File:Sea Ice off Brunt Ice Shelf (MODIS 2021-01-31).jpg

English: On January 25, 2021, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua satellite acquired a true-color image of copious sea ice floating in the Weddell Sea near the Brunt Ice Shelf.

Sea ice is frozen seawater that floats on the ocean surface. Frigid Antarctic winters cause widespread freeze up of surface water near the continent. Much of winter’s ice is “fast ice”—ice that stays fast in place because it is attached to shore. As daylight lengthens and temperatures rise through spring and summer, Antarctic sea ice inevitably begins to melt. As melting occurs, fast ice begins to break up into chunks. Many of these chunks can be classified as “bergy bits” or “growlers”, but sea ice can be even smaller especially as melting advances. According to the National Oceanic and Atmospheric Administration (NOAA), a bergy bit is a medium to large fragment of ice with a height generally greater than three feet but less than 16 feet above sea level, with an area of about 1,076-3,299 square feet. Growlers are small fragments of ice and are roughly the size of a truck or grand piano. Icebergs are larger than bergy bits. Sea ice maximum—the largest amount of sea ice—in the Antarctic usually occurs in September while the minimum usually occurs in February.

While sea ice captures attention in this image, expectations of a calving event have turned the eyes of the world the Brunt Ice Shelf itself. A substantial crack first appeared on the shelf in October 2016 and has continued to extend eastward. In January 2019, a rift that had been stable for about 35 years began to rapidly advance, moving toward the 2016 crack. By February 2019, scientists were waiting for the “imminent” calving of an iceberg that would likely measure about twice the size of New York City. While the cracking and rifting continues, the Brunt Ice Shelf has continued to hold together—so far. Whether it can withstand the warmth of another Antarctic summer or not is anyone’s guess.

On January 12, 2021, NASA’s Earth Observatory published an informative story on the Brunt Ice Shelf and the impending calving event. To enjoy this story, titled “Brunt Breaking Up with Antarctica this Year?, click here .