Saturday, November 2, 2024
Friday, November 1, 2024
Meet Japan’s hitchhiking fish
Any chance of a lift?
photograph: bence mate / naturepl.com
From The Economist
Medaka catch rides on obliging birds, confirming one of Darwin’s hunches
The japanese picture book “Soratobu medaka” tells the extraordinary tale of tiny stream-dwelling fish called medaka hitching a ride on an obliging bird to a far-off freshwater pool.
The story has delighted children in the country since 1999, when it was first published, but now comes an even more delightful twist: it is true.
Researchers have long been baffled by fish that turn up in isolated ponds and lakes far from other bodies of water.
Even Charles Darwin was puzzled by the problem.
In “On the Origin of Species”, published in 1859, he postulated that the larvae of aquatic creatures might stick to the feet of unwitting waterbirds.
But his bright idea remained little more than a theory.
In 2019 medaka, wondered if he might have been right.
Mr Yao had observed that many fish-hunting birds commonly walked around in shallow waters dense with plants.
As a number of fish species laid eggs on these aquatic plants, he further wondered if some egg-bearing plants might stick to the birds’ feet as they fly off for puddles new.
The field experiment suggests waterbirds could carry aquatic plants that serve medaka’s spawning substrates.
a Field experimental site.
b A grey heron hooked artificial aquatic plants on its foot and flew away. Arrowhead shows artificial aquatic plants
c An artificial aquatic plant was found at the sink pond. Arrowhead shows the artificial aquatic plant.
d A grey heron carried clumps of algae on its foot and walked in paddy fields. Arrowhead shows algae on heron foot
Eager to test his theory, Mr Yao and his colleagues set up two ponds one metre apart, placing 36 artificial aquatic plants in one and none in the other.
Both were stocked with baitfish to attract birds and had camera traps set to trigger when birds landed.
By the time the experiment ended, six months later, some of the plants had switched ponds.
The researchers were able to catch a bird in the act.
One of their camera traps showed a heron flying off with plants snagged on one of its feet.
Medaka Egg Development
The next step was to determine whether fish eggs could survive being carried out of the water.
Mr Yao focused on medaka, paper-clip-size fish that live in shallow water and attach their eggs to aquatic plants.
When the lab-reared medaka laid their eggs on strips of vegetation, the researchers took the plants out of the water for between zero and 24 hours—at conditions favourable to the unhatched eggs—before returning them.
In a new paper in Science of Nature, Mr Yao and his colleagues report that the medaka eggs can successfully hatch after enduring up to 18 hours out of the water attached to a plant leaf.
(Eggs without a plant leaf to cling to rarely survived for more than a few hours.)
Mr Yao focused on medaka, paper-clip-size fish that live in shallow water and attach their eggs to aquatic plants.
When the lab-reared medaka laid their eggs on strips of vegetation, the researchers took the plants out of the water for between zero and 24 hours—at conditions favourable to the unhatched eggs—before returning them.
In a new paper in Science of Nature, Mr Yao and his colleagues report that the medaka eggs can successfully hatch after enduring up to 18 hours out of the water attached to a plant leaf.
(Eggs without a plant leaf to cling to rarely survived for more than a few hours.)
The big drop in survival was at 16 hours and 20 minutes, when half the eggs became unviable.
Given that a heron’s average flight-speed is around 39kph (with top speeds of 96kph), the hardiest medaka eggs could travel quite a distance.
Whether any could actually survive the full 16.3 hours of travel at 39kph is doubtful, says Mr Yao, since wind exposure during such a long journey would dry them out.
Shorter journeys, however, are certainly possible.
And since there are dozens of other medaka-like fish species found throughout Asia, the chances are high that hitchhiking explains how so many species have ended up in ponds and lakes with seemingly no connection to other water bodies.
Yet again, it would seem, Darwin’s theories turn out to be correct.
Links :
Thursday, October 31, 2024
As ‘Doomsday’ Glacier melts, can an artificial barrier save it?
The edge of the Thwaites glacier in Antarctica.
Relatively warm ocean currents are weakening the base of Antarctica’s enormous Thwaites Glacier, whose demise could raise sea levels by as much as 7 feet.
To separate the ice from those warmer ocean waters, scientists have put forward an audacious plan to erect a massive underwater curtain.
They call it the Doomsday Glacier.
A chunk of Antarctic ice as big as Florida and two thirds of a mile thick, the Thwaites Glacier disgorges into the ocean in a remote region of West Antarctica.
Glaciologists say it may be on the verge of total collapse, which could swamp huge areas of low-lying coastal land around the world within a few decades.
Now, ambitious plans to save it are set to become an early test of whether the world is prepared to enact massive geoengineering efforts to ward off the worst effects of climate change.
Recent monitoring by uncrewed submarines and satellites, along with ice-sheet modeling, suggest that the Thwaites Glacier and its adjacent smaller twin, the Pine Island Glacier, may already be in a death spiral — eaten up by the intensifying speed and warmth of the powerful Antarctic Circumpolar Current.
If they are past a point of no return, say researchers involved in the studies, then only massive human intervention can save them.
Nothing is certain.
A new modeling study published last week said the risk of unstoppable retreat of the glacier may be overblown.
But there is no time to waste, argues the glaciologist orchestrating the call for action, John Moore of Lapland University, in northern Finland.
Within two years, he and colleagues in Europe hope to be working in a Norwegian fjord, testing prototypes for a giant submarine curtain, up to 50 miles across, that could seal off the two glaciers from the remorseless Antarctic current.
Glaciologists have discussed scary prognoses for the rapid collapse of giant Antarctic glaciers for almost half a century.
Meanwhile, some of his collaborators, fearing the logistical complications of such a task, are pondering an even more mind-bending idea.
