Southern hemispheric Heinrich events as source of glacial climate variability

The climate of the last glacial period was shaped by two dominating signals of glacial climate variability known as Dansgaard-Oeschger cycles and Heinrich events. Typically, these two modes of millennial-scale glacial climate variability are associated with dramatic, periodic climate changes in the northern hemisphere. Specifically, Heinrich events have been linked to instabilities of the Laurentide ice sheet. The discovery of Heinrich events has largely been based on the presence of repeated ice-rafted debris horizons in sediment cores from the North Atlantic. While similar geologic signatures have been found in sediment cores of the Southern Ocean, the hypothesis that the Antarctic ice sheet may have undergone similar millennial-scale episodes of instability has gained little attention in the scientific community. Here, we use a simulation of the period from 56,000 – 10,000 years before present with a novel climate-ice sheet-iceberg-solid earth model to explore the climatic response of southern hemispheric Heinrich events (SHEs). Our results reveal the global climatic fingerprint of SHEs. In addition, our simulated climate response reconciles three independent sources of proxy observations that have hitherto been interpreted in isolation. Overall, our model results suggest that the Antarctic ice sheet may have played a much more prominent role in shaping glacial climate variability than previously thought.