HOME

TheInfoList



OR:

The Ross Ice Shelf is the largest
ice shelf An ice shelf is a large 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, Northern Canada, and the Russian Arctic. The ...
of
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
(, an area of roughly and about across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than long, and between high above the water surface. Ninety percent of the floating ice, however, is below the water surface. Most of Ross Ice Shelf is in the
Ross Dependency The Ross Dependency is a region of Antarctica defined by a sector originating at the South Pole, passing along longitudes 160° east to 150° west, and terminating at latitude 60° south. It is claimed by New Zealand, a claim accepted only b ...
claimed by New Zealand. It floats in, and covers, a large southern portion of the
Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who ...
and the entire Roosevelt Island located in the east of the Ross Sea. The ice shelf is named after
Sir James Clark Ross Sir James Clark Ross (15 April 1800 – 3 April 1862) was a British Royal Navy officer and polar explorer known for his explorations of the Arctic, participating in two expeditions led by his uncle John Ross, and four led by William Edwa ...
, who discovered it on 28 January 1841. It was originally called "The Barrier", with various adjectives including "Great Ice Barrier", as it prevented sailing further south. Ross mapped the ice front eastward to 160° W. In 1947, the U.S. Board on Geographic Names applied the name "Ross Shelf Ice" to this feature and published it in the original U.S. Antarctic Gazetteer. In January 1953, the name was changed to "Ross Ice Shelf"; that name was published in 1956.


Exploration

On 5 January 1841, the British Admiralty's Ross expedition in the ''
Erebus In Greek mythology, Erebus (; grc, Ἔρεβος, Érebos, "deep darkness, shadow".), or Erebos, is the personification of darkness and one of the primordial deities. Hesiod's ''Theogony'' identifies him as one of the first five beings in exis ...
'' and the '' Terror'', three- masted ships with specially strengthened wooden hulls, was going through the pack ice of the Pacific near Antarctica in an attempt to determine the position of the South Magnetic Pole. Four days later, they found their way into open water and were hoping that they would have a clear passage to their destination. But on 11 January, the men were faced with an enormous mass of ice. Sir
James Clark Ross Sir James Clark Ross (15 April 1800 – 3 April 1862) was a British Royal Navy officer and polar explorer known for his explorations of the Arctic, participating in two expeditions led by his uncle John Ross, and four led by William Edwa ...
, the expedition's commander, remarked: "Well, there's no more chance of sailing through that than through the
cliffs of Dover The White Cliffs of Dover is the region of English coastline facing the Strait of Dover and France. The cliff face, which reaches a height of , owes its striking appearance to its composition of chalk accented by streaks of black flint, deposi ...
". Ross, who in 1831 had located the
North Magnetic Pole The north magnetic pole, also known as the magnetic north pole, is a point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downward (in other words, if a magnetic compass needle is allowed t ...
, spent the next two years vainly searching for a sea passage to the South Pole; later, his name was given to the ice shelf and the sea surrounding it. Two volcanoes in the region were named by Ross for his vessels. For later Antarctic explorers seeking to reach the South Pole, the Ross Ice Shelf became a starting area. In a first exploration of the area by the
Discovery Expedition The ''Discovery'' Expedition of 1901–1904, known officially as the British National Antarctic Expedition, was the first official British exploration of the Antarctic regions since the voyage of James Clark Ross sixty years earlier (1839–18 ...
in 1901–1904,
Robert Falcon Scott Captain Robert Falcon Scott, , (6 June 1868 – c. 29 March 1912) was a British Royal Navy officer and explorer who led two expeditions to the Antarctic regions: the ''Discovery'' expedition of 1901–1904 and the ill-fated ''Terra Nov ...
made a significant study of the shelf and its surroundings from his expedition's base on Ross Island. By measurement of calved ice bergs and their buoyancy, he estimated the ice sheet to be on average 274 meters thick; the undisturbed morphology of the ice sheet and its inverted temperature profile led him to conclude it was floating on water; and measurements in 1902–1903 showed it had advanced 555 meters northwards in 13.5 months. The findings were presented at a lecture entitled "Universitas Antarctica!" given 7 June 1911 and were published in the account of Scott's second expedition (the
Terra Nova Expedition The ''Terra Nova'' Expedition, officially the British Antarctic Expedition, was an expedition to Antarctica which took place between 1910 and 1913. Led by Captain Robert Falcon Scott, the expedition had various scientific and geographical objec ...
of 1910–1913).
Ernest Shackleton Sir Ernest Henry Shackleton (15 February 1874 – 5 January 1922) was an Anglo-Irish Antarctic explorer who led three British expeditions to the Antarctic. He was one of the principal figures of the period known as the Heroic Age of ...
's southern party (Shackleton, Adams, Marshal, Wild) of the 1908 Nimrod expedition were the first humans to cross the Ice Shelf during its failed attempt to reach the
South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...
. Both
Roald Amundsen Roald Engelbregt Gravning Amundsen (, ; ; 16 July 1872 – ) was a Norwegian explorer of polar regions. He was a key figure of the period known as the Heroic Age of Antarctic Exploration. Born in Borge, Østfold, Norway, Amundsen bega ...
and Scott crossed the shelf to reach the Pole in 1911. Amundsen wrote: "Along its outer edge the Barrier shows an even, flat surface; but here, inside the bay, the conditions were entirely different. Even from the deck of the ''
Fram Fram may refer to: Ships * ''Fram'' (ship), an arctic exploration vessel from Norway * MS ''Fram'', expedition cruise ship owned by Hurtigruten Group Places and geography * Fram, Paraguay, a town in Itapúa, Paraguay * Fram Formation, a se ...
'' we were able to observe great disturbances of the surface in every direction; huge ridges with hollows between them extended on all sides. The greatest elevation lay to the south in the form of a lofty, arched ridge, which we took to be about high on the horizon. But it might be assumed that this ridge continued to rise beyond the range of vision". The next day, the party made its first steps on the Barrier. "After half an hour's march we were already at the first important point—the connection between the sea-ice and the Barrier. This connection had always haunted our brains. What would it be like? A high, perpendicular face of ice, up which we should have to haul our things laboriously with the help of tackles? Or a great and dangerous fissure, which we should not be able to cross without going a long way round? We naturally expected something of the sort. This mighty and terrible monster would, of course, offer resistance in some form or other," he wrote. "The mystic Barrier! All accounts without exception, from the days of Ross to the present time, had spoken of this remarkable natural formation with apprehensive awe. It was as though one could always read between the lines the same sentence: 'Hush, be quiet! the mystic Barrier!' "One, two, three, and a little jump, and the Barrier was surmounted!"


