The spatial extent and dynamics of the Antarctic Cold Reversal

Pedro, J. B.; Bostock, Helen C.; Bitz, Cecilia M.; He, Feng; Vandergoes, Marcus J.; Steig, Eric J.; Chase, Brian M.; Krause, Claire E.; Rasmussen, S. O.; Markle, B. R.; Cortese, Giuseppe

doi:10.1038/ngeo2580

Cited by 156 publications

(153 citation statements)

References 29 publications

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“…There is a small improvement in the RMSE over East Antarctica (RMSE 1 = 1.5 • C) when freshwater forcing is included compared to without (RMSE 1 = 1.7 • C), although the model is still too cold by up to 2 • C, similar to Holden et al (2010). Recent work has suggested that the Southern Hemisphere cooling arising from changes in the northward heat transport in the Atlantic, such as we have here, can be communicated to Antarctica by feedbacks associated with sea ice expansion; in particular, the expanded sea ice reduces the winter warming effect of the Southern Ocean (Pedro et al, 2016).…”

Section: Resultsmentioning

confidence: 77%

Impact of meltwater on high-latitude early Last Interglacial climate

et al. 2016

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Abstract. Recent data compilations of the early Last Interglacial period have indicated a bipolar temperature response at 130 ka, with colder-than-present temperatures in the North Atlantic and warmer-than-present temperatures in the Southern Ocean and over Antarctica. However, climate model simulations of this period have been unable to reproduce this response, when only orbital and greenhouse gas forcings are considered in a climate model framework. Using a full-complexity general circulation model we perform climate model simulations representative of 130 ka conditions which include a magnitude of freshwater forcing derived from data at this time. We show that this meltwater from the remnant Northern Hemisphere ice sheets during the glacialinterglacial transition produces a modelled climate response similar to the observed colder-than-present temperatures in the North Atlantic at 130 ka and also results in warmer-thanpresent temperatures in the Southern Ocean via the bipolar seesaw mechanism. Further simulations in which the West Antarctic Ice Sheet is also removed lead to warming in East Antarctica and the Southern Ocean but do not appreciably improve the model-data comparison. This integrated modeldata approach provides evidence that Northern Hemisphere freshwater forcing is an important player in the evolution of early Last Interglacial climate.

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Section: Resultsmentioning

confidence: 77%

Impact of meltwater on high-latitude early Last Interglacial climate

et al. 2016

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“…Schmittner et al, 2003;Vettoretti and Peltier, 2015]. Earth-system model studies in which the AMOC strength is abruptly altered generally show strong temperature anomalies in the South Atlantic; the temperature response in the SO and Antarctica is less consistent between models, with a damped temperature response in some [Schmittner et al, 2003;Menviel et al, 2015;Vettoretti and Peltier, 2015;Pedro et al, 2016] and little or no response in others [e.g. see review by Kageyama et al, 2013].…”

Section: Discussionmentioning

confidence: 99%

Southern Ocean deep convection as a driver of Antarctic warming events

Pedro

Martin

Steig

et al. 2016

Geophysical Research Letters

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Simulations with a free‐running coupled climate model show that heat release associated with Southern Ocean deep convection variability can drive centennial‐scale Antarctic temperature variations of up to 2.0°C. The mechanism involves three steps: Preconditioning: heat accumulates at depth in the Southern Ocean; Convection onset: wind and/or sea ice changes tip the buoyantly unstable system into the convective state; and Antarctic warming: fast sea ice‐albedo feedbacks (on annual‐decadal time scales) and slow Southern Ocean frontal and sea surface temperature adjustments to convective heat release (on multidecadal‐century time scales) drive an increase in atmospheric heat and moisture transport toward Antarctica. We discuss the potential of this mechanism to help drive and amplify climate variability as observed in Antarctic ice core records.

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“…However, it is an uninterrupted trend with only one exception, a brief attenuation in warming, the slight cooling around~14 ka, which could reflect the Atlantic Cold Reversal (ACR; e.g., [117]). It is possible that the episodes of boreal cooling associated with AMOC shutdowns, through the ITCZ southward deflection and/or the SASM reinforcement, have allowed the conservation of the Central Andes highest glaciers after the LGM-RSL.…”

Section: Paleoclimatic Frameworkmentioning

confidence: 99%

Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes

et al. 2018

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This work investigates the timing, paleoclimatic framework and inter-hemispheric teleconnections inferred from the glaciers last maximum extension and the deglaciation onset in the Arid Tropical Andes. A study area was selected to the northeastward of the Nevado Coropuna, the volcano currently covered by the largest tropical glacier on Earth. The current glacier extent, the moraines deposited in the past and paleoglaciers at their maximum extension have been mapped. The present and past Equilibrium Line Altitudes (ELA and paleoELA) have been reconstructed and the chlorine-36 ages have been calculated, for preliminary absolute dating of glacial and volcanic processes. The paleoELA depression, the thermometers installed in the study area and the accumulation data previously published allowed development of paleotemperature and paleoprecipitation models. The Coropuna glaciers were in maximum extension (or glacial standstill) 20-12 ka ago (and maybe earlier). This last maximum extension was contemporary to the Heinrich 2-1 and Younger Dryas events and the Tauca and Coipasa paleolake transgressions on Bolivian Altiplano. The maximum paleoELA depression (991 m) shows a colder (−6.4 • C) and moister climate with precipitation ×1.2-×2.8 higher than the present. The deglaciation onset in the Arid Tropical Andes was 15-11 ka ago, earlier in the most southern, arid, and low mountains and later in the northernmost, less arid, and higher mountains.

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The spatial extent and dynamics of the Antarctic Cold Reversal

Cited by 156 publications

References 29 publications

Impact of meltwater on high-latitude early Last Interglacial climate

Impact of meltwater on high-latitude early Last Interglacial climate

Southern Ocean deep convection as a driver of Antarctic warming events

Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes

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