It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, April 01, 2023
Dispelling The Enduring Myth of Wolf Pack Pecking Order
Who's in charge here? Hint: it's whichever one of these wolves has the most life experience. Photo: Shutterstock
In 1970, biologist David Mech published The Wolf: The Ecology and Behavior of an Endangered Species. The work was a groundbreaking summation of everything science knew about the elusive animals at the time. Popular in academic circles and with laypeople, it remained in print until 2022.
There was just one problem.
Some of the information in it was wrong.
In particular, notions of pack order — the ideas that would become “alpha male” and “alpha female” — were incorrect. Much of the research used to support the concept was conducted on captive wolves by Rudolph Schenkel in the 1930s. Schenkel published a study on his findings in 1947, a paper that later influenced Mech.
“That was what we knew at the time, but I’d say we’ve learned more about wolves since publication than we had in all of previous history,” Mech recently told The New Yorker.
Biologist David Mech on Ellesmere Island. Photo: Jerry Kobalenko
Mech spent the intervening years conducting intensive studies of wolves in the wild, including 24 summers on Ellesmere Island. It was these close observations that convinced him he had to change the narrative about wolf pack behavior.
The biologist has spent years pleading with his publisher to take The Wolf out of print, a request finally granted last year. But even though biologists no longer use Alpha terminology to describe wolf behavior, the damage, such as it is, is done. Like the largely debunked left brain/right brain concept, the idea filtered into the public consciousness and refuses to leave. “Alpha” behavior and its attendant misunderstandings are now lodged firmly in the public consciousness.
So how do wolves determine pack order, if not by struggle, violence, and psychological dominance?
That’s easy, said Kira Cassidy, an associate research scientist with the National Park Service. Like so many things in life, it all comes down to wisdom and experience.
Who’s your daddy?
“The wolves…in those dominant positions are not there because they fought for it,” Cassidy told The New Yorker. “It’s not some battle to get to the top position. They’re just the oldest or the parents. Or in the case of same-sex siblings, it’s a matter of personality.”
A specialist in wolf social structures, Cassidy studies packs in Yellowstone National Park. Packs in the protected area are often large and robust, including aunts and uncles, and occasionally more than one breeding pair, she explained. Order within these large packs is maintained by respect and seniority.
Ellesmere Island’s bold Arctic wolves allowed Mech to study their behavior up close. Photo: Jerry Kobalenko
In fact, having older animals in the pack provides an unexpected bonus, Cassidy found. Older individuals provide much-needed calm and experience when the pack tussles with rival groups.
“They can ease their pack mates and bring them together. Or maybe the older ones help the pack avoid fights that they know they can’t win — which brings up their winning rate overall,” she said.
So the next time someone tries to go “alpha” on you, remember: it’s not about who’s the biggest, strongest, or most impressive. It’s about who’s the wisest.
Andrew Marshall is an award-winning painter, photographer, and freelance writer. Andrew’s essays, illustrations, photographs, and poems can be found scattered across the web and in a variety of extremely low-paying literary journals. You can find more of his work at www.andrewmarshallimages.com, @andrewmarshallimages on Instagram and Facebook, and @pawn_andrew on Twitter (for as long as that lasts).
In August 2020, a man walking along a Grecian beach spotted what looked like a small, dead shark with an odd-looking face. He picked it up from the sand, placed it on a nearby rock, and snapped a picture.
Two and a half years later, the scientific community still has not reached a consensus over what it was. The group that published the original paper on the find in 2022 deemed it a goblin shark(Mitsukurina owstoni) — a rare, deep-sea animal that had never been found in the Mediterranean before.
But on March 13, a comment from a dissenting group of scientists appeared online. “We have doubts that the specimen [from the 2022 paper] is a natural specimen,” they wrote.
The authors of the original paper fired right back with a reply published the same day. It concluded with an analysis “supporting the naturality of the specimen with no doubt.”
Naturality? The internet thinks it’s a picture of a toy.
That’s also true in many corners of the scientific community. And at a casual pass, one deep-sea ecologist’s comparison between the photo and a toy listed on eBay makes the outlook for authenticity seem grim.
(“A” shows the find, “B” shows an actual juvenile goblin shark. Compare “A” to the picture of the toy in the reply below.)
The confusion hinges on the fact that nobody except the photographer has actually seen the specimen. The gist of the dispute is that it looks so much like a toy.
