PALEOCLIMATE: Long-Term Links

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Science  29 Oct 2004:
Vol. 306, Issue 5697, pp. 781d
DOI: 10.1126/science.306.5697.781d

The Gulf Stream transports large amounts of heat from low to high latitudes in the North Atlantic region. The Florida Current is a branch of the Gulf Stream that flows through the Straits of Florida, transporting large volumes of warm water in a northerly direction, and plays a key role in regulating the climate of the circum-North Atlantic region. Although good observational records of its strength extend roughly 100 years into the past, little is known about its variability on time scales greater than that. Lund and Curry present oxygen isotopic analyses of planktonic forams from three marine sediment cores taken from near the Florida Keys, which show multiple sea surface temperature oscillations at centennial to millennial scales over the past 5200 years. The Florida Current was either cooler or more saline during the Little Ice Age and was relatively warm or fresh during the Medieval Warm Period. The Florida Current oxygen isotope signal varied coherently with atmospheric radiocarbon over periods of 1000 years or more, reinforcing suggestions that ocean circulation may help to modulate atmospheric radiocarbon on millennial time scales. — HJS

Paleoceanography 10.1029/2004PA001008 (2004).

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