Author Archives: karmour

New paper! Southern Ocean warming delayed by upwelling

Why is the Southern Ocean (SO) warming so much more slowly than the rest of the world’s oceans? It seems that it’s due to wind-driven upwelling of old, deep waters around Antarctica. These upwelled waters were last in contact with the atmosphere hundreds of years ago, at least, meaning that they have yet to feel the effects of global warming. Once these waters reach the SO surface, they’re pushed equatorward by the winds, carrying heat they receive from rising greenhouse gases with them, away from the continent.

Armour KC, J Marshall, J Scott, A Donohoe and ER Newsom (2016) Southern Ocean warming delayed by circumpolar upwelling and equatorward transport, Nature Geoscience, doi: 10.1038/ngeo2731

New paper by Yavor Kostov on SO response to SAM changes

Does the surface of the Southern Ocean (SO) cool or warm under a sustained increase in the Southern Annular Mode (SAM)? Yavor Kostov shows the answer depends how long you wait! All climate models show an initial cooling; but then some models stay cold for decades, while others warm up within a few years. Where does nature do? Hard to say definitively, but it seems that it may stay cool for a while following a strengthening of SAM. This means that the trend in SAM over recent decades (probably mostly caused by stratospheric ozone depletion) might be the reason for the observed cooling and sea-ice expansion within the SO.

Kostov Y, J Marshall, U Hausmann, KC Armour, DG Ferreira and MM Holland (2016) Fast and slow responses of Southern Ocean sea-surface temperature to SAM in coupled climate models, Climate Dynamics, doi: 10.1007/s00382-016-3162-z