GSnapshots of tropical Pacific climate variability during the time of Lapita ocean voyaging: giant clam fossils from Fijian shell middens as high resolution archives of climate information.

Records of pre-industrial climate change are vital for accurately simulating Earths climate system and reducing uncertainty in 21st century climate predictions.

Giant clams are particularly valuable archives of past climate as they are fast-growing, long-lived, and their dense shells have annual growth bands that can be subsampled and analysed to produce sub-annually resolved climate proxy records spanning multiple decades.

Furthermore, they are common in the tropical Pacific, where paleoclimate data is particularly valued as sub-annual to decadal-scale changes in this region have been linked to dramatic global temperature and rainfall anomalies with far-reaching socioeconomic and environmental effects.

Giant clams are/were a common food and tool supply in the tropical Pacific, and are abundant in Lapita-age shell middens, providing unique opportunities for paleoclimate research that have surprisingly not been exploited.In REEFCLAM, I will use giant clam shells in a ~3,000-year old shell midden to generate the first sub-annually resolved record of pre-industrial climate variability in Fiji.

Specifically, trace element and stable isotope profiles across multiple shells will be generated and stitched together, and used to reconstruct patterns of variability in sea surface temperature and salinity.

Fijis climate is highly sensitive to changes in the SPCZ and WPWP, and so these records will provide a snapshot of Mid-Late Holocene variability relating to the El Nio Southern Oscillation that will be of great value to the climate community.

I will generate the first modern clam-based geochemical proxy calibrations for Fiji providing an important platform for future work.

Importantly, the data will be also used to test the hypothesis that the pulse of eastward ocean voyaging by the Lapita people and their rapid colonisation of the Pacific coincided with more frequent El Nio events (more westerlies), a novel opportunity to marry the sciences and the humanities.