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Abrupt onset and termination of the African Humid Period: rapid climate responses to gradual insolation forcing

deMenocal, Peter and Ortiz, Joseph and Guilderson, Tom and Adkins, Jess and Sarnthein, Michael and Baker, Linda and Yarusinsky, Martha (2000) Abrupt onset and termination of the African Humid Period: rapid climate responses to gradual insolation forcing. Quaternary Science Reviews, 19 (1-5). pp. 347-361. ISSN 0277-3791. doi:10.1016/S0277-3791(99)00081-5.

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A detailed (ca. 100 yr resolution) and well-dated (18 AMS ^(14)C dates to 23 cal. ka BP) record of latest Pleistocene–Holocene variations in terrigenous (eolian) sediment deposition at ODP Site 658C off Cap Blanc, Mauritania documents very abrupt, large-scale changes in subtropical North African climate. The terrigenous record exhibits a well-defined period of low influx between 14.8 and 5.5 cal. ka BP associated with the African Humid Period, when the Sahara was nearly completely vegetated and supported numerous perennial lakes; an arid interval corresponding to the Younger Dryas Chronozone punctuates this humid period. The African Humid Period has been attributed to a strengthening of the African monsoon due to gradual orbital increases in summer season insolation. However, the onset and termination of this humid period were very abrupt, occurring within decades to centuries. Both transitions occurred when summer season insolation crossed a nearly identical threshold value, which was 4.2% greater than present. These abrupt climate responses to gradual insolation forcing require strongly non-linear feedback processes, and current coupled climate model studies invoke vegetation and ocean temperature feedbacks as candidate mechanisms for the non-linear climate sensitivity. The African monsoon climate system is thus a low-latitude corollary to the bi-stable behavior of high-latitude deep ocean thermohaline circulation, which is similarly capable of rapid and large-amplitude climate transitions.

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Adkins, Jess0000-0002-3174-5190
Additional Information:© 1999 Elsevier Science Ltd. Available online 21 April 2000. The authors would like to thank John Miller and Paula Weiss from the Ocean Drilling Program for their help in the detailed sampling Site 658C. Helpful comments and significant input to this paper were contributed by Bob Anderson, Andre Berger, Martin Claussen, Claude Hillaire-Marcel, George Kukla, and David Rind. Comments by two anonymous reviewers greatly improved the final manuscript. This project was supported by the Marine Geology and Geophysics division of the National Science Foundation. This is LDEO contribution number 5961.
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Lamont-Doherty Earth Observatory (LDEO)5961
Issue or Number:1-5
Record Number:CaltechAUTHORS:20120828-101728135
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Official Citation:Peter deMenocal, Joseph Ortiz, Tom Guilderson, Jess Adkins, Michael Sarnthein, Linda Baker, Martha Yarusinsky, Abrupt onset and termination of the African Humid Period:: rapid climate responses to gradual insolation forcing, Quaternary Science Reviews, Volume 19, Issues 1–5, 1 January 2000, Pages 347-361, ISSN 0277-3791, 10.1016/S0277-3791(99)00081-5. (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33604
Deposited On:28 Aug 2012 17:43
Last Modified:09 Nov 2021 21:35

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