Annotations: New rifts on Antarctic ice shelf
(This article is a combination of 10 Wikipedia articles, 1 CNN news and 1 external information source.)
Scientists have identified new rifts on an Antarctic ice shelf that could lead to it breaking away from the Antarctic Peninsula, the European Space Agency 1 said.
The Wilkins Ice Shelf 2, a large sheet of floating ice south of South America, is connected to two Antarctic islands by a strip of ice. That ice “bridge” has lost about 2,000 square kilometers (about 772 square miles) this year, the ESA said.
A satellite image captured November 26 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’s connected, the ESA said.
Scientists first spotted rifts in the ice shelf in late February, and they noticed further deterioration the following week. The period marks the end of the South Pole 3 summer and is the time when such events are most likely, said Ted Scambos, a glaciologist 4 at the National Snow and Ice Data Center 5 at the University of Colorado in Boulder.
Before the new rifts were spotted this week, the last cracks were noticed July 21.
“These new rifts 6, which have joined previously existing rifts on the ice shelf 7, threaten to break up the chunk of ice located beneath the 21 July date, which would cause the bridge to lose its stabilization and collapse,” said Angelika Humbert, a scientist from Germany’s Muenster University who spotted the cracks with Matthias Braun of the University of Bonn 8.
Wilkins is the size of the state of Connecticut or about half the area of Scotland 9. It is the largest ice shelf on the Antarctic Peninsula 10 yet to be threatened.
If the ice shelf breaks away from the peninsula, it will not cause a rise in sea level, because it is already floating, scientists say.
Scambos said the ice shelf is not on the path of the increasingly popular tourist ships that travel from South America to Antarctica. But some plants and animals may have to adapt to the collapse.
The ice shelf had been stable for most of the past century before it began retreating in the 1990s.
Several ice shelves — Prince Gustav Channel, Larsen Inlet, Larsen A, Larsen B, Wordie, Muller and Jones — have collapsed in the past three decades, the British Antarctic Survey 11 said.
Scientists say the western Antarctic peninsula — the piece of the continent that stretches toward South America — has warmed more than any other place on Earth over the past 50 years, rising by 0.9 degrees Fahrenheit each decade.
Annotations
1: The European Space Agency (ESA), established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states. Headquartered in Paris, ESA’s main spaceport is the Guiana Space Centre in Kourou, a site made available by France. It is close to the equator, hence commercially important orbits are easier to access. ESA became the market leader in commercial space launches in the 1990s. In recent years, ESA has also established itself as a major player in space exploration.
2: The Wilkins Ice Shelf is a rectangular ice shelf about 80 nautical miles long and 60 nautical miles wide (150 km by 110 km). 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.
3: The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the southernmost point on the surface of the Earth. It lies on the continent of Antarctica, on the opposite side of the Earth from the North Pole. It is the site of the United States Amundsen-Scott South Pole Station, which was established in 1956 and has been permanently staffed since that year. The highest temperature ever recorded at the Amundsen-Scott South Pole Station is −13.6 °C (7.5 °F: December 27, 1978), and the lowest is −82.8 °C (−117.0 °F: June 23, 1982) (however, this is not the lowest recorded anywhere on earth, that being −89.2 °C (−128.6 °F) at Vostok Station on July 21, 1983).
4: Glaciology is an interdisciplinary earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. Glaciology is the study of glaciers, or more generally ice and natural phenomena that involve ice.
5: National Snow and Ice Data Center (NSIDC) supports research into world’s frozen realms: the snow, ice, glacier, frozen ground, and climate interactions that make up Earth’s cryosphere.
6: In geology, a rift is a place where the Earth’s crust and lithosphere are being pulled apart and is an example of extensional tectonics.
7: 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 found in Antarctica, Greenland and Canada only. The boundary between the floating ice shelf and the grounded (resting on bedrock) ice that feeds it is called the grounding line. When the grounding line retreats inland, water is added to the ocean and sea level rises.
8: The University of Bonn (German: Rheinische Friedrich-Wilhelms-Universität Bonn) is a public research university located in Bonn, Germany. Founded in 1818 the University of Bonn is today one of the leading universities in Germany. According to the Academic Ranking of World Universities compiled by researchers of the Shanghai Jiao Tong University the University Bonn is ranked 97th internationally.
9: Scotland: Total area: 78,772 km² (30,414 sq mi), Capital: Edinburgh.
10: The Antarctic Peninsula is the northernmost part of the mainland of Antarctica, and the only part of that continent that extends outside the Antarctic Circle. It extends from a line between Cape Adams (Weddell Sea) and a point on the mainland south of Eklund Islands. The Antarctic Peninsula is important because research has revealed that the forces of climate change are having a great effect on the region. The remote polar position has resulted in the area being dotted with numerous research stations and multiple claims of sovereignty.
11: The British Antarctic Survey (BAS) is the United Kingdom’s national Antarctic operator and has an active role in Antarctic affairs. BAS is part of the Natural Environment Research Council (NERC) and has over 400 staff. It operates five research stations, two ships and five aircraft in and around Antarctica.
