Oh, look. Something interesting is happening. Wait. Could it be dangerous? I think it is dangerous. Oh no. The peril is growing! This time it’s serious! Oh. Oh wait. Hang on. Never mind.
[Before we start, pick your favourite areal comparator and keep it in mind: see if you spot it bolded or underlined below. I have also bolded a couple of errors of fact in the news reports.]
About four and a half years ago a large chunk of the Larsen C ice shelf broke off:
Trillion-tonne iceberg breaks off Antarctica (Update)
A Delaware-sized iceberg, one of the largest ever seen, was set adrift after snapping from a West Antarctic ice shelf that will be closely watched for signs of collapse, scientists said Wednesday. A crack in the Larsen C ice shelf, a drifting extension of the land-based ice sheet, finally broke through after inching its way across the frozen formation for years.
Phys.org 12 July 2017
Refreshingly, there was a range of opinion about the role of climate change.
For Catherine Ritz of France’s CNRS research institute, the iceberg calving pointed to rising pressure from global warming. But O’Leary [glaciologist, Swansea] and Drinkwater [ESA ice guy] said this particular iceberg calving was unrelated to global warming.”
After the breakthrough, nothing much happened for a while. A68 just hung about without moving very far. This was not surprising for such a large lump of ice in an area of sea that is frozen for most of the year. But it gradually moved north, and by late 2020 was in the open ocean. It was at this point that the British Antarctic Survey got interested. On 4th November they published a press release.
A68 iceberg heads towards South Georgia
An iceberg is heading towards the sub-Antarctic island of South Georgia. A68a – the size of the UK county of Somerset – broke off from the Larsen C ice shelf in 2017 and has been drifting north ever since. If it becomes grounded near the island, it could cause disruption to the local wildlife that forage in the food-rich ocean. Professor Geraint Tarling, an ecologist at British Antarctic Survey, says: “Ecosystems can and will bounce back of course, but there’s a danger here that if this iceberg gets stuck, it could be there for 10 years. An iceberg has massive implications for where land-based predators might be able to forage.”
BAS 4 November 2020
The idea that A68 might end up stuck on South Georgia for ten years was very far fetched. In these pages I made the point (after this date; you can accuse me of being wise after the event, and I can’t refute that) that South Georgia is at an equivalent latitude to Whitby. I did not make any comparisons between the life forms seen on the respective beaches of the two locations. (Another giant iceberg, B9, did get stuck for a long time in Commonwealth Bay, a piece of coast much farther south on the edge of the white continent. That is a different story entirely, which I might cover at some stage. This is already too long to compare A68 with B9 here.)
The BAS press release spawned some news stories.
Huge iceberg ‘the size of Norfolk’ on collision course with British overseas territory of South Georgia
Billions of tonnes of ice could scour seabed and block access to feeding grounds for seals and penguins, scientists warn
The Independent 4 November 2020, filed under climate/news
World’s Largest Iceberg on Course to Hit Penguin Populations
The world’s largest iceberg is headed for Antarctica. Scientists say there’s a possibility the iceberg could anchor itself offshore of the South Atlantic island. This spot is home to thousands of seals and penguins, which would see their food gathering disrupted should the island get the iceberg.
One Green Planet 4 November 2020
Two days after the press release, the Independent had a piece about the iceberg’s parent ice sheet, Larsen C. This drew a direct line between climate change and the melting of Larsen C.
Melting of Antarctica’s Larsen C Ice Shelf at 40-year record high, study says
Exclusive: The rapid melting of Antarctica’s fourth-largest ice shelf is a ‘glimpse of things to come’, a climate scientist told The Independent
A collapse of Larsen C, if it occurred…would impact on sub-shelf habitat and shelf ocean circulation. And, as we have seen lately with A68 drifting towards South Georgia, large icebergs heading north can pose a threat to wildlife.
The Independent, citing Suzanne Bevan of Swansea U, 6 November 2020
We have not seen that icebergs heading north pose a threat to wildlife. All we have seen so far is wise minds saying wildlife might be at risk, echoed by a compliant media. That is different from a threat being proven.
Things go a bit quiet for a while. Then on 16 December, another entry in size comparison bingo:
Un iceberg géant, plus grand que le Luxembourg, va heurter une île britannique
As the iceberg breaks up, the alarm does not begin to dial back.
Iceberg due to collide with island splits in 2
Earthsky 20 December 2020
One piece is city-sized (about 12 miles or 18 km long), and the other is much bigger (about 80 miles, or 135 km, long). Scientists said the giant berg might or might not collide with the island this month, wreaking havoc near the island’s waters.”
The ESA press release cited says:
The new chunk of ice is around 18 km [11 miles] long and approximately 140 sq km [54 sq mi], around the same size as Seville, Spain.
(The article includes a helpful link to wiki/Seville.)
As the berg drifts menacingly close to South Georgia Island, scientists around the world are watching to see what the berg [sic] will do next. Penguins and seals need access to the sea to feed so the iceberg could easily block their foraging routes and life on the seafloor could be crushed if the berg grounds. The fear, according to ESA scientists, is that if the berg does anchor against the South Georgia coast, it could remain there for up to 10 years.”
By 23rd December the danger seemed to have passed, but not according to the BBC.
Giant Antarctic iceberg A68a is not done yet
[If A68 snags on SG] then worries about the effects the berg could have on the territory’s wildlife will resurface. Penguins and seals might be obstructed as they forage for fish and krill.
