The reinvigoration of the Southern Ocean carbon sink

Abstract

Several studies have suggested that the carbon sink in the Southern Oceanthe ocean's strongest region for uptake of anthropogenic CO 2 -has weakened in recent decades. Here, we demonstrate on the basis of multi-decadal analyses 1

Southern Ocean carbon-wind stress feedback

“…These changes are an order of magnitude smaller than the decadal variability in the carbon flux (Landschutzer et al 2015). However, this variability is on top of the long term trend.…”

“…However, this variability is on top of the long term trend. Using the measured trends in Southern Ocean wind stress from Swart and Fyfe (2012), Landschutzer et al (2015)'s results suggest that if Southern Ocean winds and atmospheric pCO 2 were to stabilize, 2 as a function of channel wind stress relative to a control state (red, the same as in Fig. 5a) and elevated sea surface temperature control state (green), b Predicted change in atmospheric pCO 2 in HadGEM2-ES (red) and IPSL-CM5 (green) using parameters from the control run (solid lines) and from the end of a 2 × CO 2 experiment (dashed lines).…”

“…They attribute the reduction in the sink to the observed increase in westerly winds. However, natural variability can strongly affect present and future estimates of changes in the Southern Ocean carbon sink, as illustrated in Fay and McKinley (2013), Majkut et al (2014), Landschutzer et al (2015), and McKinley et al (2016).…”

The carbon cycle in a changing climate

“…Those high-latitude regions strongly influence ocean carbon and ecosystems, so understanding the changes occurring there and how they affect ocean circulation is a key part of investigating carbon cycle-climate interactions. 18 These regions also have an abundance of eddies-swirls of water a few kilometers to a hundred kilometers wide-that influence not only the local ocean area but also large-scale ocean currents. High-resolution ocean models are now starting to resolve eddies, and new ocean observations, in particular from the more than 3000 autonomous floats in the Argo program, are revealing finer threedimensional structures in ocean properties than were previously possible.…”

Uncertainty of the global oceanic CO<sub>2</sub> uptake induced by wind forcing: quantification and spatial analysis

“…The remainder is estimated to be taken up in roughly equal shares by the land and the ocean. In past decades, the magnitude of the ocean carbon sink was mainly estimated from global ocean biogeochemistry models and atmospheric inverse models but the recent increase in oceanic CO 2 measurements and the creation of the Surface Ocean CO 2 Atlas (SOCAT) database (Bakker et al, 2014(Bakker et al, , 2016Pfeil et al, 2013;Sabine et al, 2013) has open new research avenues, including the possibility to monitor the temporal evolution of the 5 global oceanic carbon sink based on surface ocean CO 2 measurements (Landschützer et al, 2016;Rödenbeck et al, 2015).…”