TY - JOUR T1 - Deglacial variability in the surface return flow of the Atlantic meridional overturning circulation JF - Paleoceanography Y1 - 2008 A1 - Came, R. E. A1 - Oppo, D. W. A1 - Curry, W. B. A1 - Lynch-Stieglitz, J. AB - [1] Benthic foraminiferal Cd/Ca from a Florida Current sediment core documents the history of the northward penetration of southern source waters within the surface return flow of the Atlantic meridional overturning circulation (AMOC). Cd seawater estimates (Cd-W) indicate that intermediate-depth southern source waters crossed the equator and contributed to the Florida Current during the Bolling-Allerod warm period of the last deglaciation, consistent with evidence of only a modest AMOC reduction compared to today. The Cd-W estimates also provide the first paleoceanographic evidence of a reduction in the influence of intermediate-depth southern source waters within the Florida Current during the Younger Dryas, a deglacial cold event characterized by a weak North Atlantic AMOC. Our results reveal a close correspondence between the northward penetration of intermediate-depth southern source waters and the influence of North Atlantic Deep Water, suggesting a possible link between intermediate-depth southern source waters and the strength of the Atlantic AMOC. VL - 23 IS - 1 N1 - id: 838; 281YL Times Cited:4 Cited References Count:41; YY JO - Deglacial variability in the surface return flow of the Atlantic meridional overturning circulation ER - TY - JOUR T1 - Subtropical Atlantic salinity variability and Atlantic meridional circulation during the last deglaciation JF - Geology Y1 - 2008 A1 - Carlson, A. E. A1 - Oppo, D. W. A1 - Came, R. E. A1 - LeGrande, A. N. A1 - Keigwin, L. D. A1 - Curry, W. B. AB - During the last deglaciation (ca. 21-10 ka), freshening of the North Atlantic surface likely caused reductions in Atlantic meridional overturning circulation (AMOC); the mechanisms related to AMOC recovery remain poorly understood. Here we present three new deglacial surface temperature and delta O-18(seawater) (delta O-18(sw)) reconstructions from the western subtropical North and South Atlantic. Similarities to tropical Caribbean and western Atlantic delta O-18(sw) records suggest that a salty surface water mass accumulated in the western Atlantic from 27 degrees S to 33 degrees N during periods of reduced AMOC. However, delta O-18(sw) decreases led deep AMOC resumption by hundreds of years. We suggest that the northward export of salt previously trapped in the western Atlantic resulted in the early establishment of a shallow overturning circulation that eventually culminated in deep AMOC resumption, implying that AMOC may constitute a self-limiting system. VL - 36 IS - 12 N1 - id: 862; ISI Document Delivery No.: 381WN Times Cited: 5 Cited Reference Count: 32 Cited References: *CLIMAP PROJ MEMB, 1981, GEOL SOC AM MAP CHAR ANAND P, 2003, PALEOCEANOGRAPHY, V18, ARTN 1050 BENWAY HM, 2006, PALEOCEANOGRAPHY, V21, ARTN PA3008 BEVINGTON P, 2002, DATA REDUCTION ERROR BOYLE EA, 1987, NATURE, V330, P35 BROECKER WS, 1990, PALEOCEANOGRAPHY, V5, P469 CARLSON AE, 2007, P NATL ACAD SCI USA, V104, P6556, DOI 10.1073/pnas.0611313104 CLARK PU, 2004, SCIENCE, V304, P1141 GRIMM EC, 2006, QUATERNARY SCI REV, V25, P2197, DOI 10.1016/j.quascirev.2006.04.008 GROOTES PM, 1993, NATURE, V366, P552 KASPI Y, 2004, PALEOCEANOGRAPHY, V19, ARTN PA3004 KNORR G, 2003, NATURE, V424, P532, DOI 10.1038/nature01855 LEA DW, 2003, SCIENCE, V301, P1361 LEDUC G, 2007, NATURE, V445, P908, DOI 10.1038/nature05578 LEGRANDE AN, 2006, GEOPHYS RES LETT, V33, ARTN L12604 LEGRANDE AN, 2008, PALEOCEANOGRAPHY, V23, DOI 10.1029/2008PA001610 MCMANUS JF, 2004, NATURE, V428, P834, DOI 10.1038/nature02494 OPPO DW, 2007, GEOPHYS RES LETT, V34, ARTN L13701 PEETERS FJC, 2004, NATURE, V430, P661, DOI 10.1038/nature02785 