TWO PULSES OF WARMING AND EXTENSIVE GLACIER RECESSION AT SOUTHERN HEMISPHERE MIDDLE LATITUDES DURING HEINRICH STADIALS 1 AND 0

The termination of the last ice age featured a major reconfiguration of Earth’s climate and cryosphere, yet the underlying causes of these massive changes continue to be debated. Documenting the spatial and temporal variations of atmospheric temperature during deglaciation can help discriminate among potential drivers. Here, we present ¹⁰Be surface-exposure chronologies and glaciological reconstructions of ice recession following the Last Glacial Maximum in the New Zealand Southern Alps and Patagonian Andes. Our field sites straddle opposite sides of the South Pacific and record climate changes near Southern Ocean frontal boundary positions. Most of the deglacial warming in the Southern Alps and southern Andes occurred in two pulses. The first pulse was coeval with Heinrich Stadial 1 (HS1) in the North Atlantic region, and the second pulse was coeval with the Younger Dryas stadial (also known as ‘HS0’). We attribute southern mid-latitude warming and glacier recession during HS1 and HS0 to a southward shift of the Subtropical and Subantarctic Fronts. Because these oceanic fronts are associated with the position of the westerly wind belt, our findings support the concept that a southward shift of Earth’s wind belts accompanied the winter-centric HS1 and HS0 stadials in the North Atlantic region, leading to major warming and deglaciation in southern middle latitudes. Finally, comparison will be made to new moraine chronologies documenting late-glacial resurgences of mountain glaciers and ice sheets on the opposite side of the planet in the Northern Hemisphere, prompting new questions regarding the interhemispheric symmetry of climate change during the last deglaciation.