|Lowest elevation||Below sea level|
|Terminus||Pine Island Bay, part of the Amundsen Sea|
Thwaites Glacier, sometimes referred to as the Doomsday Glacier, 2 kilometres (1.2 miles) per year near its grounding line. Its fastest flowing grounded ice is centered between 50 and 100 kilometres (31 and 62 mi) east of Mount Murphy. In 1967, the Advisory Committee on Antarctic Names named the glacier after Fredrik T. Thwaites (1883–1961), a glacial geologist, geomorphologist and professor emeritus at the University of Wisconsin–Madison. The historian Reuben Gold Thwaites was his father.is an unusually broad and vast Antarctic glacier flowing into Pine Island Bay, part of the Amundsen Sea, east of Mount Murphy, on the Walgreen Coast of Marie Byrd Land. Its surface speeds exceed
Thwaites Glacier is closely watched for its potential to raise sea levels.Along with the Pine Island Glacier, it has been described as part of the "weak underbelly" of the West Antarctic Ice Sheet, due to its apparent vulnerability to significant retreat. This hypothesis is based on both theoretical studies of the stability of marine ice sheets and observations of large changes on these two glaciers. In recent years, the flow of both of these glaciers has accelerated, their surfaces have lowered, and their grounding lines have retreated.
The Thwaites Ice Shelf, a floating ice shelf which braces and restrains the eastern portion of Thwaites Glacier, is likely to collapse within a decade from 2021, leading to increased outflow and contribution to sea-level rise.For this reason, Thwaites Glacier and its ice shelf have been proposed as sites for climate engineering interventions to stabilize and preserve its ice.
In 2001, a study of Thwaites Glacier using satellite radar interferometry data from the Earth Remote Sensing Satellite 1 and 2 revealed that the grounding line of Thwaites Glacier was retreating at 1 kilometer per year and that the glacier was significantly out of mass balance, hence confirming presumptions of collapse by Terence Hughes, University of Maine, in 1973. In 2002, a team of scientists from Chile and NASA on board an Orion P3 from the Chilean Navy collected the first radar sounding and laser altimetry survey of the glacier to reveal extensive thinning and acceleration in thinning. This discovery prompted an extensive airborne campaign in 2004 by the University of Texas, Austin, Texas, to be followed by subsequent airborne campaigns under NASA's IceBridge Campaign in 2009–2018.
In 2011, using geophysical data collected from flights over Thwaites Glacier (data collected under NASA's IceBridge campaign), a study by scientists at Columbia University's Lamont-Doherty Earth Observatory showed a rock feature, a ridge 700 meters tall that helps anchor the glacier and helped slow the glacier's slide into the sea. The study also confirmed the importance of seafloor topography in predicting how the glacier will behave in the near future.However, the glacier has been considered to be the biggest threat on relevant time scales, for rising seas, current studies aim to better quantify retreat and possible impacts. Since the 1980s, the glacier had a net loss of over 600 billion tons of ice though 2017. In 2017, scientists discovered previously unknown volcanoes nearby.
In 2020, scientists discovered warm water underneath the glacier for the first time. 3 ft (0.9 m) rise in the sea level.The place where the glacier was in contact with the sea had been recorded as 2 degree Celsius above the freezing temperature. The discovery was a part of the International Thwaites Glacier Collaboration, a partnership primarily between US and UK academic institutions. This study has raised alarm regarding the glacier collapse, which can lead to nearly
Extensive calving at the marine terminus of Thwaites Glacier is monitored by remote sensing and seismological observations, with the largest events being seismically detectable at ranges up to 1600 km.
Swamp-like canal areas and streams underlie the glacier. The upstream swamp canals feed streams with dry areas between the streams which retard flow of the glacier. Due to this friction the glacier is considered stable in the short term.
A 2014 University of Washington study, using satellite measurements and computer models, predicted that the Thwaites Glacier will gradually melt, leading to an irreversible collapse over the next 200 to 1000 years.
