Carbon fluxes in the coastal ocean: synthesis, boundary processes, and future trends
Dai, M.; Su, J.; Zhao, Y.; Hofmann, E.E.; Cao, Z.; Cai, W.-J.; Gan, J.; Lacroix, F.; Laruelle, G.G.; Meng, F.; Müller, J.D.; Regnier, P.A.G.; Wang, G.; Wang, Z. (2022). Carbon fluxes in the coastal ocean: synthesis, boundary processes, and future trends. Annu. Rev. Earth Planet. Sci. 50: 593-626. https://dx.doi.org/10.1146/annurev-earth-032320-090746 In: Annual Review of Earth and Planetary Sciences. Annual Reviews: Palo Alto, Calif.,. ISSN 0084-6597; e-ISSN 1545-4495, more |  |
| Keyword | | | Author keywords | carbon cycle, coastal ocean, air-sea CO2 flux, continental margin, river-dominated ocean margin, RiOMar, ocean-dominated margin, OceMar, carbon neutrality |
| Authors | | Top | - Dai, M.
- Su, J.
- Zhao, Y.
- Hofmann, E.E.
- Cao, Z.
| - Cai, W.-J.
- Gan, J.
- Lacroix, F., more
- Laruelle, G.G., more
- Meng, F.
| - Müller, J.D.
- Regnier, P.A.G., more
- Wang, G.
- Wang, Z.
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| Abstract | This review examines the current understanding of the global coastal ocean carbon cycle and provides a new quantitative synthesis of air-sea CO2 exchange. This reanalysis yields an estimate for the globally integrated coastal ocean CO2 flux of −0.25 ± 0.05 Pg C year−1, with polar and subpolar regions accounting for most of the CO2 removal (>90%). A framework that classifies river-dominated ocean margin (RiOMar) and ocean-dominated margin (OceMar) systems is used to conceptualizecoastal carbon cycle processes. The carbon dynamics in three contrasting case study regions, the Baltic Sea, the Mid-Atlantic Bight, and the South China Sea, are compared in terms of the spatio-temporal variability of surface pCO2. Ocean carbon models that range from box models to three-dimensional coupled circulation-biogeochemical models are reviewed in terms of the ability to simulate key processes and project future changes in different continental shelf regions. Common unresolved challenges remain for implementation of these models across RiOMar and OceMar systems. The long-term trends in coastal ocean carbon fluxes for different coastal systems under anthropogenic stress that are emerging in observations and numerical simulations are highlighted. Knowledge gaps in projecting future perturbations associated with before and after net-zero CO2 emissions in the context of concurrent changes in the land-ocean-atmosphere coupled system pose a key challenge. |
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