They want to substitute the physical curtain with a giant “bubble curtain,” created by a constant injection of bubbles of air or cold surface water.
Opponents of the plans, including many glaciologists, say such outlandish proposals are a dangerous diversion from the real task of mitigating climate change by curbing carbon emissions.
But advocates say the two glaciers can’t wait.
“We can’t mitigate our way out of this,” says Moore.
“We need other tools.”
Glaciologists have discussed scary prognoses for the rapid collapse of giant Antarctic glaciers for almost half a century.
Glaciers in West Antarctica are particularly vulnerable because they are not sitting on solid land; they are surrounded by ocean and pinned precariously to the peaks of submarine mountains, between which the circumpolar current swirls.
Back in 1978, glaciologist John Mercer, of Ohio State University, warned of a “major disaster – a rapid five-meter rise in sea level, caused by deglaciation of West Antarctica” — should atmospheric levels of carbon dioxide continue to rise.
Three years later, glaciologist Terry Hughes, of the University of Maine, identified a “weak underbelly” to the West Antarctic Ice Sheet, where the Thwaites and Pine Island glaciers drain into the Amundsen Sea, an arm of the Southern Ocean.
European Space Agency / Adapted By Yale Environment 360
These glaciers are two of the ice continent’s five largest and are the gateway to the ocean for nearly half of the ice sheet.
Hughes warned that the glaciers could easily lose their grip on the submarine mountains as warmer water melts ice directly beneath them, leading to their disintegration within a few decades.
Their meltwater would raise sea levels globally by as much as 7 feet.
That would rise to more than 12 feet if, as the pair suspected, the glaciers’ demise dragged down the rest of the ice sheet with it.
These fears remained a theoretical concern until 20 years ago, when NASA glaciologist Eric Rignot warned that the seaward flow of these two giant glaciers was accelerating rapidly.
It also became clear that the waters lapping at their submerged edges were warming as a result of climate change, and that this melting effect was much greater than the effect of warming air.
Ted Scambos of the University of Colorado, who is a coordinator of the joint U.S.-UK International Thwaites Glacier Collaboration, says that now “the [Thwaites] glacier is flowing at over a mile per year,” nearly double the speed in the 1990s.
The warm ocean current is “eroding the base of the ice, erasing it as an ice cube would disappear bobbing in a glass of water.”
Scambos believes the accelerated flow is bound to continue.
“By flowing faster, the glacier pulls down the ice behind it.” While shallower ice grinds on the bedrock and gets held back, he explains, thicker ice is less constrained and so flows faster, “leading to more retreat.”
“Some say it is too late to prevent [Thwaites’] collapse,” says a glaciologist.
“Others say we could have 200 years.”
This concern has only heightened with the recent publication of satellite radar images revealing that the height of the Thwaites Glacier rises and falls with the tides.
Rignot, now at the University of California, Irvine, says this finding shows that the warm current is not just lapping at the front of the glacier but is penetrating several miles beneath the grounded ice, further loosening its contact with solid rock.
Modelers of the West Antarctic Ice Sheet caution against assuming the worst.
Much remains unknown.
Last week, Mathieu Morlighem of Dartmouth College, along with British colleagues, reported that one potential cause of collapse of the Thwaites Glacier — runaway instability of the ice cliff at the front of the glacier — was less likely than some propose, at least in the short term.
But he said there was a “pressing need” for further research into these potentially devastating processes.
There is, Moore agrees, no consensus among glaciologists about whether the Thwaites Glacier is past a point of no return unless there is drastic intervention.
“Some say it is too late to prevent its collapse; others say we could have 200 years.
But it certainly could be beyond its tipping point, and we have to be prepared.”
Time-lapse satellite imagery of ice breaking off the Pine Island Glacier from 2015 to 2020.
Last month, Moore and an international team of researchers published a “research vision” for “glacial climate intervention.” It followed workshops held last year at Stanford and the University of Chicago with fellow glaciologists, and it warned that if tipping points at the two glaciers have or will soon be crossed, then whatever happens to greenhouse gas emissions in the future “will have little effect on preserving the ice sheet.”
Ice-sheet modeling last year by Kaitlin Naughten of the British Antarctic Survey concurred.
“The opportunity to preserve the West Antarctic Ice Sheet in its present-day state has probably passed,” she concluded, “and policymakers should be prepared for several metres of sea level rise over the coming centuries.”
So what can be done? Last month’s “vision” did not directly advocate for geoengineering interventions but called for research into which of them may be viable.
It highlighted a proposal for a series of giant overlapping plastic or fiber curtains tethered to concrete foundations.
To hold the warm current at bay, the curtain would stretch for 50 miles across the entrance to the Amundsen Sea and extend upwards for much of the 2,000 feet from the sea floor to the surface.
Some experts are confident that giant undersea curtains can be built to withstand the forces they will face in the ocean.
Moore wants to get started on testing the idea, and he and his collaborators are seeking research funding.
The first experiments in a large lab tank are expected to begin within a few weeks at Cambridge University’s Centre for Climate Repair, whose mission is to advance “climate repair projects that can be rolled out at scale within the next 5-10 years.”
Real-world experiments could follow quickly, says Moore.
“Within two years, we could be working at a fjord in northern Norway, testing different designs in a marine setting.” He has identified a target fjord but won’t say where.
“If that goes well, we would want to scale up to a curtain as much as a kilometer across.” He envisions this being tested among the glaciers of Svalbard, the Norwegian Arctic archipelago that has become an international center for polar research.
“In 10-15 years, we should have something to deploy in Antarctica,” he says.
Moore is confident that such giant curtains can be built to withstand the forces they will face in the ocean.
