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Climate of 1 Climate of Antarctica

The climate of Antarctica is the coldest on the whole of . Antarctica has the lowest naturally occurring temperature ever recorded on the surface on Earth: −89.2°C (−128.6°F) at . Satellites have recorded even lower temperatures, down to -93.2°C(-135.8°F). It is also extremely dry (technically a ), averaging 166mm (6.5in) of per year. On most parts of the continent the rarely melts and is eventually compressed to Surface temperature of Antarctica in winter and become the glacial that makes up the . Weather fronts summer from the European Centre for rarely penetrate far into the continent. Most of Antarctica has an ice Medium-Range Weather Forecasts cap climate (Köppen EF) with very cold, generally extremely dry weather.

Temperature The lowest reliably measured temperature of a continuously occupied station on Earth of −89.2 °C (−128.6 °F) was on 21 July 1983 at Vostok Station.[1] For comparison, this is 10.7 °C (19.3 °F) colder than subliming (at sea level pressure). The altitude of the location is 3,900 meters (12,800 feet). The lowest recorded temperature of any location on Earth surface was −93.2 °C (−135.8 °F) at 81.8°S 59.3°E [2], which is on an unnamed between and , on August 10, 2010. The temperature was deduced from radiance measured by the Landsat 8 satellite, and discovered during a National Snow and Ice Data Center review of stored data in December, 2013. This temperature is not directly comparable to the -89.2 quoted above, since it is a skin temperature deduced from satellite-measured upwelling radiance, rather than a thermometer-measured temperature of the air 1.5m above the ground surface. The highest temperature ever recorded in Antarctica was 14.6°C (58.3°F) in two places, and , on 5 January 1974. The mean annual temperature of the interior is −57°C (−70°F). The coast is warmer. Monthly means at McMurdo Station range from −26°C (−14.8°F) in August to −3°C (26.6°F) in January.[3] At the , the highest temperature ever recorded was −12.3°C (9.9°F) on 25 December 2011. Along the , temperatures as high as 15°C (59°F) have been recorded,Wikipedia:Please clarify though the summer temperature is below 0°C (32°F)in most time. Severe low temperatures vary with latitude, elevation, and distance from the ocean. is colder than because of its higher elevation.Wikipedia:Citation needed The Antarctic Peninsula has the most moderate climate. Higher temperatures occur in January along the coast and average slightly below freezing. Climate of Antarctica 2

Precipitation

The total precipitation on Antarctica, averaged over the entire continent, is about 166 mm (6.5 in) per year (Vaughan et al., J Climate, 1999). The actual rates vary widely, from high values over the Peninsula (meters/yards per year) to very low values (as little as 50 mm (2 in) per year) in the high interior. Areas that receive less than 250 mm (10 in) of precipitation per year are classified as . Almost all Antarctic precipitation falls as snow. Note that the quoted precipitation is a measure of its equivalence to water, rather than being the actual depth of snow. The air in Antarctica is also very dry. The low temperatures result in a very low absolute humidity, which means that dry skin and cracked lips are a continual problem for scientists and expeditioners working in the continent.

Map of average annual precipitation on Weather condition classification Antarctica (mm liquid equivalent)

The weather in Antarctica can be highly variable,and the weather conditions can often change dramatically in short periods of time. There are three classifications for describing weather conditions in Antarctica. At least one of the following criteria must be met for each category described below: Condition 1 Windspeed over 55 knots (100 km/h) Visibility less than 30 metres (98 ft) Wind chill below −73 °C (−99 °F) Description: Dangerous conditions; outside travel is not permitted. Condition 2 Windspeed of 48 to 55 knots (90 to 100 km/h) Visibility 400 to 30 metres (1/4 of a mile to 100 feet) Wind chill of −60 °C (−76 °F) to −73 °C (−99 °F) Description: Unpleasant conditions; outside travel is permitted but not recommended. Condition 3 Windspeed below 48 knots (90 km/h) Visibility greater than 400 metres (1/4 of a mile) Wind chill above −60 °C (−76 °F) Description: Pleasant conditions; all outside travel is permitted.

