Earth's history is characterized by episodes of large climatic changes. The assessment of these past changes is crucial for our understanding of recent and future climate variability. However, instrumental climate data and historical records are available only for the very recent past. Sediment records offer a unique archive of climate change over longer timescales. The South Pacific comprises the largest Southern Ocean (SO) sector and therefore influences atmosphere-ocean processes on a global scale. However, relatively little is still known about its climate history as sediment records from this remote ocean are sparse. A new set of sediment cores collected in between the modern Subtropical Front (STF) and the Antarctic Polar Front (APF) enables for the first time climate reconstruction on a wide spatial coverage.

Molecular organic proxies are increasingly being applied to examine modern and ancient marine and terrestrial environments. Within the project, we use the biomarker approach for the investigation of sea surface temperatures (SST), biological productivity as well as changes in mineral dust input to the Pacific SO that was so far thought to be restricted to the Atlantic sector of the SO. Specifically, we apply some of the commonly used temperature proxies that are based on alkenones (UK'₃₇) and glycerol dialkyl glycerol tetraethers GDGTs (TEX₈₆). Terrigenous proxies, which are measures of continental vegetation and climate conditions, are based on long-chain n-alkanes (leaf waxes of land plants) and branched GDGTs (membrane lipids of soil bacteria). These compounds are being transported in the organic fraction of eolian dust from major sources in Australia and New Zealand to the open ocean. In combination with detailed mineral provenance analyses, we want to investigate dust input changes and their impact on iron-fertilization over multiple glacial-interglacial cycles, thus deciphering the role of the Southern Ocean in regulating past atmospheric CO2 variability.