Regional climate variability in the western subtropical North Atlantic during the past two millennia
Saenger, Casey P.
Came, Rosemarie E.
Oppo, Delia W.
Keigwin, Lloyd D.
Cohen, Anne L.
MetadataShow full item record
Western subtropical North Atlantic oceanic and atmospheric circulations connect tropical and subpolar climates. Variations in these circulations can generate regional climate anomalies that are not reflected in Northern Hemisphere averages. Assessing the significance of anthropogenic climate change at regional scales requires proxy records that allow recent trends to be interpreted in the context of long-term regional variability. We present reconstructions of Gulf Stream sea surface temperature (SST) and hydrographic variability during the past two millennia based on the magnesium/calcium ratio and oxygen isotopic composition of planktic foraminifera preserved in two western subtropical North Atlantic sediment cores. Reconstructed SST suggests low-frequency variability of ∼1°C during an interval that includes the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). A warm interval near 1250 A.D. is distinct from regional and hemispheric temperature, possibly reflecting regional variations in ocean-atmosphere heat flux associated with changes in atmospheric circulation (e.g., the North Atlantic Oscillation) or the Atlantic Meridional Overturning Circulation. Seawater δ 18O, which is marked by a fresher MCA and a more saline LIA, covaries with meridional migrations of the Atlantic Intertropical Convergence Zone. The northward advection of tropical salinity anomalies by mean surface currents provides a plausible mechanism linking Carolina Slope and tropical Atlantic hydrology.
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 26 (2011): PA2206, doi:10.1029/2010PA002038.
Showing items related by title, author, creator and subject.
Investigations into the seasonal deep chlorophyll maximum in the western North Atlantic, and its possible significande to regional food chain relationships Ortner, Peter B. (Woods Hole Oceanographic Institution, 1977-10)In many marine environments accumulations of chlorophyll have been reported to occur at or below depths to which 1% of ambient light penetrates. The phenomenon has been called the Deep Chlorophyll Maximum (DCM). On ...
Interannual sea level variability in the western North Atlantic : regional forcing and remote response Andres, Magdalena; Gawarkiewicz, Glen G.; Toole, John M. (John Wiley & Sons, 2013-11-20)Annually averaged sea level (1970–2012) measured by tide gauges along the North American east coast is remarkably coherent over a 1700 km swath from Nova Scotia to North Carolina. Satellite altimetry (1993–2011) shows that ...
Glacial‐interglacial circulation changes inferred from 231Pa/230Th sedimentary record in the North Atlantic region Gherardi, J.‐M.; Labeyrie, L.; Nave, S.; Francois, Roger; McManus, Jerry F.; Cortijo, E. (American Geophysical Union, 2009-05-02)Studies from the subtropical western and eastern Atlantic Ocean, using the 231Pa/230Th ratio as a kinematic proxy for deep water circulation, provided compelling evidence for a strong link between climate and the rate of ...