To the naked eye, it’s harder to find differences between the objects in the two photos than similarities. Color notwithstanding, there’s the shape and relative position of each fin, the protruding mouth, and the wrinkle or seam running from the corner of the mouth to the pectoral fin.
Scientific sparring
Athanasios Anastasiadis of Greece’s University of Patras co-authored the original paper claiming the specimen was real. The paper, called New records of rare species in the Mediterranean Sea, is a roundup of novel species recently found in the area. It qualifies the supposed goblin shark with these characteristics:
“[T]he key external taxonomical characters of the species were identified, including an extremely elongated, flat and blade-like snout; relatively small eyes; highly protrusible jaws; and absence of lower lobe from the tail.”
However, the scientists never actually laid eyes on the specimen. The individual who found it, the paper claimed, “placed [it] on rocks to allow the capture of the best possible photograph.”
The dissenting group drew that into focus: “Providing more than one photograph of the record would be of high value,” they wrote.
That’s partly because it’s hard to glean much fine detail from the fairly low-resolution photo. The scientists thus squabbled over whether the specimen had four or five gill slits (four would prove it fake), the size of its teeth, and even the size of the specimen overall.
The smallest goblin shark ever found is around 80cm long. In its initial paper, the team only stated the find wasn’t bigger than that — but in its later reply, it divulged a best estimate that it was only 17-20cm long.
Many opinions, few witnesses
A litany of shark biologists and other experts gave Gizmodo their opinions on the photo — with few suggestions that the photograph shows a real animal.
Jurgen Pollerspock, a co-author of the challenging comment, blamed the lapse on the paper’s reviewers — not its authors.
“In my opinion, the problem and responsibility lie more with the editor of the journal and the reviewers,” he wrote to Gizmodo. He is “convinced that it was an accident” on the authors’ part.
Emails to Anastasiadis had gone unanswered as of this writing. Meanwhile, the only person to have actually seen the “specimen” is the beachcomber who photographed it: Giannis Papadakis.
Sam Anderson takes any writing assignments he can talk his way into while intermittently traveling the American West and Mexico in search of margaritas — er, adventure. He parlayed a decade of roving trade work into a life of fair-weather rock climbing and truck dwelling before (to his parents’ evident relief) finding a way to put his BA in English to use. Sam loves animals, sleeping outdoors, campfire refreshments and a good story.
Elusive ‘einstein’ solves a long-standing math problem An image provided by David Smith, a self-described shape hobbyist who lives in Bridlington, England, of his ‘aperiodic monotile’ shape.
[David Smith via The New York Times]
Siobhan Roberts
29.03.2023 • 03:10
Last November, after a decade of failed attempts, David Smith, a self-described shape hobbyist of Bridlington in East Yorkshire, England, suspected that he might have finally solved an open problem in the mathematics of tiling: That is, he thought he might have discovered an “einstein.”
In less poetic terms, an einstein is an “aperiodic monotile,” a shape that tiles a plane, or an infinite two-dimensional flat surface, but only in a nonrepeating pattern. (The term “einstein” comes from the German “ein stein,” or “one stone” – more loosely, “one tile” or “one shape.”) Your typical wallpaper or tiled floor is part of an infinite pattern that repeats periodically; when shifted, or “translated,” the pattern can be exactly superimposed on itself. An aperiodic tiling displays no such “translational symmetry,” and mathematicians have long sought a single shape that could tile the plane in such a fashion. This is known as the einstein problem.
“I’m always messing about and experimenting with shapes,” said Smith, 64, who worked as a printing technician, among other jobs, and retired early. Although he enjoyed math in high school, he didn’t excel at it, he said. But he has long been “obsessively intrigued” by the einstein problem.
And now a new paper – by Smith and three co-authors with mathematical and computational expertise – proves Smith’s discovery true. The researchers called their einstein “the hat,” as it resembles a fedora. (Smith often sports a bandanna tied around his head.) The paper has not yet been peer reviewed.
“This appears to be a remarkable discovery!” Joshua Socolar, a physicist at Duke University who read an early copy of the paper provided by The New York Times, said in an email. “The most significant aspect for me is that the tiling does not clearly fall into any of the familiar classes of structures that we understand.”