Composition and movement

Ice shelves An ice shelf is a large 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, Northern Canada, and the Russian Arctic. The b ...
are thick plates of ice, formed continuously by glaciers, that float atop an ocean. The shelves act as "brakes" for the glaciers. These shelves serve another important purpose—"they moderate the amount of melting that occurs on the glaciers' surfaces. Once their ice shelves are removed, the glaciers increase in speed due to meltwater percolation and/or a reduction of braking forces, and they may begin to dump more ice into the ocean than they gather as snow in their catchments. Glacier ice speed increases are already observed in Peninsula areas where ice shelves disintegrated in prior years." The Ross Ice Shelf is one of many such shelves. It reaches into Antarctica from the north, and covers an area of about , nearly the size of France. The ice mass is about wide and long. In some places, namely its southern areas, the ice shelf can be almost 750 m (2,450 ft) thick. The Ross Ice Shelf pushes out into the sea at between a day. Other
glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...
s gradually add bulk to it. At the same time, the
freezing Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid ...
of seawater below the ice mass increases the thickness of the ice from . Sometimes,
fissures A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure ...
and cracks may cause part of the shelf to break off; the largest known is about , that is, slightly larger than Belgium.
Iceberg B-15 Iceberg B-15 was the largest recorded iceberg by area. It measured around , with a surface area of , about the size of the island of Jamaica. Calved from the Ross Ice Shelf of Antarctica in March 2000, Iceberg B-15 broke up into smaller icebergs, ...
, the world's largest recorded iceberg, was calved from the Ross Ice Shelf during March 2000. Scientists have long been intrigued by the shelf and its composition. Many scientific teams researching the Antarctic have made camps on or adjacent to the Ross Ice Shelf. This includes McMurdo Station. One major effort was a series of studies conducted in 1957 and 1958, which were continued during the 1960–61 season. The efforts involved an international team of scientists. Some parties explored the glaciers and others the valleys on the ice shelf. From 1967 to 1972 the Scott Polar Research Institute reported extensive observations using
radio echo sounding Radioglaciology is the study of glaciers, ice sheets, ice caps and icy moons using ice penetrating radar. It employs a geophysical method similar to ground-penetrating radar and typically operates at frequencies in the MF, HF, VHF and UHF porti ...
. The technique allowed measurements to be taken from the air; allowing a criss cross track of 35,000 km to be covered; compared with a 3,000 km track from previous seismic sounding on the ground. More detailed surveys were executed between 1973 and 1978. A significant scientific endeavor called the Ross Ice Shelf Project was launched with a plan of drilling into the shelf to sample the biomass in the area and make other determinations about the shelf and its relationship to the sea floor. This is believed to be the first oceanographic ice shelf borehole. The project included surface glaciological observations as well as drilling, and the glaciological portion started during the planning phase of the drilling. The drilling portion of the project was to have begun during 1974, but the actual drilling was delayed until 1976. Finally, in 1977, the scientists were able to drill successfully through the ice, making a hole that could be sampled every few days for three weeks. The team was able to map the sea floor, study the tides, and assess the fish and various other forms of life in the waters. The team also examined the oceanographic and geological conditions as well as the temperature of the ice. They estimated that the base of the shelf was −2.16° Celsius (27.3 °F). They also made other calculations about the fluctuations of the temperatures. The results of these various projects were published in a series of reports in the 2 February 1979 issue of ''
Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...
