Past and future grounding-line retreat of the West Antarctic Ice Sheet

Science

Volumn 286, Issue 5438, 1999, Pages 280-283

  Conway, H ^a   Hall, B L ^b,c   Denton, G H ^b   Gades, A M ^a   Waddington, E D ^a  

^a UNIVERSITY OF WASHINGTON   (United States)

^b UNIVERSITY OF MAINE   (United States)

^c WOODS HOLE OCEANOGRAPHIC INSTITUTION   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ICE;

DEGLACIATION; HOLOCENE; ICE MOVEMENT; ICE SHEET;

ANTARCTICA; ARTICLE; ELECTRIC CONDUCTIVITY; GEOLOGY; HISTORY; MOLLUSC; PRIORITY JOURNAL;

ANTARCTICA; ROSS SEA;

MOLLUSCA;

EID: 0033536598     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.286.5438.280     Document Type: Article

References (55)

1. J. B. Anderson, S. S. Shipp, L. R. Bartek, D. E. Reid, in Contributions to Antarctic Research III. vol. 57 of Antarctic Research Series (American Geophysical Union, Washington, DC, 1992), pp. 39-62; S. S. Shipp, J. B. Anderson, E. Domack, Geol. Soc. Am. Bull., in press.
2. J. B. Anderson, S. S. Shipp, L. R. Bartek, D. E. Reid, in Contributions to Antarctic Research III. vol. 57 of Antarctic Research Series (American Geophysical Union, Washington, DC, 1992), pp. 39-62; S. S. Shipp, J. B. Anderson, E. Domack, Geol. Soc. Am. Bull., in press.
3. K. J. Licht, A. E. Jennings, J. T. Andrews, K. M. Williams, Geology 24, 223 (1996); K. J. Licht, N. W. Dunbar, J. T. Andrews, A. E. Jennings, Geol. Soc. Am. Bull. 111, 91 (1999).
4. K. J. Licht, A. E. Jennings, J. T. Andrews, K. M. Williams, Geology 24, 223 (1996); K. J. Licht, N. W. Dunbar, J. T. Andrews, A. E. Jennings, Geol. Soc. Am. Bull. 111, 91 (1999).
5. M. Stuiver, G. H. Denton, T. J. Hughes, J. L. Fastook, in The Last Great Ice Sheets, G. H. Denton and T. J. Hughes, Eds. (Wiley-Interscience, New York, 1981). pp. 319-436; G. H. Denton, J. G. Bockheim, S. C. Wilson, M. Stuiver, Quat. Res. 31, 151 (1989).
6. M. Stuiver, G. H. Denton, T. J. Hughes, J. L. Fastook, in The Last Great Ice Sheets, G. H. Denton and T. J. Hughes, Eds. (Wiley-Interscience, New York, 1981). pp. 319-436; G. H. Denton, J. G. Bockheim, S. C. Wilson, M. Stuiver, Quat. Res. 31, 151 (1989).
7. -1 [S. Shabtaie and C. R. Bentley, J. Geophys. Res. 92, 1311 (1987)]. The large uncertainty arises because mass balance is the difference between two large numbers, each with large uncertainties; the few available point measurements of accumulation and thinning show large spatial variability.
8. D. R. MacAyeal, Nature 359, 29 (1992); R. B. Alley and I. M. Whillans, Science 254, 959 (1991).
9. D. R. MacAyeal, Nature 359, 29 (1992); R. B. Alley and I. M. Whillans, Science 254, 959 (1991).
10. R. Retzlaff and C. R. Bentley, J. Glaciol. 39, 495 (1993); R. Jacobel, T. Scambos, C. Raymond, A. Gades, J. Geophys. Res. 101, 5499 (1996); C. R. Bentley, J. Glaciol. 44, 157 (1998).
11. R. Retzlaff and C. R. Bentley, J. Glaciol. 39, 495 (1993); R. Jacobel, T. Scambos, C. Raymond, A. Gades, J. Geophys. Res. 101, 5499 (1996); C. R. Bentley, J. Glaciol. 44, 157 (1998).
12. R. Retzlaff and C. R. Bentley, J. Glaciol. 39, 495 (1993); R. Jacobel, T. Scambos, C. Raymond, A. Gades, J. Geophys. Res. 101, 5499 (1996); C. R. Bentley, J. Glaciol. 44, 157 (1998).
13. B. L. Hall, G. H. Denton, C. H. Hendy, Geograf. Ann., in press.
14. B. L. Hall and G. H. Denton, ibid., in press; J. M. Clayton-Greene, C. H. Hendy, A. C. Hogg., N. Z. J. Geol. Geophys. 31, 353 (1988); M. A. Dagel, thesis, University of. Maine, Orono (1989).
15. B. L. Hall and G. H. Denton, ibid., in press; J. M. Clayton-Greene, C. H. Hendy, A. C. Hogg., N. Z. J. Geol. Geophys. 31, 353 (1988); M. A. Dagel, thesis, University of. Maine, Orono (1989).
16. B. L. Hall and G. H. Denton, ibid., in press; J. M. Clayton-Greene, C. H. Hendy, A. C. Hogg., N. Z. J. Geol. Geophys. 31, 353 (1988); M. A. Dagel, thesis, University of. Maine, Orono (1989).
17. 14C ages were converted to calendar years with algorithms of M. Stuiver et al. [Radiocarbon, 40, 1041 (1998)] and E. Bard [Geochim. Cosmochim. Acta 62, 2025 (1998)].
18. 14C ages were converted to calendar years with algorithms of M. Stuiver et al. [Radiocarbon, 40, 1041 (1998)] and E. Bard [Geochim. Cosmochim. Acta 62, 2025 (1998)].
