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Response of the ocean natural carbon storage to projected twenty-first-century climate change

Response of the ocean natural carbon storage to projected twenty-first-century climate change
Response of the ocean natural carbon storage to projected twenty-first-century climate change
The separate impacts of wind stress, buoyancy fluxes, and CO2 solubility on the oceanic storage of natural carbon are assessed in an ensemble of twentieth- to twenty-first-century simulations, using a coupled atmosphere–ocean–carbon cycle model. Time-varying perturbations for surface wind stress, temperature, and salinity are calculated from the difference between climate change and preindustrial control simulations, and are imposed on the ocean in separate simulations. The response of the natural carbon storage to each perturbation is assessed with novel prognostic biogeochemical tracers, which can explicitly decompose dissolved inorganic carbon into biological, preformed, equilibrium, and disequilibrium components. Strong responses of these components to changes in buoyancy and winds are seen at high latitudes, reflecting the critical role of intermediate and deep waters. Overall, circulation-driven changes in carbon storage are mainly due to changes in buoyancy fluxes, with wind-driven changes playing an opposite but smaller role. Results suggest that climate-driven perturbations to the ocean natural carbon cycle will contribute 20 Pg C to the reduction of the ocean accumulated total carbon uptake over the period 1860–2100. This reflects a strong compensation between a buildup of remineralized organic matter associated with reduced deep-water formation (+96 Pg C) and a decrease of preformed carbon (?116 Pg C). The latter is due to a warming-induced decrease in CO2 solubility (?52 Pg C) and a circulation-induced decrease in disequilibrium carbon storage (?64 Pg C). Climate change gives rise to a large spatial redistribution of ocean carbon, with increasing concentrations at high latitudes and stronger vertical gradients at low latitudes.
Carbon cycle, Climate change, Coupled models
0894-8755
2033-2053
Bernardello, R.
7db9abe7-7079-4f14-8397-6371d96e2420
Marinov, I.
f82e7a23-9a7b-46bf-8702-3ce4660ebe23
Palter, J.B.
c7fafac1-31e3-48f8-97a2-62b27373a36a
Sarmiento, J.L.
5887047e-92ac-47f7-a504-fb1699dd8d17
Galbraith, E.D.
cc8cae0d-d549-4a66-bccc-2e5ba88e167f
Slater, R.D.
02cdf450-d76f-468f-9eee-9afd70d9e05c
Bernardello, R.
7db9abe7-7079-4f14-8397-6371d96e2420
Marinov, I.
f82e7a23-9a7b-46bf-8702-3ce4660ebe23
Palter, J.B.
c7fafac1-31e3-48f8-97a2-62b27373a36a
Sarmiento, J.L.
5887047e-92ac-47f7-a504-fb1699dd8d17
Galbraith, E.D.
cc8cae0d-d549-4a66-bccc-2e5ba88e167f
Slater, R.D.
02cdf450-d76f-468f-9eee-9afd70d9e05c

Bernardello, R., Marinov, I., Palter, J.B., Sarmiento, J.L., Galbraith, E.D. and Slater, R.D. (2014) Response of the ocean natural carbon storage to projected twenty-first-century climate change. Journal of Climate, 27 (5), 2033-2053. (doi:10.1175/JCLI-D-13-00343.1).

Record type: Article

Abstract

The separate impacts of wind stress, buoyancy fluxes, and CO2 solubility on the oceanic storage of natural carbon are assessed in an ensemble of twentieth- to twenty-first-century simulations, using a coupled atmosphere–ocean–carbon cycle model. Time-varying perturbations for surface wind stress, temperature, and salinity are calculated from the difference between climate change and preindustrial control simulations, and are imposed on the ocean in separate simulations. The response of the natural carbon storage to each perturbation is assessed with novel prognostic biogeochemical tracers, which can explicitly decompose dissolved inorganic carbon into biological, preformed, equilibrium, and disequilibrium components. Strong responses of these components to changes in buoyancy and winds are seen at high latitudes, reflecting the critical role of intermediate and deep waters. Overall, circulation-driven changes in carbon storage are mainly due to changes in buoyancy fluxes, with wind-driven changes playing an opposite but smaller role. Results suggest that climate-driven perturbations to the ocean natural carbon cycle will contribute 20 Pg C to the reduction of the ocean accumulated total carbon uptake over the period 1860–2100. This reflects a strong compensation between a buildup of remineralized organic matter associated with reduced deep-water formation (+96 Pg C) and a decrease of preformed carbon (?116 Pg C). The latter is due to a warming-induced decrease in CO2 solubility (?52 Pg C) and a circulation-induced decrease in disequilibrium carbon storage (?64 Pg C). Climate change gives rise to a large spatial redistribution of ocean carbon, with increasing concentrations at high latitudes and stronger vertical gradients at low latitudes.

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Published date: March 2014
Keywords: Carbon cycle, Climate change, Coupled models
Organisations: Marine Biogeochemistry

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Local EPrints ID: 372715
URI: http://eprints.soton.ac.uk/id/eprint/372715
ISSN: 0894-8755
PURE UUID: bbb18568-509a-45f3-937f-d528d0e6d039

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Date deposited: 15 Dec 2014 15:40
Last modified: 14 Mar 2024 18:41

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Contributors

Author: R. Bernardello
Author: I. Marinov
Author: J.B. Palter
Author: J.L. Sarmiento
Author: E.D. Galbraith
Author: R.D. Slater

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