Oceanic sources, sinks, and transport of atmospheric CO2

• Published in: Global Biogeochemical Cycles
• Main Authors: Gruber, Nicolas, Gloor, Manuel, Fletcher, Sara E Mikaloff, Doney, Scott C, Dutkiewicz, Stephanie, Follows, Michael J, Gerber, Markus, Jacobson, Andrew R, Joos, Fortunat, Lindsay, Keith, Menemenlis, Dimitris, Mouchet, Anne, Mueller, Simon A, Sarmiento, Jorge L, Takahashi, Taro
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2009
• Subjects: Life sciences; Aquatic sciences & oceanology; Physical; chemical; mathematical & earth Sciences; Sciences du vivant; Sciences aquatiques & océanologie; Physique; chimie; mathématiques & sciences de la terre; Southern Ocean
• Online Access: https://orbi.uliege.be/handle/2268/39996; https://doi.org/10.1029/2008GB003349

peer reviewed We synthesize estimates of the contemporary net air-sea CO2 flux on the basis of an inversion of interior ocean carbon observations using a suite of 10 ocean general circulation models (Mikaloff Fletcher et al., 2006, 2007) and compare them to estimates based on a new climatology of the air-sea difference of the partial pressure of CO2 (pCO(2)) (Takahashi et al., 2008). These two independent flux estimates reveal a consistent description of the regional distribution of annual mean sources and sinks of atmospheric CO2 for the decade of the 1990s and the early 2000s with differences at the regional level of generally less than 0.1 Pg C a(-1). This distribution is characterized by outgassing in the tropics, uptake in midlatitudes, and comparatively small fluxes in the high latitudes. Both estimates point toward a small(similar to -0.3 Pg C a(-1)) contemporary CO2 sink in the Southern Ocean (south of 44 degrees S), a result of the near cancellation between a substantial outgassing of natural CO2 and a strong uptake of anthropogenic CO2. A notable exception in the generally good agreement between the two estimates exists within the Southern Ocean: the ocean inversion suggests a relatively uniform uptake, while the pCO(2)-based estimate suggests strong uptake in the region between 58 degrees S and 44 degrees S, and a source in the region south of 58 degrees S. Globally and for a nominal period between 1995 and 2000, the contemporary net air-sea flux of CO2 is estimated to be -1.7 +/- 0.4 Pg C a(-1) (inversion) and -1.4 +/- 0.7 Pg C a(-1) (pCO(2)-climatology), respectively, consisting of an outgassing flux of river-derived carbon of similar to+0.5 Pg C a(-1), and an uptake flux of anthropogenic carbon of -2.2 +/- 0.3 Pg C a(-1) (inversion) and -1.9 +/- 0.7 Pg C a(-1) (pCO(2)-climatology). The two flux estimates also imply a consistent description of the contemporary meridional transport of carbon with southward ocean transport throughout most of the Atlantic basin, and strong equatorward convergence in ...