19. 14C ages were converted to calendar years with algorithms of M. Stuiver et al. [Radiocarbon, 40, 1041 (1998)] and E. Bard [Geochim. Cosmochim. Acta 62, 2025 (1998)].
20. 14C ages were converted to calendar years with algorithms of M. Stuiver et al. [Radiocarbon, 40, 1041 (1998)] and E. Bard [Geochim. Cosmochim. Acta 62, 2025 (1998)].
21. B. L. Hall and G. H. Denton, J. Quat. Sci., in press.
22. W. R. Peltier, Rev. Geophys. 36, 603 (1998); A. M. Tushingham and W. R. Peltier, J. Geophys. Res. 96, 4497 (1991); W. R. Peltier, Quat. Res. 29, 93 (1988).
23. W. R. Peltier, Rev. Geophys. 36, 603 (1998); A. M. Tushingham and W. R. Peltier, J. Geophys. Res. 96, 4497 (1991); W. R. Peltier, Quat. Res. 29, 93 (1988).
24. W. R. Peltier, Rev. Geophys. 36, 603 (1998); A. M. Tushingham and W. R. Peltier, J. Geophys. Res. 96, 4497 (1991); W. R. Peltier, Quat. Res. 29, 93 (1988).
25. D. R. Marchant, G. H. Denton, T. M. Dochat, Geograf. Ann., in press.
26. J. G. Bockcheim, G. H. Denton, B. G. Anderson, M. Stuiver, Quat. Res. 31, 229 (1989).
27. Our conceptual model invokes northward or westward How of thick WAIS ice across Roosevelt Island during glacial times. During deglaciation, the thicker ice in the deep surrounding troughs underwent more rapid strain thinning than did the relatively shallow ice of Roosevelt Island, producing first a N-S ridge and then an isolated dome.
28. Variations of ice thickness and internal stratigraphy were measured from radio echo-sounding traverses with a center frequency of 7 MHz, which corresponds to a wavelength of ∼20 m in ice. Surface velocities and topography were measured by repeat surveys of poles with the Global Positioning System. Accumulation rate was estimated from stratigraphic profiles in three 2-m snow pits and from beta activity of three 16-m cores analyzed by J. Dibb (University of New Hampshire). Spikes in beta activity represent horizons deposited in 1955 and 1965; the depth of the horizon, together with measurements of the fim density profile, was used to calculate the average accumulation rate.
29. C. F. Raymond, J. Glaciol. 29, 357 (1983).
30. D. C. Vaughan, H. F. J. Corr, C. S. M. Doake, E. D. Waddington, Nature 398, 323 (1999).
31. flank.
32. -1.
33. -1.
34. Bedrock beneath Roosevelt Island is ∼200 m below present-day sea level (Fig. 3), and the surrounding trough is about 500 m below sea level. If ice surrounding the island was floating (requiring ice <560 m thick, or less if sea level was lower), and the ice surface across the island was flat (no dome), then ice on the island would have to be ∼260 m thick. This is unlikely because it requires thickening of ∼460 m to achieve present morphology: this conflicts with the continuity analysis (19) and with the pattern of bumps beneath the divide (Fig. 3), both of which imply thinning.
35. C. Baroni and G. Orombelli, Quat. Res. 36, 157 (1991).
36. _, Geology 22, 23 (1994).
37. R. H. Fillon, I. A. Hardy, F. J. E. Wagner, J. T. Andrews, H. W. Josenhans, Current Res. Part B Geol. Surv. Can. Pap. 81-1B, 105 (1981); E. W. Domack, A. J. T. Jull, J. B. Anderson, T. W. Linick, C. R. Williams, Quat. Res. 31, 277 (1989); P. T. Harris, P. E. O'Brien, P. Sedwick, E. M. Truswell, Pap. Proc. R. Soc. Tasmania 130, 47 (1996).
38. R. H. Fillon, I. A. Hardy, F. J. E. Wagner, J. T. Andrews, H. W. Josenhans, Current Res. Part B Geol. Surv. Can. Pap. 81-1B, 105 (1981); E. W. Domack, A. J. T. Jull, J. B. Anderson, T. W. Linick, C. R. Williams, Quat. Res. 31, 277 (1989); P. T. Harris, P. E. O'Brien, P. Sedwick, E. M. Truswell, Pap. Proc. R. Soc. Tasmania 130, 47 (1996).
39. R. H. Fillon, I. A. Hardy, F. J. E. Wagner, J. T. Andrews, H. W. Josenhans, Current Res. Part B Geol. Surv. Can. Pap. 81-1B, 105 (1981); E. W. Domack, A. J. T. Jull, J. B. Anderson, T. W. Linick, C. R. Williams, Quat. Res. 31, 277 (1989); P. T. Harris, P. E. O'Brien, P. Sedwick, E. M. Truswell, Pap. Proc. R. Soc. Tasmania 130, 47 (1996).
40. J. T. Andrews et al., Quat. Res. 52, 206 (1999); K. J. Licht, W. L. Cunningham, J. T. Andrews, E. U. Domack, A. E. Jennings, Polar Res. 17, 203 (1998).
