Improved prediction of the vertical distribution of ground ice in Arctic-Antarctic permafrost sediments

Frost susceptibility of permafrost sediments is strongly influenced by unfrozen water content, which is dependent on sediment type, soil water chemistry, and temperature, according to field observations and ensemble modeling prediction of ground ice formation in Arctic-Antarctic sediments. Global warming and permafrost degradation are impacting landscapes, ecosystems and the climate-carbon system. Current ground ice and geohazard maps rely on the frost susceptibility of surficial sediments, and substantial areas underestimate ice abundance. Here we use a soil environmental model to show the importance of considering unfrozen water content (dependent on sediment type, soil water chemistry, and temperature) when assessing the frost susceptibility of sediments. Our ensemble modeling of the vertical structure and evolution of ground ice for fine to coarse-grained sediments matches reasonably well with field measurements at sites from the low Arctic to the cold and hyper-arid Dry Valleys of Antarctica. Our modeling indicates a need to re-evaluate how frost-susceptible sediments are identified when mapping ice-rich permafrost landscapes and provides a framework for the development of quantitative estimates of the vertical distribution of ground ice in permafrost sediments at regional scale.