TY - JOUR T1 - Episodic reductions in bottom-water currents since the last ice age JF - Nature Geoscience Y1 - 2008 A1 - Praetorius, S. K. A1 - McManus, J. F. A1 - Oppo, D. W. A1 - Curry, W. B. AB - Past changes in the freshwater balance of the surface North Atlantic Ocean are thought to have influenced the rate of deep-water formation, and consequently climate(1,2). Although water-mass proxies are generally consistent with an impact of freshwater input on meridional overturning circulation(3), there has been little dynamic evidence to support this linkage. Here we present a 25,000 year record of variations in sediment grain size from south of Iceland, which indicates vigorous bottom-water currents during both the last glacial maximum and the Holocene period. Together with reconstructions of North Atlantic water-mass distribution, vigorous bottom currents suggest a shorter residence time of northern-source waters during the last glacial maximum, relative to the Holocene period. The most significant reductions in flow strength occur during periods that have been associated with freshening of the surface North Atlantic. The short-term deglacial oscillations in bottom current strength are closely coupled to changes in Greenland air temperature, with a minimum during the Younger Dryas cold reversal and a maximum at the time of rapid warming at the onset of the Holocene. Our results support a strong connection between ocean circulation and rapid climate change. VL - 1 IS - 7 N1 - id: 1896; ISI Document Delivery No.: 331AG Times Cited: 9 Cited Reference Count: 34 Cited References: ALLEY RB, 1997, GEOLOGY, V25, P483 BARBER DC, 1999, NATURE, V400, P344 BARD E, 1994, EARTH PLANET SC LETT, V126, P275 BIANCHI GG, 1999, NATURE, V397, P515 BIANCHI GG, 1999, SEDIMENTOLOGY, V46, P1001 BOND G, 1992, NATURE, V360, P245 BOYLE EA, 1987, NATURE, V330, P35 BROECKER WS, 1989, GEOCHIM COSMOCHIM AC, V53, P2465 BROECKER WS, 1989, NATURE, V341, P318 CAME RE, 2007, GEOLOGY, V35, P315, DOI 10.1130/G23455A.1 CURRY WB, 2005, PALEOCEANOGRAPHY, V20, ARTN PA1017 DUPLESSY JC, 1980, NATURE, V286, P479 DUPLESSY JC, 1988, PALEOCEANOGRAPHY, V3, P343 ELLISON CRW, 2006, SCIENCE, V312, P1929, DOI 10.1126/science.1127213 FIRESTONE RB, 2007, P NATL ACAD SCI USA, V104, P16016, DOI 10.1073/pnas.0706977104 GHERARDI JM, 2005, EARTH PLANET SC LETT, V240, P710, DOI 10.1016/j.epsl.2005.09.061 GROOTES PM, 1993, NATURE, V366, P552 HALL IR, 2004, QUATERNARY SCI REV, V23, P1529, DOI 10.1016/j.quascirev.2004.04.004 KENNETT JP, 2007, EOS T AGU JOINT AS S, V88, UNSP PP41A05 KROOPNICK P, 1980, EARTH PLAN, V49, P469 LEGRAND P, 1995, PALEOCEANOGRAPHY, V10, P1011 MANABE S, 1995, NATURE, V378, P165 MCCARTNEY MS, 1996, OCEANUS, V39, P19 MCCAVE IN, 1995, NATURE, V374, P149 MCCAVE IN, 1995, PALEOCEANOGRAPHY, V10, P593 MCCAVE IN, 2006, GEOCHEM GEOPHY GEOSY, V7, P37 MCMANUS JF, 2004, NATURE, V428, P824 OPPO DW, 1993, SCIENCE, V259, P1148 ROHLING EJ, 2005, NATURE, V434, P975, DOI 10.1038/nature03421 RUDDIMAN WF, 1981, PALAEOGEOGR PALAEOCL, V35, P145 SARNTHEIN M, 1994, PALEOCEANOGRAPHY, V9, P209 TARASOV L, 2005, NATURE, V435, P662, DOI 10.1038/nature03617 WORTHINGTON LV, 1976, N ATLANTIC CIRCULATI YU EF, 1996, NATURE, V379, P689 Praetorius, Summer K. McManus, Jerry F. Oppo, Delia W. Curry, William B. Nature publishing group New york; YY JO - Episodic reductions in bottom-water currents since the last ice age ER -