RT Journal Article
SR Electronic
T1 Rainfall regimes of the Green Sahara
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP e1601503
DO 10.1126/sciadv.1601503
VO 3
IS 1
A1 Tierney, Jessica E.
A1 Pausata, Francesco S. R.
A1 deMenocal, Peter B.
YR 2017
UL http://advances.sciencemag.org/content/3/1/e1601503.abstract
AB During the “Green Sahara” period (11,000 to 5000 years before the present), the Sahara desert received high amounts of rainfall, supporting diverse vegetation, permanent lakes, and human populations. Our knowledge of rainfall rates and the spatiotemporal extent of wet conditions has suffered from a lack of continuous sedimentary records. We present a quantitative reconstruction of western Saharan precipitation derived from leaf wax isotopes in marine sediments. Our data indicate that the Green Sahara extended to 31°N and likely ended abruptly. We find evidence for a prolonged “pause” in Green Sahara conditions 8000 years ago, coincident with a temporary abandonment of occupational sites by Neolithic humans. The rainfall rates inferred from our data are best explained by strong vegetation and dust feedbacks; without these mechanisms, climate models systematically fail to reproduce the Green Sahara. This study suggests that accurate simulations of future climate change in the Sahara and Sahel will require improvements in our ability to simulate vegetation and dust feedbacks.