“The mathematical result begs some interesting physics questions,” he added. “One could imagine encountering or fabricating a material with this type of internal structure.” Socolar and Joan Taylor, an independent researcher in Burnie, Tasmania, previously found a hexagonal monotile made of disconnected pieces, which according to some, stretched the rules. (They also found a connected 3D version of the Socolar-Taylor tile.) From 20,426 to 1
Initially, mathematical tiling pursuits were motivated by a broad question: Was there a set of shapes that could tile the plane only nonperiodically? In 1961, mathematician Hao Wang conjectured that such sets were impossible, but his student Robert Berger soon proved the conjecture wrong. Berger discovered an aperiodic set of 20,426 tiles, and thereafter a set of 104.
Then the game became: How few tiles would do the trick? In the 1970s, Sir Roger Penrose, a mathematical physicist at University of Oxford who won the 2020 Nobel Prize in physics for his research on black holes, got the number down to two.
Others have since hit upon shapes for two tiles. “I have a pair or two of my own,” said Chaim Goodman-Strauss, another of the paper’s authors, a professor at the University of Arkansas, who also holds the title of outreach mathematician at the National Museum of Mathematics in New York.
He noted that black and white squares also can make weird nonperiodic patterns, in addition to the familiar, periodic checkerboard pattern. “It’s really pretty trivial to be able to make weird and interesting patterns,” he said. The magic of the two Penrose tiles is that they make only nonperiodic patterns – that’s all they can do.
“But then the Holy Grail was, could you do with one – one tile?” Goodman-Strauss said.
As recently as a few years ago, Sir Roger was in pursuit of an einstein, but he set that exploration aside. “I got the number down to two, and now we have it down to one!” he said of the hat. “It’s a tour de force. I see no reason to disbelieve it.”
The paper provided two proofs, both executed by Joseph Myers, a co-author and a software developer in Cambridge, England. One was a traditional proof, based on a previous method, plus custom code; another deployed a new technique, not computer assisted, devised by Myers.
Sir Roger found the proofs “very complicated.” Nonetheless, he was “extremely intrigued” by the einstein, he said: “It’s a really good shape, strikingly simple.” Imaginative tinkering
The simplicity came honestly. Smith’s investigations were mostly by hand; one of his co-authors described him as an “imaginative tinkerer.”
To begin, he would “fiddle about” on the computer screen with PolyForm Puzzle Solver, software developed by Jaap Scherphuis, a tiling enthusiast and puzzle theorist in Delft, the Netherlands. But if a shape had potential, Smith used a Silhouette cutting machine to produce a first batch of 32 copies from card stock. Then he would fit the tiles together, with no gaps or overlaps, like a jigsaw puzzle, reflecting and rotating tiles as necessary.
“It’s always nice to get hands-on,” Smith said. “It can be quite meditative. And it provides a better understanding of how a shape does or does not tessellate.”
When in November he found a tile that seemed to fill the plane without a repeating pattern, he emailed Craig Kaplan, a co-author and a computer scientist at the University of Waterloo.
“Could this shape be an answer to the so-called ‘einstein problem’ – now wouldn’t that be a thing?” Smith wrote.
“It was clear that something unusual was happening with this shape,” Kaplan said. Taking a computational approach that built on previous research, his algorithm generated larger and larger swaths of hat tiles. “There didn’t seem to be any limit to how large a blob of tiles the software could construct,” he said.
With this raw data, Smith and Kaplan studied the tiling’s hierarchical structure by eye. Kaplan detected and unlocked telltale behavior that opened up a traditional aperiodicity proof – the method mathematicians “pull out of the drawer anytime you have a candidate set of aperiodic tiles,” he said.
The first step, Kaplan said, was to “define a set of four ‘metatiles,’ simple shapes that stand in for small groupings of one, two, or four hats.” The metatiles assemble into four larger shapes that behave similarly. This assembly, from metatiles to supertiles to supersupertiles, ad infinitum, covered “larger and larger mathematical ‘floors’ with copies of the hat,” Kaplan said. “We then show that this sort of hierarchical assembly is essentially the only way to tile the plane with hats, which turns out to be enough to show that it can never tile periodically.”
“It’s very clever,” Berger, a retired electrical engineer in Lexington, Massachusetts, said in an interview. At the risk of seeming picky, he pointed out that because the hat tiling uses reflections – the hat-shaped tile and its mirror image – some might wonder whether this is a two-tile, not one-tile, set of aperiodic monotiles.
