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Mahesh

31/10/23 10:19 AM IST

Rapid ice melt in West Antarctica

In News
  • The rapid melting of West Antarctica’s ice sheet due to warm waters around it is now unavoidable, no matter how much carbon emissions are cut, according to a new study.
  • The study, ‘Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century’.
  • It was carried out by Kaitlin Naughten and Paul R Holland, both of whom work at the British Antarctic Survey, and Jan De Rydt of the Northumbria University (UK).
Repercussions of the Ice melting
  • If lost completely, the ice sheet would raise the global mean sea level by 5.3 metres or 17.4 feet — a potentially devastating consequence for millions of people living in vulnerable coastal cities across the world, including in India.
  • Even under a best-case scenario of limiting global warming to 1.5 degree Celsius above pre-industrial levels, water in West Antarctica will continue to get warmer three times faster than in the 20th century, leading to an increased melting of the region’s ice sheet, the analysis has found.
Ice Sheet
  • An ice sheet is essentially a mass of glacial ice that covers more than 50,000 square kilometres of land — roughly large enough to blanket Uttarakhand in ice.
  • There are two major ice sheets in the world today: Greenland ice sheet and Antarctica ice sheet.
  • Together, they contain about two-thirds of all the freshwater on Earth.
  • This means that over time, when ice sheets gain mass, they contribute to a fall in global mean sea level, and when they lose mass, they contribute to a rise in global mean sea level.
Reasons for melting
  • There are various processes through which ice sheets melt. One of them is when warm ocean waters melt ice shelves — the edges of an ice sheet which floats on the ocean.
  • Ice shelves stabilise the land-based glaciers just behind them.
  • If an ice shelf thins or disappears, these glaciers tend to speed up, discharging more ice into the ocean and causing sea level rise.”
  • Note that both ice shelves and ice sheets are different from sea ice, which is the free-floating ice that surrounds the polar regions.
  • Sea ice is created by sea water freezing.
  • The same process is taking place in West Antarctica, particularly the Amundsen Sea.
  • For decades, the region’s ice shelves have been depleting, glaciers have been flowing faster towards the ocean and the ice sheet has been shrinking.
Major findings of the study
  • To conduct the analysis, the scientists have used a high-resolution computer model of the Amundsen Sea to provide the most comprehensive assessment of warming in West Antarctica to date.
  • They have used the model to run many different simulations of the 21st century, totalling over 4,000 years of ocean warming and ice-shelf melting in the Amundsen Sea.
  • The findings are grim.
  • All scenarios show significant and widespread future warming of the Amundsen Sea and increased ice shelves melting. Moreover, there is little to no difference between the scenarios up to 2045.
  • India has a long coastline and a dense population and is therefore vulnerable to sea level rise.
  • If coastal communities cannot afford to defend against the rising seas, for example by building walls, the people would have to move elsewhere or become refugees.
Source- Indian Express

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