Will there be more landslides and slushflows in Norway in a future climate?

Abstract. Norway is exposed to mass movement type of natural hazards, such as landslides and slushflows, due to its steep terrain, wet climate, and long winter season. Understanding how these hazards may evolve under future climate conditions is essential for land-use planning and design of protective measures, among others. This study provides the first nationwide, quantitative assessment of how climate change may affect the hazard of landslides and slushflows in Norway, using operational hydrometeorological threshold models coupled to high‑resolution climate and hydrological projections. These models are used to simulate daily landslide and slushflow hazard levels at 1×1 km resolution for both a reference period (1991–2020) and a future period (2071–2100) under a high greenhouse gas emission scenario. The results indicate a clear increase in landslide hazard across all regions of Norway. The frequency of moderate hazard levels (≥yellow) is projected to increase by 55–107 % depending on the region, mainly driven by increased water supply to the soil. In contrast, the response of slushflow hazard is strongly elevation‑dependent. At lower elevations, reduced snow depth and shorter snow seasons lead to a decrease in slushflow hazard (−54 to −68 % depending on the region), while at higher elevations more liquid water supply cause a marked increase (+138 to +159 % depending on the region). Future research should focus on improving observational datasets and better evaluating the performance of hydrometeorological threshold models.