Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009
The Southern Ocean (44–75° S) plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled ocean regions. Different approaches have been used to estimate sea–air CO2 fluxes in this region: synthesis of surface ocean observations, ocean biogeochemical models, and atmos...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/70775 2023-05-15T18:24:51+02:00 Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009 Lenton, Andrew Tilbrook, Bronte D. Law, Rachel M. Bakker, Dorothee C.E. Doney, Scott C. Gruber, Nicolas Ishii, Masao Hoppema, M. Lovenduski, Nicole S. McNeil, Ben Metzl, Nicolas Mikaloff Fletcher, Sara E. Monteiro, Pedro Rödenbeck, Christian Sweeney, Colm Takahashi, T. 2013 application/application/pdf https://hdl.handle.net/20.500.11850/70775 https://doi.org/10.3929/ethz-b-000070775 en eng Copernicus info:eu-repo/semantics/altIdentifier/doi/10.5194/bg-10-4037-2013 info:eu-repo/semantics/altIdentifier/wos/000321122700038 http://hdl.handle.net/20.500.11850/70775 doi:10.3929/ethz-b-000070775 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 Unported CC-BY Biogeosciences, 10 (6) info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2013 ftethz https://doi.org/20.500.11850/70775 https://doi.org/10.3929/ethz-b-000070775 https://doi.org/10.5194/bg-10-4037-2013 2022-04-25T13:34:42Z The Southern Ocean (44–75° S) plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled ocean regions. Different approaches have been used to estimate sea–air CO2 fluxes in this region: synthesis of surface ocean observations, ocean biogeochemical models, and atmospheric and ocean inversions. As part of the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we combine these different approaches to quantify and assess the magnitude and variability in Southern Ocean sea–air CO2 fluxes between 1990–2009. Using all models and inversions (26), the integrated median annual sea–air CO2 flux of −0.42 ± 0.07 Pg C yr−1 for the 44–75° S region, is consistent with the −0.27 ± 0.13 Pg C yr−1 calculated using surface observations. The circumpolar region south of 58° S has a small net annual flux (model and inversion median: −0.04 ± 0.07 Pg C yr−1 and observations: +0.04 ± 0.02 Pg C yr−1), with most of the net annual flux located in the 44 to 58° S circumpolar band (model and inversion median: −0.36 ± 0.09 Pg C yr−1 and observations: −0.35 ± 0.09 Pg C yr−1). Seasonally, in the 44–58° S region, the median of 5 ocean biogeochemical models captures the observed sea–air CO2 flux seasonal cycle, while the median of 11 atmospheric inversions shows little seasonal change in the net flux. South of 58° S, neither atmospheric inversions nor ocean biogeochemical models reproduce the phase and amplitude of the observed seasonal sea–air CO2 flux, particularly in the Austral Winter. Importantly, no individual atmospheric inversion or ocean biogeochemical model is capable of reproducing both the observed annual mean uptake and the observed seasonal cycle. This raises concerns about projecting future changes in Southern Ocean CO2 fluxes. The median interannual variability from atmospheric inversions and ocean biogeochemical models is substantial in the Southern Ocean; up to 25% of the annual mean flux, with 25% of this interannual variability attributed to the region south of 58° S. Resolving long-term trends is difficult due to the large interannual variability and short time frame (1990–2009) of this study; this is particularly evident from the large spread in trends from inversions and ocean biogeochemical models. Nevertheless, in the period 1990–2009 ocean biogeochemical models do show increasing oceanic uptake consistent with the expected increase of −0.05 Pg C yr−1 decade−1. In contrast, atmospheric inversions suggest little change in the strength of the CO2 sink broadly consistent with the results of Le Quéré et al. (2007). ISSN:1726-4170 ISSN:1726-4170 Article in Journal/Newspaper Southern Ocean ETH Zürich Research Collection Austral Southern Ocean |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
description |
