EGU21-10048, updated on 10 Jan 2023
EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

The spatiotemporal dynamics of the sources and sinks of CO2 in the global coastal ocean

Alizee Roobaert1, Goulven Laruelle1, Laure Resplandy4, Peter Landschützer2, Nicolas Gruber3, Enhui Liao4, Lei Chou1, and Pierre Regnier1
Alizee Roobaert et al.
  • 1Université Libre de Bruxelles, Department Geoscience, Environment and Society, Bruxelles, Belgium (
  • 2Max Planck Institute for Meteorology, Bundesstr 53, Hamburg, 20146,
  • 3Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Universitätstrasse 16, 8092 Zürich, Switzerland.
  • 4Department of Geosciences, Princeton environmental institute, Princeton University, Princeton, NJ 08544

The spatio-temporal variability and the underlying drivers of the carbon dioxide (CO2) exchange at the air-water interface (FCO2) of the global coastal ocean are still poorly understood and their quantification remains highly uncertain. Here, we present an analysis of the spatial and seasonal variability of FCO2 using a high-resolution (0.25 degree) monthly climatology (1998-2015 period) for coastal sea surface partial pressure in CO2 (pCO2), globally.

Overall, a clear latitudinal pattern emerges from our analysis regarding sources/sinks distribution of atmospheric CO2 and we find that in most regions, annual mean CO2 flux densities are comparable in sign and magnitude to those of the adjacent open ocean except for river dominated systems. Globally, coastal regions act as a CO2 sink with a more intense uptake occurring in summer because of the disproportionate influence of high latitude coastal seas in the Northern Hemisphere. The majority of the coastal seasonal FCO2 variations stems from the air-sea pCO2 gradient, although changes in wind speed and sea-ice cover can also be significant regionally. To investigate further the drivers of the spatio-seasonal variability, our observation-based pCO2 climatology is used in conjunction with global ocean biogeochemistry model MOM6-COBALT. The model outputs allow us to quantify the respective contributions of thermal effects, biology, and non-thermal physical processes (circulation and freshwater inputs) to seasonal variations in coastal pCO2. Generally, biological activity is the dominant driver of the pCO2 seasonal variability in temperate and high latitudes while thermal and non-thermal physical processes dominate in low latitudes.

How to cite: Roobaert, A., Laruelle, G., Resplandy, L., Landschützer, P., Gruber, N., Liao, E., Chou, L., and Regnier, P.: The spatiotemporal dynamics of the sources and sinks of CO2 in the global coastal ocean, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10048,, 2021.