Colder and wetter conditions in western Patagonia during the 16th to 19th centuries

Resumen: The Baker-Martínez fjord system (central Patagonia, Chile, 48°S) is a 150 km-long estuarine system located between the Northern and Southern Patagonian icefields, at the land-ocean interface between the Andes Mountains and the southeastern Pacific Ocean. This estuarine system is located near the core of the present-day southern westerly wind belt and receives high precipitation year-round. A 64-cm long sediment core was used to reconstruct the evolution of water temperature and precipitation of the fjord system over the past 500 years. A multiproxy approach was applied, combining sediment grain-size, bulk organic geochemistry, stable isotopes, and biomarkers to infer sediment dynamics, the origin of organic matter, and variations in water temperature. We identified a ∼ 0.4 °C cooling of the fjord subsurface waters between 1575 and 1890 CE accompanied by higher precipitation compared to present-day conditions, which we attribute to an equatorward movement of the Southern Westerlies. This cold and wet period is also recorded elsewhere along western Patagonia, indicating the regional presence of higher precipitation, advanced glaciers and colder fjord temperature during Neoglaciation V.