| Summary: | <p>Contrasting Greenland and Antarctic temperatures during the last glacial period (115,000 to 11,650 years ago) are thought to have been driven by imbalances in the rates of formation of North Atlantic and Antarctic Deep Water (the ‘bipolar seesaw’). Here we exploit a bidecadally-resolved <sup>14</sup>C dataset obtained from New Zealand kauri (<i>Agathis australis</i>) to undertake high-precision alignment of key climate datasets spanning iceberg-rafted debris event Heinrich 3 and Greenland Interstadial (GI) 5.1 in the North Atlantic (~30,400 to 28,400 to years ago). We observe no divergence between the kauri and Atlantic marine sediment <sup>14</sup>C datasets, implying limited changes in deep water formation. However, a Southern Ocean (Atlantic-sector) iceberg rafted debris event appears to have occurred synchronously with GI-5.1 warming and decreased precipitation over the western equatorial Pacific and Atlantic. An ensemble of transient meltwater simulations shows that Antarctic-sourced salinity anomalies can be propagated globally via an atmospheric Rossby wave train.</p>
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