expanded observational efforts and improved
ice sheet models.
Protecting individual cities with walls and
barriers only protects those living behind the
protection. An ice sheet–based solution might be
more equitable. Possible approaches to slow
the flow of ice and reduce the future sea level
rise are being considered. Early proposals in-
clude snowblowers depositing snow in the in-
terior of Antarctica, building protective berms
or curtains to isolate the ice from warming
ocean waters or cooling the margins of fast
flowing glaciers ( 46 – 48 ). However, serious con-
cerns about the efficacy and cost-benefit of such
solutions remain. Looking at global solutions
to the changing ice is essential for humanity’s
evolving coastlines but should be thoroughly
investigated because unintended consequences
and unknown feedbacks are likely ( 49 ).
Conclusions
Over the 200 years since Antarctica was first
spotted, our knowledge of the continent has
shifted from the notion of a stagnant piece of
ice to a constantly evolving continent interact-
ing with the ocean around, the atmosphere
above, and the solid Earth under it and affected
by human activities. Advancing our knowledge
of the basic history and fundamental processes
that control the ice sheet evolution is crucial to
future generations. This knowledge will im-
prove predictive capabilities of Antarctica’s
evolution and help better inform coastal com-
munities worldwide.REFERENCESANDNOTES- H. A. Fricker, T. Scambos, R. Bindschadler, L. Padman,Science
315 , 1544–1548 (2007). - T. T. Creytset al.,Geophys. Res. Lett. 41 , 8114–8122 (2014).
- H. D. Pritchard, R. J. Arthern, D. G. Vaughan, L. A. Edwards,
Nature 461 , 971–975 (2009). - J. Mouginot, E. Rignot, B. Scheuchl, R. Millan,Remote Sens. 9 ,
364 (2017). - IMBIE team,Nature 558 , 219–222 (2018).
- J. Wuiteet al.,Cryosphere 9 , 957–969 (2015).
- E. Rignot, J. Mouginot, M. Morlighem, H. Seroussi, B. Scheuchl,
Geophys. Res. Lett. 41 , 3502–3509 (2014). - J. Franciset al., 100 million years of Antarctic climate evolution:
Evidence from fossil plants, inAntarctica: A Keystone in a
Changing World(National Academies Press, 2008), pp. 19–28. - R. M. DeConto, D. Pollard,Nature 421 , 245–249 (2003).
- R. Livermore, C. D. Hillenbrand, M. Meredith, G. Eagles,
Geochem. Geophys. Geosyst. 8 , Q01005 (2007). - C. Escutiaet al.,Oceanography 32 , 32–46 (2019).
- T. A. Jordan, T. R. Riley, C. S. Siddoway,Nat. Rev. Earth Environ.
1 , 117–132 (2020). - K. Tintoet al.,Nat. Geosci. 12 , 441–449 (2019).
- J.-R. Petitet al.,Nature 399 , 429–436 (1999).
15. T. Naishet al.,Nature 458 , 322–328 (2009).
16. R. H. Levyet al.,Nat. Geosci. 12 , 132–137 (2019).
17. P. Fretwellet al.,Cryosphere 7 , 375–393 (2012).
18. R. B. Alley, D. D. Blankenship, C. R. Bentley, S. T. Rooney,
Nature 322 , 57–59 (1986).
19. M. Morlighemet al.,Nat. Geosci. 13 , 132–137 (2019).
20. E. Rignot, S. Jacobs, J. Mouginot, B. Scheuchl,Science 341 ,
266 – 270 (2013).
21. A. P. Kapitsa, J. K. Ridley, G. de Q. Robin, M. J. Siegert,
I. A. Zotikov,Nature 381 , 684–686 (1996).
22. R. E. Bell, M. Studinger, M. A. Fahnestock, C. A. Shuman,
Geophys. Res. Lett. 33 , L02504 (2006).
23. J. Jouzelet al.,Science 317 , 793–796 (2007).
24. K. Kawamuraet al.,Nature 448 , 912–916 (2007).
25. V. R. Barlettaet al.,Science 360 , 1335–1339 (2018).
26. E. Rignot, J. Mouginot, B. Scheuchl,Geophys. Res. Lett. 38 ,
L10504 (2011).
27. WAIS Divide Project Members,Nature 520 , 661–665 (2015).
28. M. M. Watkins, D. N. Wiese, D. N. Yuan, C. Boening, F. W. Landerer,
J. Geophys. Res. Solid Earth 120 , 2648–2671 (2015).
29. C. Boening, M. Lebsock, F. Landerer, G. Stephens,Geophys.
Res. Lett. 39 , 21 (2012).
30. J. Turneret al.,Nature 535 , 411–415 (2016).
31. H. Rott, F. Müller, T. Nagler, D. Floricioiu,Cryosphere 5 ,
125 – 134 (2011).
32. A. F. Banwell, D. R. MacAyeal, O. V. Sergienko,Geophys. Res.
Lett. 40 , 5872–5876 (2013).
33. S. S. Jacobs, A. Jenkins, C. F. Giulivi, P. Dutrieux,Nat. Geosci.
4 , 519–523 (2011).
34. L. D. Truselet al.,Nat. Geosci. 8 , 927–932 (2015).
35. J. Mouginotet al.,Proc. Natl. Acad. Sci. U.S.A. 116 , 9239– 9244
(2019).
