Scientists have been carrying out investigations in mountain caves that contain ice all year round, found in high mountain areas of the Pyrenees and Cantabrian mountains.
Ana Moreno, Miguel Bartolomé, Reyes Giménez, María Leunda and Ánchel Belmonte-Ribas reported that the caves are unique and part of the nation’s heritage.
Acting under the umbrella of the national science council (CSIC), they note that specific conditions are required to form the ice deposit.
This is facilitated by their position on a mountain and ‘sufficiently low temperatures’.
“Precipitation enters the caves as snow during winter storms; as water during the thaw; or it filters in during rain,” they explain.
The ice forms as the water freezes in the galleries of the caves or at the entrance where snow is driven in by the wind.
These ice deposits ‘have great value’ as they are ‘excellent sensors of environmental changes’.
The scientists have been carrying studies on the ice mass in the interiors of around 100 caves.
They have measured isotopic modifications in the ice, allowing them to find out more about changes in the climate in past centuries and even millennia.
This is allowing them to measure the impact that global warming is having on high mountain areas.
The scientists noted that the Espluca Negra (or Castaret) cave at Monte Perdido, the highest limestone peak in Europe which stands at the head of the Ordesa canyon, contains some of the best ‘fossil ice’ in the Pyrenees.
It has a 120-metre-long gallery which connects the highest entrance to the cave at 2,710 metres above sea level with the lowest at 2,690m.
A large amount of snow fills the higher entrance which penetrates into the interior and melts in the summer.
The first recorded observations where made by Norbert Casteret, which show the quantity of ice decreased slowly between 1926 and 1950, and then remained fairly constant until the 1980s.
“From that point the regression has been significant, greatly affecting some areas,” they state.
Ice columns have receded to a minimum or even disappeared.
The scientists have found that ice, which had been in situ for millennia, has melted in recent years in some of the caves.
The sensors that they have installed inside and outside caves show the temperature is increasing in these high mountain areas ‘year after year’.
By studying the formation of ancient ice which still remains, they can observe a long sequence of how the climate has changed over time.
They highlighted the A-294 cave which stands at 2,238m in the Cotiella massif in the Pyrenees of Huesca province.
It has a circular entrance and a ramp of snow runs for 10 metres into a cavity, where an ice deposit is situated.
The position of the cave has allowed deposits of flora to enter along with the snow, which became part of the ice.
Carbon dating of the vegetation shows that the layers of ice are between 1,880 and 6,100 years old.
This has allowed the scientists to discover the chronology of periods in which more or less ice formed in the cave.
The nature of the flora has also allowed the scientists to discover the types of plants which grew near the cave and how the pine forest had reached a higher level in yesteryear.
“The caves are allowing us to unravel the climatic history of our mountains,” said the scientists.
However, the fast disappearing ice means that they will have to move fast in order to extract more secrets from these ancient deposits in high mountains areas, described as ‘national archives’ by the scientists.
Photos by Reyes Giménez
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