Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 106, Issue 48, Pages 20159-20163Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0905771106
Keywords
n-alkane carbon isotopes; vegetation; atlantic meridional overturning circulation (AMOC)
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Funding
- Netherlands Bremen Oceanography 2
- Deutsche Forschungsgemeinschaft
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The carbon isotopic composition of individual plant leaf waxes (a proxy for C-3 vs. C-4 vegetation) in a marine sediment core collected from beneath the plume of Sahara-derived dust in northwest Africa reveals three periods during the past 192,000 years when the central Sahara/Sahel contained C-3 plants (likely trees), indicating substantially wetter conditions than at present. Our data suggest that variability in the strength of Atlantic meridional overturning circulation (AMOC) is a main control on vegetation distribution in central North Africa, and we note expansions of C-3 vegetation during the African Humid Period (early Holocene) and within Marine Isotope Stage (MIS) 3 (approximate to 50-45 ka) and MIS 5 (approximate to 120-110 ka). The wet periods within MIS 3 and 5 coincide with major human migration events out of sub-Saharan Africa. Our results thus suggest that changes in AMOC influenced North African climate and, at times, contributed to amenable conditions in the central Sahara/Sahel, allowing humans to cross this otherwise inhospitable region.
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