It is worth noting the decline in ice deposits in the frozen caves of the Ordesa and Monte Perdido National Park. Since 2014, a team of scientists from the Pyrenean Institute of Ecology (IPE/CSIC) has been able to measure and observe how the melting rate has increased from 25 centimetres per year between 2017 and 2022 to more than one metre per year between 2022 and 2024. The frozen caves of the Pyrenees are unique cavities, unprecedented from a scientific point of view, which contain accumulations of fossil ice inherited from the climatic conditions of the last millennia, threatened with imminent disappearance due to current global warming.
Caves, mainly in their stalagmites, hide information about the evolution of the climate in the past. They show periods that were very hot or very cold or how precipitation has changed due to its relationship with the climate: for a stalagmite to form, there must be drops inside a cave and for drops to occur, it must rain in that area. Thanks to the type of rain, you can know what the temperature was in that area or what different types of rain could be found.
Most of them contain frozen ice inside, but some also contain snow transformation ice. In both cases, this is fossil ice accumulated over the last millennia and centuries. It contains paleobotanical and isotopic indicators that provide valuable information about past environmental and climatic conditions, of great interest for the study of future climate. Currently, the volume of these ice masses is undergoing an accelerated decrease due to global warming, so that in a few decades they will have disappeared. Given these prospects, frozen caves require urgent research attention.
On July 22, a new research campaign began in these caves as part of the Orquestra project, led by Ana Moreno and Miguel Bartolomé. During the last week of July, the team formed by Reyes Giménez, Mario Bielsa, David Serrano and Juan Fernández carried out ice monitoring work in several caves at an altitude of over 2,700 meters, in collaboration with members of the French group Société de Speleologie et de Préhistoire des Pyrénées Occidentales (SSPPO). Sensors were installed in hard-to-reach places to explore new ice deposits over 30 meters thick.
The research focuses on frozen caves and their fossil ice sequences as a record of past environmental variations and as a means of monitoring the impact of global change in the high mountains of the Ordesa y Monte Perdido National Park. The work has focused on downloading and maintaining sensors, monitoring temperatures inside the caves, measuring ice volume variation and sampling drops for isotopic analysis (this helps to understand how the climate signal is recorded in the ice column).
As long as the ice can be dated (from 14 degrees in external plant remains or from cryogenic calcite precipitated inside the ice body using Uranium-Thorium), the climate variability of the last hundreds or thousands of years can be reconstructed. Thus, the response of the ice body to past environmental changes can be assessed, its current state of preservation established and the impact of global warming on its preservation and current dynamics.
In 2024, the research team celebrates the 10th anniversary of the studies carried out in some frozen caves in the National Park. Since 2014, they have been able to measure and observe the significant decrease in ice deposits. In some of these caves, the rate of ice melting has increased from 25 centimeters per year (between 2017 and 2022) to more than one meter per year between 2022 and 2024.
