Did the Antarctic ice sheets expand during the early Pliocene?

Geology ◽  
2001 ◽  
Vol 29 (1) ◽  
pp. 67 ◽  
Author(s):  
P.J. Bart
Keyword(s):  
Ice Sheets ◽  
Early Pliocene ◽  
The Antarctic ◽  
Antarctic Ice Sheets

scholarly journals Supplementary material to "Sensitivity of the Antarctic ice sheets to the peak warming of Marine Isotope Stage 11"

2020 ◽  
Author(s):  
Martim Mas e Braga ◽  
Jorge Bernales ◽  
Matthias Prange ◽  
Arjen P. Stroeven ◽  
Irina Rogozhina
Keyword(s):  
Ice Sheets ◽  
Marine Isotope Stage ◽  
Supplementary Material ◽  
The Antarctic ◽  
Antarctic Ice Sheets

scholarly journals The glacial geomorphology of the Antarctic ice sheet bed

2014 ◽  
Vol 26 (6) ◽  
pp. 724-741 ◽  
Author(s):  
Stewart S.R. Jamieson ◽  
Chris R. Stokes ◽  
Neil Ross ◽  
David M. Rippin ◽  
Robert G. Bingham ◽  
...  
Keyword(s):  
Large Scale ◽  
Landscape Evolution ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Glacial Erosion ◽  
Antarctic Ice Sheet ◽  
The Past ◽  
Valley Network ◽  
The Antarctic ◽  
Antarctic Ice Sheets

AbstractIn 1976, David Sugden and Brian John developed a classification for Antarctic landscapes of glacial erosion based upon exposed and eroded coastal topography, providing insight into the past glacial dynamics of the Antarctic ice sheets. We extend this classification to cover the continental interior of Antarctica by analysing the hypsometry of the subglacial landscape using a recently released dataset of bed topography (BEDMAP2). We used the existing classification as a basis for first developing a low-resolution description of landscape evolution under the ice sheet before building a more detailed classification of patterns of glacial erosion. Our key finding is that a more widespread distribution of ancient, preserved alpine landscapes may survive beneath the Antarctic ice sheets than has been previously recognized. Furthermore, the findings suggest that landscapes of selective erosion exist further inland than might be expected, and may reflect the presence of thinner, less extensive ice in the past. Much of the selective nature of erosion may be controlled by pre-glacial topography, and especially by the large-scale tectonic structure and fluvial valley network. The hypotheses of landscape evolution presented here can be tested by future surveys of the Antarctic ice sheet bed.

scholarly journals Rapid Access Ice Drill: a new tool for exploration of the deep Antarctic ice sheets and subglacial geology

2016 ◽  
Vol 62 (236) ◽  
pp. 1049-1064 ◽  
Author(s):  
JOHN W. GOODGE ◽  
JEFFREY P. SEVERINGHAUS
Keyword(s):  
Mineral Exploration ◽  
Drill Pipe ◽  
Ice Sheets ◽  
Rapid Access ◽  
Reverse Circulation ◽  
Field Season ◽  
Pressure Compensation ◽  
Single Field ◽  
The Antarctic ◽  
Antarctic Ice Sheets

ABSTRACTA new Rapid Access Ice Drill (RAID) will penetrate the Antarctic ice sheets in order to create borehole observatories and take cores in deep ice, the glacial bed and bedrock below. RAID is a mobile drilling system to make multiple long, narrow boreholes in a single field season in Antarctica. RAID is based on a mineral exploration-type rotary rock-coring system using threaded drill pipe to cut through ice using reverse circulation of a non-freezing fluid for pressure-compensation, maintenance of temperature and removal of ice cuttings. Near the bottom of the ice sheet, a wireline latching assembly will enable rapid coring of ice, the glacial bed and bedrock below. Once complete, boreholes will be kept open with fluid, capped and available for future down-hole measurement of temperature gradient, heat flow, ice chronology and ice deformation. RAID is designed to penetrate up to 3300 m of ice and take cores in <200 hours, allowing completion of a borehole and coring in ~10 d at each site. Together, the rapid drilling capability and mobility of the system, along with ice-penetrating imaging methods, will provide a unique 3-D picture of interior and subglacial features of the Antarctic ice sheets.

scholarly journals Antarctic climate and ice sheet configuration during a peak-warmth Early Pliocene interglacial

2016 ◽  
Author(s):  
Nicholas R. Golledge ◽  
Zoë A. Thomas ◽  
Richard H. Levy ◽  
Edward G. W. Gasson ◽  
Timothy R. Naish ◽  
...  
Keyword(s):  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Co2 Concentration ◽  
Geological Evidence ◽  
Early Pliocene ◽  
Air Temperatures ◽  
Climate Envelope ◽  
Global Sea Level ◽  
Antarctic Ice Sheets

Abstract. 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 a peak warmth interglacial in the early Pliocene at 4.23 Ma. Using offline-coupled climate and ice-sheet models, together with 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 approximately 8.5 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.