Ice cover Nearly all of Antarctica is covered by an ice sheet that is, on average, at least a mile thick (1.6 km). Antarctica contains 90% of the world's ice and more than 70% of its . 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 Climate of Antarctica 3

from thermal expansion of the oceans. During a recent decade, East Antarctica thickened at an average rate of about 1.8 centimetres per year while West Antarctica showed an overall thinning of 0.9 centimetres per year.[4] 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 Percent Mean ice Volume Percent (km²) thickness (km³) (m)

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 Mean Volume (km²) ice (km³) thickness (m)

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 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 Climate of Antarctica 4

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: 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 broke up in recent decades. • 1995: The Larsen A ice shelf disintegrated in January 1995. Antarctic ice shelves, 1998

• 2001: 3,250 km² of the Larsen B ice shelf disintegrated in February 2001. It had been gradually retreating before the breakup event. The George VI Ice Shelf, which may be on the brink of instability,[5] has probably existed for approximately 8000 years, after melting 1500 years earlier.[6] Warm ocean currents may have been the cause of the melting. The idea that it was warmer in Antarctica 10,000 years ago is supported by ice cores, though the timing is not quite right.

Climate change

The continent-wide average surface temperature trend of Antarctica is positive and significant at >0.05°C/decade since 1957.[7][8][9][10] The has warmed by more than 0.1°C/decade in the last 50 years, and is strongest in winter and spring. Although this is partly offset by fall cooling in East Antarctica, this effect is restricted to the 1980s and 1990s.

Research published in 2009 found that overall the continent had become warmer since the 1950s, a finding consistent with the influence of man-made : "We can't pin it down, but it certainly is consistent with the influence of greenhouse gases from fossil fuels", said NASA scientist Drew Shindell, Antarctic Skin Temperature Trends between 1981 and 2007, based on thermal infrared observations made by a series of NOAA satellite sensors. Skin another study co-author. Some of the temperature trends do not necessarily reflect air temperature trends. effects also could be natural variability, he said.[11]

The , which has undertaken the majority of Britain's scientific research in the area, has the following positions: [12] • Ice makes sensitive by introducing a strong positive feedback loop. Climate of Antarctica 5

• 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. • Antarctica seems to be both warming around the edges and cooling at the center at the same time. Thus it is not possible to say whether it is warming or cooling overall. • There is no evidence for a decline in overall extent.[13] • 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. The area of strongest cooling appears at the South Pole, and the region of strongest warming lies along the Antarctic Peninsula. A possible explanation is that loss of UV-absorbing ozone may have cooled the stratosphere and strengthened the polar vortex, a pattern of spinning winds around the South Pole. The vortex acts like an atmospheric barrier, preventing warmer, coastal air from moving into the continent's interior. A stronger polar vortex might explain the cooling trend in the interior of Antarctica. [14]

In their latest study (September 20, 2007) NASA researchers have confirmed that Antarctic snow is melting farther inland from the coast over time, melting at higher altitudes than ever and increasingly melting on Antarctica's largest ice shelf.[15]

September 20, 2007 NASA map showing previously un-melted There is also evidence for widespread [17] snowmelt retreat[16] around the Antarctic Peninsula. Researchers reported December 21, 2012 in Nature Geoscience that from 1958 to 2010, the average temperature at the mile-high rose by 2.4 degrees Celsius, with warming fastest in its winter and spring. The spot which is in the heart of the West Antarctic Ice Sheet is one of the fastest-warming places on Earth.[18][19]

References

[1] http:/ / wmo. asu. edu/ world-lowest-temperature

[2] http:/ / tools. wmflabs. org/ geohack/ geohack. php?pagename=Climate_of_Antarctica& params=81. 8_S_59. 3_E_dim:10000km

[3] Antarctica Climate Data and Climate Graphs (http:/ / www. coolantarctica. com/ Antarctica fact file/ antarctica environment/ climate_graph/

vostok_south_pole_mcmurdo. htm) [4] Davis et al., Science 2005 Snowfall-Driven Growth in Mitigates Recent Sea-Level Rise, Science, 24 June 2005: Vol. 308 no. 5730 pp. 1898-1901

[5] Millennial-scale variability of George VI Ice Shelf, Antarctic Peninsula (http:/ / www. antarctica. ac. uk/ BAS_Science/ Highlights/ 2001/

george_vi. html)

