scholarly journals Ice Budgets for Antarctica and Changes in Sea-Level

1961 ◽  
Vol 3 (29) ◽  
pp. 867-872
Author(s):  
H. Wexler
Keyword(s):  
Thermal Expansion ◽  
Atlantic Ocean ◽  
Sea Level ◽  
Ice Sheet ◽  
Tropical Atlantic ◽  
Climatic Warming ◽  
Antarctic Ice Sheet ◽  
Tropical Atlantic Ocean ◽  
The Antarctic ◽  
Good Agreement

AbstractEight different ice budgets for the Antarctic Ice Sheet are examined. Five of these budgets call for rates of increase of the ice which are in surprisingly good agreement considering the wide dispersion of individual components of the budgets. The observed rise in sea-level of the world’s oceans would appear to contradict the removal of water required to nourish the Antarctic Ice Sheet at the claimed rates. The thermal expansion of oceanic columns, caused by “climatic” warming of the oceans, has been invoked to resolve this contradiction but it appears that this is not large enough judging from the 30 yr. difference in water temperatures measured by the Meteor and the Crawford in two profiles across the tropical Atlantic Ocean.

scholarly journals Ice Budgets for Antarctica and Changes in Sea-Level

1961 ◽  
Vol 3 (29) ◽  
pp. 867-872 ◽  
Author(s):  
H. Wexler
Keyword(s):  
Thermal Expansion ◽  
Atlantic Ocean ◽  
Sea Level ◽  
Ice Sheet ◽  
Tropical Atlantic ◽  
Climatic Warming ◽  
Antarctic Ice Sheet ◽  
Tropical Atlantic Ocean ◽  
The Antarctic ◽  
Good Agreement

Abstract Eight different ice budgets for the Antarctic Ice Sheet are examined. Five of these budgets call for rates of increase of the ice which are in surprisingly good agreement considering the wide dispersion of individual components of the budgets. The observed rise in sea-level of the world’s oceans would appear to contradict the removal of water required to nourish the Antarctic Ice Sheet at the claimed rates. The thermal expansion of oceanic columns, caused by “climatic” warming of the oceans, has been invoked to resolve this contradiction but it appears that this is not large enough judging from the 30 yr. difference in water temperatures measured by the Meteor and the Crawford in two profiles across the tropical Atlantic Ocean.

Antarctic ice sheet response to upper-bound scenarios

2021 ◽  
Author(s):  
Sainan Sun ◽  
Frank Pattyn
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Upper Bound ◽  
Ice Sheet ◽  
Climate Forcing ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
Basal Sliding ◽  
The Antarctic

<p>Mass loss of the Antarctic ice sheet contributes the largest uncertainty of future sea-level rise projections. Ice-sheet model predictions are limited by uncertainties in climate forcing and poor understanding of processes such as ice viscosity. The Antarctic BUttressing Model Intercomparison Project (ABUMIP) has investigated the 'end-member' scenario, i.e., a total and sustained removal of buttressing from all Antarctic ice shelves, which can be regarded as the upper-bound physical possible, but implausible contribution of sea-level rise due to ice-shelf loss. In this study, we add successive layers of ‘realism’ to the ABUMIP scenario by considering sustained regional ice-shelf collapse and by introducing ice-shelf regrowth after collapse with the inclusion of ice-sheet and ice-shelf damage (Sun et al., 2017). Ice shelf regrowth has the ability to stabilize grounding lines, while ice shelf damage may reinforce ice loss. In combination with uncertainties from basal sliding and ice rheology, a more realistic physical upperbound to ice loss is sought. Results are compared in the light of other proposed mechanisms, such as MICI due to ice cliff collapse.</p>

scholarly journals Late Neogene Sirius Group strata in Reedy Valley, Antarctica: a multiple-resolution record of climate, ice-sheet and sea-level events

1998 ◽  
Vol 44 (148) ◽  
pp. 437-447 ◽  
Author(s):  
Gary S. Wilson ◽  
David M. Harwood ◽  
Rosemary A. Askin ◽  
Richard H. Levy
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Glacier Area ◽  
Antarctic Ice Sheet ◽  
Western Margin ◽  
Type Section ◽  
Late Neogene ◽  
Formation Type ◽  
Spur Formation ◽  
The Antarctic

