Predicting Changes in Hillslope Freeze–Thaw Potential Due To Climate Change

Abstract Freeze‐thaw (FT) is a key hillslope weathering process in cold regions, influencing hillslope stability and sediment delivery to rivers. To understand how climate change will impact FT, we conducted field monitoring in the Pekerebetsu River basin, Hokkaido, Japan, and calibrated a numerical model to predict FT changes. Field measurements show that erosion and deposition of colluvium depends on local snow cover, because snow insulates the ground when present and greatly reduces FT cycles. We then generalize our results using a calibrated soil temperature equation and climate model scenarios to predict how FT may change under future climate. When snow cover is ignored, FT is predicted to decrease in the study area due to future warming. However, when insulating effects of snow cover are included, the area is predicted to have little change in FT in some places, and potentially large FT increases in other locations. The impact of decreased snow cover tends to be greater than that of increased temperature.