Happy to share our study “Antarctic ice dynamics amplified by Northern Hemisphere sea level forcing” out in @Nature today exploring the connection of distant ice sheets through sea level change in and out of the last ice age. Here is a thread about it 1/n https://www.nature.com/articles/s41586-020-2916-2

We modeled the Antarctic ice sheet + global sea levels over the last 40,000 yrs and found that sea level changes due to Northern Hemisphere ice changes drove the Ant. ice sheet to grow larger at the Last Glacial Maximum and retreat earlier + more dynamically and extensively. 2/n

This is because marine-based sectors of the Antarctic ice sheet that terminate in the ocean are sensitive to water depths at their edges. A sea level rise increases ice loss across the grounding line driving retreat, while a sea level fall leads to grounding line advance 3/n

We compared our simulations to a range of geological indicators of ice cover and sea level in Antarctica and found that the influence of the Northern Hemisphere ice sheets on Antarctic sea levels was needed to bring our model results in accord with the data. 4/n

In particular, we looked at iceberg rafted debris records from cores of sediment in the Southern ocean - rocks that were transported from the Antarctic continent out into the ocean in icebergs and deposited on the ocean floor when the icebergs melted. 5/n

These records show that there were intermittent periods of accelerated Antarctic ice loss during the deglaciation. When we include the North. Hemisphere sea level forcing (that was punctuated by periods of accelerated sea level rise) we could model this behavior. 6/n

Finally, this effect may not be limited to the Northern Hemisphere influencing Antarctica. Any distant ice sheets might have communicated through sea level change in areas that are marine-based. The next step is to look at this effect at other locations and times. 7/n

Here is a link from @nature to view the whole article: https://rdcu.be/cbjf7 , which was coauthored by me @mcgillu, Mike Weber @UniBonn, Peter Clark @OregonState, Jerry Mitrovica @Harvard and @hollyhan2015 at McGill.