Jonathan Amos
jcdamos.bsky.social
Jonathan Amos
@jcdamos.bsky.social
Journalist. Former BBC Science Correspondent. Way too interested in icebergs for my own good.
Reposted by Jonathan Amos
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.
November 4, 2025 at 7:54 PM
And if you want a longer read, my old mate Mark Poynting has a great write-up on Auntie Beeb. www.bbc.co.uk/news/article...
Rapid Antarctic glacier retreat sparks scientific 'whodunnit'
A new study suggests that changes to Hektoria Glacier are unprecedented - but not all scientists agree.
www.bbc.co.uk
November 3, 2025 at 5:00 PM
"Such records are vital for distinguishing between rapid grounding-line retreat, as is reported to have occurred at Hektoria Glacier, versus the retreat of a floating ice margin through “conventional” iceberg calving processes," says polar SAR specialist Frazer Christie at Airbus Defence and Space.
November 3, 2025 at 5:00 PM
But the paper has caused a stir because there is wide disagreement in the glaciology community about precisely where Hektoria had been fully grounded on bedrock due to a lack of high-accuracy satellite records.
November 3, 2025 at 5:00 PM
Swansea Uni co-author @adrianluckman.bsky.social put this Sentinel-1 movie together. "Although the paleo record indicates some very rapid retreats in the past, the pace of retreat of Hektoria Glacier and its neighbours is unprecedented in the observational record," Adrian says.
November 3, 2025 at 5:00 PM
Ochwat and Colorado/Boulder co-author Ted Scambos described the lightning-fast fracturing as “shocking” and warned that the retreat “changes what’s possible” for important glaciers elsewhere on the continent. www.nature.com/articles/s41...
Record grounded glacier retreat caused by an ice plain calving process - Nature Geoscience
An Antarctic glacier retreated after the loss of landfast ice at a peak rate almost an order of magnitude faster than previously recorded because of buoyancy-driven ice calving, according to an analys...
www.nature.com
November 3, 2025 at 5:00 PM
Hektoria lost ~25km in 15 months, with 8.2km fragmenting in just the Nov/Dec of 2022. Naomi Ochwat et al point to a particular vulnerability: an "ice plain" - a big section of glacier ice sitting on flat seabed rock that suddenly goes afloat, spitting off icebergs like crazy.
November 3, 2025 at 5:00 PM
OK, the US National Ice Center was being a bit more generous than me. It logged A23a at 2,371 sq km. For comparison, the current title holder of the "world's biggest iceberg" is A15a at 3,070 sq km, grounded in the Amery Sea off East Antarctica.
August 29, 2025 at 11:23 AM
Iceberg D15a, grounded in the Amery Sea, is now officially "the world's biggest iceberg".
June 15, 2025 at 7:57 AM
You can see the original grounded position in this BBC map. The berg is following the expected track, riding the prevailing current and hugging the continental shelf. It could always ground again. But if not, it should sweep around SG and go north.
June 4, 2025 at 2:41 PM
And I'm pretty sure now that A23a is no longer the "World's Biggest Iceberg". D15a is larger in my view. But only the US National Ice Center can make that determination and its listing doesn't yet reflect this.
June 1, 2025 at 6:25 PM