A new insight of the MIS 3 Dansgaard-Oeschger climate oscillations in western Europe from the study of a Belgium isotopically equilibrated speleothem

The Marine Isotope Stage (MIS) 3 records abrupt transitions from cold stadial to temperate interstadial climate conditions, termed Dansgaard-Oeschger (DO) events. Reconstructing these rapid climate changes is crucial for documenting the prevailing climatic conditions in Europe during the extinction of the Neanderthals. However, only few continental records are available to define the continental climatic responses to DO changes. Here, the elemental and stable isotope compositions of a well-dated speleothem in Belgium covering the MIS 3 are documented. This speleothem precipitated under equilibrium conditions based on Δ₄₈ thermometry, allowing the use of Δ₄₇ thermometry with confidence. Moreover, the precision and accuracy of our clumped-isotope analyses are demonstrated through the long-term monitoring of international Δ₄₇ standards. The acquired unique thermometry paleoclimatic dataset enables the reconstruction of temperature based on the hydrological information (oxygen-18 of drip water; δ¹⁸Ow) and sheds new light on the DO climate variations. A temperature differential of ∼7 °C is associated with alternating temperate warm and wet Interstadials to cold and dry stadials. The DO-12 is the most pronounced MIS 3 interstadial in the record and appears to be marked by a delay of 1000 years between climate enhancement (warmer temperature) and water availability (moisture increase). By combining our speleothem record with other continental and marine archive, the spatial variability of DO changes in Europe during the MIS 3 is defined. A gradual climate deterioration with colder and drier conditions, associated with the Heinrich 4 event, progressed southwards through Europe. This spatial climatic degradation, during the last phase of Neanderthal populations occupation in Europe, provides better environmental constraints for human mobility models.