“And installation seems feasible with existing technology,” he says.
Even so, deployment and maintenance would be a huge undertaking in an environmentally hostile region some 1,500 miles from the nearest ice-free land in South America.
And potential impacts on local marine ecosystems from both installation and operation remain essentially unknown, he says.
So a diminished version might be tried at the start, says Michael Wolovick of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany.
Much could be accomplished with a curtain just three miles wide stretching across a “choke point” in front of the most vulnerable part of the Thwaites Glacier.
Diagram Of A Proposed Glacial Curtain.
Nature / Adapted By Yale Environment 360
Nature / Adapted By Yale Environment 360
Hugh Hunt, an engineering professor and deputy director of Cambridge’s Centre for Climate Repair, has another proposal.
“We have been looking for ideas that involve less infrastructure,” he says.
The most promising would replace a fabricated curtain with a more natural barrier.
He proposes laying a pipe along the bed of the Amundsen Sea that would release a constant stream of either air bubbles or cold water pumped down from the surface.
“A bubble barrier probably wouldn’t completely halt the flow of warm water,” he says.
“But it would disturb that flow, creating turbulence that would force it to mix with the colder water above.”
Offshore civil engineering companies already use bubble barriers to contain silt and protect marine life from their operations, Hunt says.
A giant bubble machine off Antarctica would require a continuous supply of energy, which would have to be renewable.
“With no winter sunlight, solar power wouldn’t work,” he says.
“But offshore wind farms would.
And with long-distance submarine cabling improving all the time, we could even generate power far away.”
Moore calls the bubble barrier a “wild card.” But, he says, “it is great they are pursuing it, because the potential payoff is huge.” Its main problem right now, he says, is that it remains almost entirely unresearched.
An Antarctic curtain would be hugely expensive, but far less than the cost to protect coastlines from rising tides.
There are other glacier-protecting strategies that avoid the need for curtains or other barriers.
Slawek Tulaczyk, a glaciologist at the University of California, Santa Cruz, has proposed stabilizing the two imperiled glaciers by draining the meltwaters that currently seep to their base, lubricating the pinning points and accelerating the glaciers’ seaward flow.
By drilling holes through the glaciers and inserting pumps, engineers could dry up the lubricant and bring that flow to a halt.
The extracted water could then be sprayed across the glacier surface, where it would freeze, helping to rebuild the glacier.
Are such ideas feasible, how much would they cost, and what are the ethics of all this? Moore puts the likely bill for erecting a curtain across the Amundsen Sea at up to $80 billion.
That is a lot of money.
But much less, he says, than the trillions of dollars that might be needed to protect coastlines from rising tides caused by the loss of the two glaciers.
Others question this analysis.
“I don’t doubt we could spend a decade building the curtain,” says Twila Moon, a glaciologist at the National Snow and Ice Data Center at the University of Colorado.
“It is a naturally attractive idea that one big project can make the difference.
But curtains may just displace the heat elsewhere, melting other ice.” In any event, she says, sea-level rise would continue as a result of factors such as thermal warming of the oceans, land subsidence, and changes in ocean circulation, as well as the melting of other land ice, such as on Greenland.
“So the question is whether this is the right place to put our resources, including limited research funding.”
The Thwaites Glacier, photographed on a research flight.
U.S. Antarctic Program
Her Colorado colleague and Thwaites Glacier expert Scambos is more open to geoengineering research, but still skeptical.
“I think the ideas are worth pursuing,” he says.
“We could explore them at a meaningfully large scale in sites with low negative consequences if things don’t go well.” But, like Moon, he fears the impact on climate policymaking.
In an ideal world, Scambos says, “we could pursue engineering solutions for the poles while at the same time directly decarbonizing our societies.” But the world isn’t like that.
Climate negotiators at the UN COP28 meeting last December “brought up the notion that decarbonizing could go slower now that these [geoengineering] ideas are out there,” Scambos says.
“The idea that ‘scientists are working on the problem’ could be a death knell for the 22nd century.”
Moore has heard these criticisms.
“Yes, there is opposition,” he says.
“We need to address that.
We need a social licence.” He agrees that there are other important causes of current and future sea-level rise.
But “none of these other sources have the potential to raise sea level at the extreme rates and magnitudes that could be realized from a rapid marine ice sheet collapse.”
If the glaciers are past their tipping points, dooming the world’s coastal lands, he says, we may have no alternative but to bite the geoengineering bullet.
And the sooner we get started, he says, the better.
“I think the ideas are worth pursuing,” he says.
“We could explore them at a meaningfully large scale in sites with low negative consequences if things don’t go well.” But, like Moon, he fears the impact on climate policymaking.
In an ideal world, Scambos says, “we could pursue engineering solutions for the poles while at the same time directly decarbonizing our societies.” But the world isn’t like that.
Climate negotiators at the UN COP28 meeting last December “brought up the notion that decarbonizing could go slower now that these [geoengineering] ideas are out there,” Scambos says.
“The idea that ‘scientists are working on the problem’ could be a death knell for the 22nd century.”
Moore has heard these criticisms.
“Yes, there is opposition,” he says.
“We need to address that.
We need a social licence.” He agrees that there are other important causes of current and future sea-level rise.
But “none of these other sources have the potential to raise sea level at the extreme rates and magnitudes that could be realized from a rapid marine ice sheet collapse.”
If the glaciers are past their tipping points, dooming the world’s coastal lands, he says, we may have no alternative but to bite the geoengineering bullet.
And the sooner we get started, he says, the better.
