Jonathan Amos

@jcdamos.bsky.social

Journalist. Former BBC Science Correspondent. Way too interested in icebergs for my own good.

End days for Iceberg A23. The two largest remaining fragments - A and K - had major blowouts on or just after the 28th of March. The largest chunks are ~50 sq km. A23 calved from the Filchner-Ronne Ice Shelf in 1986. Quite the journey it's had over four decades.

2 April. A23k after fragmentation event (Nasa)2 April. A23a after fragmentation event (Nasa)

The last two big fragments of the once mighty A23 iceberg. The US National Ice Center calls the bottom-left object A23k and the top-right, A23a. Its latest report (20/3/26) said both were about 140 sq km. Latitude is roughly 50 deg S.

Image by Nasa/Terra/Modis 26/3/2026

Iceberg A23a today (17 Feb). A totally clear sky. Utterly stunning. Still refusing to die. Still 500 sq km in area. Image from the Modis instrument on the venerable Aqua satellite, another oldie that's still plugging away.

Iceberg A23a, 17 Feb 2026, Aqua/Modis

The landscape hidden beneath Antarctica's ice sheet has been mapped from space for the first time. Scientists used hi‑res satellite observations to track how the continent’s frozen surface bunches and dips as it moves over the rugged rock bed below. www.bbc.co.uk/news/article...

New map reveals landscape beneath Antarctica in unprecedented detail

Scientists believe the map could shed light on how Antarctica's vast ice sheet will respond to climate change.

bbc.co.uk

One big paddling pool becomes three. Today's view of iceberg A23a (left) and a view from the end of December (right). Notice how the raised rim effect, holding in surface meltwater, has re-established on all three main segments of the broken berg. A23a is turning to slush puppie.

NASA Modis

💥 Boom! And it's just happened. The huge volumes of meltwater that had collected on the surface of iceberg A23a have triggered a massive and catastrophic hydrofracture event. Much of the berg has turned to mush. Three major segments remain, the largest about 500 sq km.

NASA Aqua Modis 11 January

Want to see an iceberg turn to mush? What remains of iceberg A23a (<1,000 sq km) is about to experience death by hydrofracture. Look at all the meltwater sitting atop the berg. The whole thing could just fall apart any day now.

NOAA 20 / VIIRS - Iceberg A23a viewed on 24 December 2025

I haven't heard about the disagreements. The ice was sitting on an ice plain - a very flat bed with low basal drag. These are present beneath the downstream parts of many Antarctic glaciers where the sediment they transport has built a depositional body known as a grounding zone wedge.

A fascinating paper in @NatureGeosci that has already sparked considerable debate in the ice community. It's the super-fast withdrawal of Hektoria Glacier on the eastern side of the Antarctic Peninsula in 2022/23. Words by me in @newscientist.com www.newscientist.com/article/2502...

Antarctic glacier's alarming retreat is the fastest ever seen

Hektoria glacier on the Antarctic Peninsula retreated 25 kilometres in just 15 months. Its rapid melt could have implications for other glaciers and the rate of sea level rise

newscientist.com

Ooops! It's happened again. The remnants of iceberg A23a have been caught on another Taylor Column, this time above the NorthWest Georgia Rise to the north of South Georgia BOT. The fragments have spun around and around for more than a month now.

Fab first data from the UK-supplied Microwave Sounder on the new Metop weather satellite. MWS combines obs from the old MHS & AMSU instruments. MWS measures the temperature and water content sitting at different altitudes. Fundamental data needed by computer models' for medium range forecasts.

European Space Agency@esa.int · 11mo ago

🌎 Fresh data just in from space: the first results from the Microwave Sounder and Radio Occultation Sounder onboard @eumetsat.int’s MetOp-SG-A1 satellite are here, after less than a month in orbit: esa.int/Applications... 📸Eumetsat

First glimpse of MetOp-SG-A1 Microwave Sounder data.

Really clear view today of Iceberg A23a's big fragmentation event. Going back through the data, I think it happened on the 25th/26th. Image from NASA/Terra/Modis. Each new fragment is probably big enough to get a US National Ice Center designation. Likely A23g, A23h and A23i.

NASA Terra/Modis 30/8/25

🚨🚨🚨Boom! Iceberg A23a looks to have undergone a major fragmentation event in the past 24 hours. I count at least three "daughter" bergs (g, h and i ?). Further satellite imagery will confirm. The last intact measurement I made was ~2,250 sq km. @bas.ac.uk

Iceberg A23a Nasa Terra/Modis 28/8/25

Sentinel-1 has finally got a clear view of iceberg A23a (13/6/25). The berg is much diminished as it skirts around South Georgia. And the US National Ice Center has updated its stats: A23a is now only the world's second biggest berg at 829.79 sqNM, or 2846,11 sqKM.

PolarView 13/5/25

The movement of iceberg A23a over the past seven days. It's moved about 80km to the southeast of the position where it grounded off the coast of South Georgia in early March. Zoomed in animation from Meteosat-12.

Somebody's got itchy feet! Iceberg A23a has moved in the past couple of days. It grounded close to South Georgia back at the beginning of March. But the erosion and melting since then has clearly allowed it to break free. Does it now reground or sweep off around the island?

Nasa Worldview image of iceberg A23a

Latest #CopernicusAtmosphere AOD forecast (from 30/05 00 UTC) shows smoke plume from devastating (&growing) Canadian #wildfires continuing across the Atlantic with hazy skies for Europe over next few days atmosphere.copernicus.eu/charts/packa... @copernicusecmwf.bsky.social @ecmwf.int

Mark Parrington@mparrington.bsky.social · last yr.

A new smoke plume from Canadian #wildfires crossing the North Atlantic in next few days to Europe noting also #SaharanDust for NW Africa/SW Europe. #CopernicusAtmosphere 27 May 00 UTC aerosol optical depth forecast atmosphere.copernicus.eu/charts/packa... @copernicusecmwf.bsky.social @ecmwf.int

With days shortening at South Georgia (it's about 8 hours from sunrise to sunset), optical satellite coverage in the region is getting more restricted. Not so for Meteosat, which images the Europe/Africa hemisphere regardless of season. Hence we get a few views of iceberg A23a. Still grounded.

Meteosat view of South Georgia and iceberg A23a. 30/5/25

There was a spectacular view of iceberg A23a on 3 May. Clear skies over the berg and South Georgia. By my measurement, A23a is no longer the world's biggest iceberg. At ~2850 sq km, it's now bested by D15a - but only just. The US National Ice Center will be the final judge on the matter.

Iceberg A23a on 3 May. Copernicus / Sentinel-3

This is almost unbelievable. It's now May and there is still virtually no new sea ice forming in the Bellingshausen Sea (lower left region in image). Image showing sea ice concentration derived from AMSR satellite data is by Institute of Environmental Physics, University of Bremen, Germany.

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