Goodman-Strauss had raised this subtlety on a tiling listserv: “Is there one hat or two?” The consensus was that a monotile counts as such even using its reflection. That leaves an open question, Berger said: Is there an einstein that will do the job without reflection? Hiding in the hexagons
Kaplan clarified that “the hat” was not a new geometric invention. It is a polykite – it consists of eight kites. (Take a hexagon and draw three lines, connecting the center of each side to the center of its opposite side; the six shapes that result are kites.)
“It’s likely that others have contemplated this hat shape in the past, just not in a context where they proceeded to investigate its tiling properties,” Kaplan said. “I like to think that it was hiding in plain sight.”
Marjorie Senechal, a mathematician at Smith College, said, “In a certain sense, it has been sitting there all this time, waiting for somebody to find it.” Senechal’s research explores the neighboring realm of mathematical crystallography, and connections with quasicrystals.
“What blows my mind the most is that this aperiodic tiling is laid down on a hexagonal grid, which is about as periodic as you can possibly get,” said Doris Schattschneider, a mathematician at Moravian University, whose research focuses on the mathematical analysis of periodic tilings, especially those by Dutch artist M.C. Escher.
Senechal agreed. “It’s sitting right in the hexagons,” she said. “How many people are going to be kicking themselves around the world wondering, why didn’t I see that?”
The einstein family
Incredibly, Smith later found a second einstein. He called it “the turtle” – a polykite made of not eight kites but 10. It was “uncanny,” Kaplan said. He recalled feeling panicked; he was already “neck deep in the hat.”
But Myers, who had done similar computations, promptly discovered a profound connection between the hat and the turtle. And he discerned that, in fact, there was an entire family of related einsteins – a continuous, uncountable infinity of shapes that morph one to the next.
Smith wasn’t so impressed by some of the other family members. “They looked a bit like impostors, or mutants,” he said.
But this einstein family motivated the second proof, which offers a new tool for proving aperiodicity. The math seemed “too good to be true,” Myers said in an email. “I wasn’t expecting such a different approach to proving aperiodicity – but everything seemed to hold together as I wrote up the details.”
Goodman-Strauss views the new technique as a crucial aspect of the discovery; to date, there were only a handful of aperiodicity proofs. He conceded it was “strong cheese,” perhaps only for hard-core connoisseurs. It took him a couple of days to process. “Then I was thunderstruck,” he said.
Smith was amazed to see the research paper come together. “I was no help, to be honest.” He appreciated the illustrations, he said: “I’m more of a pictures person.”
This shape never existed before (and I'm mesmerised)
Just when you think you've seen it all, mathematicians go and discover the existence of a new shape. That's right a new shape. The new 13-sided two-dimensional shape has been called the 'Hat' and could open up all manner of new design and graphic design challenges and ideas.
You may be asking what makes this 'new'? And why can't anyone just doodle a shape and call it a discovery? The difference between the Hat and any other shape you may draw is it can be used indefinitely in a pattern without ever repeating. This was previously only a theoretical shape, but now it's a reality.
So what does this mean for design and graphic design? Well, for one designers and artists have a new shape to play with, one that has never been used before. The circle is considered the most overused shape in graphic design, and can be found in everything from the Twitter logo to the Apple logo, so a new shape could spark ideas in the best graphic designers.
The Hat is a new 13-sided polykite shape that can be reused in a pattern without ever repeating (Image credit: Smith et al. (2023))
Here's a bit of maths detail: the new Hat shape is known as an aperiodic monotile, which is a maths way of saying a single tile can be used across an entire surface without ever repeating. Once just a theoretical shape, a 13-sided polykite shape made up of eight kites connected at their edges, was discovered by mathematician David Smith and his team when they published a research paper this month.
Co-author Chaim Goodman-Strauss, a mathematician at the National Museum of Mathematics, told the New Scientist(opens in new tab): "You’re literally looking for like a one in a million thing. You filter out the 999,999 of the boring ones, then you’ve got something that’s weird, and then that’s worth further exploration."
What's amazing is the team had to turn off their computers and work out the shape by hand and eye: "And then by hand you start examining them and try to understand them, and start to pull out the structure. That’s where a computer would be worthless as a human had to be involved in constructing a proof that a human could understand."
What will graphic designers do with this new shape? (Image credit: Smith et al. (2023))
The Hat isn't the most accessible shape for design, its angles and 13-sides could make it a tricky one to work into new logos and projects. But I find this new shape absolutely mesmerising. I can already imagine crafters being eager to break out the best laser cutters and Cricut machines and start creating abstract and geometric designs.