Links :
- CNN : Scientists looked deep beneath the Doomsday Glacier. What they found spells potential disaster for the planet
- New Scientist : Antarctica’s 'doomsday' glacier is heading for catastrophic collapse
- Phys : 'Doomsday' glacier set to melt faster and swell seas as world heats up, say scientists
- GeoGarage blog :A robot finds more trouble under the Doomsday glacier / Thwaites: 'Doomsday Glacier' vulnerability seen in new maps / Antarctica's Doomsday glacier: how doomed are we? / Doomsday glacier “Holding on by its fingernails” – spine-chilling ... / Rapid melting in West Antarctica is 'unavoidable,' with potentially ... / Scientists are uncovering ominous waters under Antarctic ice
Wednesday, October 30, 2024
How AI can help satellites track ‘dark ships’ from space
At least half of them are carrying cargo, shifting the world’s goods from port to port.
And that’s not counting those that would rather remain incognito — the illegal fishing boats and the craft carrying out piracy attacks, for example.
In recent years, satellite mapping has helped pinpoint what the maritime sector calls ‘dark ships’ — the vessels that switch off their Automatic Identification System (AIS) to avoid detection.
Earth-observation satellites can monitor and photograph objects on the ocean to aid vessel detection — vital when over 100 ships are attacked by pirates annually — but it’s a time-consuming process.
In recent years, satellite mapping has helped pinpoint what the maritime sector calls ‘dark ships’ — the vessels that switch off their Automatic Identification System (AIS) to avoid detection.
Earth-observation satellites can monitor and photograph objects on the ocean to aid vessel detection — vital when over 100 ships are attacked by pirates annually — but it’s a time-consuming process.
Now artificial intelligence (AI) can help those searching for dark ships to cut to the chase.
AI can help identify covert ships, including illegal fishing vessels
(Note: The resolution of the captured image depends on the performance of the camera being used)
(Note: The resolution of the captured image depends on the performance of the camera being used)
How satellites can track down ships
Identifying covert ships has traditionally relied on downloading high-resolution optical images captured by Earth-observation cameras.
Identifying covert ships has traditionally relied on downloading high-resolution optical images captured by Earth-observation cameras.
However, both data transmission capacity and storage are very limited, so these images cannot always be transmitted to a computer back down on Earth.
And when they can, these vast quantities of data need to be combed through by humans, who must then painstakingly match up each satellite image of an evasive ship with its AIS details.
This can cause delays in identifying perpetrators and launching interventions.
AIRIS consists of an Earth-observation camera (right) and an AI-based object detector
Mitsubishi Heavy Industries (MHI) Group has developed a device that, like other Earth-observation equipment, takes images of terrestrial objects, but unlike other satellite technology, simultaneously processes that visual data using AI.
AIRIS consists of an Earth-observation camera (right) and an AI-based object detectorUsing AI to fine-tune satellite data
The satellite-mounted detector, called AIRIS (or Artificial Intelligence Retraining In Space), consists of an Earth-observation camera and an AI-equipped data processor.
When the camera scans the Earth’s surface, rather than automatically sending all that data back for processing, AIRIS deploys its AI to detect target objects — such as dark ships — and selects and transmits only data from the areas where those objects are located.
Also, Imagine, a ship was originally identified via its AIS when it set off from port, but then switched its system off mid-voyage.
The satellite-mounted detector, called AIRIS (or Artificial Intelligence Retraining In Space), consists of an Earth-observation camera and an AI-equipped data processor.
When the camera scans the Earth’s surface, rather than automatically sending all that data back for processing, AIRIS deploys its AI to detect target objects — such as dark ships — and selects and transmits only data from the areas where those objects are located.
Also, Imagine, a ship was originally identified via its AIS when it set off from port, but then switched its system off mid-voyage.
In those cases, AIRIS is capable of tracking this ship via images captured by its Earth observation cameras and detecting them with on-board AI.
It can also be updated while in orbit, as AIRIS is capable of receiving a ‘retrained’ AI model from the ground to update and fine-tune its own onboard AI.
It can also be updated while in orbit, as AIRIS is capable of receiving a ‘retrained’ AI model from the ground to update and fine-tune its own onboard AI.
The AI-enabled satellite device allows information to flow both to and from Earth
AI for economic security
AIRIS is selected as one of demonstration themes of Innovative Satellite Technology Demonstration Program conducted by Japan Aerospace Exploration Agency (JAXA). It is due to be launched in FY2025 onboard JAXA's demonstration satellite RAISE-4.
MHI says its initial usage of the technology will be in the field of economic security, tracking down ships on the world’s oceans.
With illegal, unreported and unregulated fishing activities responsible for the loss of up to 26 million tonnes of fish a year — resulting in up to $23 billion of economic losses — it’s not hard to see why this is a priority area.
But the technology can also be applied more widely. MHI envisages this detection capability will be expanded in the future to include other objects, such as aircraft or vehicles.
In the meantime, the deployment of AIRIS marks a significant advancement in maritime monitoring, enhancing the ability to track elusive vessels and mitigate illegal activities on the high seas.
AIRIS is selected as one of demonstration themes of Innovative Satellite Technology Demonstration Program conducted by Japan Aerospace Exploration Agency (JAXA). It is due to be launched in FY2025 onboard JAXA's demonstration satellite RAISE-4.
MHI says its initial usage of the technology will be in the field of economic security, tracking down ships on the world’s oceans.
With illegal, unreported and unregulated fishing activities responsible for the loss of up to 26 million tonnes of fish a year — resulting in up to $23 billion of economic losses — it’s not hard to see why this is a priority area.
But the technology can also be applied more widely. MHI envisages this detection capability will be expanded in the future to include other objects, such as aircraft or vehicles.
In the meantime, the deployment of AIRIS marks a significant advancement in maritime monitoring, enhancing the ability to track elusive vessels and mitigate illegal activities on the high seas.
