Wilkins Sound
Encyclopedia
Wilkins Sound is a seaway
in Antarctica that is largely occupied by the Wilkins Ice Shelf. It is located on the southwest side of the Antarctic Peninsula
between the concave western coastline of Alexander Island
and the shores of Charcot Island
and Latady Island
farther to the west.
Its northern portion was first seen and roughly mapped in 1910 by the French Antarctic Expedition
under Jean-Baptiste Charcot and was observed from the air in 1929 by Sir Hubert Wilkins
. The configuration of the sound was determined in 1940 on exploratory flights by the US Antarctic Service (USAS). It was named by the USAS for Sir Hubert Wilkins, who in 1929 first proved "Charcot Land" to be an island (see Charcot Island
) and thereby indirectly discovered this feature. The existence of Latady Island at the southwest side of the sound was determined in 1960 by D.J.H. Searle of Falkland Islands Dependencies Survey (FIDS) by examination of air photos taken by the Ronne Antarctic Research Expedition
(RARE), 1947–48.
On 5 April 2009 the thin bridge of ice to the Wilkins Ice Shelf off the coast of Antarctica splintered, and scientists expect it could cause the collapse of the Shelf. There are reports the shelf has exploded into hundreds of small iceberg
s. David Vaughan
of the British Antarctic Survey
has attributed these events to global warming
.
The Wilkins Ice Shelf is a rectangular ice shelf
about 80 nautical miles (148.2 km) long and 60 nautical miles (111.1 km) wide (150 by). This feature occupies the central part of Wilkins Sound, from which it takes its name. The name was proposed by the UK Antarctic Place-Names Committee
(UK-APC) in 1971.
(BAS) predicted that the northern part of the Wilkins ice shelf was likely to be lost within 30 years if climate warming on the Peninsula were to continue at the same rate.
A study by the National Academy of Sciences
in 2002 stated, "Because air temperatures are statistically increasing along the Antarctic Peninsula
region, the presence of glacial meltwater
is likely to become more prevalent in these surface waters and continue to play an ever-increasing role in driving this fragile ecosystem." In 2008 David Vaughan conceded his predictions had been too conservative and that events on the ground were moving quicker than he anticipated.
On 25 March 2008 a 405 km² (156.4 sq mi) chunk of the Wilkins ice shelf disintegrated, putting an even larger portion of the glacial ice shelf at risk. While temperature may have played a part in this disintegration, several recent earthquake
s magnitude 5.0 and greater along the Pacific-Antarctic Ridge may also have contributed. Scientists were surprised when they discovered the rest of the 14000 km² (5,405.4 sq mi) ice shelf is beginning to break away from the continent. What is left of the Wilkins ice shelf is now connected by only a narrow beam of ice. At the end of May, another break-off further reduced the width of the connecting ice strip from 6 to 2.7 km (3.7 to 1.7 mi). This second smaller event, with about 160 km² (61.8 sq mi) of ice separating, was the first documented break-up that occurred in winter.
The Wilkins Ice Shelf is not connected to inland glaciers in the same way as the Larsen B Ice Shelf was and will therefore have a negligible effect on sea level rise.
On 29 November 2008, the European Space Agency
(ESA) announced that the Wilkins Ice Shelf has lost around 2000 square kilometres (772.2 sq mi) so far in 2008. A satellite image captured 26 November 2008 shows new rifts on the ice shelf that make it dangerously close to breaking away from the strip of ice—and the islands to which it is connected, the ESA said.
On 20 January 2009, Reuters
reported that the ice shelf could collapse into the ocean within "weeks or months". The shelf was then only held up by a very thin strip of ice (varying from 2 km to 500 meters at the narrowest), which made it very vulnerable to cracks and fissures. If the strip were to break, it would release the ice shelf, which now has the area of the state of Connecticut
(about 14,000 km²). Satellite evidence from 2 April 2009 led ESA analysts to conclude that the collapse of the strip (which would result in a partial break-away from the Antarctic Peninsula) was "imminent". Pursuant to this determination, ESA's Envisat
satellite is observing the area on a daily basis. The satellite acquisitions are updated automatically to monitor the developments immediately as they occur. Additionally NASA
's Terra
and Aqua
satellites overfly the area several times a day and some of the images acquired are also available.
