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Colossal Iceberg Trapped Near Antarctica’s ‘Doomsday Glacier’ for 20 Years Is Finally on the Move

Iceberg B-22A, which first broke off from Antarctica’s Thwaites Glacier in 2002, is finally moving away from the South Pole after being freed from its seafloor tether

An aerial image of B-22A (center) captured by NASA's Terra satellite

An aerial image of B-22A (center) captured by NASA's Terra satellite on Feb. 2, 2022.

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An enormous iceberg that first broke off Antarctica's "Doomsday Glacier" more than 20 years ago is finally waving goodbye to the icy continent after being freed from the seafloor, which had trapped the ice chunk in place for over a decade.

The long-lived berg, known as B-22A, is the largest remaining piece of B-22, a colossal icy mass the size of Rhode Island that snapped off Thwaites Glacier — also known as the Doomsday Glacier — in March 2002. During this time, B-22A has retained a lot of its original ice and covers around 1,160 square miles (3,000 square kilometers), which is around twice the size of Houston, Texas.

After breaking free from the glacier in the early aughts, B-22A floated freely just off the Antarctic coast until it got caught on a raised section of the seafloor in 2012. The berg became stuck around 32 miles (53 kilometers) from where it was birthed, meaning it averaged a pitiful 1.6 miles (2.6 km) of movement per year, which is one of the slowest average crawls of any iceberg on record, according to .


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But now, the aging iceberg has been set free and is making up for lost time. Satellite photos from NASA's Terra and Aqua satellites revealed that the berg began to move again on Oct. 24, 2022, according to NASA's . As of March 26, B-22A has drifted around 110 miles (175 km) to the northwest, meaning it has traveled more than three times as far in six months than it managed in the previous 247 months. 

A timelapse of the iceberg moving away from Antarctica between Oct. 24, 2002 and March 26, 2023. Credit: Gif from video by Lauren Dauphin, using MODIS data from NASA EOSDIS  and 

Once a large iceberg calves from an ice sheet or glacier, it normally takes only a few years to journey away from polar regions and into warmer waters, where it will eventually break apart. It's rare for the floating ice chunks to stay intact for more than a decade, but it is not unheard of. In March 2013, a massive iceberg named B-15T was , by which time it had circled half the continent.

Scientists are particularly concerned about B-22A venturing away from  because it may impact the stability of the Thwaites Glacier. 

Stationary icebergs can cool the surrounding waters, which can have a stabilizing effect on glaciers and other ice masses but also harm marine ecosystems if they get stuck further afield, according to the Earth Observatory. In spring 2020, alarms were raised when the world's formerly largest iceberg, A68, became set on a collision course with South Georgia, an island in the Southern Atlantic Ocean. Experts feared that the mighty berg would become trapped on the surrounding seafloor, like B-22A, and that its cooling effect . (A68 eventually broke apart after narrowly missing South Georgia.)

Despite , the Doomsday Glacier remains in a precarious situation, and recent research has shown that its melt rate . Therefore, it is important that researchers monitor any changes that may be triggered by an iceberg's departure.

Scientists will also track B-22A as it moves away from Antarctica to see where and when it will break apart. Icebergs can dump a lot of fresh water as they melt, which can impact ecosystems and ocean currents as they slowly die: A68  over a period of three years. 

B-22A is not the only major Antarctic iceberg to embark on a journey recently. In early March, researchers from the British Antarctic Survey , an iceberg the size of Los Angeles that broke off from the Brunt Ice Shelf on Jan. 22 after an . And in October 2022, satellites spotted the world's largest iceberg, A-76A, as it  and began drifting toward the equator.

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Harry Baker is a U.K.-based staff writer at Live Science.
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