Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23 Ma

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doi: 10.5194/cp-13-959-2017
Author(s): Golledge, Nicholas R.; Thomas, Zoë A.; Levy, Richard H.; Gasson, Edward G. W.; Naish, Timothy R.; McKay, Robert M.; Kowalewski, Douglas E.; Fogwill, Christopher J.
Author Affiliation(s): Primary:
Victoria University of Wellington, Antarctic Research Centre, Wellington, New Zealand
Other:
University of New South Wales, Australia
GNS Science, New Zealand
University of Sheffield, United Kingdom
Worcester State University, United States
Volume Title: Climate of the Past
Source: Climate of the Past, 13(7), p.959-975. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1814-9324
Note: In English. 83 refs.; illus., incl. 3 tables
Summary: The geometry of Antarctic ice sheets during warm periods of the geological past is difficult to determine from geological evidence, but is important to know because such reconstructions enable a more complete understanding of how the ice-sheet system responds to changes in climate. Here we investigate how Antarctica evolved under orbital and greenhouse gas conditions representative of an interglacial in the early Pliocene at 4.23 Ma, when Southern Hemisphere insolation reached a maximum. Using offline-coupled climate and ice-sheet models, together with a new synthesis of high-latitude palaeoenvironmental proxy data to define a likely climate envelope, we simulate a range of ice-sheet geometries and calculate their likely contribution to sea level. In addition, we use these simulations to investigate the processes by which the West and East Antarctic ice sheets respond to environmental forcings and the timescales over which these behaviours manifest. We conclude that the Antarctic ice sheet contributed 8.6 ± 2.8 m to global sea level at this time, under an atmospheric CO2 concentration identical to present (400 ppm). Warmer-than-present ocean temperatures led to the collapse of West Antarctica over centuries, whereas higher air temperatures initiated surface melting in parts of East Antarctica that over one to two millennia led to lowering of the ice-sheet surface, flotation of grounded margins in some areas, and retreat of the ice sheet into the Wilkes Subglacial Basin. The results show that regional variations in climate, ice-sheet geometry, and topography produce long-term sea-level contributions that are non-linear with respect to the applied forcings, and which under certain conditions exhibit threshold behaviour associated with behavioural tipping points.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Air; Antarctic ice sheet; Antarctica; Atmospheric precipitation; Autocorrelation; Carbon dioxide; Cenozoic; Climate forcing; Concentration; Deglaciation; Dry Valley Drilling Project; East Antarctic ice sheet; Eccentricity; Expedition 318; Geometry; Glacial geology; Greenhouse gases; IODP Site U1361; Ice movement; Ice sheets; Insolation; Integrated Ocean Drilling Program; Interglacial environment; Leg 178; Leg 188; Lower Pliocene; Mass balance; Models; Neogene; ODP Site 1096; ODP Site 1165; Obliquity of the ecliptic; Ocean Drilling Program; Orbital forcing; Paleoclimatology; Paleoenvironment; Pliocene; Precession; Sea-level changes; Sea-surface temperature; Skewness; Southern Ocean; Statistical analysis; Subglacial environment; Subglacial processes; Temperature; Tertiary; Variance analysis; Velocity; Vestfold Hills; West Antarctic ice sheet; Wilkes Land
Coordinates: S673401 S673401 W0765749 W0765749
S642300 S642200 E0671400 E0671300
S642434 S642434 E1435312 E1435312
Record ID: 2018003546
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Copernicus Gesellschaft, Katlenburg-Lindau, Germany