The Southern Ocean (44–75° S) plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled ocean regions. Different approaches have been used to estimate sea–air CO2 fluxes in this region: synthesis of surface ocean observations, ocean biogeochemical models, and atmospheric and ocean inversions. As part of the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we combine these different approaches to quantify and assess the magnitude and variability in Southern Ocean sea–air CO2 fluxes between 1990–2009. Using all models and inversions (26), the integrated median annual sea–air CO2 flux of −0.42 ± 0.07 Pg C yr−1 for the 44–75° S region, is consistent with the −0.27 ± 0.13 Pg C yr−1 calculated using surface observations. The circumpolar region south of 58° S has a small net annual flux (model and inversion median: −0.04 ± 0.07 Pg C yr−1 and observations: +0.04 ± 0.02 Pg C yr−1), with most of the net annual flux located in the 44 to 58° S circumpolar band (model and inversion median: −0.36 ± 0.09 Pg C yr−1 and observations: −0.35 ± 0.09 Pg C yr−1). Seasonally, in the 44–58° S region, the median of 5 ocean biogeochemical models captures the observed sea–air CO2 flux seasonal cycle, while the median of 11 atmospheric inversions shows little seasonal change in the net flux. South of 58° S, neither atmospheric inversions nor ocean biogeochemical models reproduce the phase and amplitude of the observed seasonal sea–air CO2 flux, particularly in the Austral Winter. Importantly, no individual atmospheric inversion or ocean biogeochemical model is capable of reproducing both the observed annual mean uptake and the observed seasonal cycle. This raises concerns about projecting future changes in Southern Ocean CO2 fluxes. The median interannual variability from atmospheric inversions and ocean biogeochemical models is substantial in the Southern Ocean; up to 25% of the annual mean flux, with 25% of this interannual variability attributed to the region south of 58° S. Resolving long-term trends is difficult due to the large interannual variability and short time frame (1990–2009) of this study; this is particularly evident from the large spread in trends from inversions and ocean biogeochemical models. Nevertheless, in the period 1990–2009 ocean biogeochemical models do show increasing oceanic uptake consistent with the expected increase of −0.05 Pg C yr−1 decade−1. In contrast, atmospheric inversions suggest little change in the strength of the CO2 sink broadly consistent with the results of Le Quéré et al. (2007). ISSN:1726-4170 ISSN:1726-4170 |
format |
Article in Journal/Newspaper |
author |
Lenton, Andrew Tilbrook, Bronte D. Law, Rachel M. Bakker, Dorothee C.E. Doney, Scott C. Gruber, Nicolas Ishii, Masao Hoppema, M. Lovenduski, Nicole S. McNeil, Ben Metzl, Nicolas Mikaloff Fletcher, Sara E. Monteiro, Pedro Rödenbeck, Christian Sweeney, Colm Takahashi, T. |
spellingShingle |
Lenton, Andrew Tilbrook, Bronte D. Law, Rachel M. Bakker, Dorothee C.E. Doney, Scott C. Gruber, Nicolas Ishii, Masao Hoppema, M. Lovenduski, Nicole S. McNeil, Ben Metzl, Nicolas Mikaloff Fletcher, Sara E. Monteiro, Pedro Rödenbeck, Christian Sweeney, Colm Takahashi, T. Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009 |
author_facet |
Lenton, Andrew Tilbrook, Bronte D. Law, Rachel M. Bakker, Dorothee C.E. Doney, Scott C. Gruber, Nicolas Ishii, Masao Hoppema, M. Lovenduski, Nicole S. McNeil, Ben Metzl, Nicolas Mikaloff Fletcher, Sara E. Monteiro, Pedro Rödenbeck, Christian Sweeney, Colm Takahashi, T. |
author_sort |
Lenton, Andrew |
title |
Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009 |
title_short |
Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009 |
title_full |
Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009 |
title_fullStr |
Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009 |
title_full_unstemmed |
Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009 |
title_sort |
sea-air co2 fluxes in the southern ocean for the period 1990-2009 |
publisher |
Copernicus |
publishDate |
2013 |
url |
https://hdl.handle.net/20.500.11850/70775 https://doi.org/10.3929/ethz-b-000070775 |
geographic |
Austral Southern Ocean |
geographic_facet |
Austral Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Biogeosciences, 10 (6) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/bg-10-4037-2013 info:eu-repo/semantics/altIdentifier/wos/000321122700038 http://hdl.handle.net/20.500.11850/70775 doi:10.3929/ethz-b-000070775 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 Unported |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/70775 https://doi.org/10.3929/ethz-b-000070775 https://doi.org/10.5194/bg-10-4037-2013 |
_version_ |
1766205816285691904 |