Dansgaard-Oeschger cycles of the penultimate and last glacial period recorded in stalagmites from Türkiye

TL;DR

Stalagmite records from Türkiye reveal evidence of abrupt climate shifts called Dansgaard-Oeschger cycles during the penultimate and last glacial periods.

Contribution

The study provides the first clear evidence of Dansgaard-Oeschger cycles during the penultimate glacial period using precisely dated stalagmite data.

Findings

Dansgaard-Oeschger cycles are clearly recorded in carbon isotope data from a stalagmite in Sofular Cave.

D-O cycles during MIS 6 were approximately twice as long as those in MIS 2-4.

The pacing difference may be linked to a weaker Atlantic Meridional Overturning Circulation and a different climate state during MIS 6.

Abstract

The last glacial period is characterized by abrupt climate oscillations, also known as Dansgaard-Oeschger (D-O) cycles. However, D-O cycles remain poorly documented in climate proxy records covering the penultimate glacial period. Here we present highly resolved and precisely dated speleothem time series from Sofular Cave in northern Türkiye to provide clear evidence for D-O cycles during Marine Isotope Stage (MIS) 6 as well as MIS 2-4. D-O cycles are most clearly expressed in the Sofular carbon isotope time series, which correlate inversely with regional sea surface temperature (SST) records from the Black Sea. The pacing of D-O cycles is almost twice as long during MIS 6 compared to MIS 2-4, and could be related to a weaker Atlantic Meridional Overturning Circulation (AMOC) and a different mean climate during MIS 6 compared to MIS 2-4, leading most likely to a higher threshold for the occurrence of D-O cycles.

Abrupt millennial-scale climate variability, known as Dansgaard-Oeschger (D-O) events, characterized the last glacial. Stalagmite data from northern Türkiye show D-O events for the penultimate glacial period, though they were less frequent.

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