Exploring the oxygen isotope fingerprint of Dansgaard-Oeschger variability and Heinrich events

- North Atlantic δ18O records consistent with AMOC-driven stadial-interstadial changes.
- North Atlantic δ18O consistent with 18O-depleted meltwater input during stadials.
- Oceanic δ18O signal differs significantly between Heinrich and non-Heinrich stadials.

We present the first transient simulations of Marine Isotope Stage 3 (MIS 3) performed with an oxygen isotope-enabled climate model. Our simulations span several Dansgaard-Oeschger cycles and three Heinrich stadials and are directly compared with oxygen isotope records from 13 sediment and 2 ice cores. Our results are consistent with a 30-50% weakening of the Atlantic Meridional Overturning Circulation during Dansgaard-Oeschger stadials and a complete shutdown during Heinrich stadials. We find that the simulated δ18O anomalies differ significantly between Heinrich stadials and non-Heinrich stadials. This difference is mainly due to different responses in ocean circulation, and therefore climate, impacting oceanic δ18O, while the volume of 18O-depleted meltwater plays a secondary role.