The Antarctic Peninsula is the long, mountainous arm of West Antarctica that reaches north towards South America, ending about 1,000 km from Tierra del Fuego across the Drake Passage. It runs about 1,300 km from its base to its tip, covers roughly 522,000 km², is about 80 percent covered by ice, and rises to 3,239 m at Mount Hope in the Eternity Range. It is the mildest and most visited part of the continent, it holds the densest cluster of research stations in Antarctica, and Argentina, Chile and the United Kingdom all claim it under overlapping, unrecognised claims frozen by the Antarctic Treaty. It is also warming far faster than the continent as a whole: the old British station at Faraday recorded 2.94 °C of warming between 1951 and 2004, and three great ice shelves along its eastern coast have broken up since 1995.
Faraday station and 2.94 °C of warming since 1951
The longest record of the change comes from a small island off the west coast. The British set up a station on the Argentine Islands in 1947, later named Faraday, and kept a weather record there for almost half a century before handing the base to Ukraine in 1996, when it became the Vernadsky Research Base. A study in the Journal of Climate in 2006 found that Faraday warmed by 2.94 °C between 1951 and 2004, far faster than Antarctica as a whole and faster than the global average. Across the region the figure usually quoted is about 0.5 °C per decade since the late 1940s. The cause is linked to human-driven climate change acting through stronger westerly winds circling the continent.
On the ground, the warm, moist maritime climate of the northern west coast has been creeping south over the past 50 years, displacing the cold, dry continental climate. Sea ice forms later and melts sooner. Adélie penguins, which depend on sea ice, have declined locally, while gentoo and chinstrap penguins, which tolerate open water, have increased. Mosses are spreading and the peninsula is greening, and the plankton and krill at the base of the food web are shifting with the water temperature.
Larsen A in 1995 and Larsen B in 2002
The most visible damage has been to the ice shelves, the floating platforms of glacier ice that fringe the east coast in the Weddell Sea. The Larsen Ice Shelf, named after the Norwegian whaling captain Carl Anton Larsen, who sailed along its front in December 1893, is really a series of shelves in separate bays, labelled from north to south Larsen A, B, C and D. Together they once covered about 85,000 km²; today they cover about 67,000 km².
Larsen A, the most northerly and just outside the Antarctic Circle, went first. Around 4,000 km² in area from 1961, it calved heavily in the 1980s and disintegrated in January 1995, when about 2,000 km² shattered into small icebergs, a pattern of break-up scientists had not seen before. Larsen B followed between 31 January and March 2002, when 3,250 km² of ice about 220 m thick broke apart in three weeks or less, an area comparable to Rhode Island. Meltwater ponds formed on the surface in the near-continuous summer daylight, drained into crevasses and wedged the shelf apart, while warmer water ate at it from below. Larsen B had been stable for at least 10,000 years.
Ice shelves already float, so their collapse barely changes sea level directly. What they do is hold back the glaciers behind them. After Larsen B went, Crane Glacier, which had fed it, sped up threefold, pouring land ice into the sea. The collapse also exposed seafloor that had been covered for millennia: scientists found a chemical-powered ecosystem of microbial mats and clams living around cold seeps 800 m down.
Larsen C and iceberg A-68 in July 2017
Larsen C, the largest of the series, was the fourth-largest ice shelf in Antarctica in 2017, at about 44,200 km². A rift had been growing across it since at least 2016; by November that year it was about 110 km long, more than 91 m wide and 500 m deep. In July 2017 it broke through, and an iceberg of about 5,800 km², roughly 175 km long and 50 km wide and twice the size of Luxembourg, drifted away. Named A-68, it cut the shelf's area by 12 percent and drifted north into the South Atlantic towards South Georgia, breaking into fragments until, by 16 April 2021, nothing significant remained. Scientists studying the rift warned that the remaining shelf would be less stable than before and could one day go the way of Larsen B.
Similar stresses have reached the west coast. In April 2009 the thin bridge of ice linking the Wilkins Ice Shelf to Charcot Island splintered, and the British Antarctic Survey glaciologist David Vaughan attributed the break-up to warming.
