North Atlantic climate and deep-ocean flow speed changes during the last 230 years

TitleNorth Atlantic climate and deep-ocean flow speed changes during the last 230 years
Publication TypeJournal Article
Year of Publication2007
AuthorsBoessenkool, KP, Hall, IR, Elderfield, H, Yashayaev, I
JournalGeophys. Res. Lett.
ISBN Number0094-8276
Keywords1616 Global Change: Climate variability, 3022 Marine Geology and Geophysics: Marine sediments: processes and transport, 4513 Oceanography: Physical: Decadal ocean variability, 4576 Oceanography: Physical: Western boundary currents, 9325 Geographic Location: Atlantic Ocean, deep ocean circulation, drift sediments, North Atlantic Oscillation

Variations in the near-bottom flow speed of Iceland-Scotland Overflow Water (ISOW) are documented in a 230-year-long deep-sea sediment record from the eastern flank of Reykjanes Ridge in the subpolar North Atlantic at (sub)decadal time scales. For recent decades, the ISOW palaeocurrent reconstructions show similarities with observational hydrographic data. Furthermore, recent ISOW flow changes fall mostly within the range of its variability of the past 230 years. The record also reveals a hitherto unrecognized coupling of deep flow speeds in the subpolar North Atlantic with the North Atlantic Oscillation (NAO) index, with more (less) vigorous ISOW flow during negative (positive) phases of the NAO. Our results suggest that the changes in ISOW vigor are largely controlled by the transport and characteristics of Labrador Sea Water rather than variations in the overflow itself, with implications for the meridional overturning of the Atlantic Ocean and climate.