Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes

McManus, Jerry F; François, Roger; Gherardi, Jeanne-Marie; Keigwin, Lloyd D; Brown-Leger, S.

doi:10.1038/nature02494

Cited by 1,856 publications

(2,074 citation statements)

References 34 publications

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“…These occurred at near regular intervals at the end of longer term D/O cooling trends, followed by rapid warming, as recorded both in Greenland ice and North Atlantic sea surface temperatures (Bond et al, 1993;Hemming, 2004). The exact cause for these iceberg discharge events is not yet resolved but Atlantic water mass stratification and overturning circulation clearly changed during these events (Vidal et al, 1997;Rasmussen et al, 2003;McManus et al, 2004).…”

Section: Climate and Hydrographymentioning

confidence: 99%

Changes in North Atlantic Deep Water strength and bottom water masses during Marine Isotope Stage 3 (45–35kaBP)

Gutjahr

Hoogakker

McCave

2010

Quaternary Science Reviews

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a b s t r a c tThe strength of the North Atlantic Meridional Overturning Circulation during climatically highly variable Marine Isotope Stage (MIS) 3 has attracted much attention in recent years. Here we present highresolution Nd isotope compositions of past seawater derived from authigenic FeeMn oxyhydroxides recovered from drift sediments on the Blake Ridge in the deep western North Atlantic (ODP Leg 172, Site 1060, 3481 m water depth). The data cover the period from 45 to 35 ka BP, tracing circulation changes during major Heinrich iceberg discharge event 4 (H4, w40e39 ka BP). The Nd isotope record suggests that there was no northern-source water (NSW) mass like modern NADW at the deeper part of Blake Ridge at any time between 45 and 35 ka. This is fundamentally different from the hydrographic situation during the Holocene where NADW extends below 4500 m at this location. The 3 Nd of past deep water recorded in the Blake Ridge sediments was least radiogenic during Dansgaard/Oeschger (D/O) Interstadial (IS) 8 (3 Nd ¼ À11.3) and most radiogenic immediately preceding IS 9 (3 Nd ¼ À9.8). More radiogenic compositions were also recorded during H4 (À10.2 3 Nd À9.9). The Nd isotope variability in MIS 3 matches that of a physical bottom current strength reconstruction from the same location. Neither record follows the pattern of Northern Hemisphere D/O climatic cycles. In our record, reduced mixing with northern source waters started in stadial 12 and lasted until after H4 in stadial 9, followed by a rapid increase in NSW contribution thereafter. This major change in the Nd isotope record predates the iceberg discharge event Heinrich 4 by more than 3 ka indicating a shallowing of the water mass boundary between Glacial North Atlantic Intermediate Water and Southern Source Water beneath. This early change in bottom water properties at the deep Blake Ridge suggests that North Atlantic deep water advection may already have decreased several thousand years before the actual iceberg discharge event and associated freshening of the surface waters in the North Atlantic. The change can thus not be attributed to climatic events in the North Atlantic but may be related to changes in flux of deep water from the South.

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Section: Climate and Hydrographymentioning

confidence: 99%

Changes in North Atlantic Deep Water strength and bottom water masses during Marine Isotope Stage 3 (45–35kaBP)

Gutjahr

Hoogakker

McCave

2010

Quaternary Science Reviews

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“…This might be expected during NACE events if those events were accompanied by AMOC shutdown (e.g., McManus et al, 2004). We have made some effort to test this possibility for the detrital-rich intervals in CDH 86, but thus far no provenance indicators that we have measured (elemental chemistry, strontium isotopic ratios, and mineralogy of glacial sediments from both the Amazon Fan and this site) disprove a Nordeste source.…”

Section: Periods Of Anomalous Warmth In the Northern Tropical Atlantimentioning

confidence: 99%

The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary

Nace

Baker

Dwyer

et al. 2014

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…These abrupt events are of particular interest because they were rapidly communicated through the ocean by a slowdown, or potentially a shutdown, of the Atlantic meridional overturning circulation 7 (AMOC) and through the atmospheric circulation 8 causing climate anomalies worldwide. Climate archives document a significant tropical hydrologic response to these events.…”

mentioning

confidence: 99%

North Atlantic forcing of tropical Indian Ocean climate

Mohtadi

Prange

Oppo

et al. 2014

Nature

233

228

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The response of the tropical climate in the Indian Ocean realm to abrupt climate change events in the North Atlantic Ocean is contentious. Repositioning of the intertropical convergence zone is thought to have been responsible for changes in tropical hydroclimate during North Atlantic cold spells 1-5 , but the dearth of high-resolution records outside the monsoon realm in the Indian Ocean precludes a full understanding of this remote relationship and its underlying mechanisms. Here we show that slowdowns of the Atlantic meridional overturning circulation during Heinrich stadials and the Younger Dryas stadial affected the tropical Indian Ocean hydroclimate through changes to the Hadley circulation including a southward shift in the rising branch (the intertropical convergence zone) and an overall weakening over the southern Indian Ocean. Our results are based on new, high-resolution sea surface temperature and seawater oxygen isotope records of well dated sedimentary archives from the tropical eastern Indian Ocean for the past 45,000 years, combined with climate model simulations of Atlantic circulation slowdown under Marine Isotope Stages 2 and 3 boundary conditions. Similar conditions in the east and west of the basin rule out a zonal dipole structure as the dominant forcing of the tropical Indian Ocean hydroclimate of millennial-scale events. Results from our simulations and proxy data suggest dry conditions in the northern Indian Ocean realm and wet and warm conditions in the southern realm during North Atlantic cold spells.In the North Atlantic, the most recent glacial and deglacial periods are characterized by a series of abrupt and severe cold snaps of millennial duration associated with either iceberg instabilities and surges (Heinrich events) or freshwater input from the Arctic Ocean 6 (the Younger Dryas). These abrupt events are of particular interest because they were rapidly communicated through the ocean by a slowdown, or potentially a shutdown, of the Atlantic meridional overturning circulation 7 (AMOC) and through the atmospheric circulation 8 causing climate anomalies worldwide. Climate archives document a significant tropical hydrologic response to these events. Dry Younger Dryas and Heinrich stadials have been reported from various marine and terrestrial archives across the tropical Indian Ocean 4,9-14 .However, a few records suggest wet Younger Dryas or Heinrich stadials over northeast Australia 15 , southern Indonesia 5,16 and southeast Africa 12,17 . Although there seems to be strong evidence that the intertropical convergence zone (ITCZ) moved southwards in the tropical Atlantic 2 , a wide range of mechanisms have been offered to explain the connection between the cooling of the North Atlantic and tropical Indian Ocean hydroclimates: a weakening of the rainfall system in response to regional sea surface cooling 13,14 ; and changes in the monsoon intensity 4,10,16 associated with a southward shift in the mean 1 or winter 4,5,15 position of the ITCZ or in the position of oceanic fronts 18 .How...

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Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes

Cited by 1,856 publications

References 34 publications

Changes in North Atlantic Deep Water strength and bottom water masses during Marine Isotope Stage 3 (45–35kaBP)

Changes in North Atlantic Deep Water strength and bottom water masses during Marine Isotope Stage 3 (45–35kaBP)

The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary

North Atlantic forcing of tropical Indian Ocean climate

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