Climate change and human activities amplify aircraft icing risks in China: A 13-year nationwide analysis using first released pilot reports.

Aircraft icing poses a growing environmental hazard to aviation safety, yet its linkages to climate change and anthropogenic activities remain poorly quantified. Utilizing China's first public 13-year (2011-2023) dataset of pilot reports (PIREPs) integrated with multi-source environmental and meteorological data, this study reveals how regional climate dynamics and human factors shape the spatiotemporal patterns and mechanisms of aircraft icing across China. Key findings include: (1) a distinct spatial gradient with high frequency in the southwest, moderate in the east, and low in the northwest, strongly mediated by topography, economic activity, and aerosol emissions; (2) vertical stratification of icing risks, peaking at 2-8 km, driven by moisture-temperature coupling at mid-low altitudes and jet-stream-induced uplift at higher levels; (3) a striking winter dominance (7.3 times more than summer) and a notable post-2018 upward shift of the primary icing layer (∼500 m/yr), correlated strongly with rising freezing-level heights under global warming; and (4) region-specific mechanisms are delineated as: frontal systems and aerosol microphysical effects in North China, terrain-trapped moisture in the Sichuan Basin, and ocean-jet stream interactions along the coast.These results underscore the critical role of environmental change in amplifying aviation hazards and provide a scientific basis for developing climate-resilient warning systems and mitigation strategies.