[6] http:/ / igloo. gsfc. nasa. gov/ wais/ pastmeetings/ abstracts00/ Bentley2. htm

[7] Retrieved=2009-01-22 (http:/ / climatechangepsychology. blogspot. com/ 2009/ 01/ eric-j-steig-temperature-in-west. html)

[8] Retrieved=2009-01-22 (http:/ / www. ess. washington. edu/ web/ ess/ people/ faculty_bio/ steig-bio. html)

[9] Retrieved=2009-01-22 (http:/ / www. nature. com/ nature/ journal/ v457/ n7228/ full/ nature07669. html)

[10] Retrieved=2009-01-22 (http:/ / news. smh. com. au/ breaking-news-world/

global-warming-hitting-all-of-antarctica-scientists-20090122-7mul. html)

[11] Antarctica study challenges warming skeptics (http:/ / www. msnbc. msn. com/ id/ 28693329/ ns/ us_news-environment/ t/

antarctica-study-challenges-warming-skeptics/ #. T1Rp_d2dyAs), Jan 21, 2009

[12] http:/ / www. antarctica. ac. uk/ Key_Topics/ Climate_Change/ Climate_Change_Position. html Climate of Antarctica 6

[13] In Antarctica, melting may beget ice; Disintegration of floating could be responsible for freezing of seawater (http:/ / www.

sciencenews. org/ view/ generic/ id/ 349277/ description/ In_Antarctica_melting_may_beget_ice) March 29, 2013 Vol.183 #9 Science News

[14] http:/ / earthobservatory. nasa. gov/ Newsroom/ NewImages/ images. php3?img_id=17257

[15] "NASA Researchers Find Snowmelt in Antarctica Creeping Inland" September 20, 2007 (http:/ / www. nasa. gov/ centers/ goddard/ news/

topstory/ 2007/ antarctic_snowmelt. html)

[16] http:/ / toolserver. org/ %7Edispenser/ cgi-bin/ dab_solver. py?page=Climate_of_Antarctica& editintro=Template:Disambiguation_needed/

editintro& client=Template:Dn [17] IPCC 2007, Intergovernmental Panel on Climate Change, Climate Change 2007: The Physical Science Basis. Contribution of Working

Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (http:/ / www. ipcc. ch/ pdf/ assessment-report/

ar4/ wg1/ ar4-wg1-chapter4. pdf), Cambridge University Press, 2007, page 376.

[18] West Antarctica warming fast; Temperature record from high-altitude station shows unexpectedly rapid rise (http:/ / www. sciencenews.

org/ view/ generic/ id/ 347241/ description/ West_Antarctica_warming_fast) December 21, 2012 Science News

[19] Figure 1: Map of Antarctica and annual spatial footprint of the Byrd temperature record. (http:/ / www. nature. com/ ngeo/ journal/ v6/ n2/

fig_tab/ ngeo1671_F1. html) Notes • D. G. Vaughan, G. J. Marshall, W. M. Connolley, J. C. King, and R. M. Mulvaney (2001). "Devil in the detail".

Science 293 (5536): 1777–9. doi: 10.1126/science.1065116 (http:/ / dx. doi. org/ 10. 1126/ science. 1065116).

PMID 11546858 (http:/ / www. ncbi. nlm. nih. gov/ pubmed/ 11546858). • 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): 173–6. Bibcode:

2005Geo....33..173B (http:/ / adsabs. harvard. edu/ abs/ 2005Geo. . . . 33. . 173B). doi: 10.1130/G21203.1 (http:/ /

dx. doi. org/ 10. 1130/ G21203. 1).

