Global Warming Effects Around the World

Larsen B Ice Shelf, Antarctica

Top Impact

Temperature (Air)

Other Impacts

Freshwater (Land ice)

Oceans (Sea level)

Comparative photos show dramatic collapse of Antarctica's Larsen B Ice Shelf in 2002

These photos show the Larsen B ice shelf before (left image taken January 31) and after (right image taken March 17) it collapsed into the Weddell Sea in 2002. The lost ice—comparable in size to the U.S. state of Rhode Island—drew worldwide attention to dramatic warming of the Antarctic Peninsula over the past 50 years.1

Key Facts

The Larsen B ice shelf on the Antarctic Peninsula—southeast of Argentina and Chile—disintegrated into the ocean in 2002.5 The stunning magnitude of the collapse reflected the fact that the Antarctic Peninsula has warmed dramatically since the 1950s, at rates several times the global average.2,3,4

  • Average annual temperatures on the Antarctic Peninsula have risen 0.9° F (0.5° C) per decade over the past 50 years.2,3,7
  • As the Antarctic Peninsula has warmed, its ice shelves have become ever more unstable, and seven have collapsed in the past 20 years.6 The adjacent land ice sheets start flowing faster toward the sea because the ice shelves are no longer holding the ice in check—and loss of land ice causes sea level rise.
  • Even if only the most vulnerable parts of the West Antarctic ice sheet shrink owing to climate change, scientists project that could yield a global sea level rise of nearly 11 feet (3.3 meters).21

Details

The Antarctic Peninsula has warmed considerably over the past five to six decades, at rates that far exceed the global average.2,3,4 The Larsen B ice shelf drew the world's attention to the effects of global warming when it disintegrated into the ocean in 2002, sending a cascade of icebergs into the Weddell Sea. The area lost was comparable in size to the U.S. state of Rhode Island.5

Ice shelves are thick, floating sheets of ice attached to the coast that are not formed by freezing ocean water—unlike sea ice.6 Instead, ice shelves, which are found along 45 percent of the Antarctic coast, are fed by glaciers, ice sheets, or local snowfall.5,6 The Larsen B ice shelf was around 720 feet (220 meters) thick when it collapsed.5

The Antarctic Peninsula is mountainous, with elevations generally exceeding 6,500 feet (2,000 meters).2 Unlike other parts of Antarctica, it has a summer melting season. Isolated snow-free areas on the peninsula in summertime provide breeding ground for marine mammals and birds, as well as habitat for primitive plants, microbes, and invertebrates.2

Over the past 50 years, average annual temperatures on the Antarctic Peninsula have risen at a rate of 0.9° F (0.5° C) per decade.2,3,7 Warming has occurred at a faster pace during winter and autumn months on the west coast of the peninsula, raising the number of days with an average temperature above freezing each year by 74 percent.2,3 Expanded melting has dramatically changed the environment and ecology of the Antarctic Peninsula.2

The warming of the Antarctic Peninsula has led to the progressive instability of its ice shelves. In fact, rising temperatures in the region have contributed to the collapse of seven ice shelves in just the two decades before 2009.6

Scientists think that several mechanisms play a role in destabilizing ice shelves. These include surface warming, which creates melt ponds that fracture the ice along existing crevasses;8 melting of the ice shelf from below, caused by warming ocean waters;9 and stresses that arise from the movement of ice, such as those that produce crevasses within the ice shelf.10,6

Some 5,400 square miles (14,000 square kilometers) of ice have broken off from 10 floating Antarctic ice shelves.2,11 These ice shelves have not been as small as they are now for at least 1,000 years,12,13 and probably not for 10,000 years.14 This suggests that recent warming in the region is unique in the past 10,000 years.2,15

While the collapse of an ice shelf floating on the ocean, such as Larsen B, does not in itself raise sea level, it removes a barrier between "tidewater" glaciers and the ocean. The land ice trapped in glaciers then start to flow more rapidly toward the ocean, which contributes to sea-level rise.6,16,17,18