On 5 April 2009, the ice bridge
connecting part of the ice shelf to Charcot Island
collapsed. The break occurred at the thinnest point in the 40 kilometres (24.9 mi) long bridge and was the first in any of the sections that connect it to the mainland. While only a section has broken away, some scientists predicted that another large section the Wilkins Ice Shelf was only days away from completely breaking off. The shelf remains connected to Latady Island
, although it has been stated that this connection "looks set to collapse" as well. The breakaway is seen as firm evidence of the ongoing effects of warming. Temperatures in this region of Antarctica have risen by 2.5 degrees Celsius since the 1950s. Some scientists believe that the collapse of the weakened ice was triggered by increased wave action due to the current relative absence of sea ice, however, a prominent glaciologist, Doug MacAyeal, has said the trigger for the original break-up in March 2008 was likely the much longer wavelengths of ocean swells created by distant storms.
If the entire shelf, which is approximately the size of Jamaica
, does completely break away from land it would be the largest one to do so, thus far. In the month of April alone, approximately 700 square kilometers (about 270.3 square miles) has broken off Wilkins Sound since the collapse of the ice bridge.
Sound (geography)
In geography a sound or seaway is a large sea or ocean inlet larger than a bay, deeper than a bight and wider than a fjord; or it may be defined as a narrow sea or ocean channel between two bodies of land ....
in Antarctica that is largely occupied by the Wilkins Ice Shelf. It is located on the southwest side of the Antarctic Peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....
between the concave western coastline of Alexander Island
Alexander Island
Alexander Island or Alexander I Island or Alexander I Land or Alexander Land is the largest island of Antarctica, with an area of lying in the Bellingshausen Sea west of the base of the Antarctic Peninsula, from which it is separated by Marguerite Bay and George VI Sound. Alexander Island lies off...
and the shores of Charcot Island
Charcot Island
Charcot Island or Charcot Land is an island of the British Antarctic Territory, long and wide, which is ice covered except for prominent mountains overlooking the north coast, west of Alexander Island.-History:...
and Latady Island
Latady Island
Latady Island is a low ice-covered island off Antarctica, about long and nearly wide, lying south of Charcot Island and west of Alexander Island and its area is . An ice-covered feature in this approximate position was seen from the air and described by Sir Hubert Wilkins in 1929, but not...
farther to the west.
Its northern portion was first seen and roughly mapped in 1910 by the French Antarctic Expedition
French Antarctic Expedition
French Antarctic Expedition refers to several French expeditions in Antarctica.-First expedition:Yves-Joseph de Kerguelen-Trémarec was a French explorer....
under Jean-Baptiste Charcot and was observed from the air in 1929 by Sir Hubert Wilkins
Hubert Wilkins
Sir Hubert Wilkins MC & Bar was an Australian polar explorer, ornithologist, pilot, soldier, geographer and photographer.-Early life:...
. The configuration of the sound was determined in 1940 on exploratory flights by the US Antarctic Service (USAS). It was named by the USAS for Sir Hubert Wilkins, who in 1929 first proved "Charcot Land" to be an island (see Charcot Island
Charcot Island
Charcot Island or Charcot Land is an island of the British Antarctic Territory, long and wide, which is ice covered except for prominent mountains overlooking the north coast, west of Alexander Island.-History:...
) and thereby indirectly discovered this feature. The existence of Latady Island at the southwest side of the sound was determined in 1960 by D.J.H. Searle of Falkland Islands Dependencies Survey (FIDS) by examination of air photos taken by the Ronne Antarctic Research Expedition
Ronne Antarctic Research Expedition
The Ronne Antarctic Research Expedition was an expedition from 1947-1948 which researched the area surrounding the head of the Weddell Sea in Antarctica.-Background:...
(RARE), 1947–48.