36. H. Seroussiet al.,The Cryosphere 2020 ,1–54 (2020).
37. J. Weertman,J. Glaciol. 13 ,3–11 (1974).
38. C. Schoof,J. Geophys. Res. 112 , F03S28 (2007).
39. H. Seroussiet al.,Geophys. Res. Lett. 44 , 6191–6199 (2017).
40. P. Dutrieuxet al.,Science 343 , 174–178 (2014).
41. R. M. DeConto, D. Pollard,Nature 531 , 591–597 (2016).
42. J. A. Smithet al.,Nature 541 , 77–80 (2017).
43. J. Kingslake, J. C. Ely, I. Das, R. E. Bell,Nature 544 , 349–352 (2017).
44. R. E. Bellet al.,Nature 544 , 344–348 (2017).
45. A. A. Robel, A. F. Banwell,Geophys. Res. Lett. 46 ,
12092 – 12100 (2019).
46. M. J. Wolovick, J. C. Moore,Cryosphere 12 , 2955–2967 (2018).
47. J. Feldmann, A. Levermann, M. Mengel,Sci. Adv. 5 , eaaw4132 (2019).
48. K. Frieler, M. Mengel, A. Levermann,Earth Syst. Dynam. 7 ,
203 – 210 (2016).
49. O. Gürses, V. Kolatschek, Q. Wang, C. Rodehacke,Cryosphere
13 , 2317–2324 (2019).
50. D. N. Wiese, D.-N. Yuan, C. Boening, F. W. Landerer,
M. M. Watkins, Antarctica mass variability time series version
1 from JPL GRACE Mascon CRI Filtered, version 1 (Physical
Oceanography Distributed Active Archive Center, 2017);
https://doi.org/10.5067/TEMSC-ANTS1. - J. Mouginot, B. Scheuchl, E. Rignot, MEaSUREs annual
Antarctic ice velocity maps 2005–2017, version 1 (NASA
National Snow and Ice Data Center Distributed Active Archive
Center, 2017); https://doi.org/10.5067/9T4EPQXTJYW9. - H. Rottet al.,Cryosphere 12 , 1273–1291 (2018).
- G. L. Foster, D. L. Royer, D. J. Lunt,Nat. Commun. 8 , 14845 (2017).
- J. Hansen, M. Sato, G. Russell, P. Kharecha,Philos. Trans. A
Math. Phys. Eng. Sci. 371 , 20120294 (2013).
ACKNOWLEDGMENTS
A portion of this research was carried out at the Jet Propulsion
Laboratory, California Institute of Technology, under a contract with
the National Aeronautics and Space Administration. GRACE data
comes from ( 50 ), accessed 28 January 2020. Antarctic velocity data
comes from ( 51 ), accessed 28 January 2020. Ice front positions
for Larsen A and B comes from ( 6 , 52 ). Cryo portal Enveo snow,
glaciers, and ice sheet products and services dataset was accessed
6 February 2020. The radar data in Fig. 3 is from Gamburtsev
Mountains–International Polar Year AGAP project Line 560;
http://podds.ldeo.columbia.edu:1986/legacyData/AGAP/DataLevel_
1/RADAR/DecimatedSAR_images/L560_WholeLineEchogram.jpg;
Lake Vostok NASA Icebridge Flight 20131127, data available at
https://data.cresis.ku.edu/data/rds; and CRESIS data 20091224_
frames 24, 25, and 26. Data are available at the same web
server. B. Hönisch provided guidance on the paleoclimate data in
Fig. 1. I. Cordero and C. Dieck Locke assisted with the figure
production. K. Tinto, R. Constantino, B. Keisling, and C. Siddoway
provided important feedback on the manuscript. Funding from
Lamont Doherty Earth Observatory of Columbia University and the
Old York Foundation supported this work.Competing interests:
None declared.10.1126/science.aaz5489SCIENCEsciencemag.org 20 MARCH 2020•VOL 367 ISSUE 6484 1325
Ice Stream
Amundsen
SeaBellingshausen
Sea
KambWilkes
LandA
Antarctic ice loss 2002-2017 (m.w.e)-2.5 -2 -1.5 -1 -0.5 0 0.5 12002 2004 2006 2008 2010 2012 2014 2016 2018
Time (yrs)-2000-10000D0 1,000
KmLarsen CLarsen BLarsen AB1994
1999
2001
2005
2011
2013
2017Thwaites
GlacierPine Island
GlacierPope Gl.
Smith Gl.
Kohler Gl.
C6 V (m/yr)-500-2500250500Mass loss (Gt)Fig. 4. Evolution of the Antarctic Ice Sheet over the past two decades.(A)Spatialicemassloss(m.w.e.)
estimated from GRACE-collected data over the 2002–2017 period ( 28 ). Gray areas show the extension of the floating
ice shelves that do not contribute directly to sea level rise. (B) Ice front retreat in the Antarctic Peninsula for the
Larsen A, B, and C ice shelves between 1995 and 2017 ( 6 , 31 ). (C) Change in ice velocity between 2005 and 2017
(meters per year) for glaciers in the Amundsen Sea Sector ( 4 ). Black lines represent the ice front and grounding lines.
(D) Time series of mass loss (gigatons) and associated uncertainties estimated from GRACE-collected data ( 28 ).