Meltwater pulse recorded in Last Interglacial mollusk shells from Bermuda

Type Article
Date 2017-02
Language English
Author(s) Winkelstern Ian Z.1, Rowe Mark P.2, Lohmann Kyger C.1, Defliese William F.3, Petersen Sierra V.1, Brewer Aaron W.4
Affiliation(s) 1 : Univ Michigan, Dept Earth & Environm Sci, Ann Arbor, MI 48109 USA.
2 : Birkbeck Univ London, Dept Earth & Planetary Sci, London, England.
3 : Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA.
4 : Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA.
Source Paleoceanography (0883-8305) (Amer Geophysical Union), 2017-02 , Vol. 32 , N. 2 , P. 132-145
DOI 10.1002/2016PA003014
WOS© Times Cited 9
Abstract

The warm climate of Bermuda today is modulated by the nearby presence of the Gulf Stream current. However, iceberg scours in the Florida Strait and the presence of ice-rafted debris in Bermuda Rise sediments indicate that, during the last deglaciation, icebergs discharged from the Laurentide Ice Sheet traveled as far south as subtropical latitudes. We present evidence that an event of similar magnitude affected the subtropics during the Last Interglacial, potentially due to melting of the Greenland Ice Sheet. Using the clumped isotope paleothermometer, we found temperatures similar to 10 degrees C colder and seawater delta O-18 values similar to 2% lower than modern in Last Interglacial Cittarium pica shells from Grape Bay, Bermuda. In contrast, Last Interglacial shells from Rocky Bay, Bermuda, record temperatures only slightly colder and seawater delta O-18 values similar to modern, likely representing more typical Last Interglacial conditions in Bermuda outside of a meltwater event. The significantly colder ocean temperatures observed in Grape Bay samples illustrate the extreme sensitivity of Bermudian climate to broad-scale ocean circulation changes. They indicate routine meltwater transport in the North Atlantic to near-equatorial latitudes, which would likely have resulted in disruption of the Atlantic Meridional Overturning Circulation. These data demonstrate that future melting of the Greenland Ice Sheet, a potential source of the Last Interglacial meltwater event, could have dramatic climate effects outside of the high latitudes.

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