On 5 April 2009 the thin bridge of ice to the Wilkins Ice Shelf off the coast of Antarctica splintered, and scientists expect it could cause the collapse of the Shelf. There are reports the shelf has exploded into hundreds of small iceberg
Iceberg
An iceberg is a large piece of ice from freshwater that has broken off from a snow-formed glacier or ice shelf and is floating in open water. It may subsequently become frozen into pack ice...
s. David Vaughan
David Vaughan (scientist)
David Vaughan is a climate scientist at the British Antarctic Survey. His research focus is the role of ice sheets in the Earth system and the societal threat of climate change and rising sea levels. He is a co-ordinating Lead Author of the IPCC Fourth Assessment Report...
of the British Antarctic Survey
British Antarctic Survey
The British Antarctic Survey is the United Kingdom's national Antarctic operation and has an active role in Antarctic affairs. BAS is part of the Natural Environment Research Council and has over 400 staff. It operates five research stations, two ships and five aircraft in and around Antarctica....
has attributed these events to global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
.
Wilkins Ice Shelf
The Wilkins Ice Shelf is a rectangular ice shelf
Ice shelf
An ice shelf is a thick, floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are only found in Antarctica, Greenland and Canada. The boundary between the floating ice shelf and the grounded ice that feeds it is called...
about 80 nautical miles (148.2 km) long and 60 nautical miles (111.1 km) wide (150 by). This feature occupies the central part of Wilkins Sound, from which it takes its name. The name was proposed by the UK Antarctic Place-Names Committee
UK Antarctic Place-Names Committee
The UK Antarctic Place-Names Committee is a United Kingdom government committee, part of the Foreign and Commonwealth Office, responsible for recommending names of geographical locations within the British Antarctic Territory and the South Georgia and the South Sandwich Islands...
(UK-APC) in 1971.
Breakup and collapse events
In 1993, Professor David Vaughan of the British Antarctic SurveyBritish Antarctic Survey
The British Antarctic Survey is the United Kingdom's national Antarctic operation and has an active role in Antarctic affairs. BAS is part of the Natural Environment Research Council and has over 400 staff. It operates five research stations, two ships and five aircraft in and around Antarctica....
(BAS) predicted that the northern part of the Wilkins ice shelf was likely to be lost within 30 years if climate warming on the Peninsula were to continue at the same rate.
A study by the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
in 2002 stated, "Because air temperatures are statistically increasing along the Antarctic Peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....
region, the presence of glacial meltwater
Meltwater
Meltwater is the water released by the melting of snow or ice, including glacial ice and ice shelfs over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing...
is likely to become more prevalent in these surface waters and continue to play an ever-increasing role in driving this fragile ecosystem." In 2008 David Vaughan conceded his predictions had been too conservative and that events on the ground were moving quicker than he anticipated.
On 25 March 2008 a 405 km² (156.4 sq mi) chunk of the Wilkins ice shelf disintegrated, putting an even larger portion of the glacial ice shelf at risk. While temperature may have played a part in this disintegration, several recent earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s magnitude 5.0 and greater along the Pacific-Antarctic Ridge may also have contributed. Scientists were surprised when they discovered the rest of the 14000 km² (5,405.4 sq mi) ice shelf is beginning to break away from the continent. What is left of the Wilkins ice shelf is now connected by only a narrow beam of ice. At the end of May, another break-off further reduced the width of the connecting ice strip from 6 to 2.7 km (3.7 to 1.7 mi). This second smaller event, with about 160 km² (61.8 sq mi) of ice separating, was the first documented break-up that occurred in winter.
The Wilkins Ice Shelf is not connected to inland glaciers in the same way as the Larsen B Ice Shelf was and will therefore have a negligible effect on sea level rise.
On 29 November 2008, the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
(ESA) announced that the Wilkins Ice Shelf has lost around 2000 square kilometres (772.2 sq mi) so far in 2008. A satellite image captured 26 November 2008 shows new rifts on the ice shelf that make it dangerously close to breaking away from the strip of ice—and the islands to which it is connected, the ESA said.
On 20 January 2009, Reuters
Reuters
Reuters is a news agency headquartered in New York City. Until 2008 the Reuters news agency formed part of a British independent company, Reuters Group plc, which was also a provider of financial market data...
reported that the ice shelf could collapse into the ocean within "weeks or months". The shelf was then only held up by a very thin strip of ice (varying from 2 km to 500 meters at the narrowest), which made it very vulnerable to cracks and fissures. If the strip were to break, it would release the ice shelf, which now has the area of the state of Connecticut
Connecticut
Connecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...
