Evolution of the northeast Labrador Sea during the last interglaciation

Type Article
Date 2012-11
Language English
Author(s) Winsor Kelsey1, Carlson Anders E.1, 2, Klinkhammer Gary P.3, Stoner Joseph S.3, Hatfield Robert G.3
Affiliation(s) 1 : Univ Wisconsin Madison, Dept Geosci, Madison, WI 53706 USA.
2 : Univ Wisconsin Madison, Ctr Climat Res, Madison, WI 53706 USA.
3 : Oregon State Univ, Coll Earth Ocean & Atmospher Sci, Corvallis, OR 97331 USA.
Source Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2012-11 , Vol. 13 , N. 11 , P. Q11006
DOI 10.1029/2012GC004263
WOS© Times Cited 28
Keyword(s) Neogloboquadrina pachyderma (sinistral), Labrador Sea, Mg/Ca, deglaciations, interglaciations, subpolar gyre
Abstract Boreal summer insolation during the last interglaciation (LIG) generally warmed the subpolar to polar Northern Hemisphere more than during the early Holocene, yet regional climate variations between the two periods remain. We investigate northeast Labrador Sea subsurface temperature and hydrography across terminations (T) I and II and during the LIG to assess the impact of two different magnitudes of boreal summer insolation increase on the northeast Labrador Sea. We use Mg/Ca ratios in Neogloboquadrina pachyderma (sinistral) as a proxy of calcification temperature to document changes in subsurface temperatures over Eirik Drift. Our corresponding record of delta O-18 of seawater documents changes in water mass salinity. Mg/Ca calcification temperatures peak early in the Holocene coincident with peak boreal summer insolation. In contrast, LIG temperatures are relatively constant through the interglaciation, and are no warmer than peak Holocene temperatures. During the first half of the LIG, delta O-18 of seawater remains depleted, likely from southern Greenland Ice Sheet retreat and enhanced Arctic freshwater and sea-ice export to the Labrador Sea. The consequent stratification of the Labrador Sea and attendant suppressed convection explains delayed deep-ocean ventilation and a cooler subsurface in the northeast Labrador Sea during the LIG.
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