''. During the 1980s, a network of weather stations was installed to record temperatures on the shelf and throughout the more remote parts of the continent. University of Colorado's National Snow and Ice Data Center has been studying ice shelves and, in 2002, announced that, based on several breakups of ice shelves, including Larsen B, has begun to reassess their stability. Their scientists stated that the temperature of the warmest portion of the shelf is "only a few degrees too cool in summer presently to undergo the same kind of retreat process. The Ross Ice Shelf is the main outlet for several major glaciers draining the
West Antarctic Ice Sheet The Western Antarctic Ice Sheet (WAIS) is the segment of the continental ice sheet that covers West Antarctica, the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere. The WAIS is classified as ...
, which contains the equivalent of 5 m of
sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cry ...
in its above-sea-level ice." The report added that observations of "iceberg calving" on the Ross Ice Shelf are, in their opinion, unrelated to its stability. Scientific exploration continues to uncover interesting information and the analyses have resulted in some interesting theories being posited and publicized. One such opinion, given in 2006 based on a geological survey, suggested that the ice shelf had collapsed previously, perhaps suddenly, which could well happen again. A science team from
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
installed a camp in the centre of the shelf in late 2017. The expedition was led by glaciologist
Christina Hulbe Christina Hulbe is an American Antarctic researcher, and serves as professor and Dean of Surveying at the University of Otago in New Zealand. She was previously Chair of the Geology Department at Portland State University in Portland, Oregon. ...
and brought together oceanographers, glaciologists, biologists and sedimentologists to examine the ice, ocean and sediment in the central shelf region. One of the key findings was that the ice in the region was re-freezing. This re-freezing and growth of an ice shelf is not uncommon but the Ross Ice Shelf situation appeared to be very variable as there was no evidence of long-term freezing. A recent study attribute this variability in-part to tidal mixing. A second New Zealand expedition in 2019 traveled to the grounding line region of the
Kamb Ice Stream Kamb Ice Stream (), a glaciological feature of the Ross Ice Shelf of the West Antarctic Ice Sheet, formerly known as Ice Stream C, the ice stream was renamed in 2001 in honor of Caltech The California Institute of Technology (branded as Calte ...
. The hot water drill borehole at this site penetrated through over 500 m of snow and ice to an ocean cavity only 30 m deep at this location. As well as sampling the ocean and sediment, it was the first deployment beneath the Ross Ice Shelf of the
Remotely operated underwater vehicle A remotely operated underwater vehicle (technically ROUV or just ROV) is a tethered underwater mobile device, commonly called ''underwater robot''. Definition This meaning is different from remote control vehicles operating on land or in the ai ...
Icefin developed at
Georgia Tech The Georgia Institute of Technology, commonly referred to as Georgia Tech or, in the state of Georgia, as Tech or The Institute, is a public research university and institute of technology in Atlanta, Georgia. Established in 1885, it is part of ...
, a vehicle designed around parameters suitable for exploration of the liquid cavities of places like
Europa Europa may refer to: Places * Europe * Europa (Roman province), a province within the Diocese of Thrace * Europa (Seville Metro), Seville, Spain; a station on the Seville Metro * Europa City, Paris, France; a planned development * Europa Cliff ...
. The same New Zealand team returned to another site along the Kamb coast in December 2021, this time drilling through an under-ice river that proved to be essentially oceanic. The team were able to melt through the ice to discover the 250 m deep river had formed a relatively narrow channel beneath the ice. They also recorded evidence of the tsunami generated by the 2022 Hunga Tonga–Hunga Ha'apai eruption and tsunami.Horgan, H. and Stevens C. (2022) Exploring Antarctica's hidden under-ice rivers and their role in future sea-level rise, The Conversation, https://theconversation.com/exploring-antarcticas-hidden-under-ice-rivers-and-their-role-in-future-sea-level-rise-176456


