Late glacial climate evolution in the Patagonian Andes (44-47° S) from alpine glacier modelling

Numerical glacier models applied to moraine chronologies provide an opportunity to quantify past climate change. Here we apply a two-dimensional coupled mass balance -ice flow model to well-dated moraine sequences deposited by former alpine glaciers at two central Patagonian sites: Cerro Rinon (43.97 degrees S, 71.64 degrees W) and Rio Tranquilo (47.50 degrees S, 72.38 degrees W), to reconstruct the local temperatures during both the Antarctic Cold Reversal (14.7-13 ka) and the Younger Dryas (12.9-11 ka). Modelled tempera-ture anomalies during the Antarctic Cold Reversal are-2.6 +/- 0.4 degrees C at 44 degrees S, and-2.9 +/- 0.6 degrees C at 47 degrees S. At both locations this cold event is followed by temperature increases of +0.6-0.7 degrees C or precipitation re-ductions of c. 20% to drive glacier retreat to moraines deposited during Younger Dryas time. The consistent climatic anomalies between these two latitudes suggest this region of Patagonia was responding to a common climatic event. Further, the late-glacial temperature anomalies found here compare well to those determined by similar glacier modelling techniques in New Zealand, at 43-44 degrees S. These results support a trans-Pacific response throughout the southern mid to high latitudes (43-47 degrees S) during the ACR that is best explained by a northward expansion of the south westerly winds.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).