Could Climate Change Decrease Landslide Hazard in Snow‐Dominated Mountainous Regions? Insights From a Distributed Hydrology‐Shallow Landslide Model of the North Cascades, USA

Abstract In snow‐dominated mountain belts, understanding how runoff hydrology and landslide hazard will respond to climate change requires the integration of climate science, hydrology, and geomorphology. In this study, we use the DHSVM distributed hydrology model coupled with a Landlab shallow landslide probability model (LandslideProbability) to assess future shallow landslide hazard in the North Cascades Mountains of Washington, United States where high‐relief terrain leads to distinct rain‐dominated, transient (rain and snow) and snow‐dominated precipitation zones. Three future climate scenarios that represent median, low and high warming scenarios from a collection of Coupled Model Intercomparison Project 5 models of future climate are used to force the hydrology model. We find that, for all scenarios, landslide hazard increases in the transient and rain‐dominated zones but counter to our expectations, decreases in the snow dominated zone. In the rain‐dominated and transient zones, peak saturation is driven by rainfall inputs during the fall‐winter period and increased future precipitation rates directly translate to increased recharge. In contrast, in the snow‐dominated zone, future peak saturation is driven by snowmelt water inputs, which historically occurred during the early summer months, when temperature and total incoming radiation are high. In the future, warmer temperatures cause the snowpack to melt before reaching the high‐melt‐energy summer months which results in a decrease in melt that exceeds the increase in precipitation and overall lower recharge rates.