The intensification of winter mid-latitude storms in the Southern Hemisphere

TL;DR

This study reveals that current climate models underestimate the recent intensification of winter mid-latitude storms in the Southern Hemisphere, raising concerns about their accuracy in predicting future climate impacts.

Contribution

It demonstrates that climate models significantly underestimate recent storm intensification and links this bias to zonal flow inaccuracies, challenging future projections.

Findings

Reanalyses show recent storm intensification has reached model projections for end-of-century.

Climate models underestimate recent storm intensification in the Southern Hemisphere.

Biases in zonal flow are linked to model underestimation of storm intensification.

Abstract

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.