Argentine Antarctica mainland. Argentina was the only nation to have an Antarctic base for 40 years until the British built a base on the same islands. Argentina bases its claims on this sector of Antarctica on the following grounds: Argentina's claim to the Antarctic Peninsula overlaps with the Antarctic claims of Chile, 53°W to 90°W, and the UK claims, 20°W to 80°W. Currently, there are no attempts by Argentina or any other country to enforce territorial claims in Antarctica. See List of Antarctic territorial claims. None of these claims have international recognition and have been suspended by the Antarctic Treaty in 1961.
West Antarctica Year (1957–1958) and explorations which disclosed that the Transantarctic Mountains provide a useful regional border between West Antarctica and East Antarctica. Advisory Committee on Antarctic Names (US-ACAN) approved the name in 1962. West Antarctica is mostly covered by a massive ice sheet referred to as the West Antarctic Ice Sheet (WAIS). In recent decades this ice sheet has shown signs of decreasing mass. Unlike East Antarctica, West Antarctica has shown some effects of global warming. The parts of West Antarctica not covered with ice (Antarctic oasis), which are the coasts of the Antarctic Peninsula, constitute a biodiversity region known as