(Department of Marine Chemistry and Geochemistry), fourth-year Ph.D. student, studies climate variability in the Atlantic basin.
Nathalie uses brain coral (Diploria labyrinthiformis) collected from the south shore of Bermuda to increase our understanding of changes in climate and the North Atlantic Oscillation (NAO) over the last several centuries. In particular, Nathalie samples down the growth axis of the coral at sub-annual resolution measuring trace metals and stable isotopes in the coral aragonite. Strontium to calcium concentration ratios in the skeleton provide information about the sea surface temperature at the time the skeleton was formed and oxygen isotope levels provide information about sea surface temperature and salinity. Because corals are slow growing over their long life-spans, they provide monthly resolution records over several centuries. X-radiographs show high and low density bands laid down over the summer and winter and provide a clear way to date the records.
Since the NAO causes anomalies in sea surface temperature, the coral records additionally provide insights into the variability of the NAO. The NAO strongly influences Northern Hemisphere weather and may be impacted by anthropogenic influences. In gaining a better understanding about past changes in the NAO, Nathalie hopes to elucidate how the NAO may change in the future.