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Vellinga, Michael; Wood, Richard

doi:10.1023/a:1016168827653

Cited by 775 publications

(156 citation statements)

References 37 publications

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“…The use of marine records for calibration of terrestrial radiocarbon dates is complicated by the potential for climatically driven variations in marine reservoir age. It is well known that large and rapid changes in climate occurred during the deglacial period, which were likely associated with changes in the Atlantic Meridional Overturning Circulation (McManus et al, 2004;Vellinga and Wood, 2002). These climatic changes were accompanied by large variations in surface ocean 14 C (Broecker and Barker, 2007;Hughen et al, 2000), consistent with the idea that they involved major shifts in the carbon cycle, which would have had large impacts on marine reservoir ages.…”

Section: Calibration Of Atmospheric Radiocarbonsupporting

confidence: 54%

Assessing influences on speleothem dead carbon variability over the Holocene: Implications for speleothem-based radiocarbon calibration

Noronha¹,

Johnson²,

et al. 2014

Earth and Planetary Science Letters

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Recently, it has been shown that U-Th dated speleothems may provide a valuable archive of atmospheric radiocarbon ( 14 C), but the reliability of these records is dependent upon the stability of the dead carbon proportion (DCP) derived from the soil and bedrock. In order to assess climatic influences on speleothem DCP, we have investigated DCP variability over the Holocene interval where atmospheric 14 C is well known based on dendrochronologically dated tree rings by conducting 14 C measurements on a U-Th dated stalagmite (HS4) from Heshang Cave, Hubei Province, China (30 • 27 N, 110 • 25 E; 294 m) spanning 0.5-9.6 ka. We investigated climatic controls on DCP, and found that DCP in HS4 has an average value over the Holocene of 10.3 ± 1.5%, with an average age offset from atmospheric radiocarbon of 875 ± 130 years, and displays a response to both precipitation increases and decreases. HS4 DCP increases during the wetter mid-Holocene interval (∼5.5-7.1 ka), likely reflecting a shift to more closed-system dissolution in response to increased soil moisture. DCP decreases during the 8.2 ka event, a time period of dry conditions at Heshang Cave, though the lower amplitude of this shift indicates that DCP may be less sensitive to dry events. Speleothems are potentially valuable archives of atmospheric radiocarbon, especially in older portions of the 14 C calibration curve where knowledge of atmospheric 14 C is limited, however minor climatic influences on DCP could introduce uncertainties of several hundred years to calibrated ages.

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Section: Calibration Of Atmospheric Radiocarbonsupporting

confidence: 54%

Assessing influences on speleothem dead carbon variability over the Holocene: Implications for speleothem-based radiocarbon calibration

Noronha¹,

Johnson²,

et al. 2014

Earth and Planetary Science Letters

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“…The lack of sensitivity of Greenland climate is a general modeling problem seen in other studies (22,23).…”

Section: Resultsmentioning

confidence: 97%

Consistent simulations of multiple proxy responses to an abrupt climate change event

LeGrande

Schmidt

Shindell

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

183

164

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Isotope, aerosol, and methane records document an abrupt cooling event across the Northern Hemisphere at 8.2 kiloyears before present (kyr), while separate geologic lines of evidence document the catastrophic drainage of the glacial Lakes Agassiz and Ojibway into the Hudson Bay at approximately the same time. This melt water pulse may have been the catalyst for a decrease in North Atlantic Deep Water formation and subsequent cooling around the Northern Hemisphere. However, lack of direct evidence for ocean cooling has lead to speculation that this abrupt event was purely local to Greenland and called into question this proposed mechanism. We simulate the response to this melt water pulse using a coupled general circulation model that explicitly tracks water isotopes and with atmosphere-only experiments that calculate changes in atmospheric aerosol deposition (specifically 10 Be and dust) and wetland methane emissions. The simulations produce a short period of significantly diminished North Atlantic Deep Water and are able to quantitatively match paleoclimate observations, including the lack of isotopic signal in the North Atlantic. This direct comparison with multiple proxy records provides compelling evidence that changes in ocean circulation played a major role in this abrupt climate change event.

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“…If the AMOC was to collapse it would have severe impacts on the climate in this region, causing reductions in surface air temperatures of up to 10°C in the North Atlantic according to modelling studies (Manabe and Stouffer, 1988;Vellinga and Wood, 2002;Jackson et al, 2015). Past evidence of temperature changes of these magnitudes has been observed in paleo-proxy records (Dansgaard et al, 1993;Blunier and Brook, 2001;de Abreu et al, 2003), and was originally linked to the possibility of a bi-stable AMOC by Broecker et al (1990).…”

Section: Introductionmentioning

confidence: 99%

The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability

Mecking¹,

Drijfhout²,

Jackson³

et al. 2017

Tellus A: Dynamic Meteorology and Oceanography

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Evidence from paleo-proxy records suggests that the Atlantic Meridional Overturning Circulation (AMOC) can be in both an AMOC on state, the AMOC as we observe it today, and an AMOC off state, where the AMOC becomes extremely weak or even collapses. The freshwater transport due to the AMOC (M ov ) at 34°S in the Atlantic has often been used as an indicator for bi-stability, with a positive M ov suggesting a monostable AMOC and a negative M ov suggesting a bi-stable AMOC. Often studies have shown that the sign of the divergence of the M ov might be a good indicator of AMOC bi-stability. In this study we investigate how model bias affects the sign of M ov across all latitudes in the Atlantic basin, through a detailed analysis of the Coupled Model Inter-Comparison Project 5 (CMIP5) model ensemble. M ov , in the CMIP5 models is generally too positive in the southern Atlantic due to a salinity bias, while in the subtropical North Atlantic the values of M ov are influenced by a combination of velocity and salinity biases. We compare these results to observations, reanalysis products and Hadley Centre Global Environmental Model version 3 global configuration version 2, a current generation coupled model which exhibits a stable AMOC off state, and discuss the differences that can lead to the possibility of a bi-stable AMOC as opposed to a monostable AMOC.

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Untitled

Cited by 775 publications

References 37 publications

Assessing influences on speleothem dead carbon variability over the Holocene: Implications for speleothem-based radiocarbon calibration

Assessing influences on speleothem dead carbon variability over the Holocene: Implications for speleothem-based radiocarbon calibration

Consistent simulations of multiple proxy responses to an abrupt climate change event

The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability

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