AbstractLate Neogene Sirius Group strata from Tillite Spur and Quartz Hills in the Reedy Glacier area, Antarctica, demonstrate the variability in Sirius Group facies and contrasts Sirius Group strata deposited at high and low paleo-elevation, respectively. The Tillite Spur and Quartz Hills Formations (Pliocene) are formally defined here.The Tillite Spur Formation type section crops out on the edge of the Wisconsin Plateau overlooking Tillite Spur. It comprises 32m of alternating coarse gray conglomerate and muddy olive-brown diamictites. The Quartz Hills Formation type section crops out above the western margin of Reedy Glacier in a pre-existing cirque towards the southern end of the Quartz Hills. It comprises c.100m of alternating massive diamictites and rhythmically interbedded sandstone and laminated mudstones which were deposited close to sea level and subsequently rapidly uplifted (>500 m Myr−1) to their present elevation at c. 1500 m. Three orders of paleoclimatic variability are recorded in the Sirius Group strata from Reedy Valley: (1) recycled marine microfloras in glacial diamictites indicate intervals of marine incursion into the Antarctic cratonic interior co-occurring with reductions in the East Antarctic ice sheet; (2) an advancing and retreating paleo-Reedy Glacier deposited a glacial/interglacial sequence alternating on a 10-100 kyr scale; 3) Centimeter and millimeter stratification in strata of the Quartz Hills Formation record annual kyr scale variability.

scholarly journals Antarctic Ice-Sheet Volume at 18000 Years B.P. and Holocene Sea-Level Changes at the West Antarctic Margin

1979 ◽  
Vol 24 (90) ◽  
pp. 213-230 ◽  
Author(s):  
Craig S. Lingle ◽  
James A. Clark
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Sea Level Changes ◽  
Ice Shelf ◽  
Relative Sea Level ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
The Antarctic

AbstractThe Antarctic ice sheet has been reconstructed at 18000 years b.p. by Hughes and others (in press) using an ice-flow model. The volume of the portion of this reconstruction which contributed to a rise of post-glacial eustatic sea-level has been calculated and found to be (9.8±1.5) × 106 km3. This volume is equivalent to 25±4 m of eustatic sea-level rise, defined as the volume of water added to the ocean divided by ocean area. The total volume of the reconstructed Antarctic ice sheet was found to be (37±6) × 106 km3. If the results of Hughes and others are correct, Antarctica was the second largest contributor to post-glacial eustatic sea-level rise after the Laurentide ice sheet. The Farrell and Clark (1976) model for computation of the relative sea-level changes caused by changes in ice and water loading on a visco-elastic Earth has been applied to the ice-sheet reconstruction, and the results have been combined with the changes in relative sea-level caused by Northern Hemisphere deglaciation as previously calculated by Clark and others (1978). Three families of curves have been compiled, showing calculated relative sea-level change at different times near the margin of the possibly unstable West Antarctic ice sheet in the Ross Sea, Pine Island Bay, and the Weddell Sea. The curves suggest that the West Antarctic ice sheet remained grounded to the edge of the continental shelf until c. 13000 years b.p., when the rate of sea-level rise due to northern ice disintegration became sufficient to dominate emergence near the margin predicted otherwise to have been caused by shrinkage of the Antarctic ice mass. In addition, the curves suggest that falling relative sea-levels played a significant role in slowing and, perhaps, reversing retreat when grounding lines approached their present positions in the Ross and Weddell Seas. A predicted fall of relative sea-level beneath the central Ross Ice Shelf of as much as 23 m during the past 2000 years is found to be compatible with recent field evidence that the ice shelf is thickening in the south-east quadrant.

