885105 |
container_title |
Proceedings of the National Academy of Sciences |
container_volume |
106 |
container_issue |
49 |
container_start_page |
20596 |
op_container_end_page |
20601 |
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1775346808797528064 |