A 2021 study suggested that the Thwaites Ice Shelf, which currently restrains eastern portion of the Thwaites Glacier, could collapse within 3-5 years, leading to the contribution to sea level rise from the eastern portion increasing and eventually becoming equivalent to that of the other, undefended portions of the glacier.Scientists do not claim that the entire glacier will collapse within 3-5 years, only the ice shelf which rests on the ocean and restrains the eastern portion of the Thwaites Glacier. The floating ice shelf acts as a brace that prevents faster flow of the upstream ice. This would mean an increased outflow from the glacier and thus an increased contribution to sea level rise (increasing from 4% of sea level rise to 5% of sea level rise in the short term). Under the hypothesis of marine ice cliff instability, the exposing of tall cliffs from the ice shelf's failure may lead to a chain reaction of collapse over centuries, although the veracity of this hypothesis has been disputed by other studies.
According to Ted Scambos, a glaciologist at the University of Colorado Boulder and a leader of the International Thwaites Glacier Collaboration, in a late 2021 interview from McMurdo Station, "Things are evolving really rapidly here. It's daunting."At a meeting of the American Geophysical Union in New Orleans, Louisiana in December the situation was described as worrisome.
The Thwaites Glacier Tongue, or Thwaites Ice Tongue ( km wide and has progressively shortened due to ice calving, based on the observational record. It was initially delineated from aerial photographs collected during Operation Highjump in January 1947.), is about 50
On 15 March 2002, the National Ice Center reported that an iceberg named B-22 broke off from the ice tongue. This iceberg was about 85 km long by 65 km wide, with a total area of some 5,490 km2. As of 2003, B-22 had broken into five pieces, with B-22A still in the vicinity of the tongue, while the other smaller pieces had drifted farther west.
The Thwaites Iceberg Tongue ( km northeast of Bear Peninsula. The feature was about 112 km long and 32 km wide, and in January 1966 its southern extent was only 5 km north of Thwaites Glacier Tongue. It consisted of icebergs which had broken off from the Thwaites Ice Tongue and ran aground, and should not be confused with the latter, which is still attached to the grounded ice. It was delineated by the USGS from aerial photographs collected during Operation Highjump and Operation Deepfreeze. It was first noted in the 1930s, but finally detached from the ice tongue and broke up in the late 1980s.) was a large iceberg tongue which was aground in the Amundsen Sea, about 32
In January 2019, NASA discovered an underwater cavity underneath the glacier, with an area two-thirds the size of Manhattan. The cavity formed mostly in the previous three years and is nearly a thousand feet tall, likely speeding up the glacier's decay. Thwaites currently contributes roughly 4% to global sea level rise.
A 5-year international collaboration to study the Thwaites Glacier was established in 2018.
At the beginning of 2020, researchers from the ITGC took measurements to develop scenarios for the future of the glacier and to predict the time frame for a possible collapse: The erosion of the glacier by warmed ocean water seems to be stronger than expected. The researchers noted with concern, that at the baseline of the glacier, the temperature of the water is already more than two degrees above freezing point. They confirm thawing of the Thwaites glacier contributes about four percent of global sea-level rise.The collapse of this glacier alone would raise the sea level by about 65 centimetres (25 inches).
An iceberg is a piece of freshwater ice more than 15 m long that has broken off a glacier or an ice shelf and is floating freely in open (salt) water. Smaller chunks of floating glacially-derived ice are called "growlers" or "bergy bits". Both are generally spawned from disintegrating icebergs. Iceberg size classes, as established by the International Ice Patrol, are summarized in Table 1. The 1912 loss of the RMS Titanic led to the formation of the International Ice Patrol in 1914. Much of an iceberg is below the surface, which led to the expression "tip of the iceberg" to illustrate a small part of a larger unseen issue. Icebergs are considered a serious maritime hazard.
The Ross Ice Shelf is the largest ice shelf of Antarctica. It is several hundred metres thick. The nearly vertical ice front to the open sea is more than 600 kilometres (370 mi) long, and between 15 and 50 metres high above the water surface. Ninety percent of the floating ice, however, is below the water surface.
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 boundary between the floating ice shelf and the anchor ice that feeds it is the grounding line. The thickness of ice shelves can range from about 100 m (330 ft) to 1,000 m (3,300 ft).
