ABR: Reconstructing deep ocean circulation in the North Atlantic through the last ice-age climate cycle

The ocean plays an important and variable role in Earth’s climate system, as it works with the atmosphere to move and store heat and moisture throughout the globe. In the Atlantic Ocean, a series of surface currents brings warm, salty seawater northward, where it cools and becomes dense enough to sink to great depths. The atmosphere receives the heat from the cooling ocean, warming the climate at high latitudes, and the newly dense water spreads southward at depth and throughout the world’s ocean as the North Atlantic Deep Water. This system of surface and deep currents is called the Atlantic meridional overturning circulation (AMOC), and there is evidence from computer models and deep-sea sediments that when it has changed in the past, the North Atlantic region experienced dramatic and abrupt climate change. There is also increasing concern that this ocean circulation might slow down in the future. This project is designed to take advantage of high-quality deep-sea sediment cores to examine evidence of the behavior of the ocean circulation in connection with warm and cold intervals during the last ice-age climate cycle. It will help establish the link between ocean circulation and climate change in the past, with potential implications for the future. This research project will promote training and learning for a postdoctoral investigator, science educators and students. This project will involve the generation of high-quality, high-resolution paleoceanographic data, including multiple proxies for deep-ocean circulation, largely utilizing legacy materials from a suite of deep-sea drilling sediment cores from the North Atlantic Ocean. The project will fill substantial knowledge gaps and allow hypothesis testing by improving the resolution of sedimentary data from the peak last interglacial interval at the Bermuda Rise in the western basin, and by generating the first deglacial depth transects and long, high-resolution datasets of these combined AMOC proxies from the eastern basin at the Iberian Margin. The data will be used to test hypotheses regarding the spatial structure and role of AMOC in past climate change, including glacial, interglacial, and abrupt oscillations in the climate system. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.