A 1,300 km spine from Graham Land to Palmer Land
Under its ice, the peninsula is not one solid landmass but a string of bedrock islands separated by deep channels, joined together by a grounded ice sheet. Its mountains are a continuation of the Andes: a submarine ridge, the Scotia Arc, links them to the peaks of Tierra del Fuego, and volcanic rocks along western Graham Land record the same subduction that built the Andes. The Drake Passage opened about 30 million years ago as Antarctica pulled away from South America.
The northern part is Graham Land and the southern part Palmer Land, divided by a line between Cape Jeremy and Cape Agassiz at roughly 69° S. The two names reflect old British and American usage; a 1964 agreement settled on "Antarctic Peninsula" for the whole. Chile calls it Tierra de O'Higgins and Argentina Tierra de San Martín. The tip, the Trinity Peninsula, curls north-east to Prime Head at 63°13′S. Most peaks rise to around 2,800 m, but Mount Hope in northern Palmer Land reaches 3,239 m, a height confirmed by a British Antarctic Survey team in 2017.
The coasts are cut by narrow straits. On the west side the Gerlache Strait and the Lemaire Channel separate the mainland from Anvers, Booth and other islands; at the northern tip the Antarctic Sound and the Erebus and Terror Gulf separate it from its outlying islands. Offshore to the north-west lie the South Shetland Islands, split from Graham Land about 4 million years ago by a volcanic rift in the Bransfield Strait; Deception Island at its southern end is an active volcano. The climate is the mildest on the continent: averages of 1 to 2 °C in January and −15 to −20 °C in June, with the west coast north of 68° S above freezing for three or four months each summer.
Esperanza, Rothera and Palmer: stations along the coast
Because it is the mildest and most reachable part of Antarctica, the peninsula and its islands hold the continent's highest concentration of research stations. The first were built during the Second World War by a British military operation, Operation Tabarin, and many more followed in the 1950s as Britain, Chile and Argentina competed to back their claims. Argentina has more bases and personnel on the peninsula than any other country.
Argentina's Esperanza Base at Hope Bay, built in 1953, is the only civilian settlement on the Antarctic mainland, with a school, families and around 56 winter residents; Emilio Marcos Palma, the first person born in Antarctica, was born there. Britain's Rothera Research Station, on Adelaide Island since 1975, serves as the capital of the British Antarctic Territory. The United States runs Palmer Station on Anvers Island, its only station north of the Antarctic Circle, and Ukraine runs Vernadsky, the former Faraday. Others include Chile's Base General Bernardo O'Higgins and Brazil's Comandante Ferraz station.
Three overlapping claims under the 1959 Antarctic Treaty
The peninsula lies where three national claims overlap. The United Kingdom claimed Graham Land in 1908 as part of the Falkland Islands Dependencies, now the British Antarctic Territory. Chile defined its claim, between 53° W and 90° W, in a decree of 6 November 1940. Argentina's claim, between 25° W and 74° W, was formulated from 1941 and officially declared in 1957, and rests partly on its continuous presence at Orcadas Base in the South Orkneys since 1904. Chile and Argentina both cite the continuity of the Andes and the peninsula's proximity to South America. None of the claims has wide international recognition, though Australia, France, New Zealand and Norway recognise the British one. Under the Antarctic Treaty, signed on 1 December 1959 and in force since 1961, all three set their claims aside: the continent south of 60° S is reserved for peaceful scientific use.
Lemaire Channel and a record tourist season
The peninsula is where most Antarctic tourism happens. Ships cross the Drake Passage from Ushuaia and other ports in Tierra del Fuego, and the season runs from November to March. Numbers have climbed steeply: about 14,762 visitors in 1999–2000, more than 37,000 in 2009–10, and around 124,000 cruise visitors a year by 2025, mostly on ships bound for the peninsula. The narrow Lemaire Channel, nicknamed "Kodak Gap", and the sheltered bay of Paradise Harbour are standard stops, and the restored British base at Port Lockroy on Goudier Island, staffed each summer by the UK Antarctic Heritage Trust, receives about 10,000 visitors a year. Researchers have raised concerns about what that growth means for coasts that are already changing so quickly, including the risk of visitors copying hazardous stunts they have seen on social media.
For the stormy water every ship has to cross first, see our guide to the Drake Passage; for how floating ice like Larsen forms and fails, read what an ice shelf is; and for how the peninsula fits into the seven national claims on the continent, our page on Antarctica's territorial claims maps them out.