The southern hemisphere westerly wind belt (SHW) encircles Antarctica, tracking the mid-latitude meridional sea surface temperature gradient (e.g. Lamy et al., 2010). The SHW is an important component of global climate because it exerts a major control on global ocean-circulation (Marshall and Speer, 2012) and hence also on the global CO₂ budget (Anderson et al., 2009). The SHW intersects Southern Chile, bringing precipitation to the region (Fig. 1). Thus, reconstruction of past precipitation represents an approach to understand the past dynamics of the SHW. Similarly, it is important to understand how the SHW interacted with past changes in sea surface temperature and how this is linked to changes in Antarctica.

We aim to reconstruct precipitation and sea surface temperature on decadal to millennial timescales since the last glacial period to develop a comprehensive understanding of the dynamics of the SHW and temperature evolution. To this end, we investigate a north-south transect of marine and lake sediment cores spanning the range of the SHW (Fig. 1). From these sediments, we analyse a range of biomarker proxies including: the hydrogen isotopic composition of plant leaf wax lipids (a proxy for precipitation), the alkenone unsaturation index (a proxy for sea surface temperature) and the distribution of branched GDGTs (a proxy for lake temperature).

James A. Collins
Frank Lamy
Nicoletta Ruggieri
Ralf Tiedemann