Anthropogenic forcing drives divergent changes in winter extreme temperature drops across eastern China

Résumé fourni par la source

Rapid temperature drops over a few days can seriously affect human health and socioeconomic systems. While previous studies have focused on extreme low temperatures, the characteristics of extreme (i.e., maximum) winter temperature drops and their responses to external forcings in China remain less well understood. Using station observations and CMIP6 multi-model ensembles, we assess anthropogenic influences on extreme 24-, 48-, and 72-h temperature drops across eastern China, a region highly vulnerable to cold extremes. We find that since 1961, observed winter extreme temperature drops across eastern China have exhibited two leading EOF modes: a basin-wide intensification with pronounced multi-decadal variability, and a north–south dipole pattern featuring weakening in the north, intensification in the south, and a significant long-term strengthening of this contrast. Historical simulations with all external forcings successfully reproduce the dipole structure over the period 1961–2023, indicating that anthropogenic forcing plays a dominant role in driving this long-term evolution. Further analysis shows greenhouse gases intensify drops across broader southern areas, while aerosols exert opposing effects. Future projections under the SSP5-8.5 scenario indicate enhanced north–south divergence. Attribution analysis indicates a 2.4-fold reduction in northern record-breaking event probability under anthropogenic forcing in the current climate, with minimal impact in the south. With increasing forcing under future warming, external forcing exerts a pronounced north–south contrast in event probability, decreasing eightfold in the north and doubling in the south by century’s end. These findings demonstrate divergent regional responses of extreme temperature drops to external forcings, necessitating distinct adaptation strategies for future climate regimes.

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