Coherent changes of southeastern equatorial and northern African rainfall during the last deglaciation

• Published in: Science (American Association for the Advancement of Science) Vol. 346; no. 6214; pp. 1223 - 1227
• Main Authors: Otto-Bliesner, Bette L., Russell, James M., Clark, Peter U., Liu, Zhengyu, Overpeck, Jonathan T., Konecky, Bronwen, deMenocal, Peter, Nicholson, Sharon E., He, Feng, Lu, Zhengyao
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 05.12.2014; The American Association for the Advancement of Science; AAAS
• Subjects: Africa, Northern; Climate change; Climate models; Freezing; Glaciers; Global Warming; Greenhouse Effect; Greenhouse gases; Ice Cover; Insolation; Oceans; Precipitation; Proxy reporting; Proxy statements; Rain; Rainfall measurement; Science & Technology - Other Topics; Simulations; Summer; Africa, Northern; Africa
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1259531

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.