Modelling the transfer of long-term temperature changes in the atmosphere to the vadose zone of karst regions: from glacial cycles to the ongoing global warming

Karst covers approximately 20% of land on Earth, and most caves are in these regions.

Temperature records of most caves in the vadose zone (above the phreatic level) have a limited variability through the year and its value is close to the mean annual temperature of the atmosphere above the cave.

This thermal coupling is the result of the atmospheric thermal signal being transferred underground by conduction and its anomalies being attenuated and delayed with depth. However, during persistent climate changes, cave and external atmosphere temperatures are temporarily decoupled.

The change in cave temperatures (and in the full vadose zone) has major implications for numerous disciplines: ecology of underground environments, conservation of cave art, endurance/formation of ice in alpine caves or in permafrost regions, geochemistry of groundwater and paleoclimate records of speleothems, and also climate change because of the radiation of ground heat to the atmosphere.

Experimental studies in karst regions already confirmed that thermal conduction models reproduce the cave temperature of past decades.

So, the MOTKA proposal aims to simulate the temperature of caves during long-term climate changes using thermal conduction models, as well as to study the consequences of those changes in one particular discipline: paleoclimate d18O records from speleothems.

Our integrated view of ocean paleoclimate records and cave environments is pioneer and enables to simulate past cave temperature records.

The MOTKA proposal will apply for the first time thermal models to long-term climate changes, including glacial cycles, millennial oscillations, the ongoing global warming and its projection into the future. The simulations of this research will add a temporal dimension to the complex dynamics in underground environments.

As an applied example, MOTKA proposal will explore the impact of thermal decoupling in the paleoclimate interpretation of speleothem d18O records.