Dansgaard‐Oeschger oscillations predicted in a comprehensive model of glacial climate: A “kicked” salt oscillator in the Atlantic

Peltier, W. R.; Vettoretti, G.

doi:10.1002/2014gl061413

Cited by 176 publications

(235 citation statements)

References 44 publications

Supporting

Mentioning

192

Contrasting

Order By: Relevance

“…For example, some have linked it to a change in ocean circulation induced by the delivery of Antarctic ice melt to the Southern Ocean (Menviel et al, 2010(Menviel et al, , 2011, or possibly as a bipolar response to AMOC recovery and Northern Hemisphere warming during the Bølling Warming (Menviel et al, 2011;Stocker, 1998). Using a Coupled Model Intercomparison Project Phase 5 (CMIP5) level coupled atmosphere-ocean model, Peltier and Vettoretti (2014) and Vettoretti and Peltier (2015) have recently shown that ice-core inferred Southern Hemisphere cooling and Northern Hemisphere warming could have been caused by a non-linear salt oscillator mechanism. Others have argued that a change in Southern Hemisphere winds and ocean circulation is the explanation; for example, a simultaneous northward migration of the southern Subtropical Front and northward expansion of cold water originating in the Southern Ocean (Putnam et al, 2010).…”

Section: Climate Evolution Over the Last Deglaciationmentioning

confidence: 99%

Transient climate simulations of the deglaciation 21–9 thousand years before present (version 1) – PMIP4 Core experiment design and boundary conditions

et al. 2016

Self Cite

View full text Add to dashboard Cite

Abstract. The last deglaciation, which marked the transition between the last glacial and present interglacial periods, was punctuated by a series of rapid (centennial and decadal) climate changes. Numerical climate models are useful for investigating mechanisms that underpin the climate change events, especially now that some of the complex models can be run for multiple millennia. We have set up a Paleoclimate Modelling Intercomparison Project (PMIP) working group to coordinate efforts to run transient simulations of the last deglaciation, and to facilitate the dissemination of expertise between modellers and those engaged with reconstructing the climate of the last 21 000 years. Here, we present the design of a coordinated Core experiment over the period 21–9 thousand years before present (ka) with time-varying orbital forcing, greenhouse gases, ice sheets and other geographical changes. A choice of two ice sheet reconstructions is given, and we make recommendations for prescribing ice meltwater (or not) in the Core experiment. Additional focussed simulations will also be coordinated on an ad hoc basis by the working group, for example to investigate more thoroughly the effect of ice meltwater on climate system evolution, and to examine the uncertainty in other forcings. Some of these focussed simulations will target shorter durations around specific events in order to understand them in more detail and allow for the more computationally expensive models to take part.

show abstract

Section: Climate Evolution Over the Last Deglaciationmentioning

confidence: 99%

Transient climate simulations of the deglaciation 21–9 thousand years before present (version 1) – PMIP4 Core experiment design and boundary conditions

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…This feature, although shorter than non-Heinrich-DO events during Marine Isotope Stage (MIS) 3 (for example, DO events 5-7) (ref. 1), provides a potential approach to explain their occurrence 39 , but requires further investigation in the future.…”

Section: Amoc Response To Co 2 Change In the Presence Of Hosingmentioning

confidence: 99%

Abrupt North Atlantic circulation changes in response to gradual CO2 forcing in a glacial climate state

