Transient Simulation of Last Deglaciation with a New Mechanism for Bølling-Allerød Warming
- Z. Liu1,2,3,*,
- B. L. Otto-Bliesner4,
- F. He3,
- E. C. Brady4,
- R. Tomas4,
- P. U. Clark5,
- A. E. Carlson6,
- J. Lynch-Stieglitz7,
- W. Curry8,
- E. Brook5,
- D. Erickson9,
- R. Jacob10,
- J. Kutzbach3,
- J. Cheng1,3
- 1Key Laboratory of Meteorological Disaster, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
- 2State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710075, China.
- 3Center for Climatic Research and Department of Atmospheric and Oceanic Sciences, University of Wisconsin, Madison, WI 53706, USA.
- 4Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, CO 80307–3000, USA.
- 5Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
- 6Department of Geology and Geophysics and Center for Climatic Research, University of Wisconsin, Madison, WI 53706, USA.
- 7School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
- 8Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
- 9Oak Ridge National Laboratory, Oak Ridge, TN 37831–6016, USA.
- 10Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439–4843, USA.
- ↵*To whom correspondence should be addressed. E-mail: zliu3{at}wisc.edu
Abstract
We conducted the first synchronously coupled atmosphere-ocean general circulation model simulation from the Last Glacial Maximum to the Bølling-Allerød (BA) warming. Our model reproduces several major features of the deglacial climate evolution, suggesting a good agreement in climate sensitivity between the model and observations. In particular, our model simulates the abrupt BA warming as a transient response of the Atlantic meridional overturning circulation (AMOC) to a sudden termination of freshwater discharge to the North Atlantic before the BA. In contrast to previous mechanisms that invoke AMOC multiple equilibrium and Southern Hemisphere climate forcing, we propose that the BA transition is caused by the superposition of climatic responses to the transient CO2 forcing, the AMOC recovery from Heinrich Event 1, and an AMOC overshoot.
- Received for publication 16 January 2009.
- Accepted for publication 2 June 2009.
