231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

Bradtmiller, Louisa I; McManus, Jerry F; Robinson, Laura F.

doi:10.1038/ncomms6817

Cited by 75 publications

(79 citation statements)

References 66 publications

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“…Furthermore, biogenic opal has been shown to act as a strong scavenger of Pa [ Chase et al ., ] potentially influencing 231 Pa/ 230 Th on local scales. However, given opal contents below 4% in core GeoB16202‐2 (Figure c), a dominant effect of opal production on 231 Pa/ 230 Th seems unlikely, consistent with basin‐wide compilations [ Bradtmiller et al ., ; Lippold et al ., ; Lippold et al ., ].…”

Section: Resultsmentioning

confidence: 99%

Synchronous and proportional deglacial changes in Atlantic meridional overturning and northeast Brazilian precipitation

et al. 2017

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Changes in heat transport associated with fluctuations in the strength of the Atlantic meridional overturning circulation (AMOC) are widely considered to affect the position of the Intertropical Convergence Zone (ITCZ), but the temporal immediacy of this teleconnection has to date not been resolved. Based on a high‐resolution marine sediment sequence over the last deglaciation, we provide evidence for a synchronous and near‐linear link between changes in the Atlantic interhemispheric sea surface temperature difference and continental precipitation over northeast Brazil. The tight coupling between AMOC strength, sea surface temperature difference, and precipitation changes over northeast Brazil unambiguously points to a rapid and proportional adjustment of the ITCZ location to past changes in the Atlantic meridional heat transport.

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Section: Resultsmentioning

confidence: 99%

Synchronous and proportional deglacial changes in Atlantic meridional overturning and northeast Brazilian precipitation

et al. 2017

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“…This circulation, known as the Atlantic Meridional Overturning Circulation (AMOC), maintains a Stages (MIS) 2 and 3 known as Dansgaard-Oeschger (D-O) cycles (Dansgaard et al, 1993). Although the prevailing paradigm holds that rapid climate shifts associated with the extreme climate swings of the last glacial period were forced by changes in the strength and northward extension of AMOC, resulting in abrupt temperature changes recorded in the Greenland ice core records (Broecker et al, 1990;Sarnthein et al, 1995;Rahmstorf, 2002;Lohmann, 2003;Stouffer et al, 2006;Kageyama et al, 2013;Zhang et al, 2014;Barker et al, 2015), the role of AMOC as the primary driver of these millennial-scale climate events remains unclear (Jackson, 2000;Seager et al, 2002;Romanova et al, 2006;Wunsch, 2006;Skinner and Elderfield, 2007;Otto-Bliesner and Brady, 2010;Thornalley et al, 2013;Lynch-Stieglitz et al, 2014;Roberts et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Millennial-scale tropical atmospheric and Atlantic Ocean circulation change from the Last Glacial Maximum and Marine Isotope Stage 3

Them

Schmidt

Lynch‐Stieglitz

2015

Earth and Planetary Science Letters

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Abrupt, millennial-scale climate oscillations, known as Dansgaard-Oeschger (D-O) cycles, characterized the climate system of the last glacial period. Although proxy evidence shows that D-O cycles resulted in large-scale changes in atmospheric circulation patterns around the planet, an understanding of how Atlantic Meridional Overturning Circulation (AMOC) varied across these events remains unclear. Here, we take advantage of the fact that both tropical atmospheric circulation changes corresponding to northsouth shifts in the Intertropical Convergence Zone (ITCZ) and large-scale changes in ocean circulation associated with AMOC variability can be reconstructed in the same sediment core from the Florida Straits to examine the relationship between atmospheric and ocean circulation changes across D-O events. To reconstruct surface water conditions, Mg/Ca-paleothermometry and stable isotope measurements were combined on the planktonic foraminifera Globigerinoides ruber (white variety) from sediment core KNR166-2 JPC26 (24 • 19.61 N, 83 • 15.14 W; 546 m depth) to reconstruct a high-resolution record of sea surface temperature and δ 18 O seawater (a proxy for upper mixed layer salinity) during Marine Isotope Stages (MIS) 2 and 3 from 20-35 ka BP. As an additional proxy for upper water column salinity change, we also generate a faunal abundance record of the salinity-sensitive planktonic foraminifera Neogloboquadrina dutertrei. Our results suggest that rapid reductions in sea surface salinity occurred at the onset of D-O interstadials, while stadials are characterized by increased surface salinities. The most likely cause of these salinity changes was variation in the strength and position of the ITCZ across D-O events. Finally, we examine the relationship between millennial-scale atmospheric circulation changes recorded in the planktonic records and ocean circulation changes inferred from the benthic δ 18 O record from our core. Our results provide some of the first evidence that AMOC strength did vary across at least one of the millennial-scale D-O cycles of MIS 3.

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“…For the most part we take results from the literature [82][83][84][85][86], to which we add previously unpublished results from the senior author's laboratory for four sites, two on the margin and two on the MAR (table 1).…”

Section: (H) 230 Th-normalized Fluxes In Surface Sedimentsmentioning

confidence: 99%

“…For cores sampled at two depths (V30-49 and V30-51K), the average value of lithogenic flux is plotted in figure 8b. Sample V25-21 is taken from a large compilation by Bradtmiller et al [86], and included here to distinguish it from other data in that compilation. Other results are unpublished data generated in the senior author's laboratory at the LDEO.…”

Section: (A) Aerosol Depositionmentioning

confidence: 99%

How well can we quantify dust deposition to the ocean?

Anderson

Cheng

Edwards

et al. 2016

Phil. Trans. R. Soc. A.

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One contribution of 20 to a discussion meeting issue 'Biological and climatic impacts of ocean trace element chemistry'. Deposition of continental mineral aerosols (dust) in the Eastern Tropical North Atlantic Ocean, between the coast of Africa and the Mid-Atlantic Ridge, was estimated using several strategies based on the measurement of aerosols, trace metals dissolved in seawater, particulate material filtered from the water column, particles collected by sediment traps and sediments. Most of the data used in this synthesis involve samples collected during US GEOTRACES expeditions in 2010 and 2011, although some results from the literature are also used. Dust deposition generated by a global model serves as a reference against which the results from each observational strategy are compared. Observation-based dust fluxes disagree with one another by as much as two orders of magnitude, although most of the methods produce results that are consistent with the reference model to within a factor of 5. The large range of estimates indicates that further work is needed to reduce uncertainties associated with each method before it can be applied routinely to map dust deposition to the ocean. Calculated dust deposition using observational strategies thought to have the smallest uncertainties is lower than the reference model by a factor of 2-5, suggesting that the model may overestimate dust deposition in our study area.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

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231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

Cited by 75 publications

References 66 publications

Synchronous and proportional deglacial changes in Atlantic meridional overturning and northeast Brazilian precipitation

Synchronous and proportional deglacial changes in Atlantic meridional overturning and northeast Brazilian precipitation

Millennial-scale tropical atmospheric and Atlantic Ocean circulation change from the Last Glacial Maximum and Marine Isotope Stage 3

How well can we quantify dust deposition to the ocean?

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