The Filchner-Ronne Ice Shelf, also known as Ronne-Filchner Ice Shelf, is an Antarctic ice shelf bordering the Weddell Sea.
The Amundsen Sea, an arm of the Southern Ocean off Marie Byrd Land in western Antarctica, lies between Cape Flying Fish to the east and Cape Dart on Siple Island to the west. Cape Flying Fish marks the boundary between the Amundsen Sea and the Bellingshausen Sea. West of Cape Dart there is no named marginal sea of the Southern Ocean between the Amundsen and Ross Seas. The Norwegian expedition of 1928–1929 under Captain Nils Larsen named the body of water for the Norwegian polar explorer Roald Amundsen while exploring this area in February 1929.
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 a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, and outlet glaciers that drain into the Amundsen Sea.
The Larsen Ice Shelf is a long ice shelf in the northwest part of the Weddell Sea, extending along the east coast of the Antarctic Peninsula from Cape Longing to Smith Peninsula. It is named after Captain Carl Anton Larsen, the master of the Norwegian whaling vessel Jason, who sailed along the ice front as far as 68°10' South during December 1893. In finer detail, the Larsen Ice Shelf is a series of shelves that occupy distinct embayments along the coast. From north to south, the segments are called Larsen A, Larsen B, and Larsen C by researchers who work in the area. Further south, Larsen D and the much smaller Larsen E, F and G are also named.
The Antarctic ice sheet is one of the two polar ice caps of the Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million square kilometres and contains 26.5 million cubic kilometres of ice. A cubic kilometer of ice weighs approximately one metric gigaton, meaning that the ice sheet weighs 26,500,000 gigatons. Approximately 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet, an amount equivalent to about 58 m of sea-level rise. In East Antarctica, the ice sheet rests on a major land mass, while in West Antarctica the bed can extend to more than 2,500 m below sea level.
Iceberg B-15 was the largest recorded iceberg by area. It measured around 295 by 37 kilometres, with a surface area of 11,000 square kilometres. Calved from the Ross Ice Shelf of Antarctica in March 2000, Iceberg B-15 broke up into smaller icebergs, the largest of which was named Iceberg B-15-A. In 2003, B-15A drifted away from Ross Island into the Ross Sea and headed north, eventually breaking up into several smaller icebergs in October 2005. In 2018, a large piece of the original iceberg was steadily moving northward, located between the Falkland Islands and South Georgia Island. As of 2021, the U.S. National Ice Center (USNIC) still lists one extant piece of B-15 that meets the minimum threshold for tracking. This iceberg, B-15ab, measures 20 km × 7 km ; it is currently grounded off the coast of Antarctica in the western sector of the Amery region.
The Drygalski Ice Tongue or Drygalski Barrier or Drygalski Glacier Tongue is a glacier in Antarctica, on the Scott Coast, in the northern McMurdo Sound of Antarctica's Ross Dependency, 240 kilometres (150 mi) north of Ross Island. The Drygalski Ice Tongue is stable by the standards of Antarctica's icefloes, and stretches 70 kilometres (43 mi) out to sea from the David Glacier, reaching the sea from a valley in the Prince Albert Mountains of Victoria Land. The Drygalski Ice Tongue ranges from 14 to 24 kilometres wide.
Smith Glacier is a low-gradient Antarctic glacier, over 160 km (100 mi) long, draining from Toney Mountain in an ENE direction to Amundsen Sea. A northern distributary, Kohler Glacier, drains to Dotson Ice Shelf but the main flow passes to the sea between Bear Peninsula and Mount Murphy, terminating at Crosson Ice Shelf.
Denman Glacier is a glacier 11 to 16 km wide, descending north some 110 km (70 mi), which debouches into the Shackleton Ice Shelf east of David Island, Queen Mary Land. It was discovered in November 1912 by the Western Base party of the Australasian Antarctic Expedition under Sir Douglas Mawson. Mawson named the glacier for Lord Denman, Governor-General of Australia in 1911, a patron of the expedition.