Interior designers may want to explore how the shape can be used in tiled floors, fabric patterns and designer wallpaper. But can the maths behind this new shape inform a generation of logo designers to explore a new trend in design? The discovery of an actual new shape, no matter how abstract, is exciting. And for once, it wasn't created by AI.
Woman Bitten By Deadly Blue-Ringed Octopus Will Survive
On March 16, a blue-ringed octopus bit a woman swimming at a beach in Sydney, Australia. The palm-sized octopus is one of the most venomous creatures on earth.
The woman picked up a shell while swimming and one of the tiny octopuses was sheltering inside it. As she picked it up, the octopus fell out and swiftly bit her several times on the stomach. Paramedics rushed to the scene and found the woman suffering from severe abdominal pain. The medics took her to hospital where she is reportedly in a stable condition and will recover.
Limited treatment
Initially, a bite from a blue-ringed octopus is relatively painless, but the venom they inject contains tetrodotoxin, a neurotoxin that can cause respiratory arrest, heart failure, paralysis, and death. The neurotoxin kicks in anywhere between 20 minutes and 24 hours after the bite.
Healthcare professionals can do very little to help. They can only offer general pain medication and the use of a ventilator. The ventilator seems to be key to survival. The venom paralyzes muscles, including those involved in breathing.
“First, the venom blocks nerve signals throughout the body, causing muscle numbness,” scientists at the Ocean Conservancy told TheInertia. “Other symptoms include nausea, vision loss, loss of other senses, and loss of motor skills. Ultimately, it will cause muscle paralysis, leading to respiratory arrest. There is no known antidote but medics can save victims if they begin artificial respiration immediately.”
The blue-ringed octopus only shows its rings when it feels threatened. Photo: Shutterstock
The size of a ping-pong ball
The octopuses are not much larger than a ping-pong ball but contain enough venom to kill 26 adult humans. At least three people have died from their bites since the 1960s. Two of those deaths were in Australia.
The blue-ringed octopus’s neurotoxin helps them catch prey. They produce venom from their salivary glands. When they come across crabs, shrimp, or any little fish they fancy, they can use their beak to dole out some venom. The neurotoxin paralyzes their prey.
Though these little octopuses are incredibly venomous, they are quite docile animals. Their blue rings only appear when they feel threatened. It is a warning sign that they may bite. Most of the time, the species will ignore humans completely. It tries to hide in the sand around coral reefs and shallow waters.
Rebecca McPhee is a freelance writer for ExplorersWeb.
Rebecca has been writing about open water sports, adventure travel, and marine science for three years. Prior to that, Rebecca worked as an Editorial Assistant at Taylor and Francis, and a Wildlife Officer for ORCA.
Based in the UK Rebecca is a science teacher and volunteers for a number of marine charities. She enjoys open water swimming, hiking, diving, and
Photo: Mammoth Museum Laboratory of North-Eastern Federal University (NEFU)
Russian scientists have uncovered a previously unknown species of extinct bison in the Siberian permafrost. The bison is so well-preserved that they think they might be able to clone the animal.
Perfectly preserved for 8,000 years
The specimen is not complete, but the permafrost has superbly maintained the head, forelimbs, and part of its chest. During the autopsy, scientists took tissue samples and removed the bison’s brain.
Photo: NEFU
The almost perfectly preserved animal was found in the Khaastaakh locality of Russia. Initial analysis shows that the bison was between one and two years old when it died, but researchers are unsure exactly how long ago it lived. Similarities to other specimens unearthed in 2010 have led them to believe it is between 8,000 and 9,000 years ago. Radiocarbon studies of the samples should provide more information.
Could scientists clone it?
There are two ways that scientists might attempt the cloning process. The first is to recover completely intact chromosomes from the bison, but this is incredibly difficult.
Paleontologist Love Galen told Live Science, “It is more likely that you can flip a coin and get heads a thousand times in a row than it is to find intact chromosomes from a specimen that is thousands of years old.”
The main problem with the chromosome method is the age of the sample. In 2022, scientists made a breakthrough when they cloned mice from frozen cells. However, the mice cells were less than nine months old and past that point, the process was impossible.
