{"id":8783,"date":"2026-04-13T04:00:00","date_gmt":"2026-04-13T04:00:00","guid":{"rendered":"https:\/\/godshand.link\/ground_post\/megaberg-ends-its-long-odyssey-at-sea\/"},"modified":"2026-04-13T04:00:00","modified_gmt":"2026-04-13T04:00:00","slug":"megaberg-ends-its-long-odyssey-at-sea","status":"publish","type":"ground_post","link":"http:\/\/godshand.link\/en_gb\/ground_post\/megaberg-ends-its-long-odyssey-at-sea\/","title":{"rendered":"Megaberg Ends Its Long Odyssey at Sea"},"content":{"rendered":"


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Iceberg A-23A ranks among the giants known to have broken, or \u201ccalved,\u201d from Antarctica. Though several other icebergs in the satellite era have been larger, A-23A was remarkable for its longevity. After spending its early days in the Weddell Sea, its journey came to an end in the South Atlantic Ocean, months shy of its 40th birthday.<\/p>\n

These images show the iceberg at the start and end of its lifespan. The MSS<\/a> (Multispectral Scanner System) on Landsat 5<\/a> captured the top image on November 10, 1986, shortly after Iceberg A-23 broke from the Filchner Ice Shelf. (The main section was later renamed A-23A after a smaller piece split off.) It is pictured here with several other major icebergs from the same calving event. A-23A outlived all of them.\u00a0<\/p>\n

The second image, captured by the VIIRS<\/a>\u00a0(Visible Infrared Imaging Radiometer Suite) on the\u00a0NOAA-21<\/a>\u00a0satellite on April 3, 2026, shows what remained of the iceberg at the end of its journey. By this point, the ice had drifted into warmer waters north of South Georgia and the South Sandwich Islands\u2014more than 2,300 kilometers (2,000 miles) north of where the iceberg first calved.<\/p>\n

Iceberg A-23A\u2019s final months brought abundant drift, melt, and breakage. It exited the U.S. National Ice Center<\/a>\u2019s area of analysis during the week of February 6, 2026, and was transferred to the jurisdiction of the Argentinian Meteorological Service as it drifted into maritime traffic lanes, according to the center\u2019s ice analysts.<\/p>\n

Jan Lieser of Australia\u2019s Bureau of Meteorology and Christopher Shuman of the University of Maryland (retired) have long been tracking the iceberg with remote sensing. They estimated that by March 27, 2026<\/a>, A-23A had shrunk to just over 170 square kilometers (66 square miles)\u2014a small fraction of the more than 6,000 square kilometers (2,300 square miles) it spanned in 2020 as it lay grounded off the Antarctic coast. Large pools of deep-blue meltwater collected on its surface and likely contributed to its ultimate collapse, visible on March 31<\/a>.<\/p>\n

Clouds obscured some satellite observations of the berg\u2019s final days. \u201cI noticed in recent weeks how Mother Nature seemed to keep a veil (of clouds) over the dying iceberg as if trying to give it some privacy at this stage,\u201d Lieser said. There were still enough observations, however, to capture glimpses of its death throes, as well as the many stages of its long, winding journey.<\/p>\n

Iceberg A-23A \u201ccame of age\u201d during a period of advances<\/a> in Earth observation. The Landsat program, ongoing since the early 1970s<\/a>, captured detailed images throughout the iceberg\u2019s life, while the Terra and Aqua satellites\u2014imaging Earth since the early 2000s\u2014offered broader, daily snapshots as sunlight and clouds allowed.<\/p>\n

By the time A-23A broke free from the seafloor in 2022 and began drifting north, a vastly expanded fleet of missions<\/a> was available to observe its journey\u2014capturing everything from detailed images of its shifting shape to its effects on the surrounding environment. Astronauts aboard the International Space Station added their own close-up perspective<\/a>, while the newer PACE<\/a> satellite identified the iceberg\u2019s ripple effects on marine ecosystems<\/a>. The video below brings together some of NASA\u2019s most striking views of the drifting giant\u2019s journey.<\/p>\n

\u201cThe technology that allows us to tell \u2018iceberg stories\u2019 is a tribute to the engineers and funding that put crucial sensors into orbit to collect those data and make them accessible,\u201d Shuman said. \u201cThrough time, these efforts have allowed us to understand the general patterns of iceberg movement around Antarctica, especially in the last handful of decades.\u201d<\/p>\n

With all the images and data that A-23A and other bergs have left behind, scientists now have even more questions about the factors driving iceberg motion, from ocean currents to the shape of the seafloor. Lieser is particularly interested in the small- to medium-sized bergs that break from the giants, as they pose significant hazards to shipping. These smaller bergs, such as the trail near A-23A on March 1<\/a>, are also notoriously difficult to track, as well as to model in terms of their expected drift.<\/p>\n

The megabergs generated by Antarctica\u2019s vast ice shelves also still carry plenty of mystery. In the case of A-23A, Lieser and Shuman wonder what the bathymetry looks like where it became stuck shortly after calving in 1986 and how the iceberg later became ensnared<\/a> by a rotating vortex of water, or\u00a0Taylor column<\/a>, north of the South Orkney Islands.<\/p>\n

\u201cWe certainly do know a fair bit about the general drift patterns of icebergs and the general environment,\u201d Lieser said. \u201cBut when it comes to individual pieces\u2014large and small\u2014and their tracks, there’s still a fair bit to learn.\u201d<\/p>\n

NASA Earth Observatory images by Michala Garrison, using Landsat data from the\u00a0U.S. Geological Survey<\/a>, VIIRS data from NASA\u00a0EOSDIS LANCE<\/a>,\u00a0GIBS\/Worldview<\/a>, and the Joint Polar Satellite System<\/a> (JPSS). Map made using data from the U.S. National Ice Center<\/a> (USNIC) and the Antarctic Iceberg Tracking Database<\/a> (BYU). Earth Observatory video by Kathryn Hansen, featuring imagery from sources listed under References & Resources. Story by Kathryn Hansen<\/em>.<\/p>\n