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Context: Antarctica’s two sides formed millions of years apart: study

Details

Introduction

Antarctica is divided into West Antarctica and East Antarctica by the Transantarctic Mountains, which stretch from Victoria Land to the Ross Sea.

Location

• West Antarctica, or Lesser Antarctica lies within the Western Hemisphere, and includes the Antarctic Peninsula.
• Is covered by the West Antarctic Ice Sheet.
• It lies between the Ross Sea and the Weddell Sea.
• It attached to a giant peninsula, stretching from the South Pole towards the tip of South America.

• The highest point of antarctica is Vinson Massif (or Mount Vinson) at 4892 metres; and the Bentley Subglacial Trench is the lowest point of antarctica which is not covered by an ocean, at -2540 metres, both are located in west antarctica.
• Lesser Antarctica is made up of younger, volcanic and sedimentary rock.
• Lesser Antarctica is part of the “Ring of Fire,” a tectonically active area around the Pacific Ocean.
• West Antarctica is surrounded by a strong clockwise circumpolar circulation. These currents play a significant role in the global thermohaline circulation, and are one of the reasons why Antarctica is so cold.

West Antarctic Rift System (WARS)

• It is one of the major active continental rifts on Earth.It has a major influence on ice flows in West Antarctica.
• In western Marie Byrd Land, active glaciers flow through fault-bounded valleys (grabens) of the WARS.

West Antarctic Ice Sheet (WAIS)

• The West Antarctic Ice Sheet (WAIS) is the segment of the continental ice sheet that covers West Antarctica.
• It 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.
• West Antarctica is currently the world’s largest marine ice sheet.
• The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, and outlet glaciers that drain into the Amundsen Sea.
• The total volume of the entire Antarctic ice sheet is estimated at 26.92 million km3 while the WAIS contains about 2.1 million km3 in ice that is above the sea level, and 1 million km3 (240,000 cu mi) in ice that is below it.
• Climate change impact: Recent studies have shown warmer ocean water is being pushed toward the huge WAIS, destabilizing it and speeding up the decline of its huge glaciers.
• The Antarctica as a whole lost more than 3 trillion tons of ice between 1992 and 2017. Most of that came from West Antarctica, where the rate of ice loss has tripled in the last quarter century.
• Consequences: Thwaites and Pine Island Glacier have been described as part of the "weak underbelly" of the West Antarctic Ice Sheet, in part because they seem vulnerable to irreversible retreat and collapse even under relatively little warming, yet also because if they go, the entire ice sheet is likely to eventually follow.
• 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.

Recent finding

• The permanent glaciation of Antarctic ice activated roughly 34 million years ago but West Antarctica started to permanently glaciate a lot later than East Antarctica – at least seven million years.
• West Antarctica was ice-free in the first glacial maximum instead it was enveloped by dense broadleaf forests and a cool-temperate climate. This helped prevent the formation of ice.

Sources:

Wikipedia, DownToEarth,

PRACTICE QUESTION Q. Thwaites Glacier often mentioned in news is associated with which of the following? A. Greenland B. Arctic C. West Antarctica D. East Antarctica Answer C