Reagan‑era iceberg A‑23A — once twice the size of Rhode Island — is now on the verge of complete disintegration in the South Atlantic
Iceberg A‑23A, once the world’s largest and grounded for decades in the Weddell Sea, is rapidly disintegrating in the South Atlantic as meltwater ponds and fractures signal imminent collapse during the austral summer, scientists say.
- Long‑lived megaberg: A‑23A calved in 1986 from the Filchner Ice Shelf and was grounded for decades before drifting north around 2020.
- Rapid shrinkage: From ~4,000 km² at formation to roughly 1,182 km² in early January 2026 after major calving — still larger than New York City.
- Visible failure modes: Satellite and astronaut imagery show blue melt ponds, rampart‑moat features and blowouts indicating structural collapse.
- Local relevance: While no direct impacts reach the Inland Empire, the event informs ocean, ecosystem and climate science with downstream policy and planning implications.
What is A‑23A?
A‑23A is a large tabular (flat‑topped) iceberg that calved from Antarctica in 1986. Its original area was about 4,000 km² — nearly twice the size of Rhode Island. Over decades it evolved from a grounded, stable megaberg into one of the most closely tracked ice features on the planet.
Origin and age
The berg broke away from the Filchner Ice Shelf in the Weddell Sea during the Reagan era and became grounded on the shallow seafloor for more than 30 years. Around 2020 it freed itself and began a slow northward journey driven by currents and winds into the South Atlantic.
Key source material and interpretations are available via the NASA Earth Observatory and the British Antarctic Survey.
Size then and now
Initial estimates placed A‑23A at roughly 4,000 km². As it entered warmer waters and suffered multiple calving events through 2025, operational tracking showed dramatic loss. The U.S. National Ice Center Antarctic iceberg table listed an area near 1,182 km² (456 mi²) in early January 2026. Different agencies report slightly different numbers because of timing and counting rules, but all confirm a steep decline.
Recent breakup — satellite and astronaut observations
Late‑December 2025 imagery shows A‑23A’s surface saturated with blue meltwater pools and many extensive fractures. Analysts describe “blue mush”, rampart‑moat rims and apparent blowouts where ponded water has punched through edge fractures and flushed fresh water and debris into the sea — clear signs of structural failure.
For detailed interpretive imagery see the NASA Earth Observatory case note.
How the numbers differ — and why
Agencies use different measurement methods, timestamps and fragment‑counting rules. NOAA/NESDIS and GOES‑East highlighted the berg as the world’s largest in early 2025 at about Rhode Island scale; operational tables from the U.S. National Ice Center and later satellite analyses show rapid reduction after mid‑ to late‑2025 calving events. The trend — severe mass loss — is consistent across datasets.
The science of breakup: melt ponds, ramparts and Taylor columns
Scientists link several processes: surface meltwater pools concentrate weight and stress, widening cracks; rampart‑moat patterns indicate side melting and flex; and blowouts occur when ponded water forces through fractures. Ocean dynamics also matter — A‑23A was once trapped over Pirie Bank in a Taylor column that slowed and even spun the berg, delaying its trip into warmer seas. Once freed it moved into the Antarctic Circumpolar Current and then warmer South Atlantic waters that accelerated its decay.
See the EUMETSAT case study and the British Antarctic Survey analysis for process details.
Ecological and ocean chemistry effects
Large icebergs act like floating laboratories. As A‑23A melts it releases fresh water and micronutrients (including iron) that can fertilize phytoplankton and alter local food webs. British Antarctic Survey teams sampled around A‑23A in December 2023 to measure nutrient and plankton responses, informing models of carbon uptake and regional ecosystem impacts.
What experts say
“A‑23A is unlikely to last through the austral summer,” said Chris Shuman, a glaciologist cited in NASA’s analysis. Sea‑ice scientist Walt Meier noted the berg is floating in roughly 3 °C water and drifting toward even warmer seas — conditions that can fragment a decades‑old megaberg rapidly.
Monitoring and tracking
Multiple agencies continue to follow A‑23A. The U.S. National Ice Center assigns designations and publishes routine position and size tables; NOAA/NESDIS and EUMETSAT provide satellite monitoring; and NASA Earth Observatory offers visual and interpretive coverage.
Implications for the Inland Empire, California
There is no direct local economic damage to the Inland Empire (San Bernardino and Riverside counties) from A‑23A’s breakup. Still, the event carries indirect relevance:
- Economic links: Improved ocean and carbon models can affect fisheries management and seafood markets, with downstream effects on California ports and supply chains.
- Policy and planning: Rapid environmental changes like this strengthen arguments for resilient infrastructure, updated hazard planning, and investments in climate science.
- Education and outreach: Local universities and museums can use satellite imagery and the berg’s story to teach climate, remote sensing and policy lessons.
Practical takeaways for residents
Residents of the Inland Empire need not prepare for iceberg hazards. Instead, the practical message is to support local resilience measures that address heat, wildfire and water stress. Staying informed about climate science and backing conservation, heat mitigation and emergency preparedness are sensible responses.
Sources and further reading
Primary sources and extended reporting:
- NASA Earth Observatory: “Meltwater turns iceberg A‑23A blue”
- U.S. National Ice Center Antarctic iceberg table
- British Antarctic Survey media post on A‑23A
- NOAA/NESDIS tracking via GOES‑East
- EUMETSAT case study: “Iceberg A23‑A through the decades”
- Wikipedia: A23a
Reporting by Times Media Service.