The surface windfield over the Antarctic ice sheets

Nature ◽  
1987 ◽  
Vol 328 (6125) ◽  
pp. 51-54 ◽  
Author(s):  
Thomas R. Parish ◽  
David H. Bromwich
Keyword(s):  
Ice Sheets ◽  
The Antarctic ◽  
Antarctic Ice Sheets

scholarly journals Atmospheric Chemistry and Climate in the Anthropocene / Chemia Atmosferyczna I Klimat W Antropocenie

2014 ◽  
Vol 19 (1-2) ◽  
pp. 9-28 ◽  
Author(s):  
Paul J. Crutzen ◽  
Stanisław Wacławek
Keyword(s):  
Sea Level ◽  
Atmospheric Chemistry ◽  
Stratospheric Ozone ◽  
Ice Sheets ◽  
Ice Caps ◽  
Mountain Glaciers ◽  
Natural Processes ◽  
Earth’S Climate ◽  
The Antarctic ◽  
Antarctic Ice Sheets

Abstract Humankind actions are exerting increasing effect on the environment on all scales, in a lot of ways overcoming natural processes. During the last 100 years human population went up from little more than one to six billion and economic activity increased nearly ten times between 1950 and the present time. In the last few decades of the twentieth century, anthropogenic chlorofluorocarbon release have led to a dramatic decrease in levels of stratospheric ozone, creating ozone hole over the Antarctic, as a result UV-B radiation from the sun increased, leading for example to enhanced risk of skin cancer. Releasing more of a greenhouse gases by mankind, such as CO2, CH4, NOx to the atmosphere increases the greenhouse effect. Even if emission increase has held back, atmospheric greenhouse gas concentrations would continue to raise and remain high for hundreds of years, thus warming Earth’s climate. Warming temperatures contribute to sea level growth by melting mountain glaciers and ice caps, because of these portions of the Greenland and Antarctic ice sheets melt or flow into the ocean. Ice loss from the Greenland and Antarctic ice sheets could contribute an additional 19-58 centimeters of sea level rise, hinge on how the ice sheets react. Taking into account these and many other major and still growing footprints of human activities on earth and atmosphere without any doubt we can conclude that we are living in new geological epoch named by P. Crutzen and E. Stoermer in 2000 - “Anthropocene”. For the benefit of our children and their future, we must do more to struggle climate changes that have had occurred gradually over the last century.

scholarly journals Sensitivity of the Antarctic ice sheets to the warming of marine isotope substage 11c

2021 ◽  
Vol 15 (1) ◽  
pp. 459-478
Author(s):  
Martim Mas e Braga ◽  
Jorge Bernales ◽  
Matthias Prange ◽  
Arjen P. Stroeven ◽  
Irina Rogozhina
Keyword(s):  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Climate Signal ◽  
West Antarctic Ice Sheet ◽  
Climate Conditions ◽  
West Antarctic ◽  
The Antarctic ◽  
Antarctic Ice Sheets

Abstract. Studying the response of the Antarctic ice sheets during periods when climate conditions were similar to the present can provide important insights into current observed changes and help identify natural drivers of ice sheet retreat. In this context, the marine isotope substage 11c (MIS11c) interglacial offers a suitable scenario, given that during its later portion orbital parameters were close to our current interglacial. Ice core data indicate that warmer-than-present temperatures lasted for longer than during other interglacials. However, the response of the Antarctic ice sheets and their contribution to sea level rise remain unclear. We explore the dynamics of the Antarctic ice sheets during this period using a numerical ice sheet model forced by MIS11c climate conditions derived from climate model outputs scaled by three glaciological and one sedimentary proxy records of ice volume. Our results indicate that the East and West Antarctic ice sheets contributed 4.0–8.2 m to the MIS11c sea level rise. In the case of a West Antarctic Ice Sheet collapse, which is the most probable scenario according to far-field sea level reconstructions, the range is reduced to 6.7–8.2 m independently of the choices of external sea level forcing and millennial-scale climate variability. Within this latter range, the main source of uncertainty arises from the sensitivity of the East Antarctic Ice Sheet to a choice of initial ice sheet configuration. We found that the warmer regional climate signal captured by Antarctic ice cores during peak MIS11c is crucial to reproduce the contribution expected from Antarctica during the recorded global sea level highstand. This climate signal translates to a modest threshold of 0.4 ∘C oceanic warming at intermediate depths, which leads to a collapse of the West Antarctic Ice Sheet if sustained for at least 4000 years.

Sensitivity of the Antarctic ice sheets to the warming of MIS11c

2021 ◽  
Author(s):  
Martim Mas e Braga ◽  
Jorge Bernales ◽  
Matthias Prange ◽  
Arjen P. Stroeven ◽  
Irina Rogozhina
Keyword(s):  
Sea Level ◽  
Climate Model ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Climate Conditions ◽  
West Antarctic ◽  
The Antarctic ◽  
Antarctic Ice Sheets

&lt;p&gt;&lt;span&gt;&lt;span&gt;The Marine Isotope Substage 11c (MIS11c) interglacial (425 &amp;#8211; 395 thousand years before present) is a useful analogue to climate conditions that can be expected in the near future, and can provide insights on the natural response of the Antarctic ice sheets to a moderate, yet long lasting warming period. However, its response to the warming of MIS11c and consequent contribution to global sea level rise still remains unclear. We explore the dynamics of the Antarctic ice sheets during this period using a numerical ice-sheet model forced by MIS11c climate conditions derived from climate model outputs scaled by three ice core and one sedimentary proxy records of ice volume. We identify a tipping point beyond which oceanic warming becomes the dominant forcing of ice-sheet retreat, and where collapse of the West Antarctic Ice Sheet is attained when a threshold of 0.4 &lt;/span&gt;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;&lt;span&gt;o&lt;/span&gt;&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;&lt;span&gt;C oceanic warming relative to Pre-Industrial levels is sustained for at least 4 thousand years. Conversely, its eastern counterpart remains relatively stable, as it is mostly grounded above sea level. Our results suggest a total sea level contribution from the East and West Antarctic ice sheets of 4.0 &amp;#8211; 8.2 m during MIS11c. In the case of a West Antarctic Ice Sheet collapse, which is the most probable scenario according to far-field sea-level reconstructions, this range is reduced to 6.7 &amp;#8211; 8.2 m, and mostly reflects uncertainties regarding the initial configuration of the East Antarctic Ice Sheet. &lt;/span&gt;&lt;/span&gt;&lt;/p&gt;

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