Timing of meltwater pulse 1a and climate responses to meltwater injections

TitleTiming of meltwater pulse 1a and climate responses to meltwater injections
Publication TypeJournal Article
Year of Publication2006
AuthorsStanford, JD, Rohling, EJ, Hunter, SE, Roberts, AP, Rasmussen, SO, Bard, E, McManus, J, Fairbanks, RG
ISBN Number0883-8305
Keywords1135 Geochronology: Correlative geochronology, 1512 Geomagnetism and Paleomagnetism: Environmental magnetism, 1605 Global Change: Abrupt/rapid climate change, 1616 Global Change: Climate variability, 1641 Global Change: Sea level change, deglaciation, North Atlantic, overturning

The temporal relationship between meltwater pulse 1a (mwp-1a) and the climate history of the last deglaciation remains a subject of debate. By combining the Greenland Ice Core Project δ 18O ice core record on the new Greenland ice core chronology 2005 timescale with the U/Th-dated Barbados coral record, we conclusively derive that mwp-1a did not coincide with the sharp Bølling warming but instead with the abrupt cooling of the Older Dryas. To evaluate whether there is a relationship between meltwater injections, North Atlantic Deep Water (NADW) formation, and climate change, we present a high-resolution record of NADW flow intensity from Eirik Drift through the last deglaciation. It indicates only a relatively minor 200-year weakening of NADW flow, coincident with mwp-1a. Our compilation of records also indicates that during Heinrich event 1 and the Younger Dryas there were no discernible sea level rises, and yet these periods were characterized by intense NADW slowdowns/shutdowns. Clearly, deepwater formation and climate are not simply controlled by the magnitude or rate of meltwater addition. Instead, our results emphasize that the location of meltwater pulses may be more important, with NADW formation being particularly sensitive to surface freshening in the Arctic/Nordic Seas.