Melting of the Antarctic ice sheets very likely contributed to the significant acceleration of sea-level rise from 1993 to 2003.18,19,20

The Global Context

The melting of the Antarctic ice shelves is both affected by climate change and contributes to it. The melting also has implications for sea life, fishing industries, and coastal communities around the world. Continued warming of the Antarctic Peninsula is also likely to have a substantial impact on the region's unique terrestrial and marine ecosystems.2

The largest unknown for scientists projecting sea-level rise over the next century is the extent of melting of the great ice sheets of Antarctica and Greenland.6 The amount of water locked up in the West Antarctic and East Antarctic ice sheets has the potential to raise global sea levels 173 feet (52.8 meters.)6 If only the most vulnerable parts of the West Antarctic ice sheet collapse, scientists project that global sea level is likely to rise by nearly 11 feet (3.3 meters)—with consequences for coastlines worldwide, including along the Pacific and Atlantic seaboards of the United States.21

If climate change continues unabated, summer warming in the Antarctic Peninsula is expected to expose rock and permafrost—which are then likely to provide habitat for alien flora and fauna.2 Invasion by non-native species has already occurred on many sub-Antarctic islands, with negative effects on resident species.22

The shrinking sea ice cover has probably contributed to the diminished abundance of krill in the Southern Ocean west of the Antarctic Peninsula, which is expected to affect predators such as albatrosses, seals, whales, and penguins.2,23