Links :
- Maritime Executive : Mitsubishi Develops AI System to Track "Dark Fleet" From Space
- Splash: Mitsubishi Heavy debuts satellite technology capable of tracking the dark fleet
- ESA : Sentinel-1 and AI reveal 75% of fishing vessels not tracked
- GeoGarage blog : Uncovering dark vessels with fusion technology / Enhancing maritime security: Unseenlabs' RF data ... / When fishing boats go dark at sea, they're often committing ... / Under 30 satellite companies Spire and ICEYE team up to ... / New satellites will use radio waves to spy on ships and ... / Iceye releases dark vessel detection product
Tuesday, October 29, 2024
The deep-sea 'emergency service' that keeps the internet running
Getty Images
From BBC by William Park
Ninety-nine percent of the world's digital communications rely on subsea cables.
When they break, it could spell disaster for a whole country's internet.
How do you fix a fault at the bottom of the ocean?
It was a little after 17:00 on 18 November 1929 when the ground began to shake.
Just off the coast of Burin Peninsula, a finger-like protrusion on the south of Newfoundland, Canada, a 7.2 magnitude earthquake disturbed the evening's peace.
Residents noticed only a little damage at first – a few toppled chimney pots.
But out at sea, an unseen force was moving.
By around 19:30, a 13m-high (43ft) tsunami made landfall on the Burin Peninsula.
In total, 28 people lost their lives as a result of drowning or injuries caused by the wave.
The earthquake was devastating for the local communities, but it also had a long-lasting effect further out at sea.
It had triggered a submarine landslide.
People did not realise this at the time, historical records suggest, because no one knew such underwater landslides existed.
When sediment is disturbed by earthquakes and other geological activity it makes the water denser, causing it to flow downwards like an avalanche of snow down a mountain.
The submarine landslide – called a turbidity current – flowed more than 1,000km (621 miles) away from the earthquake's epicentre on the Laurentian Continental Slope at speeds between 50 and 70 knots (57-80mph).
Although the landslide was not noticed at the time, it left a tell-tale clue.
In its way lay the latest in communication technology at the time: transatlantic subsea cables.
And those cables broke.
Twelve of them were snapped in a total of 28 places.
Some of the 28 breaks happened almost synchronously with the earthquake.
But the other 16 breaks happened over a much longer period, as the cables snapped one after the other in a kind of mysterious ripple pattern, from 59 minutes after the earthquake to 13 hours and 17 minutes later, and over 500km (311 miles) away from the epicentre.
If they'd all been snapped by the quake itself, the cables would have all broken at the same time – so scientists began to wonder, why didn't they? Why did they break one after the other?
It wasn't until 1952 that researchers pieced together why the cables broke in sequence, over such a large area, and at intervals that seemed to slow with distance from the epicentre.
They figured out that a landslide smashed through them – the snapping cables traced its movement across the seafloor.
Until that point, no one knew of the existence of turbidity currents.
Because these cables broke, and because there was a record of the time they broke, they helped in the understanding of ocean movements above and below the surface.
They caused a complex repair job, but also became accidental scientific instruments, recording a fascinating natural phenomenon far out of human sight.
Over the following decades, as the global web of deep-sea cables expanded, their repair and maintenance resulted in other surprising scientific discoveries – opening up entirely new worlds and allowing us to spy on the seabed like never before, while also allowing us to communicate at record speed.
At the same time, our daily lives, incomes, health and safety have also become more and more dependent on the internet – and ultimately, this complex network of undersea cables.
So what happens when they break?
Ninety-nine percent of the world's digital communications rely on subsea cables.
When they break, it could spell disaster for a whole country's internet.
How do you fix a fault at the bottom of the ocean?
It was a little after 17:00 on 18 November 1929 when the ground began to shake.
Just off the coast of Burin Peninsula, a finger-like protrusion on the south of Newfoundland, Canada, a 7.2 magnitude earthquake disturbed the evening's peace.
Residents noticed only a little damage at first – a few toppled chimney pots.
But out at sea, an unseen force was moving.
By around 19:30, a 13m-high (43ft) tsunami made landfall on the Burin Peninsula.
In total, 28 people lost their lives as a result of drowning or injuries caused by the wave.
The earthquake was devastating for the local communities, but it also had a long-lasting effect further out at sea.
It had triggered a submarine landslide.
People did not realise this at the time, historical records suggest, because no one knew such underwater landslides existed.
When sediment is disturbed by earthquakes and other geological activity it makes the water denser, causing it to flow downwards like an avalanche of snow down a mountain.
The submarine landslide – called a turbidity current – flowed more than 1,000km (621 miles) away from the earthquake's epicentre on the Laurentian Continental Slope at speeds between 50 and 70 knots (57-80mph).
Although the landslide was not noticed at the time, it left a tell-tale clue.
In its way lay the latest in communication technology at the time: transatlantic subsea cables.
And those cables broke.
Twelve of them were snapped in a total of 28 places.
Some of the 28 breaks happened almost synchronously with the earthquake.
But the other 16 breaks happened over a much longer period, as the cables snapped one after the other in a kind of mysterious ripple pattern, from 59 minutes after the earthquake to 13 hours and 17 minutes later, and over 500km (311 miles) away from the epicentre.
If they'd all been snapped by the quake itself, the cables would have all broken at the same time – so scientists began to wonder, why didn't they? Why did they break one after the other?
It wasn't until 1952 that researchers pieced together why the cables broke in sequence, over such a large area, and at intervals that seemed to slow with distance from the epicentre.
They figured out that a landslide smashed through them – the snapping cables traced its movement across the seafloor.
Until that point, no one knew of the existence of turbidity currents.
