The oceans play a crucial role in transporting heat and moisture from the equator to the poles. Observations show that the input of freshwater in polar regions from melting glaciers and sea ice has already contributed to weakening ocean circulation. However, our understanding of these processes is limited by the length of observational records; examining previous periods of change can aid this understanding. This project focuses on the Younger Dryas (11.7-12.9 ka), a cold period that abruptly interrupted the Earth’s warming climate during deglaciation. The cause of this cooling is debated, but a leading hypothesis is that freshwater input from glacial lakes to the North Atlantic Ocean slowed ocean circulation. Alternatively, computer models indicate that sea ice export from the Arctic Ocean, traveling along the east coast of Greenland, could have been responsible for triggering the Younger Dryas. Yet, there are currently limited palaeoceanographic data from this region to evaluate this alternate hypothesis. To address this data gap, this project will utilize existing marine sediment cores to reconstruct sea ice and freshwater changes during the Younger Dryas. This research will provide quantitative data to understand what triggered an abrupt slowdown of ocean circulation that resulted in prominent cooling of the Northern Hemisphere. The results will lead to a better understanding of the sensitivity of ocean circulation to the input of freshwater from sea ice export and melt,