Proxy-model comparisons of North Atlantic sea surface conditions prior to the 8.2 ka event

One of the most pronounced abrupt climate change events of our present interglacial period, the 8.2 ka event, is evident in various paleoclimate records and as the name suggests, occurred roughly 8,200 years ago. It is proposed that this event was the result of the final drainage of Lake Agassiz into the Hudson Bay and Labrador Sea, disrupting the thermohaline circulation. This event is widely documented and the forcing is relatively well-constrained, thus providing a good case for data-model comparisons, especially in relation to Arctic climate sensitivity and response. The NCAR Community Climate System Model Version 3 (CCSM3) is being used to simulate the Arctic response to this drastic increase in freshwater. We report on ongoing investigation and data-model comparisons to analyze the conditions prior to the 8.2 ka event. Comparing proxies to the model provides necessary validation of the model to ensure realistic results from the freshwater drainage simulation. Different proxy records allow for the reconstruction of temperatures in the North Atlantic and in particular, proxies from sediment cores provide a reasonable representation of sea surface and subsurface conditions throughout the Holocene. We compiled nearly 30 temperature reconstructions from 13 different sediment core locations across the North Atlantic to create a temperature profile from roughly 8,500 years ago. Temperature reconstructions from these proxy records were analyzed and compared with the model output from the same time period. We found a fairly good agreement between the model and the proxies as a whole, though an apparent mismatch in the Gulf Stream area might warrant further investigation.