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We examine hydroclimate changes at centennial/millennial timescales since 16,000 yr BP in northwestern Patagonia based on the pollen and charcoal record from Lago El Salto, a small closed-basin lake located in the Chilean Lake District (41°38′48.02″S, 73° 5′48.42″W). We observe cold/wet conditions between 14,500–16,000 yr BP, followed by further cooling with increased precipitation until 13,000 yr BP, enhanced precipitation seasonality and/or variability between 11,600–13,000 yr BP, and an extended warm-and-dry interval between 7600 and 11,300 yr BP with peak paleofire activity. Colder-and-wetter than present conditions and muted paleofire activity prevail between 5300 and 7600 yr BP, followed by alternating cold/wet and centennial-scale warm/dry phases starting at 5300 yr BP with three conspicuous megadroughts since 2500 yr BP. The most recent megadrought occurred during the Medieval Climate Anomaly. We identify a cold reversal that spans the Antarctic Cold Reversal (ACR) and the Younger Dryas (YD) chrons with stronger-than-present westerly influence during the former and enhanced variability during the latter. These results extend the northern limit of strong cooling and increase in precipitation during the ACR and the southern limit of influence of strong hydrologic variations during the YD in terrestrial environments, suggesting an overlap in the spheres of influence of processes originating from southern and northern polar latitudes. An extended warm southern westerly wind (SWW)-minimum interval is evident between 7600 and 11,300 yr BP, followed by a rapid shift to cool-moist conditions between 5300 and 7600 yr BP brought by a mid-Holocene SWW maximum. Since then we observe centennial-scale hydroclimate variability, which has driven biodiversity and fire-regime shifts of evergreen temperate rainforests. [ABSTRACT FROM AUTHOR]

The spatial-temporal footprint of millennial-scale climate events during the last glacial-interglacial transition can yield insights into the underlying drivers of climate change, but remains poorly resolved in Patagonia. Here, we assess the glacier response to abrupt cold events and palaeolake evolution using geomorphological mapping along with 10 B e ages and optically stimulated luminescence ages from near Lago Belgrano (47.9° S) on the eastern side of Monte San Lorenzo. The former Belgrano glacier was sustained by a climatically sensitive ice cap, making the site ideal for investigating the glacier response to abrupt cold reversals. Our data reveal an extensive re-advance at 13.1 ± 0.6 ka, consistent with cooling and increased precipitation during the Antarctic Cold Reversal (ACR). Subsequently, ice retreated by at least 10 km and created an ice-dammed proglacial lake in the Belgrano valley. Rapid recession was punctuated by smaller advances/still-stands sufficient to maintain an ice-dam for the palaeolake and deposit a lateral moraine dated at 12.4 ± 0.3 ka during the Younger Dryas (YD). The final withdrawal of glaciers to the mountains allowed the palaeolake to drain and resulted in an Atlantic/Pacific drainage reversal. This marks the final separation of the Patagonian Ice Sheet into the individual ice fields at the YD-Holocene transition. Our data demonstrate the dominant ACR climate signal in central Patagonia, but also reveals a co-occurrence of the northern hemisphere YD signal, albeit of smaller magnitude. The ACR re-advance was primarily climatically controlled, but its relative magnitude was likely a consequence of ice divide migration and ice flow re-routing during the break-up of the Patagonian Ice Sheet. • Our 10Be data reveal an extensive re-advance at 13.1 ± 0.6 ka coeval the Antarctic Cold Reversal. • Subsequently ice retreated rapidly and an ice-dammed proglacial lake formed, which persisted for up to a millennium. • Together with a lateral moraine dated at 12.4 ± 0.4 ka, this indicates smaller advances/still-stands during the Younger Dryas. • The subsequent withdrawal of glaciers to the mountains allowed the proglacial lake to drain. • This marks the final break-up of the Patagonian Ice Sheet at the Younger Dryas - Holocene transition. [ABSTRACT FROM AUTHOR]