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.
Climate History of Antarctica
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 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. 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.
| Morphometric data for Antarctica (from Drewry, 1983)
|
| Surface
| Area
(km²)
| Percent
| Mean ice thickness
(m)
| Volume
(km³)
| Percent
|
| Inland ice sheet
| 11,965,700
| 85.97
| 2,450
| 29,324,700
| 97.39
|
| Ice shelves
| 1,541,710
| 11.08
| 475
| 731,900
| 2.43
|
| Ice rises
| 78,970
| .57
| 670
| 53,100
| .18
|
| Glacier ice (total)
| 13,586,380
|
| 2,160
| 30,109,800¹
|
| Rock outcrop
| 331,690
| 2.38
|
| Antarctica (total)
| 13,918,070
| 100.00
| 2,160
| 30,109,800¹
| 100.00
|
| ¹The total ice volume is different from the sum of the component parts because individual
figures have been rounded.
|
| Regional ice data (from Drewry and others, 1982; Drewry, 1983)
|
| Region
| Area
(km²)
| Mean ice
thickness
(m)
| Volume
(km³)
|
| East Antarctica
|
| Inland ice
| 9,855,570
| 2,630
| 25,920,100
|
| Ice shelves
| 293,510
| 400
| 117,400
|
| Ice rises
| 4,090
| 400
| 1,600
|
| West Antarctica (excluding Antarctic Peninsula)
|
| Inland ice sheet
| 1,809,760
| 1,780
| 3,221,400
|
| Ice shelves
| 104,860
| 375
| 39,300
|
| Ice rises
| 3,550
| 375
| 1,300
|
| Antarctic Peninsula
|
| Inland ice sheet
| 300,380
| 610
| 183,200
|
| Ice shelves
| 144,750
| 300
| 43,400
|
| Ice rises
| 1,570
| 300
| 500
|
| Ross Ice Shelf
|
| Ice shelf
| 525,840
| 427
| 224,500
|
| Ice rises
| 10,320
| 500
| 5,100
|
| Filchner-Ronne Ice Shelf
|
| Ice shelf
| 472,760
| 650
| 307,300
|
| Ice rises
| 59,440
| 750
| 44,600
|
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 Antartica.
References
External links
Climate
Climate change in Antarctica
Antarctic ice
Last updated: 06-02-2005 16:29:50