Ice-sheet surges and the geological record

1969 ◽  
Vol 6 (4) ◽  
pp. 903-910 ◽  
Author(s):  
John T. Hollin
Keyword(s):  
United States ◽  
Sea Level ◽  
Ice Sheet ◽  
The United States ◽  
Tectonic Activity ◽  
Ice Ages ◽  
Antarctic Ice Sheet ◽  
Geological Record ◽  
Glacial Time ◽  
The Antarctic

If they had occurred, ice-sheet surges would have caused sea-level rises of up to 50 m from Gondwanaland and say 20 m from Antarctica. The rises would have taken 100 years or much less, and the sub sequent falls would have taken 50 000 years or so, as the ice built up again. Such rises may explain the extensive (hundreds of miles ?) and sharp (submergence time 4 years ?) coal – marine shale contacts in the Carboniferous cyclothems. The chief rival explanation for these contacts is sudden subsidence. Tests should show (1) if such contacts are better correlated with periods of glaciation or with areas of tectonic activity, (2) how extensive the contacts really are, (3) if there is any evidence of erosion during sea-level falls, (4) if the amplitudes and periods of the cycles fit surges or subsidence, (5) how fast the submergences were, and (6) if any coolings began at the contacts. Wilson suggests that in the Pleistocene the surge coolings were sufficient to trigger the northern ice ages. If so, interglacial pollen profiles should show rapid but temporary marine transgressions beginning at the break of climate. Evidence suggesting such transgressions occurs in England and the United States, but is still insufficient to disprove explanations such as local downwarping. There is no evidence yet for surges in Wisconsin or Post-glacial time. There is some evidence that the Antarctic Ice Sheet is currently building up, but this could be a response to a Post-glacial accumulation increase rather than the prelude to a surge.

scholarly journals Increased Accumulation On The Antarctic Ice Sheet Due To Climatic Warming

1990 ◽  
Vol 14 ◽  
pp. 361-361
Author(s):  
Stephen Warren ◽  
Susan Frankenstein
Keyword(s):  
Vapor Pressure ◽  
Sea Level ◽  
Ice Sheet ◽  
Crystal Formation ◽  
Climatic Warming ◽  
Saturation Vapor Pressure ◽  
Simple Assumption ◽  
Near Surface ◽  
The Antarctic ◽  
Saturation Vapor

Climatic warming due to increased greenhouse gases is expected to cause increased precipitation in the next century because of the increased water content of the air, assuming constant relative humidity. Since temperatures over most of Antarctica are far below freezing even in the warmest month of the year, the increase in melting is probably negligible compared to the increase in precipitation.Oerlemans (1982) showed that this increase of precipitation would cause a growth of the ice sheet, tending to lower sea level. This would partially counteract the rise of sea level due to increased melting on mountain glaciers and Greenland, and to a possible (and more difficult to predict) surge of ice from West Antarctica.Oerlemans may have underestimated the increase in accumulation. He used results of General Circulation Models (GCMs) which indicated an increase of precipitation by only 12% for a temperature change ΔΤ = 3 Κ and 30% for ΔΤ = 8 K. In contrast, the change in accumulation rate at Dome C (Lorius and others, 1979) accompanying the warming from the recent ice age to the present was in accord with the simple assumption that accumulation is proportional to saturation vapor pressure at the temperature of the inversion layer, i.e. a 30% increase for ΔΤ = 3 K.The experimental results are to be preferred to the climate model results because GCMs do not represent ice-sheet accumulation processes well. Most of the accumulation is not snow falling from clouds but instead results from clear-sky ice-crystal formation in near-surface air, or hoarfrost deposition on the surface. GCMs lack sufficient vertical resolution to represent the strong temperature inversion on which these accumulation mechanisms depend.The figure shows that the increase of vapor pressure due to ΔΤ = 5 Κ varies from a factor of 1.9 at Τ = −60°C to a factor of 1.6 at Τ = −20°C. A climatic warming of 5 K. over Antarctica, which is possible during the next century, could thus increase the Antarctic accumulation from its present 17g cm−2 yr−1 to 30 g cm−2 yr−1, leading to a 50 cm drop in sea level in 100 years. This assumes that the simple proportionality of precipitation rate to saturation vapor pressure applies as well to the coastal regions, which is doubtful because the accumulation processes are not the same as on the plateau.The potential importance of Antarctic accumulation changes in contributing to changes of sea level argues for further study of the mechanisms of Antarctic precipitation and for their improved representation in climate models.

scholarly journals Increased Accumulation On The Antarctic Ice Sheet Due To Climatic Warming

1990 ◽  
Vol 14 ◽  
pp. 361
Author(s):  
Stephen Warren ◽  
Susan Frankenstein
Keyword(s):  
Vapor Pressure ◽  
Sea Level ◽  
Ice Sheet ◽  
Crystal Formation ◽  
Climatic Warming ◽  
Saturation Vapor Pressure ◽  
Simple Assumption ◽  
Near Surface ◽  
The Antarctic ◽  
Saturation Vapor