Because these cables broke, and because there was a record of the time they broke, they helped in the understanding of ocean movements above and below the surface.
They caused a complex repair job, but also became accidental scientific instruments, recording a fascinating natural phenomenon far out of human sight.
Over the following decades, as the global web of deep-sea cables expanded, their repair and maintenance resulted in other surprising scientific discoveries – opening up entirely new worlds and allowing us to spy on the seabed like never before, while also allowing us to communicate at record speed.
At the same time, our daily lives, incomes, health and safety have also become more and more dependent on the internet – and ultimately, this complex network of undersea cables.
So what happens when they break?
Submarine cables form a global web at the bottom of the sea, keeping us all connected
(Credit: Getty)
How our data travels
There are 1.4 million km (870,000 miles) of telecommunication cables on the seafloor, covering every ocean on the planet.
Laid end to end, these cables would span the diameter of the Sun, and are responsible for the transfer of 99% of all digital data.
But for something so important, they are surprisingly slender – often little more than 2cm in diameter, or about the width of a hosepipe.
A repeat of the 1929 mass cable outage would have significant impacts on communication between North America and Europe.
However, "for the most part, the global network is remarkably resilient," says Mike Clare, the International Cable Protection Committee's marine environmental advisor who researches the impacts of extreme events on submarine systems.
"There are 150 to 200 instances of damage to the global network each year.
So if we look at that against 1.4 million km, that's not very many, and for the most part, when this damage happens, it can be repaired relatively quickly."
How does the internet run on such slim cables and avoid disastrous outages?
Since the first cables were laid in the 19th Century, they have been exposed to extreme environmental events, from submarine volcanic eruption to typhoons and floods.
But the biggest cause of damage is not natural.
The idea that cables break because sharks bite through them is now a bit of an urban legend
Most faults, with figures varying 70-80% depending on where you are in the world, relate to accidental human activities like the dropping of anchors or dragging of trawler boat nets, which snag on the cables, says Stephen Holden, head of maintenance for Europe, the Middle East and Africa at Global Marine, a subsea engineering firm who respond to subsea cable repairs.
These usually occur in depths of 200-300m (but commercial fishing is increasingly pushing into deeper waters – in some places, 1,500m in the Northeast Atlantic).
Only 10-20% of faults worldwide relate to natural hazards, and more frequently relate to cables wearing thin in places where currents cause them to rub against rocks, causing what are called "shunt faults", says Holden.
(The idea that cables break because sharks bite through them is now a bit of an urban legend, adds Clare. "There were instances of sharks damaging cables, but that's long gone because the cable industry uses a layer of Kevlar to strengthen them.")
Cables have to be kept thin and light in deeper waters, though, to aid with recovery and repair.
Hauling a large, heavy cable up from thousands of metres below sea level would put a huge amount of strain on it.
It's the cables nearer the shoreline that tend to be better armoured because they are more likely to be snagged by nets and anchors.
An army of stand-by repair ships
If a fault is found, a repair ship is dispatched.
"All these vessels are strategically placed around the world to be 10-12 days from base to port," says Mick McGovern, deputy vice-president for marine operations at Alcatel Submarine Networks.
"You have that time to work out where the fault is, load the cables [and the] repeater bodies" – which increase the strength of a signal as it travels along the cables.
"In essence when you think how big the system is, it's not long to wait," he says.
While it took nine months to repair the last of the subsea cable damage caused by the 1929 Newfoundland earthquake, McGovern says a modern deep-water repair should take a week or two depending on the location and the weather.
"When you think about the water depth and where it is, that's not a bad solution."
That does not mean an entire country's internet is then down for a week.
Many nations have more cables and more bandwidth within those cables than the minimum required amount, so that if some are damaged, the others can pick up the slack.
This is called redundancy in the system.
Because of this redundancy, most of us would never notice if one subsea cable was damaged – perhaps this article would take a second or two longer to load than normal.
In extreme events, it can be the only thing keeping a country online.
The 2006 magnitude 7 earthquake off the coast of Taiwan, severed dozens of cables in the South China Sea – but a handful remained online.
In deep waters, giant underwater ploughs dig trenches for the cables
To repair the damage, the ship deploys a grapnel, or grappling hook, to lift and snip the cable, pulling one loose end up to the surface and reeling it in across the bow with large, motorised drums.
The damaged section is then winched into an internal room and analysed for a fault, repaired, tested by sending a signal back to land from the boat, sealed and then attached to a buoy while the process is repeated on the other end of the cable.
Once both ends are fixed, each optical fibre is spliced together under microscope to make sure that there is good connection, and then they are sealed together with a universal joint that is compatible with any manufacturer's cable, making life easier for international repair teams, McGovern says.
Deep-sea cables can double as scientific instruments, giving us insights into life in the ocean
(Credit: Getty)
The repaired cables are lowered back into the water, and in shallower waters where there might be more boat traffic, they are buried in trenches.
Remotely operated underwater vehicles (ROVs), equipped with high-powered jets, can blast tracks into the seabed for cables to be laid into.
In deeper waters, the job is done by ploughs which are equipped with jets and dragged along the seabed by large repair vessels above.
Some ploughs weigh more than 50 tonnes, and in extreme environments, bigger equipment is needed – such as one job McGovern recalls in the Arctic Ocean which required a ship dragging a 110-tonne plough, capable of burying cables 4m and penetrating the permafrost.
Ears on the sea floor
Laying and repairing the cables has led to some surprising scientific insights – at first somewhat accidentally, as in the case of the snapped cables and the landslide, and later, by design, as scientists began to intentionally use the cables as research tools.
These lessons from the deep sea began as the first transatlantic cables were laid in the 19th Century.
