Meltwater pulse recorded in Last Interglacial mollusk shells from Bermuda

• Main Authors: Winkelstern, Ian Z., Rowe, Mark P., Lohmann, Kyger C., Defliese, William F., Petersen, Sierra V., Brewer, Aaron W.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley Periodicals, Inc. 2017
• Subjects: Bermuda; Last Interglacial; paleoclimate; Heinrich events; clumped isotopes; Atmospheric and Oceanic Sciences; Science; Greenland; Rocky Bay; Ice Sheet; North Atlantic
• Online Access: http://hdl.handle.net/2027.42/136369; https://doi.org/10.1002/2016PA003014

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 ~10°C colder and seawater δ18O values ~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 δ18O 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.Key PointsWe used the clumped isotope thermometer to measure temperature and seawater δ18O in Bermuda during the Last InterglacialAt one locality we found cold temperatures and negative seawater δ18O values indicative of meltwater reaching subtropical latitudesThe source of this meltwater may have been the Greenland Ice Sheet, which is sensitive to future global warming Peer Reviewed https://deepblue.lib.umich.edu/bitstream/2027.42/136369/1/palo20392-sup-0001-Supplementary.pdf ...