@article {666,
	title = {Late-Quaternary lowstands of lake Bosumtwi, Ghana: evidence from high-resolution seismic-reflection and sediment-core data},
	journal = {Palaeogeography Palaeoclimatology Palaeoecology},
	volume = {216},
	year = {2005},
	note = {892ujTimes Cited:21Cited References Count:54},
	month = {Feb 1},
	pages = {235-249},
	abstract = {Results from the first high-resolution, single-channel seismic-reflection survey of tropical Lake Bosumtwi, Ghana, and sedimentological data from a C-14-dated sediment piston core were used to revise and extend the basin{\textquoteright}s late-Quaternary lake level history. We report four seismic sequence boundaries and an exposure surface from a sediment core. which are interpreted as erosional surfaces formed at times of drastic low lake level. The youngest erosional surf-ace occurs as much as 31 In below present lake level (bpll) and up to 0.7 in below the present sediment-water interface. This most recent unconformity observed in the seismic data is interpreted to be coeval with the basin-wide late-Holocene dry period between 0.5 and 1 cal ky BP (calendar years before present). Another exposure surface observed in a sediment core is based on an abrupt contact separating low density, wet, clay rich sediments from underlying high density, compact, silt-rich and rootlet-rich sediments, and is interpreted to have developed prior to 16.8 cal ky BP when the lake was similar to60 in bpll. Three older, erosional surfaces occur at depths of similar to92 +/- 3, 102 +/- 3, and 107 +/- 4 in bpll, suggesting numerous lowstands in Lake Bosumtwi during the late-Pleistocene. By extrapolation of average sedimentation rates (0.41 m/ky) from the upper similar to10.5 m of sediment, we estimate the ages of these older lowstands to be similar to65, similar to86 similar to108 cal ky BP. The lowstands of Lake Bosumtwi evidenced from the seismic and sediment core data are interpreted as a response to increased aridity in this part of the equatorial tropics and may correlate to other observed continent-wide shifts in African climate over the past 100 ky and possibly to rapid climatic shifts observed at high latitudes. Determining the precise timing of these lowstands will ultimately reveal much about the drought dynamics of tropical and subtropical Africa. (C) 2004 Elsevier B.V. All rights reserved.},
	issn = {0031-0182},
	doi = {10.1016/j.palaco.2004.10.005},
	author = {Brooks, K. and Scholz, C. A. and King, J. W. and Peck, J. and Overpeck, J. T. and Russell, J. M. and Amoako, P. Y. O.}
}
@conference {1544,
	title = {14C activity and global carbon cycle changes over the past 50,000 years},
	booktitle = {Abstracts, 18th International Radiocarbon Conf.},
	year = {2003},
	note = {id: 1079},
	month = {2003},
	address = {Wellington, NZ},
	author = {Hughen, K. A. and Lehman, S. J. and Southon, J. and Overpeck, J. T. and Marchal, O. and Herring, C. and Turnbull, J.}
}
@article {630,
	title = {Abrupt changes in the Asian southwest monsoon during the Holocene and their links to the North Atlantic Ocean},
	journal = {Nature},
	volume = {421},
	year = {2003},
	note = {637uwTimes Cited:483Cited References Count:30},
	month = {Jan 23},
	pages = {354-357},
	abstract = {During the last ice age, the Indian Ocean southwest monsoon exhibited abrupt changes that were closely correlated with millennial-scale climate events in the North Atlantic region(1-3), suggesting a mechanistic link. In the Holocene epoch, which had a more stable climate, the amplitude of abrupt changes in North Atlantic climate was much smaller, and it has been unclear whether these changes are related to monsoon variability. Here we present a continuous record of centennial-scale monsoon variability throughout the Holocene from rapidly accumulating and minimally bioturbated sediments in the anoxic Arabian Sea. Our monsoon proxy record reveals several intervals of weak summer monsoon that coincide with cold periods documented in the North Atlantic region(4)-including the most recent climate changes from the Medieval Warm Period to the Little Ice Age and then to the present. We therefore suggest that the link between North Atlantic climate and the Asian monsoon is a persistent aspect of global climate.},
