Abstract:

Glacial processes are known to impinge on many karst systems, of which the active formation of cave ice represents a salient feature. In temperate environments, the preservation of massive, perennial cave ice deposits, comprising sometimes tens of thousands cubic meters, represents probably the most severe test for models of sporadic permafrost distribution. Additionally, stratified cave ice deposits foster detailed glaciochemical investigations to decipher this environmental archive. Recent investigations have shown that the accessible time window for paleoclimate reconstructions sometimes covers several thousands of years, but understanding the relation between external climate change and the cave ice mass balance still remains challenging. Process-oriented studies suggest that interannual cave ice mass balances respond primarily to modifications in the winter thermal and precipitation regimes. By contrast, cave ice ablation is largely driven by heat exchange with the surrounding rock, which is a function of the external mean annual air temperature. Many mid-latitude, low-altitude ice caves are thus likely to disappear under a warming climate scenario. Yet, traces of former glacial processes can be observed in several temperate cave environments. Cryoclasts, solifluction lobes, sorted sediment patterns, cryogenic calcite, and broken speleothems provide clues for the reconstruction of paleo-permafrost. Because they can be accurately dated with U-series methods, cryogenic cave calcites offer a promising field of investigation for past glacial processes in caves.