Climate Change Impacts on Snow and Soil Frost Depth and Duration in Southern Wisconsin, USA

Soil frost plays a critical role in moderating the partitioning of precipitation in cold climates. Frozen soils show reduced infiltration and increased runoff and erosion, and frost can play a significant role in nutrient cycling. Frost formation, in turn, is strongly influenced by air temperature and by the depth of insulating snow cover. Understanding how the interactions between changes in temperature and precipitation impact frost and snow depth is therefore important to predictions of climate change impacts on water resources. We drove the one-dimensional Simultaneous Heat and Water (SHAW) model with a suite of four dynamically downscaled climate models based on the SRES A2 emissions scenario from the North American Climate Change Assessment Program (NARCCAP). Our modeling predicts that frost and snow cover depth and duration will decline in the future period (2041-2069) relative to the historical period (1971-1999) in southern Wisconsin, USA, despite an overall increase in winter precipitation. The magnitude of these declines varies significantly between climate models, however; with mean annual maximum snow depth change varying between -6.6 and -25.6cm, and mean annual maximum frost depth change in silt loam soils varying between -0.3 and -10cm. Frost duration is reduced in silt loam soils from 85-97 days to 44-69 days. Our modeling also shows significant reductions in runoff and increases in recharge during the winter and spring periods. These results are robust across a variety of soil types, and are attributable to the modeled changes in frost depth and duration.