Impacts of marine instability across the East Antarctic Ice Sheet on Southern Ocean dynamics

Phipps, Steven J.; Fogwill, Christopher J.; Turney, Chris S. M.

doi:10.5194/tc-10-2317-2016

Cited by 16 publications

(20 citation statements)

References 35 publications

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“…Wider palaeoceanographic evidence can be used to test the concept that major AIS melt will provide freshwater to the ocean surface, which density-stratifies the near-continental Southern ocean, impeding Antarctic Bottom Water (AABW) formation 34,35 , which in turn will lead to reduced AABW ventilation/oxygenation and an increase in North Atlantic Deep Water (NADW) proportion vs. AABW proportion in the Atlantic Ocean 28,36 . Thus, we infer strong support for early-LIG AIS melt from palaeoceanographic observations.…”

Section: Resultsmentioning

confidence: 99%

Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand

et al. 2019

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The last interglacial (LIG; ~130 to ~118 thousand years ago, ka) was the last time global sea level rose well above the present level. Greenland Ice Sheet (GrIS) contributions were insufficient to explain the highstand, so that substantial Antarctic Ice Sheet (AIS) reduction is implied. However, the nature and drivers of GrIS and AIS reductions remain enigmatic, even though they may be critical for understanding future sea-level rise. Here we complement existing records with new data, and reveal that the LIG contained an AIS-derived highstand from ~129.5 to ~125 ka, a lowstand centred on 125–124 ka, and joint AIS + GrIS contributions from ~123.5 to ~118 ka. Moreover, a dual substructure within the first highstand suggests temporal variability in the AIS contributions. Implied rates of sea-level rise are high (up to several meters per century; m c−1), and lend credibility to high rates inferred by ice modelling under certain ice-shelf instability parameterisations.

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Section: Resultsmentioning

confidence: 99%

Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand

et al. 2019

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“…Hence, both the available field data and modelling efforts indicate that the mid-Miocene Antarctic ice sheets were highly sensitive to relatively small changes in atmospheric CO 2 concentrations 21 , 22 . Such sensitivity can be triggered by changes in the ocean dynamics, which are complex, include several feedbacks, and have not yet been considered in most model simulations 23 .…”

Section: Introductionmentioning

confidence: 99%

Southern Ocean warming and Wilkes Land ice sheet retreat during the mid-Miocene

et al. 2018

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Observations and model experiments highlight the importance of ocean heat in forcing ice sheet retreat during the present and geological past, but past ocean temperature data are virtually missing in ice sheet proximal locations. Here we document paleoceanographic conditions and the (in)stability of the Wilkes Land subglacial basin (East Antarctica) during the mid-Miocene (~17–13.4 million years ago) by studying sediment cores from offshore Adélie Coast. Inland retreat of the ice sheet, temperate vegetation, and warm oligotrophic waters characterise the mid-Miocene Climatic Optimum (MCO; 17–14.8 Ma). After the MCO, expansion of a marine-based ice sheet occurs, but remains sensitive to melting upon episodic warm water incursions. Our results suggest that the mid-Miocene latitudinal temperature gradient across the Southern Ocean never resembled that of the present day. We demonstrate that a strong coupling of oceanic climate and Antarctic continental conditions existed and that the East Antarctic subglacial basins were highly sensitive to ocean warming.

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“…However, the portions of the EAIS that are grounded below sea level in prominent subglacial basins have long been identified as areas where EAIS retreat might be initiated by warmth at the marine margins (e.g., Webb et al, ). Yet observations, model simulations, and reconstructions of ice extent during past warm climate intervals (Aitken et al, ; Cook et al, ; DeConto & Pollard, ; Greenbaum et al, ; Phipps et al, ; Scherer et al, ) are only now converging to demonstrate the scope of this vulnerability in the context of our current warming. The emerging picture of a system governed by threshold behavior highlights the importance of comprehensively characterizing the environmental conditions that trigger EAIS retreat.…”

Section: Introductionmentioning

confidence: 99%

Polar Frontal Migration in the Warm Late Pliocene: Diatom Evidence From the Wilkes Land Margin, East Antarctica

Taylor-Silva

Riesselman

2018

Paleoceanog and Paleoclimatol

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The late Pliocene is the most recent interval in Earth's history to sustain global temperatures within the range of warming predicted for the 21st century, providing an appealing analog for the changes we might encounter in the coming century. Published global reconstructions and climate models find an average +2° summer sea surface temperature anomaly relative to modern during the 3.3–3.0 Ma interval of the late Pliocene, when atmospheric CO2 concentrations last reached 400 ppm. Here we present a new diatom‐based reconstruction of Pliocene interglacial sea surface conditions from IODP Site U1361, on the East Antarctic continental rise. We find that open ocean conditions in the mid‐Pliocene became increasingly influenced by sea ice from 3.6–3.2 Ma, prior to the onset of Northern Hemisphere glaciation. This cooling trend was interrupted by a temporary southward migration of the Antarctic Polar Front, bathing U1361 in subantarctic waters during a single interglacial—marine isotope stage KM3 (3.17–3.15 Ma)—after which sea ice returned. Building on the identification of this single outlier interglacial, we have revisited earlier reconstructions to explore the response of the Southern Ocean/cryosphere system to peak late Pliocene warmth. By applying a modern chronostratigraphic framework to those low‐resolution reconstructions, we identify the same frontal migration in four other cores in the Pacific sector of the Southern Ocean, documenting a major migration of the polar front during a key interval of warm climate. These new results suggest that KM3 is a crucial interval to test ice sheet stability in the context of anthropogenic warming.

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Impacts of marine instability across the East Antarctic Ice Sheet on Southern Ocean dynamics

Cited by 16 publications

References 35 publications

Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand

Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand

Southern Ocean warming and Wilkes Land ice sheet retreat during the mid-Miocene

Polar Frontal Migration in the Warm Late Pliocene: Diatom Evidence From the Wilkes Land Margin, East Antarctica

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