Images Show Iceberg as Big as Rhode Island Breaking Off Antarctica

An enormous iceberg that set off from the Antarctic coast in late 2022 has been photographed by NASA satellites as it drifts away into the Southern Ocean.

The iceberg, known as B-22A, is around 1,158 square miles in area—around 4 times the size of New York City. The piece floating off into the ocean is the largest remaining chunk of a larger, 1,500 square mile iceberg that sheared off from the Thwaites Glacier in 2002, which was around the size of Rhode Island.

The images of the iceberg floating off into the Amundsen Sea were taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA's Terra and Aqua satellites over the course of several months.

While B-22A technically separated from the Thwaites Glacier in 2001, it became grounded on the seafloor around 60 miles from where it formed and has stayed put for the subsequent two decades afterward. Now, however, the iceberg has freed itself and is floating off into the ocean.

"Large ice sheets around Antarctica do occasionally calve large icebergs, just as part of the natural process of the ice moving towards the sea," Grant R. Bigg, an emeritus professor of Earth system science at the University of Sheffield in England, previously told Newsweek.

While B-22A is a large iceberg, it isn't anywhere near the largest one ever recorded. That record is held by an iceberg called B-15, which measured a massive 4,247 square miles, and broke off from the Ross Ice Shelf of Antarctica in March 2000.

Antarctica is the coldest and driest continent on Earth, containing around 70 percent of the planet's freshwater frozen inside enormous ice sheets. The Thwaites Glacier, located on the West Antarctic ice sheet, is often nicknamed the "doomsday glacier" due to its size and its rate of disintegration.

The glacier, which currently contributes to around 4 percent of sea level rise, is closely monitored by scientists as it melts and is expected to increase its contribution to sea level rise to around 5 percent in the short term, and higher in the future, according to a paper in the journal Science. It has lost around 600 billion tons of ice between the 1980s and 2017, The New York Times reported, and if the entire glacier collapsed, it could lead to over 25 inches of sea level rise worldwide, or over 2 feet.

B-22A shearing off the glacier in 2002 was part of the glacier's slow collapse, but its becoming stuck was helping to slow the loss of floating ice from the Thwaites glacier, according to the New Scientist.

Its 20-year stall is unusual for icebergs, as most tend to free themselves in a much shorter amount of time.

"Twenty-plus years is a long-lived iceberg, generally speaking," Christopher Shuman, a University of Maryland, Baltimore County, glaciologist based at NASA's Goddard Space Flight Center, told NASA Earth Observatory.

The reason that the iceberg finally freed itself in October last year is potentially because of warm waters washing in and thinning the iceberg, enabling it to shift from the seafloor and be swept away, Shuman said.

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