Millennial-scale temperature and precipitation dynamics during Marine Isotope Stage 11a and 10

Millennial-scale climate variability is a prominent feature of the last glacial cycle, intensively studied in Greenland ice cores as well as other marine and terrestrial climate archives. The most widely recognised expressions of abrupt millennial- to centennial- scale climate oscillations during this period are Dansgaard – Oeschger (D/O) events. For the past 125 ka, Greenland ice cores provide a benchmark for studying D/O events, but their restriction to the last glacial cycle limits investigations of the timing, duration and amplitude of D/O-type events during previous glacial cycles. Synthetic Greenland ice core data suggest that D/O-type millennial-scale climate variability occurred across all glacial phases of the past 800 ka. However, a major limitation for understanding the timing and dynamics of millennial-scale climate variability in preceding glacial cycles is the progressively more challenging dating of older material and the general lack of absolutely and precisely dated high resolution climate records beyond the last interglacial.

Here we present a new speleothem record from Cueva Victoria in SE Spain covering Marine Isotope Stages (MIS) 11a and 10, showing millennial-scale climate variability in both temperature and precipitation. Previous studies confirm that speleothems from Cueva Victoria are sensitive archives of past atmospheric and hydrological changes on both millennial and orbital timescales. For the last glacial cycle, numerous D/O events have been identified in Cueva Victoria speleothem stable isotope records, demonstrating their strong connection to North Atlantic climate patterns.

During MIS 11a and 10, millennial-scale variability is evident in multiple high-resolution proxies in the Cueva Victoria speleothems, such as stable carbon and oxygen isotopes, Mg concentrations, as well as TEX₈₆-derived cave temperatures. The structure and timing of those millennial-scale events align closely with millennial-scale variability in marine sediment records, especially from the Iberian Margin, enabling direct comparison of temperature and precipitation dynamics in the marine and terrestrial realm. All events are characterised by a rapid increase in temperature and moisture availability, followed by a more gradual cooling and drying trend. This results in distinct stadial-interstadial D/O-type oscillations, particularly pronounced during MIS 10. The timing of these oscillations matches with the predicted occurrence of D/O events based on the synthetic Greenland ice core record, highlighting the potential of Cueva Victoria speleothems to reconstruct millennial scale climate variability beyond the last glacial cycle.