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The North Atlantic storm track plays a critical role in setting the regional weather and climate over Western Europe. In response to anthropogenic emissions, the summer North Atlantic storm track has weakened in recent decades and is projected to continue weakening by the end of this century. In light of growing efforts to mitigate climate change, it is crucial to assess how reversible the CO2‐induced storm track weakening is. Here, I show that under CO2 removal scenarios, the recovery timescale of the storm track is more than double its weakening period. It is found that due to a prolonged high‐latitude warming, postponing the execution of mitigation policies beyond doubling of CO2 concentrations would lead to a centennial‐scale recovery of the storms. Given the impacts of weakening summer storms on weather and extreme events, the delayed recovery of the storms might have broader regional consequences for Western Europe. Plain Language Summary: The summer North Atlantic storm track sets the regional weather and climate over Europe, by transferring heat, moisture and momentum across the North Atlantic basin. Anthropogenic emissions were found to weaken the storm track, which would greatly affect precipitation and hot‐dry extreme events over Europe. It is thus critical to assess the reversibility of the summer North Atlantic storm track weakening under a reduction in greenhouse gases. Here, using targeted numerical simulations, I show that the reversibility time‐scale of the storm track is more than double its weakening time‐scale. Thus, postponing the execution of mitigation strategies increases the reversibility time‐scales of the storm track. Specifically, avoiding centennial‐scale impacts of the weakening storm track can be achieved by executing mitigation strategies prior of reaching doubling of CO2 concentrations. Our analysis reveals that the prolonged recovery of the storm track stems from a prolonged warming of the high latitudes relative to the lower latitudes. Key Points: The reversibility time‐scale of the North Atlantic summer storm track is more than double its weakening time‐scalePostponing mitigation policies beyond a doubling of CO2 levels yields centennial‐scale recovery of the storm trackThe prolonged recovery of the storm track stems from a prolonged warming of the high latitudes relative to the lower latitudes [ABSTRACT FROM AUTHOR]

The Hadley circulation plays a central role in determining the location and intensity of the hydrological cycle in tropical and subtropical latitudes. Thus, the human-induced historical and projected weakening of the Northern Hemisphere Hadley circulation has considerable societal impacts. Yet, it is currently unknown how unparalleled this weakening is relative to the response of the circulation to natural forcings in past centuries. Here, using state-of-the-art climate models, we show that in contrast to the recent and future human-induced Hadley circulation weakening, natural forcings acted to intensify the circulation by cooling the climate over the last millennium. The reversal of a naturally-forced multi-centennial trend by human emissions highlights their unprecedented impacts on the atmospheric circulation. Given the amplifying effect of natural forcings on the Hadley circulation, our analysis stresses the importance of adequately incorporating natural forcings in climate model projections to better constrain future tropical climate changes., (© 2024. The Author(s).)