Jonathan Amos

I'm reasonably convinced now that Iceberg A23a has completely collapsed. The USNIC is no longer tracking a berg of that name. But A23k (also not listed) does however lumber on, albeit in a disheveled state. This view is from Thursday (9 April) NOAA-21 VIIRS. usicecenter.gov/Products/Ant...

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.

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.

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.

A small silver lining: Yes, NASA and NOAA did not do briefings for their global temp data sets released today. And they certainly do not emphasize the human causes. But they *did* release them. The work is still happening. data.giss.nasa.gov/gistemp/grap... www.ncei.noaa.gov/access/monit...

🌊❄️ When Antarctic glaciers collapse into the sea, they can trigger huge underwater tsunamis that mix the ocean, affecting ice loss, climate and ecosystems. The project I lead on this is now in the field and featured on Sky News: news.sky.com/story/underw... #Antarctic #OceanMixing #ClimateScience

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.

💥 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.

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.

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.

Speed reading "Science under Siege" - ahead of next week's recording of BBC Science in Action, where co-author @michaelemann.bsky.social joins a panel on the front line of the current assault on science, to answer what can be done. An appropriate topic for the last edition of the 60yr old series.

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.

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.

Iceberg A23a update. It's lost another couple of large chunks in the past few days. Are we getting close to a major fragmentation event? Likely so.

In case you were wondering... Iceberg A23a seen cruising around South Georgia today by Meteosat 12. The old berg still has an area of 2,846 sq km.

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

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.

I can't shake the feeling that these ideas are getting far more attention than their credibility and maturity warrant! Cutting global greenhouse gas emissions as soon as possible is the key to tackling global warming. www.thetimes.com/uk/science/a...

How little we’ve seen: A visual coverage estimate of the deep seafloor | Science Advances www.science.org/doi/10.1126/...

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.

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.

The Penguin Book of Penguins! Coming later this year: a beautifully illustrated book about the world’s most beloved bird, written by British Antarctic Survey’s Peter Fretwell @ptfretwell.bsky.social What better day to reveal the cover the #WorldPenguinDay? ⬇️

Icebergs? The size of a city? 90 miles from the UK? Must be a joke, right? No! Our new paper in @natcomms.nature.com shows massive tabular icebergs broke off the UK in the last ice age before the UK’s ice shelves disintegrated from climate warming. 🧵 www.nature.com/articles/s41... @bas.ac.uk

US National Ice Center formally catalogues A23c, the big off-cut from grounded behemoth A23a. Daughter berg is ~130km² - or 2x Manhattan Island. A23a (~3,100km²) only needs to lose another ~30km² to hand "World's Biggest Iceberg" title to D15a (~3,070km²) in Amery Sea.