  The strength of mid-latitude storm tracks shapes weather and climate
phenomena in the extra-tropics, as these storm tracks control the daily to
multi-decadal variability of precipitation, temperature and winds. By the end
of this century, winter mid-latitude storms are projected to intensify in the
Southern Hemisphere, with large consequences over the entire extra-tropics.
Therefore, it is critical to be able to accurately assess the impacts of
anthropogenic emissions on these storms, in order to improve societal
preparedness for future changes. Here we show that current climate models
severely underestimate the intensification in mid-latitude storm-tracks in
recent decades. Specifically, the intensification obtained from reanalyses has
already reached the model-projected end of the century intensification. The
biased intensification is found to be linked to biases in the zonal flow. These
results question the ability of climate models to accurately predict the future
impacts of anthropogenic emissions in the Southern Hemisphere mid-latitudes.
