The sea-level fingerprint of the 8.2 ka climate event

Abstract

The 8.2 ka cooling event was an abrupt, widespread climate instability. There is general consensus that the episode was likely initiated by a catastrophic outflow of proglacial Lakes Agassiz and Ojibway through the Hudson Strait, with subsequent disruption of the Atlantic meridional overturning circulation. However, the total discharge and flux during the 8.2 ka event remain uncertain. We compute the sea-level signature, or “fingerprint,” associated with the drainage of Lakes Agassiz and Ojibway, as well as the expected sea-level signal over the same time period due to glacial isostatic adjustment (GIA) in response to the Late Pleistocene deglaciation. Our analysis demonstrates that sites relatively close to the lakes, including the West and Gulf Coasts of the United States, have small signals due to the lake release and potentially large GIA signals, and thus they may not be optimal field sites for constraining the outflow volume. Other sites, such as the east coast of South America and western Africa, have significantly larger signals associated with the lake release and are thus better choices in this regard.