Neoglacial Antarctic sea-ice expansion driven by mid-Holocene retreat of the Ross Ice Shelf

Author(s): Bendle, James A.; Newton, Kate; Mckay, Robert M.; Crosta, Xavier; Etourneau, Johan; Anya, Albot B.; Seki, Osamu; Golledge, Nicholas R.; Bertler, Nancy A. N.; Willmott, Veronica; Schouten, Stefan; Riesselman, Christina R.; Masse, Guillaume; Dunbar, Robert B.
Author Affiliation(s): Primary:
University of Birmingham, Birmingham, United Kingdom
Other:
Victoria University of Wellington, New Zealand
Université de Bordeaux, Environnements et Paléoenvironnements Océaniques et Continentaux, France
Hokkaido University, Japan
GNS Science-Institute of Geological and Nuclear Sciences, New Zealand
Alfred Wegener Institut für Polar, Germany
Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Netherlands
Utrecht University, Department of Earth Sciences, Netherlands
University of Otago, New Zealand
Université Laval, Canada
Stanford University, School of Earth Sciences, United States
Volume Title: AGU 2017 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2017; American Geophysical Union 2017 fall meeting, New Orleans, LA, Dec. 11-15, 2017. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Recent decades have seen expanding Antarctic sea-ice coverage, coeval with thinning West Antarctic Ice Sheet (WAIS) ice shelves and the rapid freshening of surface and bottom waters along the Antarctic margin. The mid-Holocene Neoglacial transition represents the last comparable baseline shift in sea-ice behaviour. The drivers and feedbacks involved in both the recent and Holocene events are poorly understood and characterized by large proxy-model mismatches. We present new records of compound specific fatty acid isotope analyses (δ2H-FA), highly-branched isoprenoid alkenes (HBIs) TEX86L temperatures, grain-size, mass accumulations rates (MARs) and image analyses from a 171m Holocene sediment sequence from Site U1357 (IODP leg 318). In combination with published records we reconstruct Holocene changes in glacial meltwater, sedimentary inputs and sea-ice. The early Holocene (11 to 10 ka) is characterized by large fluctuations in inputs of deglacial meltwater and sediments and seismic evidence of downlapping material from the south, suggesting a dominating influence from glacial retreat of the local outlet glaciers. From 10 to 8 ka there is decreasing meltwater inputs, an onlapping drift and advection of material from the east. After ca. 8 ka positively correlated δ2H-FA and MARs infer that pulses of glacial melt correlate to stronger easterly currents, driving erosion of material from upstream banks and that the Ross Ice Shelf (RIS) becomes a major influence. A large mid-Holocene meltwater pulse (preceded by warming TEX86L temperatures) is evident between ca. 6 to 4.5 ka, culminating in a rapid and permanent increase in sea-ice from 4.5 ka. This is coeval with cosmogenic nuclide evidence for a rapid thinning of the Antarctic ice sheet during the mid-Holocene (Hein et al., 2016). We suggest this represents a final major pulse of deglaciation from the Ross Ice Shelf, which initiates the Neoglacial, driving cool surface waters along the coast and greater sea-ice production in the Adélie and more widely. Our work provides a mechanism for rapid expansion of Antarctic sea ice with a background of a warming climate and highlights how better representation of meltwater inputs and sea ice dynamics will be fundamental to improving projections for future climate change in the Antarctic. Hein, et al,. Nat. Comms, 12511, 2016.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Antarctica; Cenozoic; Deglaciation; Expedition 318; Glacial geology; Glaciation; Holocene; IODP Site U1357; Ice; Ice shelves; Integrated Ocean Drilling Program; Middle Holocene; Neoglacial; Quaternary; Ross Ice Shelf; Ross Sea; Sea ice; Southern Ocean
Coordinates: S662448 S662448 E1402531 E1402531
Record ID: 2019025669
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