Persistent austral winter storm track weakening beyond doubling of CO2 concentrations

The winter storm track in the Southern Hemisphere has large weather and climate impacts, as it drives daily to multi-decadal variations in extratropical winds, precipitation, and temperature. In the lower mid-latitudes, where the southern parts of the continents reside, the storm track is projected to initially increase with greenhouse gas emissions but to weaken as emissions continue. Given the extensive efforts to mitigate climate change, it is critical to assess the reversibility of the storm track under a negative emissions scenario. Here, we show that while changes in the storm track are reversible under a doubling of CO2 concentrations, beyond that point, the storm track weakening becomes irreversible for centuries. The persistent storm track weakening stems from a prolonged polar amplification, driven by ocean heat transport changes, and is associated with intensity changes of poleward heat flux and extreme warm and cold temperatures. Our results suggest that implementing mitigation pathways prior of reaching a doubling of CO2 concentrations would allow avoiding the persistent impacts of the weakening storm track.