- Sorbonne Paris Cité France
- Scripps Institution of Oceanography United States
- Max Planck Society Germany
- ETH Zurich Switzerland
- University of East Anglia United Kingdom
- French National Centre for Scientific Research France
- University of Wisconsin–Oshkosh United States
- University of California, San Diego United States
- UNIVERSITE PIERRE ET MARIE CURIE - PARIS 6 France
- Max Planck Institute for Biogeochemistry Germany
- Bermuda Institute of Ocean Sciences
- Max Planck Institute for Biogeochemistry Germany
- Instituto de Investigaciones Marinas Spain
- UNI RESEARCH AS Norway
- Woods Hole Oceanographic Institution, Physical Oceanography Department United States
- NOAA Pacific Marine Environmental Laboratory United States
- Uni Research (Norway) Norway
- University of Las Palmas de Gran Canaria Spain
- Scripps Institution of Oceanography United States
- Bermuda Institute of Ocean Sciences Bermuda
- Lamont-Doherty Earth Observatory (LDEO), Columbia University, New York, NY, USA United States
- Uni Research AS Norway
- BERMUDA INSTITUTE OF OCEAN SCIENCES, INC
- Woods Hole Oceanographic Institution United States
- Spanish National Research Council Spain
- Max Planck Institute for Biogeochemistry Germany
The Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea–air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea–air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modeling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our estimate of the contemporary sea–air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is −0.49 ± 0.05 Pg C yr−1, and by the Arctic it is −0.12 ± 0.06 Pg C yr−1, leading to a combined sea–air flux of −0.61 ± 0.06 Pg C yr−1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor, and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and southern subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and southern subtropics.