Climatic warming due to increased greenhouse gases is expected to cause increased precipitation in the next century because of the increased water content of the air, assuming constant relative humidity. Since temperatures over most of Antarctica are far below freezing even in the warmest month of the year, the increase in melting is probably negligible compared to the increase in precipitation. Oerlemans (1982) showed that this increase of precipitation would cause a growth of the ice sheet, tending to lower sea level. This would partially counteract the rise of sea level due to increased melting on mountain glaciers and Greenland, and to a possible (and more difficult to predict) surge of ice from West Antarctica. Oerlemans may have underestimated the increase in accumulation. He used results of General Circulation Models (GCMs) which indicated an increase of precipitation by only 12% for a temperature change ΔΤ = 3 Κ and 30% for ΔΤ = 8 K. In contrast, the change in accumulation rate at Dome C (Lorius and others, 1979) accompanying the warming from the recent ice age to the present was in accord with the simple assumption that accumulation is proportional to saturation vapor pressure at the temperature of the inversion layer, i.e. a 30% increase for ΔΤ = 3 K. The experimental results are to be preferred to the climate model results because GCMs do not represent ice-sheet accumulation processes well. Most of the accumulation is not snow falling from clouds but instead results from clear-sky ice-crystal formation in near-surface air, or hoarfrost deposition on the surface. GCMs lack sufficient vertical resolution to represent the strong temperature inversion on which these accumulation mechanisms depend. The figure shows that the increase of vapor pressure due to ΔΤ = 5 Κ varies from a factor of 1.9 at Τ = −60°C to a factor of 1.6 at Τ = −20°C. A climatic warming of 5 K. over Antarctica, which is possible during the next century, could thus increase the Antarctic accumulation from its present 17g cm−2 yr−1 to 30 g cm−2 yr−1, leading to a 50 cm drop in sea level in 100 years. This assumes that the simple proportionality of precipitation rate to saturation vapor pressure applies as well to the coastal regions, which is doubtful because the accumulation processes are not the same as on the plateau. The potential importance of Antarctic accumulation changes in contributing to changes of sea level argues for further study of the mechanisms of Antarctic precipitation and for their improved representation in climate models.

scholarly journals Nonlinear response of the Antarctic Ice Sheet to late Quaternary sea level and climate forcing

2019 ◽  
Vol 13 (10) ◽  
pp. 2615-2631 ◽  
Author(s):  
Michelle Tigchelaar ◽  
Axel Timmermann ◽  
Tobias Friedrich ◽  
Malte Heinemann ◽  
David Pollard
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Volume Changes ◽  
Antarctic Ice Sheet ◽  
Glacial Ice ◽  
Ice Volume ◽  
Global Sea Level ◽  
The Individual ◽  
The Antarctic

Abstract. Antarctic ice volume has varied substantially during the late Quaternary, with reconstructions suggesting a glacial ice sheet extending to the continental shelf break and interglacial sea level highstands of several meters. Throughout this period, changes in the Antarctic Ice Sheet were driven by changes in atmospheric and oceanic conditions and global sea level; yet, so far modeling studies have not addressed which of these environmental forcings dominate and how they interact in the dynamical ice sheet response. Here, we force an Antarctic Ice Sheet model with global sea level reconstructions and transient, spatially explicit boundary conditions from a 408 ka climate model simulation, not only in concert with each other but, for the first time, also separately. We find that together these forcings drive glacial–interglacial ice volume changes of 12–14 ms.l.e., in line with reconstructions and previous modeling studies. None of the individual drivers – atmospheric temperature and precipitation, ocean temperatures, or sea level – single-handedly explains the full ice sheet response. In fact, the sum of the individual ice volume changes amounts to less than half of the full ice volume response, indicating the existence of strong nonlinearities and forcing synergy. Both sea level and atmospheric forcing are necessary to create full glacial ice sheet growth, whereas the contribution of ocean melt changes is found to be more a function of ice sheet geometry than climatic change. Our results highlight the importance of accurately representing the relative timing of forcings of past ice sheet simulations and underscore the need for developing coupled climate–ice sheet modeling frameworks that properly capture key feedbacks.

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