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Author Topic: What's new in Antarctica ?  (Read 132810 times)

b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #450 on: February 15, 2019, 06:21:39 PM »
Damn! :-\

vox_mundi

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Re: What's new in Antarctica ?
« Reply #451 on: February 16, 2019, 06:53:17 PM »
More Trophic Cascade Collapse ...

Tiny Invertebrates Spell Big Trouble for Southern Ocean Fish
https://phys.org/news/2019-02-nutritious-diet-southern-ocean-fish.html

Like collapsing ice shelves, the surge of barrel-bodied salps in the Southern Ocean tells us that other life forms in Antarctica and its surrounding waters are in decline. Blooms of a gelatinous plankton, known as salp, have been identified in waters south of 60°S, in the Indian Sector of the Southern Ocean, by researcher Paige Kelly

... "In the Southern Ocean, waters south of 60°S are typically full of Antarctic krill, which are a crucial food source for mammals and fish," says Paige, a Ph.D. student at the Institute for Marine and Antarctic Studies and Antarctic Climate and Ecosystems Cooperative Research Centre.

"The presence of salps so far south means that these mammals and fish might have to eat salps instead of krill. And this could have serious consequences for the ecosystem."

The consumption of these East Antarctic salps—which contain less than one third of the calories and protein of krill—could change the weight, reproduction and behaviour of commercially fished species that prefer to feed on krill.

When salps are abundant, Antarctic krill are scarce. Krill are a keystone species here. Everything eats them directly or indirectly. Penguins, baleen whales, seals, seabirds and fish, even krill eat krill. No krill, no Antarctica.

Since the 1970s krill populations have dropped by as much as 70 per cent in their most critical habitat, the southwest Atlantic sector of the Southern Ocean. Krill, especially juveniles, depend on sea ice subsurface matrix of brine channels and crevices, a microcosm of life where innumerable plankton live, feed and hide from predators. Summer krill abundance is correlated with the extent of the previous winter's sea ice.



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Dutch Scientists Probing Mystery of Mass Bird Deaths
https://phys.org/news/2019-02-dutch-scientists-probing-mystery-mass.html

... Why, for example, are only guillemots dying all along the Dutch coastline? Leopold said he has received no similar reports from Belgium or Germany. "They are pretty robust birds," he said, but now, dead birds are washing up "in their thousands"

"That's pointing out that there is something wrong at sea, and that's alarming."
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

maga

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Re: What's new in Antarctica ?
« Reply #452 on: February 19, 2019, 10:45:12 PM »
I just want to draw some attention to a future calving in East Antarctica. I don't know the name of the ice shelf but it's the one directly west of Roi Baudouin Ice Shelf. Big calvings in this area seem to be rather rare.

maga

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Re: What's new in Antarctica ?
« Reply #453 on: February 19, 2019, 10:59:28 PM »
Also a very interesting region to watch is around the southern part of the Wilkins Ice Shelf (and its neighbours). The cracks in the picture (Beethoven Peninsula at bottom) will eventually help to break up Wilkins Ice Shelf completely within the next years.

vox_mundi

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Re: What's new in Antarctica ?
« Reply #454 on: March 05, 2019, 06:37:35 AM »
Mystery of Green Icebergs May Be Solved
https://m.phys.org/news/2019-03-mystery-green-icebergs.html

... Pure ice is blue because ice absorbs more red light than blue light. Most icebergs appear white or blue when floating in seawater, but since the early 1900s explorers and sailors have reported seeing peculiar green icebergs around certain parts of Antarctica.

The green icebergs have been a curiosity to scientists for decades, but now glaciologists report in a new study that they suspect iron oxides in rock dust from Antarctica's mainland are turning some icebergs green. They formulated the new theory after Australian researchers discovered large amounts of iron in East Antarctica's Amery Ice Shelf. Watch a video of the new findings here.



Open Access: Stephen G. Warren et al, Green Icebergs Revisited, Journal of Geophysical Research: Oceans (2019)
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

vox_mundi

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Re: What's new in Antarctica ?
« Reply #455 on: March 25, 2019, 09:49:14 PM »
Antarctic Snowfall Dominated By a Few Extreme Snowstorms
https://phys.org/news/2019-03-antarctic-snowfall-dominated-extreme-snowstorms.html

... Published this month in the journal Geophysical Research Letters, the study analysed daily Antarctic snowfall data starting in the 1970s. It reveals how the most extreme 10 percent of snowfall events account for up to 60 percent of annual snowfall in some places, and are the result of a few large storms that develop over the Southern Ocean.

In one particular case, 44 percent of annual snowfall occurred in a single day. Understanding the significance of these events is critical for scientists interpreting Antarctica's past, as well as predicting how our climate may behave in future.

... "They are often short-lived events, which arrive suddenly and deposit a large fraction of the year's snowfall. If you are an ice core scientist trying to decipher messages from our past climate, and predict the future, knowing about these extreme weather events can be the missing part of the jigsaw." ...

