Relative sea level changes in the Antarctic coastal zone

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.

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STUDY OF BEACHROCKS IN EAST ATTICA

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.11744 ◽

2017 ◽

Vol 50 (1) ◽

pp. 434 ◽

Cited By ~ 1

Author(s):

A. Karkani ◽

N. Evelpidou ◽

H. Maroukian ◽

S. Kawasaki

Keyword(s):

Sea Level ◽

Coastal Zone ◽

Sea Level Changes ◽

Relative Sea Level ◽

Carbonate Cement ◽

Quartz Grains

Sea level indicators, such as tidal notches and beachrocks, may provide valuable information for the relative sea level changes of an area. Beachrocks in particular have received various arguments concerning their use as reliable sea level indicators and their formation environment. This work focuses on the coasts of East Attica in order to trace the palaeoshorelines of the Upper Holocene through the study of beachrocks. The coastal zone was surveyed in detail by snorkelling and diving, in order to locate, map and sample beachrocks. The samples were studied under a SEM, which showed that the beachrocks are mainly composed of quartz grains, a few calcites and feldspars, while the carbonate cement is characterized with the presence of MgO at percentages between 5 and 7.8%. Based on correlations with published drillings in the study area, the studied beachrocks should not be older than 2000 years BP.

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

Journal of Glaciology ◽

10.1017/s0022143000014751 ◽

1979 ◽

Vol 24 (90) ◽

pp. 213-230 ◽

Cited By ~ 28

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) × 106km3. 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) × 106km3. 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 untilc. 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.

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Bias in Estimates of Global Mean Sea Level Change Inferred from Satellite Altimetry

Journal of Climate ◽

10.1175/jcli-d-18-0024.1 ◽

2018 ◽

Vol 31 (13) ◽

pp. 5263-5271 ◽

Cited By ~ 7

Author(s):

Megan Jeramaz Lickley ◽

Carling C. Hay ◽

Mark E. Tamisiea ◽

Jerry X. Mitrovica

Keyword(s):

Sea Level ◽

Mass Flux ◽

Satellite Altimetry ◽

Ice Sheet ◽

Sea Level Change ◽

Global Ocean ◽

Sea Level Changes ◽

Relative Sea Level ◽

Level Change ◽

The Antarctic

Estimates of regional and global average sea level change remain a focus of climate change research. One complication in obtaining coherent estimates is that geodetic datasets measure different aspects of the sea level field. Satellite altimetry constrains changes in the sea surface height (SSH; or absolute sea level), whereas tide gauge data provide a measure of changes in SSH relative to the crust (i.e., relative sea level). The latter is a direct measure of changes in ocean volume (and the combined impacts of ice sheet melt and steric effects), but the former is not since it does not account for crustal deformation. Nevertheless, the literature commonly conflates the two estimates by directly comparing them. We demonstrate that using satellite altimetry records to estimate global ocean volume changes can lead to biases that can exceed 15%. The level of bias will depend on the relative contributions to sea level changes from the Antarctic and Greenland Ice Sheets. The bias is also more sensitive to the detailed geometry of mass flux from the Antarctic Ice Sheet than the Greenland Ice Sheet due to rotational effects on sea level. Finally, in a regional sense, altimetry estimates should not be compared to relative sea level changes because radial crustal motions driven by polar ice mass flux are nonnegligible globally.

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