BBC, 23 December 2020
Size comparison bingo from the article:
What started as a behemoth measuring 5,664 sq km (that’s roughly a quarter of the area of Wales) is now down to just 2,606 sq km (about the size of the English county of Durham).
The BBC article (which is by Jonathan Amos) does to its credit have a refreshing paragraph on why A68 has “little” to do with climate change. It features new images by the RAF, “which flew another sortie… to assess the situation.”
Huge iceberg breaking up off South Georgia Island is still a threat
What effects on wildlife and the ecosystem the icebergs will have are unknown
For now, A68 poses a large threat to the region’s wildlife and marine biodiversity. Large icebergs with deep keels “scour the seabeds,” explains Tarling [BAS ecologist]. “What’s really important about South Georgia is that it’s incredibly diverse on the seabeds. It’s a diversity almost equivalent to the Galapagos.” The region’s charismatic penguins and seals will also suffer if the iceberg grounds in place, because it would create a wall between land and their feeding grounds at the edge of the coastal shelf. A68, which contains hundreds of millions of tons of freshwater, will ultimately melt, making living conditions harder for creatures such as algae and plankton that have adapted to living in saltwater.
National Geographic 28 December 2020
After another month, the threat had definitely melted away.
Split signals end for remnant of Antarctic iceberg A68a
The once-mighty iceberg A68a looks to be in its death throes. At its greatest extent, it was about a quarter of the size of Wales – or New Jersey or Israel. Towards the end of last year, A68a looked from space like a huge pointing hand. Its still significant bulk prompted fears that it could disrupt life on South Georgia should it become grounded just offshore in shallow water. The concern was that the presence of such a large obstacle might disrupt the foraging behaviour of the island’s many penguins and seals. With the latest disintegration event, the danger of this scenario seems to have passed. A major question now is whether the scientific expedition that was aiming to study the iceberg will have anything left to observe by the time it arrives on site.
BBC 28 January 2021
An excellent question, considering that the expedition hadn’t set off by then.
Giant Iceberg Mission Begins
Professor Geraint Tarling, an ecologist at British Antarctic Survey, says: “The icebergs are going to cause devastation to the sea floor by scouring the seabed communities of sponges, brittle stars, worms and sea-urchins, so decreasing biodiversity. These communities help store large amounts of carbon in their body tissue and surrounding sediment. Destruction by the icebergs will release this stored carbon back into the water and, potentially, the atmosphere, which would be a further negative impact.”
BAS 2 February 2021
A fortnight later, the scientists had made a start.
Robotic gliders deployed on giant iceberg mission
Dr Martin Collins, Science Manager for South Georgia at British Antarctic Survey, says: “We have watched with great interest as this giant iceberg has calved into smaller pieces around South Georgia. We will be looking at the impact of enormous quantities of mineral dust coming off the icebergs that will fertilise the ocean plankton around them, and cascade up the food chain.”
BAS 17 February 2021
The Mail thought it was all over:
Is this the end of the A68a iceberg? Enormous block of Antarctic ice that was once three and a half times bigger than LONDON has disintegrated into an ‘alphabet soup’, NASA reveals
“The calving of ice from the ice sheets of Antarctica is a big concern for researchers, as the continent holds enough freshwater to raise global sea levels by approximately 8.2 feet (2.5 meters).”
Daily Mail 18 February 2021
Of the fragments:
‘We will continue to monitor their movement as they may still ground on the shallower continental shelf around South Georgia, as previous icebergs have done,’ she [Laura Gerrish of BAS] added.
The mission was a resounding success:
End of giant iceberg A-68
The mission to determine the impact of the giant A-68a iceberg on the important marine ecosystem of sub-Antarctic South Georgia is a success
This week (Monday 19 April) the U.S National Ice Center declared ‘the end’ of the A68 iceberg, because its fragments are now too small to track. This coincides with the return of the mission ship to Southampton in the UK last week (13 April).
BAS 19 April 2021
(What actually happened: one glider got stuck under the ice for a fortnight, the other vanished in late February.)
It must be nice to be able to deploy vast resources to go and send two robot subs to have a poke about under an iceberg. Few ecologists know this feeling, that’s for sure.
It strikes me that there was little point getting so excited about A68 whether it had a good chance of lodging in the shallows by South Georgia or not. It is not as if the affected penguins were going to be translocated en mass to other breeding grounds. We were looking at an event that must have happened time after time in the years before Antarctica was well known – it was discovered in 1820, remember. Only now with our fancy satellites are we able to keep track of such icebergs and panic ourselves about cute little penguins. By increasing our knowledge, we paradoxically only succeed in increasing our worry.
Every animal alive today in the wild will die horribly. That’s the way Nature is. So it is irrational to panic about penguins being cut off from their feeding grounds: it happened many times before we knew about it. It seems perverse to get upset about Nature killing birds as she has done with every bird that ever lived in the pre-civilisation era, while at the same time we go on allowing humans to kill birds deliberately or by accident in other settings.
There never was a chance that A68 would beach in the shallows around South Georgia and linger there for a decade, despite the breathless reporting. Wildlife was not in serious peril. Towards the end there was a small acknowledgement that the dust released from the melting ice would fertilise the local plankton and “cascade up the food chain,” presumably to the benefit of the cute seals and penguins.
Featured image: A shot of A68 in October 2017. Nasa Aqua/Terra.
Note: the Antarctic projection used in the images has the effect of stretching things east-west the farther south you go.
via Climate Scepticism
December 21, 2021 at 10:36AM