Climate of Antarctica

The climate of Antarctica is cold and dry.

Antarctica is the coldest place on earth. The lowest temperature ever recorded on earth was -89.4 °C (-129 °F) recorded on Thursday, July 21, 1983 at Vostok Station. The highest temperature ever recorded in Antarctica was 14.6 C (58.3 F) in two places: Hope Bay and Vanda Station.

Weather patterns rarely penetrate far into the continent, leaving the center cold and dry. There is little precipitation over the continent, but ice there can last for a long time.

History

After splitting from Gondwana, Antarctica drifted slowly to its present position over the South Pole. Its climate was much warmer before it was finally separated from South America and the Drake Passage opened roughly 30 million years ago. The Antarctic Circumpolar Current was formed then, which blocked warm ocean currents from further north and froze the continent. It has been covered with ice since approximately the beginning of the Pliocene, about 5 million years ago.

Southern Ocean

From approximately 65°S, the Southern Ocean surrounds the continent. The Antarctic Circumpolar Current, the world's largest ocean current, moves eastward and connects the Pacific, Indian, and Atlantic oceans.

Ice cover

Nearly all of Antarctica is covered by an ice sheet that is, on average, 2.5 kilometres thick. Antarctica contains 90% of the world's ice and more than 70% of its fresh water. If all the land-ice covering Antarctica were to melt — around 30 million cubic kilometres of ice — the seas would rise by over 60 metres. This is, however, very unlikely within the next few centuries. The Antarctic is so cold that even with increases of a few degrees, temperatures would generally remain below the melting point of ice. Warmer temperatures are expected to lead to more snow, which would increase the amount of ice in Antarctica, offsetting approximately one third of the expected sea level rise from thermal expansion of the oceans [1].

For the contribution of Antarctica to present and future sea level change, see sea level rise.

Because ice flows, albeit slowly, the ice within the ice sheet is younger than the age of the sheet itself.

Ice shelves

Most of the coastline of Antarctica is ice shelves (floating ice sheet) or ice walls (grounded ice). Melting or breakup of floating shelf ice does not affect global sea levels, and happens regularly as shelves grow.

Known changes in coastline ice:

• Around the Antarctic Peninsula:
  • 1936-1989: Wordie Ice Shelf significantly reduced in size.
  • 1995: Prince Gustav Channel no longer blocked by ice. Last open from about 1900 years ago to 6500 years ago, probably due to warmth during the Holocene Climatic Optimum.
  • Parts of the Larsen Ice Shelf broke up in recent decades.
    • 1995: The Larsen A ice shelf disintegrated in January of 1995.
    • 2001: 3,250 km² of the Larsen B ice shelf disintegrated in February of 2001. It had been gradually retreating before the breakup event.

Changes before the Little Ice Age ended:

• The George VI Ice Shelf has existed for approximately 7945 years, after melting 650 years earlier. Warm ocean currents following the Holocene climatic optimum are believed to have been the cause of the melting.

See also: Ross Ice Shelf, Filchner-Ronne Ice Shelf, Larsen Ice Shelf, Abbot Ice Shelf, Dotson Ice Shelf, Getz Ice Shelf, Shackleton Ice Shelf, West Ice Shelf

Climate change

The British Antarctic Survey, which has undertaken the majority of Britain's scientific research in the area, has the following positions: [2]

• Ice makes polar climate sensitive by introducting a strong "feedback" mechanism.
• Melting of continental Antarctic ice could contribute to global sea level rise.
• Climate models predict more snowfall than ice melting during the next 50 years, but models are not good enough for them to be confident about the prediction.
• It is not possible to say whether Antarctica is warming or cooling.
• There is no evidence for a decline in overall Antarctic sea ice extent.
• The central and southern parts of the west coast of the Antarctic Peninsula have warmed by nearly 3°C. The cause is not known.
• Changes have occurred in the upper atmosphere over Antarctica.

References

• D. G. Vaughan, G. J. Marshall, W. M. Connolley, J. C. King, and R. M. Mulvaney (2001). "Devil in the detail". Science 293: 1777–1779. DOI:10.1126/Science.1065116
• M.J. Bentley, D.A. Hodgson, D.E. Sugden, S.J. Roberts, J.A. Smith, M.J. Leng, C. Bryant (2005). "Early Holocene retreat of the George VI Ice Shelf, Antarctic Peninsula". Geology 33 (3): 173–176. DOI:10.1130/G21203.1

External links

Climate

• http://www.antarctica.ac.uk/met/gjma/ – climate data from Antarctic surface stations with trends
• http://www.antarctica.ac.uk/met/READER/ – temperature data from the READER project
• http://www.antarctica.ac.uk/met/jds/weather/weather.htm – a pamphlet about the weather and climate of Antarctica
• http://www.antarctica.ac.uk/met/bas_publ.html – information concerning recent ice shelf calving
• http://www.antarctica.ac.uk/met/climate/wmc/ – (unreliable) maps of snowfall and temperature
• Temperature statistics at the Amundsen-Scott station on the South Pole
• http://www.science.org.au/nova/082/082key.htm

Climate change in Antarctica

• http://www.antarctica.ac.uk/Key_Topics/Climate_Change/Climate_Change_Position.html
• http://www.antarctica.ac.uk/Key_Topics/IceSheet_SeaLevel/ice_shelf_loss.html

Antarctic ice

• "Coastal-Change and Glaciological Maps of Antarctica." USGS Fact Sheet 050–98. Accessed on February 28, 2005.
  • "Coastal-change and glaciological map of the Eights Coast area, Antarctica; 1972–2001." U.S. Geological Survey Scientific Investigations Series Map, I-2600-E. Accessed on February 28, 2005.
  • "Coastal-change and glaciological map of the Bakutis Coast area, Antarctica; 1972–2002." U.S. Geological Survey Scientific Investigations Series Map, I-2600-F. Accessed on February 28, 2005.
  • "Coastal-change and glaciological map of the Saunders Coast area, Antarctica; 1972–1997." U.S. Geological Survey Scientific Investigations Series Map, I-2600-G. Accessed on February 28, 2005.
• "Satellite Image Atlas of Glaciers of the World — Antarctica." U.S. Geological Survey Professional Paper 1386-B. Accessed on February 28, 2005.