NOAA/WDS Paleoclimatology - Spannagel Cave, Austria MIS 7 (247-182ka) Stalagmite Oxygen Isotope Data

Investigating the precise timing of regional-scale climate changes during glacial terminations and the interglacial periods that follow is key to unraveling the mechanisms behind these global climate shifts. Here, we present a high precision time series of climate changes in the Austrian Alps that coincide with the later portion of Termination III (TIII), the entire penultimate interglacial (Marine Isotope Stage (MIS) 7), Termination IIIa (TIIIa), and the penultimate glacial inception (MIS 7/6 transition). Using state-of-the-art mass spectrometry techniques, we have constructed a uranium-series chronology with relative age uncertainties averaging 1.7 per mil (2S) for our study period (247 to 191 thousand years before present). Results reveal the onset of warming in the Austrian Alps associated with TIII at 242.5+-0.2 ka and the duration of MIS 7e warming between 241.8 to 236.7 (+-0.6) ka. An abrupt shift towards higher d18O values at 216.8 ka marks the onset of regional warming associated with TIIIa. Two periods of high d18O values (greater than -10 per mil VPDB) between 215.9-213.3 and 204.3-197.5 (+-0.4) ka coincide with interglacial substages MIS 7c and 7a, respectively. Multiple fluorescent inclusions suggest a partial retreat of the local Alpine glacier during peak obliquity forcings at 214.3 +-0.4 ka. Two newly collected stalagmites from Spannagel Cave (SPA146 and 183) provide high-resolution replications of the latter portion of the MIS 7a/6e transition. The resulting multi-stalagmite record reveals important chronological constraints on climate shifts in the Austrian Alps associated with MIS 7, while offering new insight into the timing of millennial-scale changes in the North Atlantic realm leading up to TIII and TIIIa.