Will Dobšinská Ice Cave stay “Icy” in the future?
Slovak scientists carry out extensive multidisciplinary research, trying to find an answer to this question for decades. The obtained data so far indicate that the amount of ice mass in the cave decreases and increases depending on the climatic conditions or the impacts caused by visitors. This unique place was discovered by Eugen Ruffínyi, András Mega and Gustáv Lang from Dobšiná on June 15, 1870. They were the first people to venture into the "ice abyss" assisted by other workers, mostly miners.
"After a more detailed geodetic observation, the initial estimates of the amount of ice in the cave turned out to be surprisingly accurate: with a volume of 115-120 thousand cubic meters, which was specified using more modern methods in 1995 to be 110 thousand m3, the cave is one of the largest in the world. It is characterized by an almost static air flow, which keeps the heavier, colder air stable in the entire volume of the space. The maximum thickness of ice is currently around 25 meters," explains Ján Madarás, director of Earth Science Institute of the SAS.
A team led by Rastislav Milovský of the detached workplace of the Earth Science Institute of the SAS in Banská Bystrica came up with a fundamental discovery in 2019 by measuring hydrogen and oxygen isotopes in ice and radiocarbon dating the frozen bodies of bats and their droppings. The oldest ice in the cave is approximately 2600 years old. This makes the cave an open book of the history of the development of the environment and climate. It is only appropriate to ask whether the current climate change affects the ice in Dobšinská Ice Cave.
"The first georadar measurements of ice thickness and characteristics come from 1995. Compared to the results of regular measurements conducted since the 2011/2012 season, ice has decreased by 1-2 meters in some parts of the cave, but increased in others. At the time of the discovery, the entrance part of the cave, which is ice-less today, was covered with ice. This was caused by the modification of the entrance space, as well as the state of the vegetation. By contrast, a continuous layer of ice thick several meters can be now found in the lower parts of the cave, which were not glaciated at the time of discovery," adds Ján Madarás.
The changes in the ice environment are undoubtedly also influenced by human activity - the presence of visitors, technical operation. Negative effects can be mitigated by a strict seasonal visiting schedule, but also by technical changes to the lighting and elements of the accessible route. Since the ice develops dynamically, reacts to seasonal changes, moves, melts, grows, sublimates, a whole set of geodetic and geophysical measurements are applied in the cave today.
"The purpose of the measurements is to determine the thickness and volume of the ice massif in different parts of the cave, record changes in the thickness of the ice at the same locations - the dynamics of the ice, its melting, or its increase in different parts of the cave. For example, during the 2019/2020 season,127 m3 of ice decreased in the Small Hall (close to the cave´s exit), but in the Great Hall, the ice increased by 84 m3," continues the geologist.
Although ice monitoring is not yet long-term, it can be said that the condition of the ice in the cave is stable for now. Dobšinská Ice Cave cave is advantageously located in the northern part of the Slovak Paradise National Park, which, from a long-term climatic point of view, is one of the coldest locations in Slovakia up to an altitude of 1000 meters. Nevertheless, thanks to shorter, milder winters with a decreasing number of very cold days, shorter series of cold days, poorer snow cover, richer summer precipitation and the influence of tourism, changes in the so far stable underground can occur in the long term with a certain delay. Detailed long-term ice monitoring is, therefore, extremely necessary.
Interesting facts about Dobšinská Ice Cave:
The breathtaking beauty of the ice attracted the first tourists to the accessible areas a year after the cave´s discovery. From 1882, the cave´s premises were lighted by Bunsen burners, and in 1887, the cave became one of the few electrically lit caves in the world and the first one in Europe. It has been a part of UNESCO's world cultural and natural heritage since 2000, and rightly so.
Genetically, the cave is part of the third longest cave system in Slovakia – the Stratenská Cave, which currently reaches 23,809 meters. However, the Dobšinská Ice Cave with a length of 1483 m is independent. It was formed after the breakdown of ceilings between the Dobšinská Ice Cave and Stratenská Cave. Conditions for glaciation arose in a large area only then. It is not known exactly when this happened,estimates range from 70,000 to 400,000 years ago.
Text: Ján Madarás, Jozef Bódi, Earth Science Institute of the SAS
Photo: Katarína Pukanská, Ema Nogová
Video: Ján Madarás
Multidisciplinary research of the cave ice:
The initiators of regular monitoring are specialists of the Institute of Geodesy, Cartography and Geographical Information Systems FBERG TU Košice (Ľubomír Kseňak, Katarína Pukanská, Karol Bartoš, Juraj Gašinec). Besides TUKE specialists (Katarína Pukanská, Blažej Pandula), Juraj Papčo of the Department of Theoretical Geodesy and Geoinformatics of the Faculty of Civil Engineering STU in Bratislava, Roman Pašteka and student, spelunker Ivan Šulek of the Department of Engineering Geology, Hydrogeology and Applied Geophysics PRIF UK in Bratislava participated in the field campaign at the beginning of February 2024. Geophysicists of the Earth Science Institute of the SAS, the Department of Gravimetry and Geodynamics and the Department of Geomagnetism were represented by gravimetrician Pavol Zahorec, doctoral students in Applied Geophysics - Ema Nogová, Lenka Ondrášová, Jozef Bódi, and the already graduated doctoral student Dominika Godová of the Institute of Geophysics of the Czech Academy of Sciences in Prague.