Photo: NEFU
The second cloning method is also incredibly tricky, though more straightforward than finding a chromosome. Researchers would need to sequence as much of the bison’s genome as possible and fill in the gaps with DNA from a living species of bison.
Good reason for skepticism
Though the Russian team hopes that cloning is possible, other experts are skeptical. That skepticism seems well-founded. One of the scientists working with the Russian team is Hwang Woo Suk. In 2005, he published a paper claiming to have cloned human embryos and extracted stem cells from them. A year later his claims were proved false. Woo Suk had fudged the data and violated medical ethics to collect the human egg cells. He only narrowly escaped jail time.
Additionally, the same Russian research team recently claimed they had discovered a 22,000-year-old cave bear in the permafrost. It later turned out to be a 3,500-year-old brown bear.
Photo: NEFU
Over the last few years, there has been a flurry of grand claims about resurrecting extinct animals. An Australian team wants to resurrect the Tasmanian tiger. A biotech company has said that they will bring back the woolly mammoth by 2027 and then plan to work on the dodo.
So far, no extinct animal projects have proven successful. The closest to success might be the Pyrenean ibex. Using frozen cells, a team successfully produced a calf, but it only survived for a few minutes because of major lung problems.
Melting Antarctic ice predicted to cause rapid slowdown of deep ocean current by 2050
New research by Australian scientists suggests 40% slowdown in just three decades could alter world’s climate for centuries
Melting ice around Antarctica will cause a rapid slowdown of a major global deep ocean current by 2050 that could alter the world’s climate for centuries and accelerate sea level rise, according to scientists behind new research.
The research suggests if greenhouse gas emissions continue at today’s levels, the current in the deepest parts of the ocean could slow down by 40% in only three decades.
This, the scientists said, could generate a cascade of impacts that could push up sea levels, alter weather patterns and starve marine life of a vital source of nutrients.
Prof Matt England, of the Climate Change Research Centre at the University of New South Wales and a co-author of the research published in Nature, said the whole deep ocean current was heading for collapse on its current trajectory.
“In the past, these circulations have taken more than 1,000 years or so to change, but this is happening over just a few decades. It’s way faster than we thought these circulations could slow down.
“We are talking about the possible long-term extinction of an iconic water mass.”
The research looked at what would happen in the deep ocean around Antarctica if the fresher water melting from ice sheets was added to climate modelling.
The modelling for the study assumed that global greenhouse gas emissions remained on their current path, but England said lower emissions could lessen the amount of ice melting which – in turn – could slow the decline.
The slowdown in the deep ocean current relates to the amount of water that sinks to the bottom and then flows north.
Dr Qian Li, formerly of the University of New South Wales and now at the Massachusetts Institute of Technology, was the lead author of the research, coordinated by England.
The study did not attempt to explain or quantify the knock-on effects, but the authors wrote the slowdown would “profoundly alter the ocean overturning of heat, fresh water, oxygen, carbon and nutrients, with impacts felt throughout the global ocean for centuries to come”.
In a briefing, the authors said the deep ocean current influenced the climate around the world, with the potential to radically shift rainfall.
England said the slowdown of the deep ocean current caused those deep waters to heat up.
But as that deep water becomes isolated, it could then cause the upper ocean around the continent to get hotter, kicking off a feedback loop where more melting causes accelerated slowing of the current, which then causes more heating and more ice sheet melt.
The deep water that warms the fastest in the study, England said, was in the same areas – particularly in west Antarctica – where ice sheets were already vulnerable and melting.
“We don’t want to set off a self-reinforcing mechanism in those places,” he said, adding that the slowdown effectively stagnates the deep ocean, starving it of oxygen.
When ocean organisms die, they add nutrients to the ocean water that sinks to the bottom and circulates around the world’s ocean. Those nutrients get returned in upwells that feed phytoplankton – a foundation for the marine food chain.
Dr Steve Rintoul, an oceanographer and expert on the Southern Ocean at the Australian government’s Commonwealth Scientific and Industrial Research Organisation, said as the deep ocean circulation slows, fewer nutrients would be returned to upper layers of the ocean – affecting the production of phytoplankton. This process would play out over century-long timescales.
He said: “Once that overturning circulation slows down, we can only get it back again by no longer releasing meltwater around Antarctica, which means we need a cooler climate and then have to wait for it to restart.
“The longer we go on with higher rates of greenhouse gas emissions, the more changes we commit ourselves to.”
