ISMAR Trieste - Consiglio Nazionale delle Ricerche
Alpine ice caves are natural caves formed in bedrock, containing perennial accumulations of water in its solid phase (Perşoiu and Onac, 2012). Since their main characteristics is to have ground ice older than 2 years, many authors are prone to consider ice caves as sporadic permafrost phenomena (e.g. Holmlund et al., 2005; Luetscher et al. 2005, Hausmann and Behm, 2011; Kern et al., 2011; Luetscher et al., 2013).
As part of the cryosphere such ice masses are linked to the climate, but they do also exist in different kinds of environments, often at an altitude with an outside mean annual air temperature (MAAT) well above 0°C (Obleitner and Spötl, 2012; Stoffel et al., 2009; Holmlund et al, 2005). The accumulation of cold air into the cave during the winter seems to represent the main reason for the development and preservation of cold conditions leading to a progressive accumulation of ice (Ford and Williams, 1989; Luetscher and Jeannin, 2004). Ice forms through different mechanisms like re-crystallization of snow, refreezing of percolating water or, with much less contribution, sublimation and deposition of cave-air vapor (Luetscher and Jeannin, 2004). Depending on their morphology, ice caves are generally described taking in account the relationships between ice-formation and cave air dynamics (CAD) and are therefore classified in: (i) static ice caves (SIC); (ii) dynamic ice caves (DIC).
In the last decades the scientific interest in ice caves of mountain areas in the world, undertaken a large improvement, also thanks to the IWIC (International Workshop on Ice caves) community.
Some of the biggest issues still to be fully understood are related to:
i) the connection between ice cave microclimate and the external climate
ii) the response of ice cave deposits to the ongoing climate change
iii) the thermodynamics of ice cave system
iv) the timing of onset and decay of ice cave deposits in a paleoclimatic perspective
Recently, a close influence of global and local climate change in the evolution of the ice deposits has been mostly highlighted in the DIC, especially in regard to the occurrence of extreme weather events (Colucci et al., 2016).
The natural feedback of the ice cave's mass balance in a warming climate and the forecasted increase of extreme weather events in the following decades, especially in regard to warmer and more intense rainfalls caused by higher 0 °C isotherm, will be crucial in the future mass balance evolution of permanent ice cave deposits in this alpine area and for this reason action should be taken immediately to avoid loosing information as soon as the underground cryosphere will disappear.
One of the issues still in debate and not well understood is related to the occurrence of ice in caves located at the same altitude and in the same area where other caves do not present such deposits.
Another important related issue is associated with the enormous dating potential the organic material included in the ice and the calcite deposits, mainly Coarser Cryogenic Calcite, (CCC) might represent. This could make more light on the climate and paleoclimate evolution during the Holocene, not only at a local scale but also at a broader scale, especially in regards to the thawing permafrost phases (Luetscher et al., 2013). CCC is in-fact considered an indicator of past temperatures at the freezing point in caves and is generally formed by precipitation triggered by freezing of water. Depending on the freezing rate and the thickness of the freezing water layer, either fine-grained CCC (CCCfine) or coarsely crystalline CCC (CCCcoarse) can be formed. Its origin can be unequivocally confirmed by U-series dating in combination with unique C and O stable isotope systematics (Žák et al., 2004, 2008; Richter and Riechelmann, 2008)
The high mountain karstic area of Canin and the Julian Alps has a great potential in this sense thanks to the old speleological tradition (first speleological explorations here started in the 1960s), to the huge number of caves some of them the deepest in the world, and to the large number of permanent ice deposits here reported by cavers and recently by the first inventory of ice caves in this area.
The C3 project begins with the aim to survey as much as ice cavities will be possibile in the Canin massif, probably one of the most reach areas of Europe and the world in terms of caves density.
Photo Fabrizio Giraldi