Award Abstract #0601998
Collaborative Research: High-Resolution, Low-Latitude Paleoclimatology From Newly Acquired Sediment Drill Cores From Lake Bosumtwi, Ghana

NSF Org:	EAR Division of Earth Sciences
Initial Amendment Date:	September 12, 2006
Latest Amendment Date:	September 12, 2006
Award Number:	0601998
Award Instrument:	Standard Grant
Program Manager:	Paul E Filmer EAR Division of Earth Sciences GEO Directorate for Geosciences
Start Date:	September 15, 2006
Expires:	August 31, 2009 (Estimated)
Awarded Amount to Date:	$244687
Investigator(s):	Jonathan Overpeck jto@email.arizona.edu (Principal Investigator)
Sponsor:	University of Arizona 888 N Euclid Ave TUCSON, AZ 85721 520/626-6000
NSF Program(s):	GLOBAL CHANGE
Field Application(s):	0000099 Other Applications NEC
Program Reference Code(s):	EGCH, 1304
Program Element Code(s):	1577

ABSTRACT

Lake Bosumtwi lies in a million-year-old meteorite impact crater located in the tropical forest lowlands of Ghana, in West Africa. The lake is hydrologically closed and known to be very sensitive to the precipitation/evaporation balance and the strength of the West African Monsoon. Lake Bosumtwi contains one of a very few, long annually laminated sediment records in the tropics, and has by far the longest, highest-resolution paleoclimate record in equatorial West Africa.

Intellectual Merit: This grant studies interannual to millennial-scale West African monsoon dynamics over the last ~430 kyr (i.e., back through Marine Isotopic Stage [MIS] 11). This work provides insight into the role of the tropics in triggering, intensifying and propagating climate changes, as well as in responding to global and highlatitude changes. This work will produce the first continuous well-dated terrestrial record of West African climate & aerosol variability over multiple glacial cycles, and provide hydrologic constraints on a key methane source region, and use the annually-laminated sediments to examine globally significant questions regarding the exact timing and patterns of change over multiple glacial terminations (e.g., What is the low-latitude response to deglaciation events, and can we assess how fast large ice sheets melt and lead to interglacial conditions? What is the nature of climatic reversals on previous terminations? How long was MIS11, how was it manifested in the tropics, and how does it really relate to orbital forcing, particularly at the end? What is the full range of drought variability during warm climates?)

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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Koeberl C., Milkereit B., Overpeck J. T., Scholz C. A., Amoako P. Y. O., Boamah D., Danuor S.K., Karp T., Kueck J., Hecky R. E., King J., and Peck J. A..  "An international and multidisciplinary drilling project into a young complex impact structure: The 2004 ICDP Bosumtwi impact crater, Ghana, drilling project - An overview.,"  Meteoritics & Planetary Science,  2007, 

Scholz, C.A, T.C. Johnson, A.S. Cohen, J.W. King, J.A. Peck, J.T. Overpeck, M.R. Talbot, E.T. Brown, L. Kalindekafeh, P.Y.O. Amoakoi, R.P. Lyons, T.M. Shanahan, I.S. Castaneda, C.W. Heile, S.L. Forman, L.R. McHarguek, K.R. Beuning, J.Gomez, and J.Pierson.  "East African megadroughts between 135 and 75 thousand years ago and bearing on early-modern human origins,"  Proc. of the National Academy of Sciences,  v.104,  2007,  p. 16416.

Shanahan, T., Overpeck, J. T., Wheeler, C. W., Beck, J. W., Pigati, J. S., Talbot, M. R., Scholz, C. A., Peck, J., and King, J. W..  "Paleoclimatic variations in West Africa from a record of late Pleistocene and Holocene lake level stands of Lake Bosumtwi, Ghana.,"  Palaeogeography Palaeoclimatology Palaeoecology,  2007, 


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