PETERSON LC, 2000, SCIENCE, V290, P1947 ROBINSON LF, 2005, SCIENCE, V310, P1469, DOI 10.1126/science.1114832 RUHLEMANN C, 1999, NATURE, V402, P511 SCHMIDT GA, 2007, J GEOPHYS RES-ATMOS, V112, ARTN D10103 SCHMIDT MW, 2004, NATURE, V428, P160, DOI 10.1038/nature02346 SCHMIDT MW, 2006, NATURE, V443, P561, DOI 10.1038/nature05121 SCHMITZ WJ, 1995, REV GEOPHYS, V33, P151 SKINNER LC, 2006, QUATERNARY SCI REV, V25, P3312, DOI 10.1016/j.quascirev.2006.07.005 STOUFFER RJ, 2006, J CLIMATE, V19, P1365 THOMAS AL, 2006, EARTH PLANET SC LETT, V241, P493, DOI 10.1016/j.epsl.2005.11.031 WANG XF, 2004, NATURE, V432, P740, DOI 10.1038/nature03067 WEAVER AJ, 2003, SCIENCE, V299, P1709 WELDEAB S, 2006, EARTH PLANET SC LETT, V241, P699, DOI 10.1016/j.epsl.2005.11.012 Carlson, Anders E. Oppo, Delia W. Came, Rosemarie E. LeGrande, Allegra N. Keigwin, Lloyd D. Curry, William B. Geological soc amer, inc Boulder; YY JO - Subtropical Atlantic salinity variability and Atlantic meridional circulation during the last deglaciation ER - TY - JOUR T1 - Amplitude and timing of temperature and salinity variability in the subpolar North Atlantic over the past 10 k.y. JF - Geology Y1 - 2007 A1 - Came, R. E. A1 - Oppo, D. W. A1 - McManus, J. F. KW - Björn Drift KW - Mg/Ca KW - Neogloboquadrina pachyderma dextral KW - Ocean Drilling Program Site 984 KW - paleotemperature AB - Paired planktic foraminiferal δ18O and Mg/Ca data reveal trends of increasing temperatures (∼3 °C) and salinities in the subpolar North Atlantic over the course of the Holocene, which were punctuated by abrupt events. The trends likely reflect an insolation-forced northward retreat of the boundary between polar and North Atlantic subsurface waters. The superimposed variability does not appear to be periodic, but tends to recur within a broad millennial band. The records provide convincing evidence of open-ocean cooling (nearly 2 °C) and freshening during the 8.2 ka event, and suggest similar conditions at 9.3 ka. However, the two largest temperature oscillations in our record (∼2 °C) occurred during the past 4 k.y., suggesting a recent increase in temperature variability relative to the mid-Holocene, perhaps in response to neoglaciation, which began at about this time. VL - 35 IS - 4 N1 - id: 983 JO - Amplitude and timing of temperature and salinity variability in the subpolar North Atlantic over the last 10,000 years ER - TY - JOUR T1 - Atlantic Ocean circulation during the Younger Dryas: Insights from a new Cd/Ca record from the western subtropical South Atlantic JF - Paleoceanography Y1 - 2003 A1 - Came, R. E. A1 - Oppo, D. W. A1 - Curry, W. B. AB - [Benthic foraminiferal Cd/ Ca from an intermediate depth, western South Atlantic core documents the history of southward penetration of North Atlantic Intermediate Water ( NAIW). Cd seawater estimates ( Cd-W) for the last glacial are consistent with the production of NAIW and its export into the South Atlantic. At similar to 14.5 ka concurrently with the onset of the Bolling- Allerod to Younger Dryas cooling, the NAIW contribution to the South Atlantic began to decrease, marking the transition from a glacial circulation pattern to a Younger Dryas circulation. High Cd-W in both the deep North Atlantic and the intermediate South Atlantic imply reduced export of deep and intermediate water during the Younger Dryas and a significant decrease in northward oceanic heat transport. A modern circulation was achieved at similar to 9 ka, concurrently with the establishment of Holocene warmth in the North Atlantic region, further supporting a close linkage between deepwater variability and North Atlantic climate. VL - 18 IS - 4 N1 - 749rtTimes Cited:30Cited References Count:39 JO - Atlantic Ocean circulation during the Younger Dryas: Insights from a new Cd/Ca record from the western subtropical South Atlantic ER -