HR: 1340h
AN: PP13B-1499 [Abstracts]
TI: Simulating Arctic Freshwater Forcing of the Younger Dryas Cold Reversal
AU: * Vettoretti, G
EM: guido@atmosp.physics.utoronto.ca
AF: University of Toronto, Department of Physics,
60 St. George Street, Toronto, ON M5S 1A7
Canada
AU: Peltier, W R
EM: peltier@atmosp.physics.utoronto.ca
AF: University of Toronto, Department of Physics,
60 St. George Street, Toronto, ON M5S 1A7
Canada
AU: Stastna, M
EM: mmstastn@math.uwaterloo.ca
AF: University of Waterloo, Department of Applied Mathematics, 200 University Ave. West, Waterloo, ON N2L
3G1
Canada
AB:
The importance of the impact of ocean thermohaline circulation (THC) upon climate system instability has led to a number of
modeling studies of the impact of freshwater forcing applied to the North Atlantic Basin. These experiments form a collection
of studies that attempt to assess the mechanisms for interstadial-stadial climate instability, in particular the
Bolling-Allerod:Yonger Dryas transition during the last deglaciation. More recently, a new focal point involves the
proposition of an Arctic freshwater forcing mechanism for the Younger Dryas cold reversal. Here we will describe a series of
experiments, constructed using the NCAR CSM version 1.4, in which a range of different freshwater forcing anomalies have been
applied to the North Atlantic Basin and Arctic Basin, both under interstadial and stadial conditions. A 100 year long 1.0Sv
freshwater forcing anomaly induces a near complete shutdown of the overturning circulation regardless of the local origin of
the forcing, whether it is from the Arctic or North Atlantic, the only difference being in the phase of the response and
complete recovery of the THC. A set of 100 year long 0.3Sv simulations provide a much more rich behaviour of the
ocean-climate system dynamics as the forcing appears to be near a transition threshold in the climate system response to
Arctic and Atlantic freshwater forcing. These series of simulations have significant implications concerning a suitable cause
for the initiation of the Younger Dryas and the question as to whether THC collapse should be viewed as a probable
consequence of ongoing global warming.
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005