Stalagmite-inferred European westerly drift with centennial-scale variability in marine isotope stage 5a

Description

Marine isotope stage (MIS) 5a, a relatively warm period occurring 85-74 thousand years ago (ka, before AD 1950) during the last glacial, provides a window for understanding the linkage between the European westerlies and Mediterranean climate. However, lack of highly-resolved paleoclimate records with absolute chronologies hampers our knowledge of decadal-to-centennial-scale climate changes and forcings in the circum-Mediterranean realm. Here, we present 230Th-dated, 5-yr-resolved stalagmite δ18O and δ13C records from Observatoire Cave (43°44'N, 7°25'E), Monaco, northern Mediterranean, for the period 83.6-80.3 ka, indicating hydrological changes over the region in the first-half of MIS 5a. Multi-centennial arid intervals are recorded in both δ18O and δ13C speleothem records, some of which correspond to North Atlantic ice rafted detritus (IRD) events. A transient simulation of MIS 5a suggests that these arid events could be due to slowdowns of Atlantic Meridional Overturning Circulation (AMOC), with the poleward-migrated westerlies. One or two drought events during the time without significant temperature drops in the high-latitude North Atlantic could be attributed centennial positive-NAO-like states. Furthermore, a significant periodicity of 210 years, matching the De Vries-Suess solar cycle, suggests a possible solar influence on hydroclimate in southern Europe at MIS 5a.

Abstract

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