Credits

Endnotes

  1. Images courtesy of the National Snow and Ice Data Center. Available online at http://nsidc.org/ news/ press/ larsen_B/ 2002_animation.html. Accessed 10 Aug 2010. For more recent images from 2005, please visit http://earthobservatory.nasa.gov/ IOTD/ view.php?id=43466.
  2. Anisimov, O.A., D.G. Vaughan, T.V. Callaghan, C. Furgal, H. Marchant, T.D. Prowse, H. Vilhjálmsson, and J.E. Walsh. 2007. Polar regions (Arctic and Antarctic). In: Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson. Cambridge University Press, pp. 653-685.
  3. Vaughan, D.G., G.J. Marshall, W.M. Connolley, C.L. Parkinson, R. Mulvaney, D.A. Hodgson, J.C. King, C.J. Pudsey, and J. Turner. 2003. Recent rapid regional climate warming on the Antarctic Peninsula. Climatic Change 60:243-274.
  4. Trenberth, K.E., P.D. Jones, P.G. Ambenje, R. Bojariu, D.R. Easterling, A.M.G. Klein Tank, D.E. Parker, J.A. Renwick, and co-authors. 2007. Observations: Surface and atmospheric climate change. In: Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H. L. Miller. Cambridge University Press, pp. 235-336.
  5. Larsen B ice shelf collapses in Antarctica. 2002. Boulder, CO: National Snow and Ice Data Center. Online at http://nsidc.org/ news/ press/ larsen_B/ 2002.html. Accessed May 6, 2010.
  6. Allison, I., N. L. Bindoff, R.A. Bindschadler, P.M. Cox, N. de Noblet, M.H. England, J.E. Francis, N. Gruber, A.M. Haywood, D.J. Karoly, G. Kaser, C. Le Quéré, T.M. Lenton, M.E. Mann, B.I. McNeil, A.J. Pitman, S. Rahmstorf, E. Rignot, H.J. Schellnhuber, S.H. Schneider, S.C. Sherwood, R.C.J. Somerville, K. Steffen, E.J. Steig, M. Visbeck, and A.J. Weaver. 2009. The Copenhagen diagnosis: Updating the world on the latest climate science. Sydney: Climate Change Research Centre, University of New South Wales.
  7. Turner, J., S.R. Colwell, G.J. Marshall, T.A. Lachlan-Cope, A.M. Carleton, P.D. Jones, V. Lagun, P.A. Reid, and S. Iagovkina. 2005. Antarctic climate change during the last 50 years. International Journal of Climatology 25:279-294.
  8. van den Broeke, M. 2005. Strong surface melting preceded collapse of Antarctic Peninsula ice shelf. Geophysical Research Letters 32:L12815.
  9. Rignot, E., Bamber, J., Van Den Broeke, M., Davis, C., Li, Y., Van De Berg, W., Van Meijgaard, E. 2008b. Recent Antarctic ice mass loss from radar interferometry and regional climate modelling. Nature Geoscience 1:106-110.
  10. Braun, M., and A. Humbert. 2009. Recent retreat of Wilkins Ice Shelf reveals new insights in ice shelf breakup mechanisms. IEEE Geoscience and Remote Sensing Letters 6:263-267.
  11. King, J.C. 2003. Antarctic Peninsula climate variability and its causes as revealed by analysis of instrumental records. In: Antarctic peninsula climate variability: Historical and paleoenvironmental perspectives. Antarctic research series 79. Washington, DC: American Geophysical Union, pp. 17-30.
  12. Pudsey, C.J., and J. Evans. 2001. First survey of Antarctic sub-ice shelf sediments reveals mid-Holocene ice shelf retreat. Geology 29:787-790.
  13. Domack, E., A. Leventer, S. Root, J. Ring, E. Williams, D. Carlson, E. Hirshorn, W. Wright, R. Gilbert, and G. Burr. 2003. Marine sedimentary record of natural environmental variability. In: Antarctic peninsula climate variability: Historical and paleoenvironmental perspectives. Edited by E. Domack, A. Leventer, A. Burnett, R. Bindschadler, P. Convey, and M. Kirby. Antarctic research series 79. Washington, DC: American Geophysical Union, pp. 61-68.
  14. Domack, E.,D. Duran, A. Leventer, S. Ishman, S. Doane, S. McCallum, D. Amblas, J. Ring, R. Gilbert, and M. Prentice. 2005. Stability of the Larsen B ice shelf on the Antarctic Peninsula during the Holocene epoch. Nature 436:681-685.
  15. Turner, J., J.E. Overland, and J.E. Walsh. 2007. An Arctic and Antarctic perspective on recent climate change. International Journal of Climatology 27:277-293.
  16. Rignot, E., Casassa, G., Gogineni, P., Krabill, W., Rivera, A. Thomas, R. 2004. Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf. Geophysical Research Letters 31:L18401.
  17. Scambos, T.A., Bohlander, J.A., Shuman, C.A., Skvarca, P. 2004. Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica. Geophysical Research Letters 31:L18402.
  18. Pritchard, H.D., and D.G. Vaughan. 2007. Widespread acceleration of tidewater glaciers on the Antarctic Peninsula. Journal of Geophysical Research 112:F03S29.
  19. Lemke, P., J. Ren, R.B. Alley, I. Allison, J. Carrasco, G. Flato, Y. Fujii, G. Kaser, P. Mote, R.H. Thomas, and T. Zhang. 2007. Observations: Changes in snow, ice and frozen ground. In: Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H. L. Miller. Cambridge University Press, pp. 337-383.
  20. Douglas, B.C. 1997. Global sea rise: A redetermination. Surveys in Geophysics 18: 279-292. doi:10.1023/A:1006544227856.
  21. Bamber, J. L., R.E.M Riva, B.L.A Vermeersen, and A.M. LeBrocq. 2009. Reassessment of the potential sea-level rise from a collapse of the West Antarctic ice sheet. Science 324:901. doi: 10.1126/science.1169335.
  22. Frenot, Y., S.L. Chown, J. Whinam, P.M. Selkirk, P. Convey, M. Skotnicki, and D.M. Bergstrom. 2005. Biological invasions in the Antarctic: Extent, impacts and implications. Biological Reviews 80:45-72.
  23. Atkinson, A., V. Siegel, E. Pakhomov, and P. Rothery. 2004. Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 432:100-103.
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