External links

Climate

• Climate data from Antarctic surface stations with trends (http:/ / www. antarctica. ac. uk/ met/ gjma/ )

• Temperature data from the READER project (http:/ / www. antarctica. ac. uk/ met/ READER/ )

• A pamphlet about the weather and climate of Antarctica (http:/ / www. antarctica. ac. uk/ met/ jds/ weather/

weather. htm)

• Information concerning recent ice shelf [[|calving (http:/ / www. antarctica. ac. uk/ met/ bas_publ. html)]]

• (unreliable) maps of snowfall and temperature (http:/ / www. antarctica. ac. uk/ met/ climate/ wmc/ )

• Temperature statistics at the Amundsen-Scott station on the South Pole (http:/ / wayback. archive. org/ web/

20120229073011/ http:/ / www. nerc-bas. ac. uk/ icd/ gjma/ pole. temps. html)

• Warmer temperatures, more snow... (http:/ / www. science. org. au/ nova/ 082/ 082key. htm) Australian Academy of Science

• Antarctica's central ice cap grows while glaciers melt (http:/ / sfgate. com/ cgi-bin/ article. cgi?f=/ c/ a/ 2005/ 05/

20/ MNGS9CS5141. DTL& type=science)

• "AWS and AMRC Real-Time Weather Observations and Data" (http:/ / amrc. ssec. wisc. edu/ realtime. html). University of Wisconsin-Madison's Antarctic Weather Stations Project and Antarctic Meteorological Research Center. Retrieved May 31, 2005.

• Antarctica Climate and Weather (http:/ / www. coolantarctica. com/ Antarctica fact file/ antarctica environment/

climate_graph/ climate_weather. htm) Climate of Antarctica 7

Climate change in Antarctica

• http:/ / www. antarctica. ac. uk/ Key_Topics/ Climate_Change/ Climate_Change_Position. html Wikipedia:Link rot

• http:/ / www. antarctica. ac. uk/ Key_Topics/ IceSheet_SeaLevel/ ice_shelf_loss. html Wikipedia:Link rot

• Western Antarctica warming confirmed (http:/ / www. usatoday. com/ story/ tech/ sciencefair/ 2012/ 12/ 23/

antarctica-warming-global/ 1782829/ ) December 23, 2012 USA Today

Antarctic ice

• "Sea Ice Index – Trends in extent – Southern Hemisphere (Antarctic)" (http:/ / www. nsidc. org/ data/

seaice_index/ ). National Snow and Ice Data Center. Retrieved Jan 9, 2009.

• "Coastal-Change and Glaciological Maps of Antarctica" (http:/ / pubs. usgs. gov/ fs/ 2005/ 3055/ ). USGS Fact Sheet 2005–3055. Retrieved May 31, 2005.

• "Coastal-Change and Glaciological Maps of Antarctica" (http:/ / pubs. usgs. gov/ fs/ fs50-98/ ). USGS Fact Sheet 050–98. Retrieved February 28, 2005.

• "Coastal-change and glaciological map of the Eights Coast area, Antarctica; 1972–2001" (http:/ / pubs. usgs.

gov/ imap/ 2600/ E). U.S. Geological Survey Scientific Investigations Series Map, I-2600-E. Retrieved February 28, 2005.

• "Coastal-change and glaciological map of the Bakutis Coast area, Antarctica; 1972–2002" (http:/ / pubs. usgs.

gov/ imap/ 2600/ F). U.S. Geological Survey Scientific Investigations Series Map, I-2600-F. Retrieved February 28, 2005.

• "Coastal-change and glaciological map of the Saunders Coast area, Antarctica; 1972–1997" (http:/ / pubs.

usgs. gov/ imap/ 2600/ G). U.S. Geological Survey Scientific Investigations Series Map, I-2600-G. Retrieved February 28, 2005.

• "Satellite Image Atlas of Glaciers of the World – Antarctica" (http:/ / pubs. usgs. gov/ prof/ p1386b/ ). U.S. Geological Survey Professional Paper 1386-B. Retrieved February 28, 2005.

Further reading • Warm Snap Turned Antarctica Green Around the Edges; Thawed-out continent was lined with trees 15 million

years ago, study says. (http:/ / news. nationalgeographic. com/ news/ 2012/ 06/

120620-green-antarctica-trees-global-warming-science-ancient/ ) June 20, 2012 National Geographic

• Taking Antarctica's temperature; Frozen continent may not be immune to global warming (http:/ / www.

sciencenews. org/ view/ feature/ id/ 351507/ description/ Taking_Antarcticas_temperature) July 27, 2013; Vol.184 #2 Science News Article Sources and Contributors 8 Article Sources and Contributors

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