et al. 2017

View full text Add to dashboard Cite

Glacial climate is marked by abrupt, millennial-scale climate changes known as Dansgaard-Oeschger cycles. The most pronounced stadial coolings, Heinrich events, are associated with massive iceberg discharges to the North Atlantic. These events have been linked to variations in the strength of the Atlantic meridional overturning circulation. However, the factors that lead to abrupt transitions between strong and weak circulation regimes remain unclear. Here we show that, in a fully coupled atmosphere-ocean model, gradual changes in atmospheric CO 2 concentrations can trigger abrupt climate changes, associated with a regime of bi-stability of the Atlantic meridional overturning circulation under intermediate glacial conditions. We find that changes in atmospheric CO 2 concentrations alter the transport of atmospheric moisture across Central America, which modulates the freshwater budget of the North Atlantic and hence deep-water formation. In our simulations, a change in atmospheric CO 2 levels of about 15 ppmv-comparable to variations during Dansgaard-Oeschger cycles containing Heinrich events-is su cient to cause transitions between a weak stadial and a strong interstadial circulation mode. Because changes in the Atlantic meridional overturning circulation are thought to alter atmospheric CO 2 levels, we infer that atmospheric CO 2 levels may serve as a negative feedback to transitions between strong and weak circulation modes.A brupt climate changes associated with Dansgaard-Oeschger (DO) events as recorded in Greenland ice cores are characterized by rapid warming from stadial to interstadial conditions. This is followed by a phase of gradual cooling before an abrupt return to cold stadial conditions 1,2 . A common explanation for these transitions involves changes in the Atlantic meridional overturning circulation (AMOC) 3 , perhaps controlled by freshwater perturbation (for example, refs 4,5) and/or Northern Hemisphere ice sheet changes (for example, refs 6-8). To reproduce the abrupt transitions into and out of cold conditions across the North Atlantic (that is, AMOC weak or 'off' mode 3 ), a common trigger mechanism is related to the timing of North Atlantic freshwater perturbations 9,10 that is mainly motivated by unequivocal ice-rafting events during Heinrich Stadials (HS) 11 . However, recent studies suggest that the Heinrich ice-surging events are in fact triggered by sea subsurface warming associated with an AMOC slow-down 12,13 . Furthermore, the duration of ice-rafting events does not systematically coincide with the beginning and end of the pronounced cold conditions during Heinrich Stadials 14,15 . This evidence thus challenges the current understanding of glacial AMOC stability 5,8 , suggesting the existence of additional control factors that should be invoked to explain abrupt millennial-scale variability in climate records. In contrast to the north, the rapid climate transitions are characterized by interhemispheric anti-phased variability, with more gradual changes in southern high latitudes 16...

show abstract

“…The motivation behind the choice of these two diapycnal mixing profiles in the context of palaeoclimate simulations, instead of the more complex and spatially varying profile that is part of CCSM4, has been previously articulated by Peltier and Vettoretti (2014) (henceforth,PV14). Essentially, the spatially varying component of the CCSM4 mixing field includes a significant contribution from the turbulent mixing that is generated by the flow of the barotropic tide over rough bottom topography and tuned in the CCSM4 model for the modern-day tidal regime (determined in part by the modern-day bathymetry and coastlines).…”

Section: Design Of the Numerical Experimentsmentioning

confidence: 99%

“…No adjustment was made to the global salinity for the +25 m mid-Pliocene sea level because any applicable adjustment would be negligible. In comparison, for the case of the Last Glacial Maximum, at which time the globally averaged sea level was lower than present by approximately 120 m, coupled climate simulations increase the ocean salinity by 1 PSU compared to modern to account for the reduced volume of the oceans (see Vettoretti and Peltier, 2013;Peltier and Vettoretti, 2014).…”

Section: Bathymetry and The Ocean Modelmentioning

confidence: 99%

Regional and global climate for the mid-Pliocene using the University of Toronto version of CCSM4 and PlioMIP2 boundary conditions

Chandan

Peltier

2017

Clim. Past

Self Cite

View full text Add to dashboard Cite

Abstract. The Pliocene Model Intercomparison ProjectPhase 2 (PlioMIP2) is an international collaboration to simulate the climate of the mid-Pliocene interglacial, corresponding to marine isotope stage KM5c (3.205 Mya), using a wide selection of climate models with the objective of understanding the nature of the warming that is known to have occurred during the broader mid-Pliocene warm period. PlioMIP2 builds on the successes of PlioMIP by shifting the focus to a specific interglacial and using a revised set of geographic and orbital boundary conditions. In this paper, we present the details of the mid-Pliocene simulations that we have performed with a slightly modified version of the Community Climate System Model version 4 (CCSM4) and the "enhanced" variant of the PlioMIP2 boundary conditions. We discuss the simulated climatology through comparisons to our control simulations and to proxy reconstructions of the mid-Pliocene climate. With the new boundary conditions, the University of Toronto version of the CCSM4 model simulates a midPliocene that is more than twice as warm as that with the boundary conditions used for PlioMIP Phase 1. The warming is more enhanced near the high latitudes, which is where most of the changes to the PlioMIP2 boundary conditions have been made. The elevated warming in the high latitudes leads to a better match between the simulated climatology and proxy-based reconstructions than possible with the previous version of the boundary conditions.

show abstract

Dansgaard‐Oeschger oscillations predicted in a comprehensive model of glacial climate: A “kicked” salt oscillator in the Atlantic

Cited by 176 publications

References 44 publications

Transient climate simulations of the deglaciation 21–9 thousand years before present (version 1) – PMIP4 Core experiment design and boundary conditions

Transient climate simulations of the deglaciation 21–9 thousand years before present (version 1) – PMIP4 Core experiment design and boundary conditions

Abrupt North Atlantic circulation changes in response to gradual CO2 forcing in a glacial climate state

Regional and global climate for the mid-Pliocene using the University of Toronto version of CCSM4 and PlioMIP2 boundary conditions

Contact Info

Product

Resources

About