	issn = {0028-0836},
	doi = {10.1038/nature01340},
	author = {Gupta, A. K. and Anderson, D. M. and Overpeck, J. T.}
}
@article {338,
	title = {Increase in the Asian southwest monsoon during the past four centuries},
	journal = {Science},
	volume = {297},
	year = {2002},
	note = {id: 536; Anderson, David M Overpeck, Jonathan T Gupta, Anil K New York, N.Y. Science. 2002 Jul 26;297(5581):596-9.},
	pages = {596-9},
	abstract = {Climate reconstructions reveal unprecedented warming in the past century; however, little is known about trends in aspects such as the monsoon. We reconstructed the monsoon winds for the past 1000 years using fossil Globigerina bulloides abundance in box cores from the Arabian Sea and found that monsoon wind strength increased during the past four centuries as the Northern Hemisphere warmed. We infer that the observed link between Eurasian snow cover and the southwest monsoon persists on a centennial scale. Alternatively, the forcing implicated in the warming trend (volcanic aerosols, solar output, and greenhouse gases) may directly affect the monsoon. Either interpretation is consistent with the hypothesis that the southwest monsoon strength will increase during the coming century as greenhouse gas concentrations continue to rise and northern latitudes continue to warm.},
	issn = {1095-9203 (Electronic) 0036-8075 (Linking)},
	doi = {10.1126/science.1072881},
	author = {Anderson, D. M. and Overpeck, J. T. and Gupta, A. K.}
}
@conference {1763,
	title = {Radiocarbon calibration and abruptchanges in atmospheric 14Cconcentration during Marine Isotope Stage 3},
	booktitle = {American Geophysical Union},
	year = {2000},
	note = {id: 327},
	month = {2000},
	address = {San Francisco, CA},
	author = {Hughen, K. A. and Southon, J. and Lehman, S. J. and Peterson, L. C. and Overpeck, J. T.}
}
@article {395,
	title = {The role of oceanic forcing in mid-Holocene Northern Hemisphere climatic change},
	journal = {Paleoceanography},
	volume = {14},
	year = {1999},
	note = {id: 1943; PT: J; UT: WOS:000079325100009},
	pages = {200-210},
	abstract = {Previous model investigations suggested that changes in orbital forcing and feedbacks associated with northward expansion of the boreal forest were both required to explain the full magnitude of enhanced high-latitude Northern Hemisphere summer warming at 6 ka, thus implying that biospheric feedbacks (decreased planetary albedo associated with forest expansion) may be large in the future [Foley ct at., 1994; TEMPO (Testing Earth System Models with Paleo-Observations), 1996]. Before the magnitude of past biospheric and other feedbacks can be estimated with confidence, however, the role of realistic high-latitude oceanic forcing (i.e., sea surface temperature (SST) increases and sea ice reductions) should also be considered. Here we review existing paleoceanographic observations that suggest portions of the North Atlantic were up to 4 degrees C warmer than today at 6 ka. We then combine our estimates of mid-Holocene North Atlantic SST and sea ice conditions with new climate model simulations to suggest that a significant portion of high-latitude summer warming at 6 ka in the Northern Hemisphere can be accounted for by altered orbital forcing, SSTs, and sea ice relative to today. Our results underscore the importance of incorporating realistic boundary conditions when using paleoenvironmental data to evaluate the climate system{\textquoteright}s sensitivity to altered forcing and suggest that high-latitude oceanic feedbacks were major contributors to enhanced high-latitude summer warming in the Northern Hemisphere at 6 ka.},
	issn = {0883-8305},
	doi = {10.1029/1998PA900011},
	author = {Kerwin, M. W. and Overpeck, J. T. and Webb, R. S. and DeVernal, A. and Rind, D. H. and Healy, R. J.}
}
