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Vast Winter Sea Ice Missing Off West Antarctica, Raising Threat to Thwaites Ice Shelf

Researchers say the large mid‑June loss of winter ice exposes floating shelves to warmer ocean water, increasing the risk of near‑term shelf break‑up and ecological harm.

Overview

  • Satellite imagery in mid‑June shows a huge winter ice shortfall in the Bellingshausen Sea with estimates ranging from about 150,000 square miles to roughly 650,000 square kilometres missing versus 1991–2020 averages.
  • NOAA temperature records and other analyses report sea surface and air temperatures in the region far above normal from January through June, a pattern scientists link to a low‑pressure anomaly and strengthened westerly winds that inhibit refreeze.
  • Glaciologists say the missing protective sea ice increases exposure of floating shelves in front of Pine Island and Thwaites glaciers and that parts of Thwaites’s remaining shelf have been deteriorating and may break off within weeks to months.
  • The ice loss creates immediate ecological stress by removing krill habitat and worsening breeding conditions for ice‑dependent species such as emperor and Adélie penguins, which have already suffered catastrophic breeding failures in recent years.
  • Scientists frame the event in a longer trend of reduced winter refreeze since about 2015 and warn that limited wintertime ocean observations make precise attribution hard even as they note the West Antarctic system’s potential to add more than 10 feet to global sea level if it were to fully collapse.