Bette L. Otto-Bliesner1, James M. Russell2, Peter U. Clark3, Zhengyu Liu4,5, Jonathan T. Overpeck6, Bronwen Konecky3,7, Peter deMenocal8, Sharon E. Nicholson9, Feng He4, Zhengyao Lu5
1 Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, CO 80307-3000, USA.
2 Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02912, USA.
3 College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA.
4 Center for Climatic Research and Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
5 Laboratory for Climate, Ocean and Atmosphere Studies, School of Physics, Peking University, Beijing 100871, P. R. China.
6 Department of Geosciences and Institute of the Environment, University of Arizona, Tucson, AZ 85721, USA.
7 Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA.
8 Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA.
9 Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USA.
Abstract
During the last deglaciation, wetter conditions developed abruptly ~14,700 years ago in southeastern equatorial and northern Africa and continued into the Holocene. Explaining the abrupt onset and hemispheric coherence of this early African Humid Period is challenging due to opposing seasonal insolation patterns. In this work, we use a transient simulation with a climate model that provides a mechanistic understanding of deglacial tropical African precipitation changes. Our results show that meltwater-induced reduction in the Atlantic meridional overturning circulation (AMOC) during the early deglaciation suppressed precipitation in both regions. Once the AMOC reestablished, wetter conditions developed north of the equator in response to high summer insolation and increasing greenhouse gas (GHG) concentrations, whereas wetter conditions south of the equator were a response primarily to the GHG increase.
Citation：Bette L. Otto-Bliesner, James M. Russell, Peter U. Clark, Zhengyu Liu, Jonathan T. Overpeck, Bronwen Konecky, Peter deMenocal, Sharon E. Nicholson, Feng He, and Zhengyao Lu, 2014: Coherent changes of southeastern equatorial and northern African rainfall during the last deglaciation. Science. 346 (6214), 1223-1227. [DOI:10.1126/science.1259531]
