Iceberg A-81, which broke away from Antarctica’s Brunt Ice Shelf in January 2023, has spent more than three years drifting through the Weddell Sea. Carried north by the clockwise-flowing Weddell Gyre, the roughly 1,550-square-kilometer (600-square-mile) iceberg reached the tip of the Antarctic Peninsula by May 2026 and approached South Georgia Island in the Scotia Sea by late October. Recent satellite imagery suggests it has slowed considerably along the island’s underwater shelf.
A long journey north
Many Antarctic icebergs remain near the ice shelf that produced them for decades, either stranded in place or circulating on coastal currents. Others escape more quickly. A-81 has followed a route north from the Weddell Sea that is also used by other icebergs.
After leaving the Brunt Ice Shelf, A-81 was carried along the Antarctic coast by the Weddell Gyre. By May 2026, it had reached the tip of the Antarctic Peninsula. It then moved into the Scotia Sea and approached South Georgia, a remote South Atlantic island located about 2,300 kilometers (1,400 miles) north-northwest of the Brunt Ice Shelf, by late October 2026.
NASA imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite showed that A-81 had recently slowed significantly and was moving along the edge of South Georgia’s underwater shelf, according to Jan Rieser of the Australian Bureau of Meteorology and Christopher Schumann, a retired researcher from the University of Maryland.
South Georgia has previously slowed or stopped drifting icebergs. In 2025, for example, iceberg A-23A ran aground on the island’s seafloor shelf and was subsequently broken apart.
From crack to iceberg
A-81’s journey began long before its release. One of the Brunt Ice Shelf’s major cracks, known as Chasm 1, remained relatively stable for about 35 years. Around 2012, it began growing again. By 2019, the crack was advancing rapidly enough to suggest that a major break was imminent, but the floating glacier held together for several more years before finally releasing A-81 in January 2023.
Ice calving is a normal part of an ice shelf’s life cycle, but scientists have been monitoring the Brunt Ice Shelf closely because several large icebergs have broken away in quick succession. The shelf is also home to the British Antarctic Survey’s Halley Research Station, a major center for Earth, atmospheric and space science research since the 1950s.
In addition to A-81, the ice shelf produced iceberg A-74 from the North Rift in 2021 and A-83 from the Halloween Crack in 2024. A-74 later disintegrated, while A-83 remained intact and followed A-81 northward, accompanied by several other icebergs. NASA has documented other icebergs traveling through the region.
Source: science.nasa.gov