HR: 1340h
AN: PP13B-1497    [Abstracts]
TI: Consistent Simulations of Multiple Proxy Responses to an Abrupt Climate Change Event
AU: * LeGrande, A N
EM: legrande@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies and Center for Climate Systems Research, 2880 Broadway, New York, NY 10025 United States
AU: Schmidt, G A
EM: gschmidt@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies and Center for Climate Systems Research, 2880 Broadway, New York, NY 10025 United States
AU: Shindell, D T
EM: dshindell@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies and Center for Climate Systems Research, 2880 Broadway, New York, NY 10025 United States
AU: Field, C
EM: cfield@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies and Center for Climate Systems Research, 2880 Broadway, New York, NY 10025 United States
AU: Miller, R L
EM: rmiller@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies and Center for Climate Systems Research, 2880 Broadway, New York, NY 10025 United States
AU: Koch, D
EM: dorothy.koch@yale.edu
AF: NASA Goddard Institute for Space Studies and Center for Climate Systems Research, 2880 Broadway, New York, NY 10025 United States
AU: Faluvegi, G
EM: gfaluvegi@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies and Center for Climate Systems Research, 2880 Broadway, New York, NY 10025 United States
AU: Hoffmann, G
EM: Georg.Hoffmann@cea.fr
AF: LSCE/CEA, Orme des Merisiers, Gif sur Yvette, 91191 France
AB: Ice cores, speleothems, and ocean sediment cores (proxy) records indicate an abrupt cooling approximately 8kyr ago, possibly confined to the North Atlantic region. The collapse of the Hudson Bay ice dome dam that released fresh glacial Lakes Aggasiz and Ojibway into the Hudson Bay is hypothesized to have created a slowdown in North Atlantic overturning circulation, creating this abrupt cooling. However, a lack of proxy cooling evidence within the North Atlantic has called this mechanism into question. We address the role of a slow down in deep water production in creating this type of climate change scenario by examining the impacts on the proxies themselves. In an ensemble of simulations using GISS modelE, we apply fresh water forcing to the Hudson Bay to simulate the impact of an 8k-like event on multiple proxies. The effect of this event on water isotopes is addressed using the fully coupled version of the model (atmosphere-ocean model with additional land surface and sea ice components), and the impact on cosmogenic isotopes (¹⁰Be), methane (wetland emissions), and dust are addressed using the atmosphere-only version of the model forced with the coupled model response. By comparing these modeled impacts on proxies with the proxy record at 8kyr, we find that a relatively short period of significantly diminished overturning provides a good match to the proxy record.
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4928 Global climate models (1626, 3337)
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005