Northern Alpine temperature lapse rates from the mid Holocene and MIS 5 based on speleothem fluid inclusions

Medium to high elevations in the European Alps may experience enhanced warming in the future (Kotlarski et al., 2023), potentially leading to a decrease of the temperature lapse rate. However, it remains unclear if such elevation dependent warming has happened during previous interglacials. Therefore, reconstructing temperature lapse rate estimates from past warm intervals offer a unique opportunity to investigate if elevation dependent warming has occurred in the past and whether we are to expect such a process in the future.

In order to examine the past temperature lapse rates, we used speleothem samples from caves collected along an altitudinal transect from the Jura mountains to the Swiss Alps. The speleothems contain past drip water that has been preserved in micrometric sized fluid inclusions (0.01 to 0.1 weight %). This drip water corresponds to precipitation water falling above the cave and thus constitutes an excellent archive of past precipitation (Affolter et al., 2025). By combining the stable isotopic compositions of speleothem fluid inclusion waters and calcite, absolute paleotemperatures can be estimated.

Here we present temperature lapse rates of the Northern Alpine region based on speleothem fluid inclusion water from the mid Holocene and the Marine Isotope stage 5 (MIS 5) intervals. Overall, ~140 fluid inclusions samples obtained from 18 stalagmites from 12 caves situated along a transect from the Jura mountains to the Swiss Alps, across elevations ranging from 373 to 1’890 meters.

Preliminary results indicate that very slight elevation dependent warming might have occurred.  However, especially for MIS 5, mountain uplift and erosion may significantly impact the temperature lapse rate as cave elevations have changed over time, increasing uncertainties. The average paleotemperatures show that modern air temperatures are ~1°C to ~1.5°C warmer compared to the mid Holocene.