David Domínguez Villar, researcher at the CENIEH, has just published in Climate Dynamics, one of the journals on Earth Sciences with the greatest impact factor, an article about the Postojna Cave, demonstrating for the first time that global warming is already affecting cave temperature of the caves, despite being highly stable environments against climate changes.

This research focuses on the mechanisms that transfer the variations in surface atmospheric temperature into caves to evaluate whether they record the warming trend of recent decades. As a study case, we use the data from a hall in Postojna Cave (Slovenia), which was monitored from 2009 to 2013.

The low-frequency thermal variability of this cave chamber is dominated by the conduction of heat from the surface through the bedrock. We implemented a thermal conduction model that reproduces low-frequency thermal gradients similar to those measured in the cave. At the 37 m depth of this chamber, the model confirms that the bedrock is already recording the local expression of global warming with a delay of 20–25 years, and predicts a cave warming during the coming decades with a mean rate of 0.015 ± 0.004 C year−1.

However, because of the transfer of surface atmosphere thermal variability depends on the duration of the oscillations, the thermal anomalies with periods 7–15 years in duration have delay times <10 years at the studied hall. The inter-annual variability of the surface tmospheric temperature is recorded in this cave hall, although due to the different delay and amplitude attenuation that depends on the duration of the anomalies, the cave temperature signal differs significantly from that at the surface. As the depth of the cave is a major factor in thermal conduction, this is a principal control on whether or not a cave has already recorded the onset of global warming.

As this geologist from CENIEH explains, it is important to know the changes in temperature because they may affect the ventilation, and may cause corrosion processes by condensation of humidity from the atmosphere. "And these processes could be critical to the management of tourist caves, such Postojna, the most visited in Europe, as well as heritage conservation, especially rock art," he concludes.

Lojen Sonja (Jozef Stefan Institute, Slovenia), Kristina Krklec (University of Zagreb, Croatia), Andy Baker (University of New South Wales, Australia) and Ian J. Fairchild (University of Birmingham, UK) have also participated in this paper entitled "Is Global warming affecting