Intermediate Water Records of Radiocarbon and Temperature from Deep-sea Corals since the LGM

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Intermediate waters in the modern ocean play an important role in global heat, salt, and nutrient transports, and have been at the heart of many explanations of the Last Glacial Maximum (LGM) and the deglaciation. Antarctic Bottom Water (AABW) is crucial in setting the pCO2 of the past but because it upwells and sinks at virtually the same temperature, it is not capable of driving significant poleward heat transport. Intermediate waters, on the other hand, contain a large component of subtropical waters that must cool before sinking to sub-thermocline depths. Here temperature contrasts can be large between source waters and sinking waters giving rise to globally significant heat transports.This research will monitor the radiocarbon content and temperature of intermediate waters from the LGM through the deglaciation in the North Atlantic, using existing deep sea coral samples collected from the New England Seamounts. The research team will measure the U-series ages, radiocarbon content, and clumped isotope composition of the fossil corals to constrain the characteristics of intermediate waters over the past ~25,000 years. This time series will help constrain the role of intermediate waters in glacial and deglacial climate change. Models have predicted, and a few studies have found, intermediate depth warming during Heinrich Stadial 1 (HS1), and the resulting data will be uniquely suited to investigate the rate and heat content of the intermediate circulation since the last glacial period. Funding supports the training of a PhD student, as well as outreach via public lectures and short videos on the links between the oceans and climate.