Pine Island Glacier (PIG) is a large ice stream, and the fastest melting glacier in Antarctica, responsible for about 25% of Antarctica's ice loss. The glacier ice streams flow west-northwest along the south side of the Hudson Mountains into Pine Island Bay, Amundsen Sea, Antarctica. It was mapped by the United States Geological Survey (USGS) from surveys and United States Navy (USN) air photos, 1960–66, and named by the Advisory Committee on Antarctic Names (US-ACAN) in association with Pine Island Bay.
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. Studied by glaciologists, the temporal coincidence of glacier retreat with the measured increase of atmospheric greenhouse gases is often cited as an evidentiary underpinning of global warming. Mid-latitude mountain ranges such as the Himalayas, Rockies, Alps, Cascades, and the southern Andes, as well as isolated tropical summits such as Mount Kilimanjaro in Africa, are showing some of the largest proportionate glacial losses.
Totten Glacier is a large glacier draining a major portion of the East Antarctic Ice Sheet, through the Budd Coast of Wilkes Land in the Australian Antarctic Territory. The catchment drained by the glacier is estimated at 538,000 km2 (208,000 sq mi), extending approximately 1,100 km (680 mi) into the interior and holds the potential to raise sea level by at least 3.5 m (11 ft). Totten drains northeastward from the continental ice but turns northwestward at the coast where it terminates in a prominent tongue close east of Cape Waldron. It was first delineated from aerial photographs taken by USN Operation Highjump (1946–47), and named by Advisory Committee on Antarctic Names (US-ACAN) for George M. Totten, midshipman on USS Vincennes of the United States Exploring Expedition (1838–42), who assisted Lieutenant Charles Wilkes with correction of the survey data obtained by the expedition.
The Erebus Ice Tongue is a mountain outlet glacier and the seaward extension of Erebus Glacier from Ross Island. It projects 11 kilometres (6.8 mi) into McMurdo Sound from the Ross Island coastline near Cape Evans, Antarctica. The glacier tongue varies in thickness from 50 metres (160 ft) at the snout to 300 metres (980 ft) at the point where it is grounded on the shoreline. Explorers from Robert F. Scott's Discovery Expedition (1901–1904) named and charted the ice tongue.
Tide gauge measurements show that the current global sea level rise began at the start of the 20th century. Between 1900 and 2017, the globally averaged sea level rose by 16–21 cm. More precise data gathered from satellite radar measurements reveal an accelerating rise of 7.5 cm (3 in) from 1993 to 2017, for an average rate of 31 mm per decade. This acceleration is due mostly to climate change, which includes heating of the ocean and melting of the land-based ice sheets and glaciers. Between 1993 and 2018, the thermal expansion of water contributed 42% to sea level rise; melting of temperate glaciers, 21%; Greenland, 15%; and Antarctica, 8%. Climate scientists expect the rate to further accelerate during the 21st century, with the latest measurements saying the sea levels are currently rising by 3.6 mm per year.
Eric J. Rignot is a Chancellor Professor of Earth system science at the University of California, Irvine, and Senior Research Scientist for the Radar Science and Engineering Section at NASA's Jet Propulsion Laboratory.
Marine ice sheet instability (MISI) describes the potential for ice sheets grounded below sea level to destabilize in a runaway fashion. The mechanism was first proposed in the 1970s and was quickly identified as a means by which even gradual anthropogenic warming could lead to relatively rapid sea level rise. In Antarctica, the West Antarctic Ice Sheet, the Aurora Subglacial Basin, and the Wilkes Basin are each grounded below sea level and are inherently subject to MISI.
Thwaites Ice Shelf, is an Antarctic ice shelf in the Amundsen Sea. It was named by ACAN after Fredrik T. Thwaites, a glacial geologist and geomorphologist. The Thwaites Ice Shelf is one of the biggest ice shelves in West Antarctica, though it is highly unstable and disintegrating rapidly. Since the 1980s, the Thwaites glacier, nicknamed the "Doomsday glacier", has had a net loss of over 600 billion tons of ice, though pinning of the Thwaites Ice Shelf has served to slow the process. The Thwaites Ice Shelf has acted like a dam for the eastern portion of glacier, bracing it and allowing for a slow melt rate, in contrast to the undefended western portion.