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North Atlantic warming during global cooling at the end of the Cretaceous

¹ Department of Geological Sciences, University of Missouri, Columbia, Missouri 65211-1380, USA
² Department of Paleobiology, Smithsonian Institution, Washington, D.C. 20013-7012, USA
³ Department of Geological Sciences, University of Missouri, Columbia, Missouri 65211-1380, USA

Differences in regional responses to climate fluctuations are well documented on short time scales (e.g., El Niño–Southern Oscillation), but with the exception of latitudinal temperature gradients, regional patterns are seldom considered in discussions of ancient greenhouse climates. Contrary to the expectation of global warming or global cooling implicit in most treatments of climate evolution over millions of years, this paper shows that the North Atlantic warmed by as much as 6 °C (1.5 decrease in ¹⁸O values of planktic foraminifera) during the Maastrichtian global cooling interval. We suggest that warming was the result of the importation of heat from the South Atlantic. Decreasing North Atlantic ¹⁸O values are also associated with increasing gradients in planktic ¹³C values, suggesting increasing surface-water stratification and a correlated strengthening of the North Atlantic Polar Front. If correct, this conclusion predicts arctic cooling during the late Maastrichtian. Beyond implications for the Maastrichtian, these data demonstrate that climate does not behave as if there is a simple global thermostat, even on geologic time scales.

Key Words: Maastrichtian • foraminifera • stable isotopes • paleoclimate • Ocean Drilling Program • greenhouse climate

This article has been cited by other articles:

				B. T. Huber, K. G. MacLeod, and N. A. Tur CHRONOSTRATIGRAPHIC FRAMEWORK FOR UPPER CAMPANIAN-MAASTRICHTIAN SEDIMENTS ON THE BLAKE NOSE (SUBTROPICAL NORTH ATLANTIC) Journal of Foraminiferal Research, April 1, 2008; 38(2): 162 - 182. [Abstract] [Full Text] [PDF]