Open Access: John Turner et al. The Dominant Role of Extreme Precipitation Events in Antarctic Snowfall Variability, Geophysical Research Letters (2019)
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

vox_mundi

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Re: What's new in Antarctica ?
« Reply #456 on: March 26, 2019, 05:06:03 PM »
Australian Researchers Find Huge Lakes Beneath Largest East Antarctic Glacier (Totten); Rethink on Sea Level Rise
https://www.abc.net.au/news/2019-03-25/totten-glacier-antarctica-research-using-seismic-study/10936998

Australian researchers have discovered huge underwater lakes beneath the largest glacier in east Antarctica.

The lakes were detected by scientists setting off small explosives 2m below the surface of the Totten glacier and listening to the reflected sound. The Totten glacier is 30km wide and up to two kilometres thick, and has the potential to raise sea levels by seven metres

This study has shown us for the first time that there are substantial amounts of water contained in subglacial lakes, not far from the ocean, that we know very little about.” AAD glaciologist Dr Ben Galton-Fenzi said in a statement.

Video: http://www.antarctica.gov.au/news/2019/seismic-study-allows-scientists-to-see-below-glacier

... "We actually know for a fact that the Totten Glacier is one of the regions that's actually changing.

"We know there's warm water present under the glacier, so we expect this is one of the regions in east Antarctica that's going to change first."
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

gerontocrat

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Re: What's new in Antarctica ?
« Reply #457 on: March 29, 2019, 12:24:03 PM »
The ice-free days project by Tealight's Avatar Nico Sun also shows so well the marked change in Antarctica over the last 4 years.

(I wish I had a computer half as good as his.)
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Susan Anderson

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Re: What's new in Antarctica ?
« Reply #458 on: March 30, 2019, 08:41:31 PM »
Thanks Gerontocrat, those visuals tell the story with excellence!

FredBear

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Re: What's new in Antarctica ?
« Reply #459 on: April 04, 2019, 06:00:45 AM »
Not quite new (the fossils, that is!):-

https://www.bbc.co.uk/news/science-environment-47806440

Susan Anderson

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Re: What's new in Antarctica ?
« Reply #460 on: April 06, 2019, 09:53:22 AM »
Not quite new (the fossils, that is!):-

https://www.bbc.co.uk/news/science-environment-47806440

Thanks, good article, except when it compresses catchup time to 300 years (I've heard 10,000 which may be optimistic, but 300? not if one listens to scientists (though they're only talking about 10-20 meters, and perhaps that's likely) The total rise I've heard for entire ice melt (which a warm Antarctica would imply) is more like 65 meters.

Quote
Temperatures may currently be lower than in the Pliocene, but that's only because there is a lag in the system


Tealight

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Re: What's new in Antarctica ?
« Reply #461 on: April 23, 2019, 01:49:47 AM »
The Antarctic Bedrock data was over 10 times harder to align than Greenland. There are hardly any landmarks, just plain white and with fast ice or ice shelfs you don't even know where the land begins. I had to use huge area images to align islands and then cut it down to individual glaciers. The bedrock resolution is just 1km/px as opposed to 0.15km/px for Greenland data.

https://cryospherecomputing.tk/Bedrock-Antarctica

b_lumenkraft

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Re: What's new in Antarctica ?
« Reply #462 on: April 23, 2019, 09:03:40 AM »
Brilliant job Tealight! Thank you so much for the best reference around.

Stephan

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Re: What's new in Antarctica ?
« Reply #463 on: April 23, 2019, 09:17:36 PM »
WOW.
That's what I'd like to see. Brilliant job, absolutely excellent. Sorry to have only one 'Like' to give...

RoxTheGeologist

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Re: What's new in Antarctica ?
« Reply #464 on: April 23, 2019, 09:26:42 PM »
Nice work Tealight!

You can see how the Pine Island and Thwaites bedrock dips away from the ocean. I wonder how quickly the grounding lines will retreat once warmer dense seawater reaches the reverse slope. Warmer salty water flows down that slope, meeting the grounding line, freshens from melting and mixing with the glacial ice water and then flows up the underside of the glacier from the increase in buoyancy? A rather terrifying thermodynamic instability.
« Last Edit: April 23, 2019, 09:34:25 PM by RoxTheGeologist »

sidd

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Re: What's new in Antarctica ?
« Reply #465 on: April 24, 2019, 05:27:03 AM »
I believe the big hole under Thwaites they found had melted out in three years ... about the size of Manhattan

Still small in the big picture. But how many more are there ?

sidd

Pmt111500

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Re: What's new in Antarctica ?
« Reply #466 on: April 24, 2019, 06:33:43 AM »
Thank you for these, Tealight! Shared the the PIG bedrock image on FB linking to your site.
Amateur observations of Sea Ice since 2003.