A new paper out in Geophysical Research Letters (GRL) highlights the contribution of both anthropogenic forcing and natural variability on Southern Ocean surface temperature trends. Kyle Armour, of the School of Oceanography and Department of Atmospheric Sciences, was part of a team that helped to shed light on this. Using an ensemble of coupled general circulation models, they evaluated possible causes of the models’ inability to reproduce the observed Southern Ocean cooling. Their research found that the CMIP5 models have diverse Southern Ocean sea-surface temperature (SST) responses to the Southern Annular Mode (SAM) and greenhouse gas forcing. Through this they show that the biases in the simulated SAM trends strongly affect the models’ historical Southern Ocean SST trends.