Soil-frost depth change in eastern Hokkaido under +2 K-world climate scenarios

A future change in the soil-frost depth in eastern Hokkaido was assessed with multiple local climate scenarios. The biascorrected downscaled data with an aid of a simple snow-depth model were applied to the empirical estimation from cumulative freezing degree-days (CFD) for days when the snow depth is less than 20 cm. Consequently, as the response to global warming climate that was defined as +2-K world in this paper, the maximum soil-frost depth significantly decreased in the coastal regions along the Pacific and in central Tokachi subprefecture with a slight variation among climate scenarios. Parameter-sweep experiments for two observed cases clarified that the temperature increase would bring the soil warming in the environment where the insulation effect of snow cover does not work at present, while it would bring the soil frosting in the environment where the insulation effect works.