Poleward shift in Southern Westerlies triggered by iceberg discharge in the North Atlantic

During the last glacial period, millennial-scale iceberg discharges in the North Atlantic, known as Heinrich Events (HEs), could have shifted the Southern Hemisphere Westerly Wind Belt (SWW) poleward and potentially led upwelling-driven CO₂ outgassing from the Southern Ocean. However, direct evidence of SWW poleward shift in response to HEs remains limited. Based on detrital elements, minerals, and grain-size records in well-dated sediment cores, MR16-09 PC02 (46°04.23′S, 76°32.10′W, 2793 m water depth) and PC03 (46°24.32′, 77°19.45′, 3082 m water depth), from off western Patagonia at ~46°S, we found abrupt onsets in the discharge of coarse silt-sized detritus during the latter half of each HEs (HE 3, 4, 5, 5a, and 6) originating from the Patagonian Batholith located in the coastal area of western Patagonia. Such abrupt discharges are unique events south of ~46°S and probably reflect the extension of glacial erosion into the western fjords related to a pronounced positive anomaly in the glacial accumulation/ablation mass balance of the western-central Patagonian ice sheet. Our climate model (MIROC4m) hosing experiment in the North Atlantic suggests the SWW and precipitation belt began shifting poleward hundreds of years after the onset of HE, which is consistent timing with our proxy data. Thus, increased precipitation south of 46°S following the poleward-SWW shift most likely generated detritus discharges. These findings provide critical evidence of abrupt climate changes propagating from the North Atlantic to the southern midlatitudes via the large-scale reorganization of the atmospheric and ocean circulations.