(about 14,000 km²). Satellite evidence from 2 April 2009 led ESA analysts to conclude that the collapse of the strip (which would result in a partial break-away from the Antarctic Peninsula) was "imminent". Pursuant to this determination, ESA's Envisat
Envisat
Envisat is an Earth-observing satellite. It was launched on 1 March 2002 aboard an Ariane 5 from the Guyana Space Centre in Kourou, French Guyana into a Sun synchronous polar orbit at an altitude of...
satellite is observing the area on a daily basis. The satellite acquisitions are updated automatically to monitor the developments immediately as they occur. Additionally NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's Terra
Terra (satellite)
Terra is a multi-national NASA scientific research satellite in a sun-synchronous orbit around the Earth. It is the flagship of the Earth Observing System...
and Aqua
Aqua (satellite)
Aqua is a multi-national NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System preceded by Terra and followed by Aura .The name "Aqua" comes from the Latin word...
satellites overfly the area several times a day and some of the images acquired are also available.
On 5 April 2009, the ice bridge
Ice bridge
An ice bridge is a frozen natural structure formed over seas, bays, rivers or lake surfaces. They facilitate migration of animals or people over a water body that was previously uncrossable by terrestrial animals, including humans. The most significant ice bridges are formed by glaciation, spanning...
connecting part of the ice shelf to Charcot Island
Charcot Island
Charcot Island or Charcot Land is an island of the British Antarctic Territory, long and wide, which is ice covered except for prominent mountains overlooking the north coast, west of Alexander Island.-History:...
collapsed. The break occurred at the thinnest point in the 40 kilometres (24.9 mi) long bridge and was the first in any of the sections that connect it to the mainland. While only a section has broken away, some scientists predicted that another large section the Wilkins Ice Shelf was only days away from completely breaking off. The shelf remains connected to Latady Island
Latady Island
Latady Island is a low ice-covered island off Antarctica, about long and nearly wide, lying south of Charcot Island and west of Alexander Island and its area is . An ice-covered feature in this approximate position was seen from the air and described by Sir Hubert Wilkins in 1929, but not...
, although it has been stated that this connection "looks set to collapse" as well. The breakaway is seen as firm evidence of the ongoing effects of warming. Temperatures in this region of Antarctica have risen by 2.5 degrees Celsius since the 1950s. Some scientists believe that the collapse of the weakened ice was triggered by increased wave action due to the current relative absence of sea ice, however, a prominent glaciologist, Doug MacAyeal, has said the trigger for the original break-up in March 2008 was likely the much longer wavelengths of ocean swells created by distant storms.
If the entire shelf, which is approximately the size of Jamaica
Jamaica
Jamaica is an island nation of the Greater Antilles, in length, up to in width and 10,990 square kilometres in area. It is situated in the Caribbean Sea, about south of Cuba, and west of Hispaniola, the island harbouring the nation-states Haiti and the Dominican Republic...
, does completely break away from land it would be the largest one to do so, thus far. In the month of April alone, approximately 700 square kilometers (about 270.3 square miles) has broken off Wilkins Sound since the collapse of the ice bridge.
See also
- Bellingshausen SeaBellingshausen SeaThe Bellingshausen Sea is an area along the west side of the Antarctic Peninsula, west of Alexander Island, east of Cape Flying Fish on Thurston Island, and south of Peter I Island . In the south are, from west to east, Eights Coast, Bryan Coast and English Coast of West Antarctica...
- George VI SoundGeorge VI SoundGeorge VI Sound or Canal Jorge VI or Canal Presidente Sarmiento or Canal Seaver or King George VI Sound or King George the Sixth Sound is a major bay/fault depression, 300 miles long in the shape of the letter J, which skirts the east and south shores of Alexander Island, separating it from the...
- Larsen Ice ShelfLarsen Ice ShelfThe Larsen Ice Shelf is a long, fringing ice shelf in the northwest part of the Weddell Sea, extending along the east coast of Antarctic Peninsula from Cape Longing to the area just southward of Hearst Island...
- List of Antarctic ice shelves
- Rothschild IslandRothschild IslandRothschild Island is an island long, mainly ice covered but surmounted by prominent peaks of Desko Mountains, west of the north part of Alexander Island in the north entrance to Wilkins Sound....