Raw 500-µm XRF titanium counts for core MLHP608, South Georgia

Observational data show that climate in the Southern Ocean region is rapidly changing. However, past the instrumental period, our understanding of climate variability in the region is limited by a scarcity of high-resolution palaeoclimate records. Alpine glaciers, present on many Southern Ocean islands, may provide such data because changes in their mass balance, extent and erosion rates often mark a response to climate shifts. Rock flour, the fine-grained fraction of the glacial erosion process, is suspended in meltwater streams and transferred into the sediments of downstream lakes, continuously recording glacier variations. Here, we utilize this relationship to present a reconstruction of the Late Holocene glacier history of subantarctic South Georgia, using sediments from the glacier-fed Middle Hamberg Lake. To fingerprint a glacial erosion/size signal, we used titanium counts, validated against changes in sediment density and grain size, allowing a continuous reconstruction of glacier variations over the past 1250 years.