Cable layers noticed that the Atlantic Ocean gets shallower in the middle, inadvertently discovering the Mid-Atlantic Ridge.
Today, telecommunication cables can be used as "acoustic sensors" to detect whales, ships, storms and earthquakes in the high seas.
The damage caused to cables offers the industry "fundamental new understandings about hazards that exist in the deep sea," says Clare.
"We'd never have known that there were landslides under the sea after volcanic eruptions if it wasn't from the damage that was created."
In some places, climate change is making matters more challenging.
Floods in West Africa are causing an increase in canyon-flushing in the Congo River, which is when large volumes of sediment flows into a river after flooding.
This sediment is then dumped out of the river mouth into the Atlantic and could damage cables.
"We know now to lay the cable further away from the estuary," says McGovern.
Some damage will be unavoidable, the experts predict.
The Hunga Tonga–Hunga Ha'apai volcanic eruption in 2021-2022 destroyed the subsea internet cable linking the Pacific Island nation of Tonga to the rest of the world.
It took five weeks until its internet connection was fully functioning again, though some make-shift services were restored after a week.
While this huge eruption (casting a plume of ash 36 miles (58km) into the air) was an unusually large event, connecting an island nation in a volcanically active area will always carry some risk, says Holden.
However, many countries are served by multiple subsea cables, meaning one fault, or even multiple faults, might not be noticed by internet users, as the network can fall back on other cables in a crisis.
"This really points to why there's a need for geographic diversity of cable routes," adds Clare.
"Particularly for small islands in places like the South Pacific that have tropical storms and earthquakes and volcanoes, they are particularly vulnerable, and with climate change, different areas are being affected in different ways."
As fishing and shipping get more sophisticated, avoiding cables might be made easier.
The advent of automatic identification system (AIS) on shipping has led to a reduction in anchoring damage, says Holden, because some firms now offer a service where you can follow a set pattern for slowing down and anchoring.
But in areas of the world where fishing vessels tend to be less sophisticated and operated by smaller crews, anchor damage still happens.
In those places, an option is to tell people where cables are, and to increase awareness, adds Clare: "It's for everyone's benefit that the internet keeps running."
Links :
- BBC : The undersea rivers that threaten the world's internet
- The Verge : The invisable seafaring industry that keeps the Internet afloat
- Popular Science : Melting ice makes Arctic a target for a new deep sea internet cable
- CNN : Exclusive: US sees increasing risk of Russian ‘sabotage’ of key undersea cables by secretive military unit
- The Economist : How China and Russia could hobble the internet
- ZME Science : The Invisible Backbone of the Internet: Nearly A Million Miles of Undersea Cables Keep the World Connected — But What Happens If They Break?
- GeoGarage blog : Russia is signaling it could take out the West's internet and GPS.
There's no good backup plan. / The secret life of the 500+ cables that run the Internet / Feast your eyes on the 2023 submarine cable map / A deep dive into risks for undersea cables, pipes / The threat to world's communications backbone / The most vulnerable place on the Internet / A subsea cable went missing.
Was Russia to blame / The Houthis' next target may be underwater / The Coast Guard should lead to protect undersea cables
Monday, October 28, 2024
‘Scramble for the oceans’: how countries are racing to name and claim remote parts of the seabed
An illustration of 3D mapping of the ocean.
New technology has enabled exploration of the sea floor.
source : Hypack
From The Guardian by Donna Ferguson
Newly ‘discovered’ underwater topographical features are paving the way
for nation states to exploit previously untouched marine resources
“The sea does not belong to despots,” Jules Verne wrote in 1869 in Twenty Thousand Leagues Under the Sea.
“Upon its surface men can still exercise unjust laws, fight, tear one another to pieces, and be carried away with terrestrial horrors.
But at 30 feet below its level, their reign ceases, their influence is quenched, and their power disappears.”
Now, more than 150 years later, geopolitics experts are warning that Verne’s final sentiment, expressed as it was through the character of Captain Nemo, was wrong.
From seabeds and sea caves to sea canyons, underwater ridges, seamounts, sea knolls and reefs, academics say countries around the world are using the politics of nationalism to permanently stamp their mark on the topography of the ocean.
“The sea does not belong to despots,” Jules Verne wrote in 1869 in Twenty Thousand Leagues Under the Sea.
“Upon its surface men can still exercise unjust laws, fight, tear one another to pieces, and be carried away with terrestrial horrors.
But at 30 feet below its level, their reign ceases, their influence is quenched, and their power disappears.”
Now, more than 150 years later, geopolitics experts are warning that Verne’s final sentiment, expressed as it was through the character of Captain Nemo, was wrong.
From seabeds and sea caves to sea canyons, underwater ridges, seamounts, sea knolls and reefs, academics say countries around the world are using the politics of nationalism to permanently stamp their mark on the topography of the ocean.
The title page of Jules Verne’s Twenty Thousand Leagues Under the Sea, written in 1869-70.
Photograph: Chronicle/Alamy
Klaus Dodds, professor of geopolitics at Royal Holloway, University of London, says that countries today are engaged in a “scramble for the oceans”.
“There’s more and more ocean grabbing going on in the world, because countries have been given legal permission to do that.”
Dr Sergei Basik, a geographer at Conestoga College in Ontario, Canada, says a relatively recent process of 3D mapping the ocean floor has allowed nations to assert their sovereignty over newfound undersea features, known as “bathyonyms”.
Just as in 1492, when it was a new map of the ocean that inspired and emboldened Christopher Columbus to set sail across the world to find a new trade route to Asia, leading to the colonisation of America, the once murky abyss of the ocean has now resolved into clearly defined topographical features on a 3D map.
All of these require a name – and nation states hungry for valuable natural resources and national territory are staking symbolic claims on their “discoveries”.
