A Modeling Perspective on the Magnitude of the Rapid Sea Level Rise Associated with the 8.2 Ka Abrupt Cooling Event

Sediments along the United States Gulf coast provide an important archive for documenting the Late Quaternary sea-level history. In the Mississippi Delta, a rapid sea-level rise of < 1.2 m at ~ 8200 years ago was recorded and has been linked to a contemporary large, widespread, and abrupt cooling event. The 8.2 ka abrupt cooling event is largely believed to result from the catastrophic drainage of proglacial Lake Agassiz and Ojibway (LAO) into the North Atlantic Ocean, which disrupted ocean circulation and triggered large-scale climate change. One critical issue in understanding of this abrupt climate event is the amount of freshwater release from LAO. Available estimates of the amount of drainage range from ~ 0.4 m sea-level equivalent (SLE) to ~ 1.4 m SLE and the < 1.2 m sea-level rise recorded in the Mississippi Delta should represent the upper bound of the estimates. A recent geophysical modeling study, however, suggests that the sea-level rise recorded in the Mississippi Delta may have considerably underestimated the amount of LAO drainage around 8.2 ka due to gravitation effects associated with the catastrophic drainage. Here we investigate the feasibility of a large volume of freshwater drainage using an intermediate complexity atmosphere-ocean model ECBilt-CLIO-VECODE. Modeling experiments with the amount of freshwater drainage of 1.35 m SLE and 2.50 m SLE are performed and compared to assess the impact of a large amount of freshwater drainage on ocean circulation and thus climate. In addition, proxy data-model comparison will be discussed in this presentation.