Featured Science Paper
Sensitivity of the overturning circulation in the Southern Ocean to decadal changes in wind forcing
The overturning circulation in the Southern Ocean is fundamentally important to global climate, not least because it draws down anthropogenic carbon from the atmosphere and stores it deep in the ocean, thereby acting as a sink that slows the rate of global warming. This overturning is partly wind-forced, and the strengthening of the winds in recent decades has led to fears that this carbon sink may have become saturated. Understanding the likelihood of this requires detailed knowledge of the role of mesoscale eddies – the weather systems of the ocean – in damping the directly wind-forced changes in overturning.
New research has demonstrated that, contrary to previous assertions, the role of eddies is to partly (not completely) counteract the changes in overturning driven by the winds. This is of great significance, since it means that the Southern Ocean sink for carbon is vulnerable to climatic increases in wind strength, such as have occurred in recent decades.
Most climate models represent the effects of eddies very coarsely. This research has demonstrated that new and improved schemes for dealing with eddies are vital if this key part of the climate system is to be adequately represented in future climate predictions.
Meredith, M.P., A.C. Naveira Garabato, A. McC. Hogg and R. Farneti
Journal of Climate, doi:10.1175/2011JCLI4204.1, 2012