A huge 20-year-old stationary iceberg in Antarctica has started to move



by LORENZO CIOTTI

A huge 20-year-old stationary iceberg in Antarctica has started to move

B-22A, A huge iceberg that has been stationary off the coast of Antarctica for over 20 years has started to move. The definitive detachment of B-22A is an event that worries scientists, who are waiting to see if and how this change will affect the Thwaites Glacier which is not visible in these images as it is located out of frame, at the top.

Stranded icebergs play an important role in stabilizing the area's sea ice, which in turn helps support the continental ice shelf and slow its melting, thereby counteracting sea level rise. According to Christopher Shuman, a glaciologist at the University of Maryland who works at NASA's Goddard Space Flight Center, there are several factors that may have helped the iceberg get moving again.

The relatively warm waters that reach the Amundsen Sea basin probably thinned its mass in the submerged part until it was freed from the shallow sea bed. Wind, waves and tides did the rest. By mid-April, the southern winter has almost completely shrouded this part of Antarctica in darkness.

Some satellite instruments can still "see" the iceberg even in the dark, but to have new natural color images it will be necessary to wait for the return of sunlight at the end of August. The B-22A, which has an area of over 3,000 square kilometers is the largest fragment of the gigantic shelf that separated in early 2002 from the Thwaites Glacier.

But since then it has remained immobile, relatively close to shore in the Amundsen Sea, stranded just 100 kilometers from its place of origin, in relatively shallow water. Now he has taken off. In the fall of 2022, iceberg B-22A broke off the seabed and began drifting northwestward.

The moment when the iceberg set sail was immortalized by these images from the Moderate Resolution Imaging Spectroradiometer instruments of NASA's Terra and Aqua satellites, which show the iceberg's departure from the continent between October 24, 2022 and March 26, 2023. During this period, the B-22A covered about 175 kilometers.