See also

* Cape Huinga * Eady Ice Piedmont *
Howard-Williams Point Howard-Williams Point () is a prominent point extending into the Ross Ice Shelf, located just north of Beaumont Bay, north east of the Surveyors Range, Antarctica. It was named in honor of Clive Howard-Williams, an ecologist who led several rese ...
*
Iceberg B-17B Iceberg B-17B was an iceberg twice the size of Manhattan, that floated in the southern ocean approximately off the coast of Western Australia. Iceberg B-17B measured approximately . B-17B originated in the first half of 2000 when the iceberg B1 ...
*
List of Antarctic ice shelves This is a list of Antarctic ice shelves. Ice shelves are attached to a large portion of the Antarctic coastline. Their total area is 1,541,700 km2. Names are also listed in the Scientific Committee on Antarctic Research, Gazetteer. The ...
*
Nimrod Expedition The ''Nimrod'' Expedition of 1907–1909, otherwise known as the British Antarctic Expedition, was the first of three successful expeditions to the Antarctic led by Ernest Shackleton and his second expedition to the Antarctic. Its main target, ...
*
Retreat of glaciers since 1850 The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use, mountain recreation, animals and plants that depend on glacier-melt, and, in the longer term, the level of the oceans. Deglaciation occu ...
*
Ross Embayment The Ross Embayment is a large region of Antarctica, comprising the Ross Ice Shelf and the Ross Sea, that lies between East and West Antarctica. Extent The continent of Antarctica has two major divisions; West Antarctica in mostly western longitu ...
*
Ross Gyre The Ross Gyre is one of the two gyres that exist within the Southern Ocean. The gyre is located in the Ross Sea, and rotates clockwise. The gyre is formed by interactions between the Antarctic Circumpolar Current and the Antarctic Continental She ...
* Steershead Crevasses *
West Antarctic Rift System The West Antarctic Rift System is a series of rift valleys between East and West Antarctica. It encompasses the Ross Embayment, the Ross Sea, the area under the Ross Ice Shelf and a part of Marie Byrd Land in West Antarctica, reaching to the ...


References


External links


Polar Discovery: Ross Sea Penguins and Lava Flows



Massive ice shelf 'may collapse without warning'

Photograph of Ross Ice Shelf edge
{{Authority control Ice shelves of Antarctica
Ice Shelf An ice shelf is a large 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, Northern Canada, and the Russian Arctic. The ...