Climate and environmental history of Laguna Polo, Santa Cruz, Southern Patagonia (49 °S) since 1300 AD

Abstract

Patagonia is located in a unique area for climate studies. It is exposed to the strong Southern Hemisphere Westerly Winds (SWW), which are modulated by the Southern Annular Mode (SAM) and is also directly affected by volcanic eruptions of the Andes Mountain Range. In addition, Patagonia is rich in lacustrine environments, which are ideal for paleocological and palaeoclimatological reconstructions. These characteristics make it an ideal location to study not only the effects of global climate change, but also the impact of local volcanic activities on these still pristine freshwater ecosystems. Here, we present a high-resolution paleolimnological reconstruction using testate amoebae and chironomid assemblages along with organic and inorganic sediment geochemistry (Ca, K, Ti, N, TOC, TOC/N δ15N, δ13C) in a sediment core from Laguna Polo (49 °S, Santa Cruz, Argentina) covering the last 1300 yrs AD. Our results show a warm-dry productive environment at ca. 1300-1420 AD associated to the Medieval Climate Anomaly, colder and less productive environments at the time of the Little Ice Age (LIA: 1420-1720 AD) followed by high volcanic activity affecting the lake water mixing at ca. 1700-1960 AD. Finally, warm-stenothermic chironomid species indicate a progressive increase in temperature since 1960 AD. Thus, the sediments of Laguna Polo provide an excellent opportunity to study the responses of aquatic communities to major climatic and environmental events.