41. J. T. Andrews et al., Quat. Res. 52, 206 (1999); K. J. Licht, W. L. Cunningham, J. T. Andrews, E. U. Domack, A. E. Jennings, Polar Res. 17, 203 (1998).
42. D. L. Morse, E. D. Waddington, E. J. Steig, Geophys. Res. Lett. 25, 3383 (1998).
43. Changes in global sea level have been inferred from elevations and ages of drowned reefs in the Caribbean-Atlantic region and Tahiti [R. G. Fairbanks, Nature 342, 637 (1989); E. Bard et al., ibid. 382, 241 (1996); P. Blanchon and J. Shaw, Geology 23, 4 (1995)].
44. Changes in global sea level have been inferred from elevations and ages of drowned reefs in the Caribbean-Atlantic region and Tahiti [R. G. Fairbanks, Nature 342, 637 (1989); E. Bard et al., ibid. 382, 241 (1996); P. Blanchon and J. Shaw, Geology 23, 4 (1995)].
45. Changes in global sea level have been inferred from elevations and ages of drowned reefs in the Caribbean-Atlantic region and Tahiti [R. G. Fairbanks, Nature 342, 637 (1989); E. Bard et al., ibid. 382, 241 (1996); P. Blanchon and J. Shaw, Geology 23, 4 (1995)].
46. -1 over the past 7500 years.
47. J. Weertman, J. Glaciol. 13, 3 (1974).
48. R. H. Thomas, S. N. Stephenson, R. A. Bindschadler, S. Shabtale, C. R. Bentley, Ann. Glaciol. 11, 8 (1988).
49. Comparison of declassified satellite photography taken with more recent images shows that the ridge between Ice Streams B and C has eroded 14 km and that Ice Stream B has widened 4 km in the 29 years between measurements [R. A. Sindschadler and P. Vomberger, Science 279, 689 (1998)].
50. 10Be beneath parts of the WAIS that are now grounded [R. P. Scherer et al., Science 281, 82 (1998)]. B. L. Hall and G. H. Denton [Antarct. J. U.S. 31, 78 (1996)] suggested that the grounding line receded from McMurdo Sound to its present position in Holocene time and that retreat might continue back into the interior reservoir of the WAIS. R. Bindschadler [Science 282, 428 (1998)] calculated the time of complete deglaciation by assuming that the grounding line will continue to retreat to the divide at the average rate.
51. 10Be beneath parts of the WAIS that are now grounded [R. P. Scherer et al., Science 281, 82 (1998)]. B. L. Hall and G. H. Denton [Antarct. J. U.S. 31, 78 (1996)] suggested that the grounding line receded from McMurdo Sound to its present position in Holocene time and that retreat might continue back into the interior reservoir of the WAIS. R. Bindschadler [Science 282, 428 (1998)] calculated the time of complete deglaciation by assuming that the grounding line will continue to retreat to the divide at the average rate.
52. 10Be beneath parts of the WAIS that are now grounded [R. P. Scherer et al., Science 281, 82 (1998)]. B. L. Hall and G. H. Denton [Antarct. J. U.S. 31, 78 (1996)] suggested that the grounding line receded from McMurdo Sound to its present position in Holocene time and that retreat might continue back into the interior reservoir of the WAIS. R. Bindschadler [Science 282, 428 (1998)] calculated the time of complete deglaciation by assuming that the grounding line will continue to retreat to the divide at the average rate.
53. 10Be beneath parts of the WAIS that are now grounded [R. P. Scherer et al., Science 281, 82 (1998)]. B. L. Hall and G. H. Denton [Antarct. J. U.S. 31, 78 (1996)] suggested that the grounding line receded from McMurdo Sound to its present position in Holocene time and that retreat might continue back into the interior reservoir of the WAIS. R. Bindschadler [Science 282, 428 (1998)] calculated the time of complete deglaciation by assuming that the grounding line will continue to retreat to the divide at the average rate.
54. T. B. Kellogg, D. E. Kellogg, M. Stuiver, in Contributions to Antarctic Research I, vol. 50 of Antarctic Research Series, D. H. Elliot Ed. (American Geophysical Union. Washington, DC, 1990), pp. 25-56.
55. 14C data. A.M.G. and H.C. collected and interpreted the geophysical data from Roosevelt Island E.D.W. conceived and implemented the internal layer evolution model B.L.H. and H.C. wrote the report.