Variation in Solar Insolation to the South Polar Region as a Trigger which Induces Instability in the Antarctic Ice Sheet

Nature ◽  
1966 ◽  
Vol 210 (5035) ◽  
pp. 477-478 ◽  
Author(s):  
A. T. WILSON
Polar Record ◽  
2013 ◽  
Vol 50 (1) ◽  
pp. 112-112
Author(s):  
Ann Savours

Polar bibliophiles, librarians and readers will be familiar with the three handsome facsimile volumes of the first Antarctic newspaper, published in 1907 and 1914 and edited in turn by E. Shackleton, L.C. Bernacchi and A. Cherry-Garrard during the National Antarctic Expedition, 1901–1904 and the British Antarctic Expedition 1910–1913. These expeditions were led by Captain R.F. Scott R.N. in Discovery and Terra Nova respectively. From S.Y. Discovery, beset for two winters in the ice of McMurdo Sound were made the first extensive sledge journeys into the interior of the Antarctic continent, including the great ice sheet or plateau. These were further prolonged, following Shackleton's Nimrod expedition, while the pursuit of science during both Scott expeditions led to the publication in London of two monumental sets of scientific and geographical results, plus new charts and maps.


2021 ◽  
Author(s):  
Lennert B. Stap ◽  
Roderik S. W. van de Wal ◽  
Johannes Sutter ◽  
Gregor Knorr ◽  
Gerrit Lohmann

<p>Large benthic δ<sup>18</sup>O fluctuations, which are caused by deep-ocean temperature and ice-volume changes, are shown on multiple time scales during the early to mid-Miocene (23-14 Myr ago). To understand how these signals are related to orbital changes, it is necessary to disentangle them. Here, we approach this problem by simulating how the Antarctic ice sheet (AIS) responds to typical CO<sub>2</sub> changes during this period. We use the 3D thermodynamical model PISM, forced by climate model output, to conduct both transient and steady-state experiments. Our results indicate that even if equilibrium differences are relatively large (~40 m.s.l.e.), transient AIS variability on orbital time scales (20-400 kyr) still has a much smaller amplitude due to the slow ice-volume response to climatic changes. We analyse our results further using a conceptual model, based on the notion that at any CO<sub>2</sub> level an ice sheet will grow (shrink) by a specific rate towards its smaller (larger) equilibrium size. We show that phases of concurrent ice volume increase and rising CO<sub>2</sub> levels are possible, even though the equilibrium ice volume decreases monotonically with CO<sub>2</sub>. When the AIS volume is out of equilibrium with the forcing climate, the ice sheet can still be adapting to a relatively large equilibrium size, although CO<sub>2</sub> is rising after a phase of decrease. A delayed response of Antarctic ice volume to in-sync solar insolation and CO<sub>2</sub> changes can cause discrepancies between Miocene solar insolation and benthic δ<sup>18</sup>O variability.</p>


1981 ◽  
Vol 15 (1) ◽  
pp. 1-17 ◽  
Author(s):  
D.D. Kvasov ◽  
M.Ya. Verbitsky

AbstractThe causes of Antarctic glaciation are analyzed by means of numeral experiments based on the three-dimensional thermodynamic model of a large ice sheet. Refrigeration of the climate between the Eocene and the Oligocene was due to the opening of the passage south of Australia and to the formation of the South Ring Stream. Calculations have shown that this led to the development of the East Antarctic Ice Sheet which might have existed in spite of relatively high temperatures of the surrounding ocean air. A new cooling of the climate in the Middle Miocene is connected with the fact that the South Ring Stream found its way through the Drake Passage glaciers spreading on to the Western Antarctic. Between Miocene and Pliocene, glaciation of the South Polar regions was at its maximum due to the regression of the world ocean. In Quaternary time, sea level was lowering due to the glaciation of the Northern Hemisphere, which resulted in glacier growth in the Antarctic. The anticipated warming of the climate due to the activity of man is not likely to bring about any considerable change in the size of the East Antarctic Ice Sheet.


2019 ◽  
Vol 11 (6) ◽  
pp. 653 ◽  
Author(s):  
Chunchun Gao ◽  
Yang Lu ◽  
Zizhan Zhang ◽  
Hongling Shi

Many recent mass balance estimates using the Gravity Recovery and Climate Experiment (GRACE) and satellite altimetry (including two kinds of sensors of radar and laser) show that the ice mass of the Antarctic ice sheet (AIS) is in overall decline. However, there are still large differences among previously published estimates of the total mass change, even in the same observed periods. The considerable error sources mainly arise from the forward models (e.g., glacial isostatic adjustment [GIA] and firn compaction) that may be uncertain but indispensable to simulate some processes not directly measured or obtained by these observations. To minimize the use of these forward models, we estimate the mass change of ice sheet and present-day GIA using multi-geodetic observations, including GRACE and Ice, Cloud and land Elevation Satellite (ICESat), as well as Global Positioning System (GPS), by an improved method of joint inversion estimate (JIE), which enables us to solve simultaneously for the Antarctic GIA and ice mass trends. The GIA uplift rates generated from our JIE method show a good agreement with the elastic-corrected GPS uplift rates, and the total GIA-induced mass change estimate for the AIS is 54 ± 27 Gt/yr, which is in line with many recent GPS calibrated GIA estimates. Our GIA result displays the presence of significant uplift rates in the Amundsen Sea Embayment of West Antarctica, where strong uplift has been observed by GPS. Over the period February 2003 to October 2009, the entire AIS changed in mass by −84 ± 31 Gt/yr (West Antarctica: −69 ± 24, East Antarctica: 12 ± 16 and the Antarctic Peninsula: −27 ± 8), greater than the GRACE-only estimates obtained from three Mascon solutions (CSR: −50 ± 30, JPL: −71 ± 30, and GSFC: −51 ± 33 Gt/yr) for the same period. This may imply that single GRACE data tend to underestimate ice mass loss due to the signal leakage and attenuation errors of ice discharge are often worse than that of surface mass balance over the AIS.


Nature ◽  
1959 ◽  
Vol 183 (4675) ◽  
pp. 1575-1577 ◽  
Author(s):  
T. F. GASKELL

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