When we give a name to an object, we claim it … not only the surface.
We claim the territory and all of its resourcesDr Sergei Basik, geographer
“When we give a name to an object, we claim it. And we claim not only the surface. We claim the territory and all of its resources,” says Basik.
“From an economic perspective nations are thinking about the potential [of the features]: how can we use this?”
Basik, who first outlined his thesis in the geography journal Area, fears that countries will one day mine these features for minerals or other economic assets whose power or value is not yet known.
“The first step is the symbolic claim, and after that, we’re talking about commodification of the ocean and resources in the ocean.”
Countries must petition the International Hydrographic Organization (IHO), an intergovernmental body based in Monaco with 100 member states, for the right to name the features in internationally recognised nautical charts and documents.
An illustration of mapped features of the seabed.
Newly found features can be named and claimed by countries.
Newly found features can be named and claimed by countries.
Photograph: International Hydrographic Organization
During the 20th century, just 17 names for bathyonyms were proposed on average each year, Basik’s research shows.
But since 2000, countries have proposed 95 names on average a year – and recently this trend has strengthened, with more than 1,000 names put forward since 2016.
Basik’s research reveals that Japan is the most zealous proposer of names for seabed objects in the world: it is responsible for naming 615 bathyonyms, followed by the US (560), France (346), Russia (313), New Zealand (308) and China (261).
Dodds says that, in part, this rush to name areas of the seabed has been stimulated by coastal states trying to extend their sovereign rights, which really revolve around potential mineral resources in the sea.
“There’s been a lot of enthusiasm for mapping, surveying and carrying out geological investigations.”
Some countries are seeking to demonstrate that a nearby seabed is part of their continental shelf and therefore belongs to them.
This then enables that country – under the rules and procedures of international sea laws – to potentially extend its underwater sovereignty by as much as 350 nautical miles from its coastline, Dodds says.
“These are really huge areas we’re talking about.”
Naming a feature reinforces the point about exclusive ownership.
“It’s saying: this is my space.” You name to begin the process of developing a more refined sense of ownership and sovereign authority, he says.
For this reason, “the politics of naming is always tied to expressions of national identity”.
The Makassar Strait, left of Sulawesi Island in the Java Sea, where Indonesia named the Alamang Reefs.
UKHO nautical raster chart with the GeoGarage platform
For example, the Alamang Reefs in the Makassar Strait were discovered by the Indonesian navy in 2022 and named by Indonesia after a traditional Indonesian sword.
Similarly, the O’Higgins Guyot and Seamount, which were discovered in the south Pacific by a Chilean vessel, were named by Chile after the 19th-century Chilean independence leader Bernardo O’Higgins Riquelme last year.
Countries do not always restrict themselves to proposing names for geographical features near their own coastlines.
“A lot of this attention around naming is now being increasingly developed to ever remoter parts of the seabed,” says Dodds.
For example, Bulgaria, which has a very modest presence in the Antarctic, has been one of the most enthusiastic exponents of Antarctic place naming.
“This is probably a bit counterintuitive, because there are other countries that have done far more in Antarctica and have actually named far fewer features,” says Dodds.
“But Bulgaria has conducted research in the Antarctic.
And the whole point about Antarctica and the oceans, at that sort of depth, is that no country is close.”
He adds: “What’s happening is we’ve got an international legal system that is encouraging mapping and surveying and claiming.
And one of the things that historically has driven a lot of this work is an interest in mining the deep seabed.”
For Basik too, the naming – and claiming – of ocean features is not merely a territorial issue.
“This is not only about possible geopolitical conflicts and potential wars,” he says.
“This is about the future and future development.
This is about the potential for using the oceans in an absolutely unacceptable manner from an environmental point of view.”
And one of the things that historically has driven a lot of this work is an interest in mining the deep seabed.”
The seabed contains valuable resources, such as this ‘astonishingly rich’ rock found in a seamount off the Canary Islands by the UK’s National Oceanography Centre, containing tellurium, used in solar PV panels, as well as rare earth elements.
Photograph: NOC
For Basik too, the naming – and claiming – of ocean features is not merely a territorial issue.
“This is not only about possible geopolitical conflicts and potential wars,” he says.
“This is about the future and future development.
This is about the potential for using the oceans in an absolutely unacceptable manner from an environmental point of view.”
Links :
Sunday, October 27, 2024
Geopolitics of the South China Sea
At least 3.4 trillion USD worth of trade passes through the South China Sea annually, accounting for a third of the global maritime trade.
In various parts of the sea, there is the promise of crude oil and natural gas beneath the seabed, while other areas hold rich fishing grounds.
But, the sea is also loaded with distinct hazards and chokepoints such as straits, reefs, smugglers, secessionists, and so on.
On top of everything are the political boundaries of the nearby coastal states.
No fewer than seven countries have maritime claims in the South China Sea, each overlapping the other.
But, one nation, in particular, makes the most daring claim.
The People's Republic of China not only disputes the waters of each of its neighbours but in doing so it seeks to cast its hegemony over the nations bordering the South China Sea.
In various parts of the sea, there is the promise of crude oil and natural gas beneath the seabed, while other areas hold rich fishing grounds.
But, the sea is also loaded with distinct hazards and chokepoints such as straits, reefs, smugglers, secessionists, and so on.
On top of everything are the political boundaries of the nearby coastal states.
No fewer than seven countries have maritime claims in the South China Sea, each overlapping the other.
But, one nation, in particular, makes the most daring claim.
The People's Republic of China not only disputes the waters of each of its neighbours but in doing so it seeks to cast its hegemony over the nations bordering the South China Sea.
Links :
- E-Flux : South China Sea Monument
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