Premium
The climate influence on the mid‐depth Northeast Atlantic gyres viewed by cold‐water corals
Author(s) -
MonteroSerrano JeanCarlos,
Frank Norbert,
Colin Christophe,
Wienberg Claudia,
Eisele Markus
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl048733
Subject(s) - oceanography , ocean gyre , north atlantic deep water , geology , thermocline , thermohaline circulation , north atlantic oscillation , water mass , circumpolar deep water , westerlies , atlantic multidecadal oscillation , temperate climate , climatology , subtropics , fishery , biology , botany
The neodymium (Nd) isotopic composition (expressed in epsilon units, ɛNd) of reef framework‐forming cold‐water corals provides unique measures of water mass provenance and mixing within the Northeast Atlantic today and in the past. A reconstruction of near thermocline water ɛNd from cold‐water corals of the Gulf of Cádiz and Porcupine Seabight spanning over the past 300,000 years, now revealed that climate cooling during Marine Isotope Stages (MIS) 7.2 and MIS 8/9 led to a retraction of the mid‐depth Subpolar Gyre (mSPG) to the west. Conversely, Northern Hemisphere warming and increasing fresh water fluxes to the northwest (Labrador Sea) favor a stronger eastward extension of the mSPG blocking the northward flow of temperate Atlantic water as observed during the early MIS 1 and the early stage MIS 5.5. These changes are likely the result of large‐scale south‐north displacement of the westerlies similar to present‐day observations that the North Atlantic Oscillation (NAO) is linked with mid‐depth ocean circulation. Based on these observations, we hypothesize that further climate warming will also strengthen the mSPG leading to a salt and temperature decrease in the Northeast Atlantic whereas salinity and temperature will increase in the temperate Atlantic. However, the amplitude of such changes on North Atlantic overturning remains to be tested.