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PALEOCEANOGRAPHY, VOL. 20, PA4006, doi:10.1029/2005PA001145, 2005

Multiproxy evidence of Holocene climate variability from estuarine sediments, eastern North America

T. M. Cronin

U.S. Geological Survey, Reston, Virginia, USA


R. Thunell

Department of Geological Sciences, University of South Carolina, Columbia, South Carolina, USA


G. S. Dwyer

Nicholas School of the Environment, Earth and Ocean Sciences, Duke University, Durham, North Carolina, USA


C. Saenger

U.S. Geological Survey, Reston, Virginia, USA


M. E. Mann

Department of Environmental Science, University of Virginia, Charlottesville, Virginia, USA


C. Vann

U.S. Geological Survey, Reston, Virginia, USA


R. R. Seal II

U.S. Geological Survey, Reston, Virginia, USA


Abstract

We reconstructed paleoclimate patterns from oxygen and carbon isotope records from the fossil estuarine benthic foraminifera Elphidium and Mg/Ca ratios from the ostracode Loxoconcha from sediment cores from Chesapeake Bay to examine the Holocene evolution of North Atlantic Oscillation (NAO)-type climate variability. Precipitation-driven river discharge and regional temperature variability are the primary influences on Chesapeake Bay salinity and water temperature, respectively. We first calibrated modern δ18Owater to salinity and applied this relationship to calculate trends in paleosalinity from the δ18Oforam, correcting for changes in water temperature estimated from ostracode Mg/Ca ratios. The results indicate a much drier early Holocene in which mean paleosalinity was ∼28 ppt in the northern bay, falling ∼25% to ∼20 ppt during the late Holocene. Early Holocene Mg/Ca-derived temperatures varied in a relatively narrow range of 13° to 16°C with a mean temperature of 14.2°C and excursions above 16°C; the late Holocene was on average cooler (mean temperature of 12.8°C). In addition to the large contrast between early and late Holocene regional climate conditions, multidecadal (20–40 years) salinity and temperature variability is an inherent part of the region's climate during both the early and late Holocene, including the Medieval Warm Period and Little Ice Age. These patterns are similar to those observed during the twentieth century caused by NAO-related processes. Comparison of the midlatitude Chesapeake Bay salinity record with tropical climate records of Intertropical Convergence Zone fluctuations inferred from the Cariaco Basin titanium record suggests an anticorrelation between precipitation in the two regions at both millennial and centennial timescales.

Received 14 February 2005; accepted 8 July 2005; published 19 October 2005.

Keywords: Holocene; benthic foraminifera; ostracodes; stable isotopes; North Atlantic Oscillation; estuaries.

Index Terms: 0473 Biogeosciences: Paleoclimatology and paleoceanography (3344, 4900); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 4235 Oceanography: General: Estuarine processes (0442); 4513 Oceanography: Physical: Decadal ocean variability (1616, 1635, 3305, 4215); 4870 Oceanography: Biological and Chemical: Stable isotopes (0454, 1041).

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 1290184 bytes)

Citation: Cronin, T. M., R. Thunell, G. S. Dwyer, C. Saenger, M. E. Mann, C. Vann, and R. R. Seal II (2005), Multiproxy evidence of Holocene climate variability from estuarine sediments, eastern North America, Paleoceanography, 20, PA4006, doi:10.1029/2005PA001145.