Has global warming slowed the uptake of atmospheric carbon dioxide by the Southern Ocean? A COD-funded study by Landschützer et al. say no.
Previous work suggested that the strength of the Southern Ocean carbon sink fell during the 1990s. This raised concerns that such a decline would exacerbate the rise of atmospheric CO2 and thereby increase global surface air temperatures and ocean acidity.
The newer data analyzed in this Science-published paper show that the Southern Ocean carbon sink strengthened again over the past decade, which illustrates the dynamic nature of the process and alleviates some of the anxiety about its earlier weakening trend.
Several studies have suggested that the carbon sink in the Southern Ocean—the ocean’s strongest region for the uptake of anthropogenic CO2 —has weakened in recent decades. We demonstrated, on the basis of multidecadal analyses of surface ocean CO2 observations, that this weakening trend stopped around 2002, and by 2012, the Southern Ocean had regained its expected strength based on the growth of atmospheric CO2. All three Southern Ocean sectors have contributed to this reinvigoration of the carbon sink, yet differences in the processes between sectors exist, related to a tendency toward a zonally more asymmetric atmospheric circulation. The large decadal variations in the Southern Ocean carbon sink suggest a rather dynamic ocean carbon cycle that varies more in time than previously recognized.
Access the paper at: science.sciencemag.org/content/349/6253/1221
Peter Landschützer, Nicolas Gruber, F. Alexander Haumann, Christian Rödenbeck, Dorothee C. E. Bakker, Steven van Heuven, Mario Hoppema, Nicolas Metzl, Colm Sweeney (ESRL), Taro Takahashi, Bronte Tilbrook,Rik Wanninkhof (AOML) Published: Sept. 11, 2015 Science, • VOL 349 ISSUE 6253