Future Changes in Northern Hemisphere Extreme Snowfall

Abstract

Snowfall extremes in the Northern Hemisphere are projected to shift significantly under global warming, impacting infrastructure, ecosystems, hydrology and the cryosphere. Arctic and high-elevation regions in particular are expected to experience shifts in snowfall patterns as near-surface air temperatures increase and more often approach or exceed freezing. Changes in precipitation phase accelerates sea ice and snow melt, altering surface albedo and runoff, affecting glacier and ice sheet surface mass balance (SMB). Simultaneously, warming enhances atmospheric moisture capacity, increasing the likelihood of snowfall extremes occurring for regions remaining sufficiently cold. This study investigates projected changes in the frequency, intensity, and amount of extreme snowfall events under a 2°C global warming scenario, using the KNMI Large ENsemble TIme Slice (LENTIS) dataset. LENTIS is based on the EC-Earth3 global climate model with 80 km resolution, consisting of two 1600 year time slices: present-day (PD ; 2000-2009) and 2K (2075-2084) based on the SSP2-4.5 pathway. Under the 2K scenario, snowfall extremes decrease in mid-latitude and coastal regions due to the northward shift of the zero degree isotherm and an enhanced rainfall fraction. Sea ice retreat in marginal Arctic seas amplifies this decrease through altered surface energy fluxes and atmospheric moisture. Conversely, high-latitude continental regions see increases in snowfall extremes, supported by persistent freezing temperatures and enhanced moisture availability. Over Greenland, orographic effects and North Atlantic storm tracks produce the most intense winter snowfall extremes. A sea level pressure anomaly dipole, negative over Western Greenland, positive over Northern Europe emerges as a characteristic dynamical pattern associated with extreme snowfall events, driving moist air advection from the North Atlantic.