Anthropogenic carbon and heat uptake by the ocean: Will the Southern Ocean remain a major sink?

Abstract

The global ocean has taken up more than a quarter of the carbon emitted fromhuman activities (since 1750; e.g., Sabine et al. 2004) and more than 90% of theexcess heat that has accumulated in the Earth system as a result of these emissions(since 1971; e.g., Church et al. 2011). Hence, the ocean is greatly mitigating the riseof global mean surface temperatures. Among all the oceanic basins, the SouthernOcean, which we define here as the vast area south of 30°S that surroundsAntarctica, is thought to play a dominant role in the uptake of anthropogenic carbonand heat (e.g., Frölicher et al. 2015, Roemmich et al. 2015). Over recent decades,the Southern Ocean has experienced significant changes such as increases in airtemperature, precipitation, glacial melting and westerly winds. These changes areexpected to intensify over the 21st century and have the potential to greatly impactthe uptake of carbon and heat. Careful monitoring of key properties and processesin the Southern Ocean and an improved understanding of their effects on heat andcarbon uptake are thus needed to assess the present and project the future of theclimate system