Ice in Caves

Motivated by progressive climate-change influence on ice degradation in caves, in this paper we present a novel methodology to investigate the link between air dynamics and ice melting. Specifically, we use surveys available for the Leupa ice cave (LIC), located in the Canin-Kanin group in the southeastern Alps and a general purpose computational fluid dynamics model (CFD). Detailed numerical simulations are evaluated on the basis of well-established approaches that consider domain, grid, boundary-conditions, turbulence closure models, buoyancy effects, porous media properties and verification with measured data. External atmospheric conditions are the main trigger for internal circulation but morphology and thermal characteristics of ice and bedrock induce a dynamical process of heat exchange ultimately responsible for ice melting. This process is generally poorly documented in real conditions. Using CFD analyses we show that both in summer and winter, warm and cold air currents within the cave are “disturbed” by several vortices and stagnation zones which locally modify the energy balance. To account for this we introduce a macroscopic physical model based on energy balance between ice surfaces and the inner ice cave airflow to determine the heat exchanged between ice and air. Using this model, a prediction of ice thickness decay over time is obtained. In the case of LIC a reduction of initial 4 cm per year is first obtained with projection of a much faster increase. The methodology is general and easily extendable to other sites, proving to be a powerful method to estimate ice evolution in caves induced by external and internal forcing.

Perennial ice deposits in caves represent unique, but underexplored, terrestrial sequences that potentially contain outstanding palaeoclimatic records. Here, we present a pioneer palaeoenvironmental study of an ice deposit preserved in a small sag-type cave (A294) in the Central Pyrenees (northern Iberian Peninsula). The 9.25-m-thick sequence, which is dated from 6100 ± 107 to 1888 ± 64 cal BP, represents the oldest known firn ice record worldwide. The stratigraphy (detrital layers, unconformities, and cross stratification), plant macrofossils, and isotopic signature (similarity between the ice linear distribution, ${\delta }^2\text{H}=7.83{\delta }^{18}\text{O}+8.4$, and the Global Meteoric Water Line) of the ice point to the diagenesis of snow introduced to the cave by winter snowstorms. Four phases of rapid ice accumulation (6100–5515, 4945–4250, 3810–3155, and 2450–1890 cal BP) are related to wetter and colder winters. Comparison of the isotopic composition (${\delta }^{18}\text{O}$ and deuterium excess) of the ice with other paleoclimate records show that both source effects and the North Atlantic Oscillation (NAO) mechanism exert a dominant influence on the ice cave record. The NAO signal may be a combination of source effects and rainfall amount. Three intervals with low ice accumulation occurred between the phases of rapid accumulation and were related to drier, and possibly warmer, winters. These centennial-scale episodes appear to be in-phase with regional arid events, as established from high altitude lacustrine records and can be correlated to global Rapid Climate Change events. The current warming trend has dramatically decreased the volume of the ice deposit in cave A294.

The microbial life thriving in a wide variety of frozen environments raised a high interest in understanding their adaptation mechanisms to temperatures below 0°C and for using their advantageous applicative characteristics. Recent findings revealed the presence of complex microbial communities, comprising bacteria, archaea, and fungi in perennial ice blocks located in ice caves. The diversity of these relatively secluded glacial ecosystems responds to their particular sunlight regime, substrate geochemistry and age of the subterranean ice block deposits. This current synopsis of total and culturable microorganisms reported so far in ice caves in relation to the geochemical characteristics of the ice substrate and their spatial and temporal distribution highlights the viability and structural/functional diversity of this particular microcosm, and argues for the putative role of key microbial species from such ice habitats as proxies for palaeoclimate dating.

Ice caves in Macedonia, being caves with perennial (ice or snow) and/or seasonal ice deposits, are found on Jakupica Massif and Krčin Mountain, with entrances at elevations between 991 and 2340 m and latitudes between 41.59°N and 41.87°N. As no studies have been done, this chapter summarizes information collected from reports of a number of cave explorations conducted during the past 35 years. In total, 25 ice caves are registered, 4 being deep vertical caves with large perennial ice/snow deposits, 13 being < 60 m deep pits ending with snow plugs, 6 being smaller caves with passages partly covered by perennial snow/ice deposits, and 2 having seasonal ice formations. The most important ones are Solunska Jama, Lednik, Slovačka Jama, and Solunska Glava 5, all located on Jakupica Massif with entrances above 2100 m and with Solunska Galva having a huge room filled with a large ice body several meters thick.

Physically, Iran is best known for its warm-to-hot, semiarid to arid climatic conditions. In the north (Alborz Mountains) and west (Zagros Mountains) it has mountain ranges rising to 3500–4500 m a.s.l., however, which supported major alpine glaciers during the Quaternary Ice Ages and maintain a few much smaller ones today. Scientific investigation of caves in the mountains is in its early stages. Two examples with perennial ice have received preliminary study; (1) Yakh-Morad Ice, at 2490 m above sea level in the Alborz, has perennial ice from seepage entering a lower level cold trap and retains seasonal ice into Aug. in warmer upper levels; it is believed that a net loss of the perennial ice is occurring. Dena Ice Cave, at 3900 m a.s.l. in the Zagros, is a single descending passage with large ice stalactites, stalagmites, and flowstones from seepage. The cave may be experiencing net accumulation of ice today.

Ice and snow caves are distributed throughout Croatia in the Dinaric karst mountain belt. Most of them are located on Velebit Mt., 1200 m a.s.l. in the zone with snow (boreal) climate. In the past, some of them were used for ice excavation for water and conservation purposes. First mentions occurred in the 17th century and the first researches in 19th century. During the second half of 20th century in some ice cave microclimates, geomorphological and glaciochemical researches started. According to data from deep shafts in Velebit Mt., there is the deepest recorded cave ice in the World. The depth of the ice recorded there is up to 550 m. In the frame of chemical researches, tritium and element concentration, stable isotope and age of the ice were studied.