The Deglacial Evolution of North Atlantic Deep Convection

Radiocarbon data reveal changes in the timing and strength of deep ocean convection during the last glacial termination. Deepwater formation in the North Atlantic by open-ocean convection is an essential component of the overturning circulation of the Atlantic Ocean, which helps regulate global climate. We use water-column radiocarbon reconstructions to examine changes in northeast Atlantic convection since the Last Glacial Maximum. During cold intervals, we infer a reduction in open-ocean convection and an associated incursion of an extremely radiocarbon (14C)–depleted water mass, interpreted to be Antarctic Intermediate Water. Comparing the timing of deep convection changes in the northeast and northwest Atlantic, we suggest that, despite a strong control on Greenland temperature by northeast Atlantic convection, reduced open-ocean convection in both the northwest and northeast Atlantic is necessary to account for contemporaneous perturbations in atmospheric circulation.

[1]  M. Sarnthein,et al.  14C reservoir ages show deglacial changes in ocean currents and carbon cycle , 2013 .

[2]  C. Buck,et al.  IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP , 2013, Radiocarbon.

[3]  Henry Elderfield,et al.  Reconstructing North Atlantic deglacial surface hydrography and its link to the Atlantic overturning circulation , 2011 .

[4]  Camille Li,et al.  Can North Atlantic Sea Ice Anomalies Account for Dansgaard–Oeschger Climate Signals?* , 2010 .

[5]  J. Duplessy,et al.  Response of South Atlantic deep waters to deglacial warming during Terminations V and I , 2010 .

[6]  S. Lehman,et al.  The release of 14 C-depleted carbon from the deep ocean during the last deglaciation: Evidence from the Arabian Sea , 2010 .

[7]  M. Vautravers,et al.  Extreme deepening of the Atlantic overturning circulation during deglaciation , 2010 .

[8]  E. Michel,et al.  Ventilation of the Deep Southern Ocean and Deglacial CO2 Rise , 2010, Science.

[9]  Henry Elderfield,et al.  Intermediate and deep water paleoceanography of the northern North Atlantic over the past 21,000 years , 2010 .

[10]  W. Broecker,et al.  Putting the Younger Dryas Cold Event into Context (Invited) , 2009 .

[11]  W. Broecker,et al.  A Great Basin-wide dry episode during the first half of the Mystery Interval? , 2009 .

[12]  W. Broecker,et al.  Interhemispheric Atlantic seesaw response during the last deglaciation , 2009, Nature.

[13]  Saleem H Ali,et al.  Wind-Driven Upwelling in the Southern Ocean and the Deglacial Rise in Atmospheric CO2 , 2008, Science.

[14]  S. Goldstein,et al.  Abrupt changes in Antarctic Intermediate Water circulation over the past 25,000 years , 2008 .

[15]  S. Lehman,et al.  Marine Radiocarbon Evidence for the Mechanism of Deglacial Atmospheric CO2 Rise , 2007, Science.

[16]  A. Roberts,et al.  Timing of meltwater pulse 1a and climate responses to meltwater injections , 2006 .

[17]  Marie-Louise Siggaard-Andersen,et al.  A new Greenland ice core chronology for the last glacial termination , 2006 .

[18]  Michael Sarnthein,et al.  Variability of the Denmark Strait Overflow during the Last Glacial Maximum , 2006 .

[19]  Henry Elderfield,et al.  Evidence from the high‐latitude North Atlantic for variations in Antarctic Intermediate water flow during the last deglaciation , 2005 .

[20]  J. Southon,et al.  Radiocarbon Variability in the Western North Atlantic During the Last Deglaciation , 2005, Science.

[21]  N. Shackleton,et al.  Rapid transient changes in northeast Atlantic deep water ventilation age across Termination I , 2004 .

[22]  D. Hodell,et al.  Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean , 2003 .

[23]  R. L. Edwards,et al.  A High-Resolution Absolute-Dated Late Pleistocene Monsoon Record from Hulu Cave, China , 2001, Science.

[24]  B. Stephens,et al.  Erratum: ``Antarctic sea ice and the control of Pleistocene climate instability'' , 2001 .

[25]  E. Brook,et al.  Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period. , 2001, Science.

[26]  A. Soloviev,et al.  Open Ocean Convection , 2001 .

[27]  John Marshall,et al.  Open‐ocean convection: Observations, theory, and models , 1999 .

[28]  William B. Curry,et al.  Millennial-scale changes in North Atlantic circulation since the last glaciation , 1998, Nature.

[29]  W. Broecker,et al.  The influence of air‐sea exchange on the isotopic composition of oceanic carbon: Observations and modeling , 1995 .

[30]  E. Boyle,et al.  Deglacial meltwater discharge, North Atlantic Deep Circulation, and abrupt climate change , 1991 .

[31]  M. Sarnthein,et al.  Younger Dryas‐Style Cooling Events at Glacial Terminations I‐VI at ODP Site 658: Associated benthic δ13C anomalies constrain meltwater hypothesis , 1990 .

[32]  W. Broecker,et al.  Routing of meltwater from the Laurentide Ice Sheet during the Younger Dryas cold episode , 1989, Nature.

[33]  M. Bender,et al.  Tracers in the Sea , 1984 .