Synchronous Radiocarbon and Climate Shifts
During the Last Deglaciation

Synchronous Radiocarbon and Climate Shifts
During the Last Deglaciation

Science v.290, pp 1951-1954, 8 Dec 2000.

Konrad A. Hughen
Woods Hole Oceanographic Institution
John R. Southon
Lawrence Livermore National Laboratory
Scott Lehman
University of Colorado
Jonathan Overpeck
University of Arizona

ABSTRACT:
Radiocarbon data from the Cariaco Basin provide calibration of the carbon-14 time scale across the period of deglaciation (15,000 to 10,000 years ago) with resolution available previously only from Holocene tree rings. Reconstructed changes in atmospheric carbon-14 are larger than previously thought, with the largest change occurring simultaneously with the sudden climatic cooling of the Younger Dryas event. Carbon-14 and published beryllium-10 data together suggest that concurrent climate and carbon-14 changes were predominantly the result of abrupt shifts in deep ocean ventilation.

Download the Cariaco Basin Greyscale and Radiocarbon data and data description from this study from the WDC Paleo Archive.

To read or view the full study, please visit the Science website.
It was published in Science v.290, pp 1951-1954, 8 Dec 2000.

Fig. 1 (left)
Correlation of variations in 14C compared with calendar age for Cariaco Basin core PL07-58PC and German pines. Thick gray line, German pine data set; thin black line and solid circles, Cariaco Basin data. The German pine data set has been revised recently with the addition of 40 years at 11,330 cal yr B.P.. The Cariaco and pine 14C data sets were interpolated and resampled at even 5-year increments and were correlated within a moving 1370-year window. The window was shifted in 5-year steps through time lags of ±300 years. The moving correlation yielded a single point of maximum agreement, r = 0.989 (inset), fixing the beginning of the floating Cariaco Basin varve chronology at 10,490 cal yr B.P. The gray bar shows the timing of the abrupt warming at the transition from Younger Dryas (YD) to Preboreal (PB) conditions in both chronologies. The YD transition was determined by ring widths in the German pines and by gray scale in the Cariaco Basin. 14C uncertainties are shown at 1 sigma.

Fig. 2 (right)
Radiocarbon calibration data set from Cariaco Basin core PL07-58PC compared with those from coral U/Th dates and varved lake sediments. Thin black line and solid circles, Cariaco Basin data; thin gray line, German pine data; upright open triangles, coral U/Th from Barbados; open squares, coral U/Th from Papua New Guinea; upside-down open triangles, coral U/Th from Tahiti; open diamonds, coral U/Th from Vanuatu; and open circles, varves from Lake Suigetsu, Japan. Climatic period abbreviations are as follows: Preboreal, PB; Younger Dryas, YD; Bølling/Allerød, B/A; and Glacial, GL. Gray bars indicate timing of the Glacial-Bølling transition and the beginning and end of the Younger Dryas based on Cariaco Basin gray scale. 14C and U/Th uncertainties are shown at 1 sigma.
Fig. 3 (left)
Atmospheric radiocarbon concentration (d14C) calculated from Cariaco Basin and tree ring data sets. Solid circles and thin black line, Cariaco Basin core PL07-58PC data; thick gray line, German pine data spliced to the end of the INTCAL98 data set. Dashed line is a linear model approximating geomagnetic field intensity used to detrend the raw Cariaco Basin d14C data for comparison to other cosmogenic and paleoclimatic data sets. Error bars are 1 sigma uncertainty calculated by taking into account 14C uncertainties only. The wide gray swath shows total d14C uncertainty, including the uncertainty contributed by calendar age error.

Fig. 4 (right) Observed paleoclimate and detrended d14C from the Cariaco Basin and tree rings compared with paleoclimate and cosmogenic isotopes from the GISP2 ice core. Each set of records during deglaciation was measured on the same core and is shown plotted on its own independent time scale, ice-layer chronology for GISP2, and anchored varve chronology for the Cariaco Basin. (A) Thin line (upper curve) is GISP2 ice accumulation data. Line with solid circles (lower curve) is atmospheric 10Be concentration (10Beatm) calculated from ice 10Be concentrations and snow accumulation measured in the GISP2 ice core. Gray bars indicate climate transitions based on shifts in accumulation rate. (B) Gray line, detrended atmospheric d14C data from German pines spliced together with INTCAL98 data; black line with solid circles, detrended d14C measured in Cariaco Basin core PL07-58PC (upper curves). Black line (lower curve) is Cariaco Basin gray scale. Gray bars indicate climate transitions based on shifts in gray scale and light laminae thickness. Previous work suggests that abrupt climate shifts in both regions were synchronous. The age differences for the events shown here (gray bars) are well within the combined errors of the Cariaco Basin and GISP2 chronologies. Dashed lines indicate century-scale anomalies common to both cosmogenic 10Be and 14C, seen throughout the Holocene and attributed to solar variability.


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12 Dec 2000