In a briefing, the scientists said the modelling was in line with recent observations of changes to the deep ocean circulation that was suggesting a slowdown may already be taking place.
Rintoul added: “Going back 20 years, we thought the deep ocean wasn’t changing that much. It was too far away to be responsive. But the observations and the models have shown that’s not the case.” Frozen memories: rare Antarctic expedition images – in pictures
Scientists also think another major ocean circulation in shallower waters that spans the entire Atlantic Ocean – known as the Atlantic Meridional Overturning Circulation – is also slowing down.
Prof Stefan Rahmstorf, an oceanographer and head of earth system analysis at the Potsdam Institute for Climate Impact Research, said the new study – with which he was not involved – showed “a dramatic further weakening is likely around Antarctica in the coming decades”.
He said models presented in major UN climate reports had a “longstanding and major shortcoming” because they didn’t capture how meltwater influenced the deep ocean.
The ocean depths were refreshed in only a few places on the planet close to major ice sheets in Greenland and Antarctica.
“Unfortunately, these locations are all close to the ice sheets of Greenland and Antarctica, which are melting away as a result of fossil-fuel-caused global warming.
“The meltwater dilutes the salt content of these ocean regions, thereby making the ocean waters less dense and thus not heavy enough to sink down and push away the waters already there.”
A slowdown in the deep ocean current could also affect the amount of CO2 that the deep oceans could lock away, Rahmstorf said.
Deep ocean currents around Antarctica headed for collapse, study finds
The deep ocean circulation that forms around Antarctica could be headed for collapse, say scientists.
Such decline of this ocean circulation will stagnate the bottom of the oceans and generate further impacts affecting climate and marine ecosystems for centuries to come.
The results are detailed in a new study coordinated by Scientia Professor Matthew England, Deputy Director of the ARC Centre for Excellence in Antarctic Science (ACEAS) at UNSW Sydney. The work, published today in Nature, includes lead author Dr. Qian Li—formerly from UNSW and now at the Massachusetts Institute of Technology (MIT)—as well as co-authors from the Australian National University (ANU) and CSIRO.
Cold water that sinks near Antarctica drives the deepest flow of the overturning circulation—a network of currents that spans the world's oceans. The overturning carries heat, carbon, oxygen and nutrients around the globe. This influences climate, sea level and the productivity of marine ecosystems.
"Our modeling shows that if global carbon emissions continue at the current rate, then the Antarctic overturning will slow by more than 40 percent in the next 30 years—and on a trajectory that looks headed towards collapse," says Prof England.
Modeling the deep ocean
About 250 trillion tons of cold, salty, oxygen-rich water sinks near Antarctica each year. This water then spreads northwards and carries oxygen into the deep Indian, Pacific and Atlantic Oceans.
"If the oceans had lungs, this would be one of them," Prof England says.
The international team of scientists modeled the amount of Antarctic deep water produced under the IPCC "high emissions scenario," until 2050.
The model captures detail of the ocean processes that previous models haven't been able to, including how predictions for meltwater from ice might influence the circulation.
This deep ocean current has remained in a relatively stable state for thousands of years, but with increasing greenhouse gas emissions, Antarctic overturning is predicted to slow down significantly over the next few decades.
Impacts of reduced Antarctic overturning
With a collapse of this deep ocean current, the oceans below 4000 meters would stagnate.
"This would trap nutrients in the deep ocean, reducing the nutrients available to support marine life near the ocean surface," says Prof England.
Co-author Dr. Steve Rintoul of CSIRO and the Australian Antarctic Program Partnership says the model simulations show a slowing of the overturning, which then leads to rapid warming of the deep ocean.
"Direct measurements confirm that warming of the deep ocean is indeed already underway," says Dr. Rintoul. The study found melting ice around Antarctica makes the nearby ocean waters less dense, which slows the Antarctic overturning circulation. The melt of the Antarctic and Greenland ice sheets is expected to continue to accelerate as the planet warms.
"Our study shows that the melting of the ice sheets has a dramatic impact on the overturning circulation that regulates Earth's climate," says Dr. Adele Morrison, also from ACEAS and the ANU Research School of Earth Sciences.
"We are talking about the possible long-term extinction of an iconic water mass," says Prof England.
"Such profound changes to the ocean's overturning of heat, freshwater, oxygen, carbon and nutrients will have a significant adverse impact on the oceans for centuries to come."
