The Shifting Distribution of Arctic Daily Temperatures Under Global Warming.

We examine daily surface air temperatures (SAT) in the Arctic under global warming, synthesizing changes in mean temperature, variability, seasonality, and extremes based on five Earth system model large ensembles from the Coupled Model Intercomparison Project Phase 6. Our analysis shows that the distribution of daily Arctic SAT changes substantially, with Arctic mean temperatures being distinguishable from pre‐industrial levels on 84% and 97% of days at 1.5 and 2°C of global warming, respectively, and on virtually every day at 3°C of global warming. This shift is primarily due to the rapid rise in average temperature resulting from Arctic amplification and is exacerbated by a decrease in the variability of daily Arctic SAT of approximately 8.5% per degree of global warming. The changes in mean temperature and variability are more pronounced in the cold seasons than in summer, resulting in a weakened and shifted seasonal cycle of Arctic SAT. Moreover, the intensity and frequency of warm and cold extreme events change to varying degrees. The hottest days warm slightly more, while the coldest days warm 4–5 times more than the global average temperature, making extreme cold events rare. Changes in local SAT vary regionally across the Arctic and are most significant in areas of sea‐ice loss. Our findings underscore the Arctic's amplified sensitivity to global warming and emphasize the urgent need to limit global warming to mitigate impacts on human and natural systems. Plain Language Summary: The Arctic warms about three times faster than the globe on average, impacting ecosystems and human societies profoundly. While such average warming is scientifically interesting, it is the changes in local temperatures on a daily basis that humans will be experiencing. Based on climate model simulations, we therefore examine how these daily temperatures in the Arctic change with global warming. We find that the distribution of daily Arctic temperatures shifts dramatically under global warming, barely overlapping with pre‐industrial temperatures. This shift is mainly due to the amplified mean warming of the Arctic and is exacerbated by the lower fluctuations in daily temperatures with global warming. The changes in mean temperature and variability are more pronounced in winter, leading to shifting seasons and a decreasing temperature contrast between Arctic summers and winters. The intensity and frequency of warm and cold extreme events are changing. In particular, the coldest days warm 4–5 times more than the global average temperature, making extreme cold events rare. These changes vary across the Arctic, with areas losing sea ice experiencing the most significant shifts. This study emphasizes the urgent need to reduce global warming to protect Arctic ecosystems and communities. Key Points: The distribution of daily Arctic temperatures shifts drastically under global warming, barely overlapping with pre‐industrial temperaturesThis is due to amplified Arctic warming, along with a reduction in the variability of daily temperaturesThe hottest days warm slightly more, while the coldest days warm 4–5 times more than the global mean temperature [ABSTRACT FROM AUTHOR]