Recent globally synchronous seasonal warm events unprecedented since 850 CE

Duan, J., Hao, F., Zhou, Y., Chen, S., Wang, A., Xiao, C., Ljungqvist, F. C., Dong, B. ORCID: https://orcid.org/0000-0003-0809-7911, Luterbacher, J., Stott, P. A. and Xoplaki, E. (2026) Recent globally synchronous seasonal warm events unprecedented since 850 CE. Nature Communications. ISSN 2041-1723 doi: 10.1038/s41467-026-76985-4 (In Press)

Abstract/Summary

Spatially synchronous extreme warm events can amplify environmental and societal impacts by affecting multiple regions simultaneously. However, previous studies have largely focused on June–August (JJA) events during the instrumental period, limiting understanding of their seasonal prevalence and long-term evolution. Here, we examine globally synchronous seasonal warm events (GSSWEs) using seasonal mean near-surface air temperature (SAT) and introduce an Extremity Index (EI) that combines normalized local land SAT anomaly intensity with the spatial extent of land areas exceeding a specified SAT threshold. Using instrumental observations, paleo-reanalysis products and climate model simulations, we assess changes in global-land GSSWE extremity since 850 Common Era (CE). We find that GSSWEs have intensified sharply since the 1970s across all four seasons, reaching levels not found earlier in the multi-dataset records. Detection and attribution analyses indicate that anthropogenic forcing, dominated by greenhouse-gas forcing, is the main contributor to this recent intensification. Spatially, the tropics contribute greatly to the recent extremity of GSSWEs due to their lower intrinsic variability. These findings highlight that climate-risk assessment and adaptation planning need to consider the growing spatial coherence and intensity of seasonal warm extremes.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/131526
Identification Number/DOI	10.1038/s41467-026-76985-4
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > NCAS Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Nature Publishing Group
Download/View statistics	View download statistics for this item