Dual Risks Associated with Extreme Snowfall Regimes

Under global warming, snow accumulation exhibits increasing variability and more frequent extremes, giving rise to dual risks associated with extreme snowfall regimes. Excessive snowfall enhances snowpack loading and instability and, when combined with triggers such as wind redistribution, rapid warming, or intense snowfall events, substantially elevates avalanche risk. In contrast, insufficient snowfall reduces snow water storage, weakens and advances meltwater supply, and intensifies seasonal water deficits, leading to snow-drought conditions with cascading impacts on ecosystems, agriculture, and water resources. These risks are driven not only by the cumulative effects of long-term warming—which alters precipitation phase, snow-season duration, and snowpack structure—but also by short-lived strong perturbations such as warm intrusions, abrupt temperature rises, and rain-on-snow events. The coupling of cumulative climate forcing and transient disturbances governs the occurrence and evolution of avalanches and snow drought across time scales, increasing the likelihood of compound or alternating risks within the same region or snow season. Observational records indicate that around 2000, snow-related hazards underwent pronounced structural shifts, with concurrent changes in the frequency, intensity, and seasonal timing of both avalanches and snow droughts, suggesting a critical turning point in snow-hazard dynamics. Focusing on this transition, the present study integrates multi-source snow and hazard datasets to characterize pre- and post-2000 regime changes, elucidate the underlying coupled mechanisms, and inform mountain hazard mitigation and climate-resilient water-resource management.