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Lower-latitude oceans drive complex changes in the Arctic Ocean,

Arctic Ocean changes driven by sub-Arctic seas   https://www.eurekalert.org/pub_releases/2020-07/uoaf-aoc071020.php  b  UNIVERSITY OF ALASKA FAIRBANK  New research explores how lower-latitude oceans drive complex changes in the Arctic Ocean, pushing the region into a new reality distinct from the 20th-century norm.

The University of Alaska Fairbanks and Finnish Meteorological Institute led the international effort, which included researchers from six countries. The first of several related papers was published this month in Frontiers in Marine Science.

Climate change is most pronounced in the Arctic. The Arctic Ocean, which covers less than 3% of the Earth’s surface, appears to be quite sensitive to abnormal conditions in lower-latitude oceans.

“With this in mind, the goal of our research was to illustrate the part of Arctic climate change driven by anomalous [different from the norm] influxes of oceanic water from the Atlantic Ocean and the Pacific Ocean, a process which we refer to as borealization,” said lead author Igor Polyakov, an oceanographer at UAF’s International Arctic Research Center and FMI.

Although the Arctic is often viewed as a single system that is impacted by climate change uniformly, the research stressed that the Arctic’s Amerasian Basin (influenced by Pacific waters) and its Eurasian Basin (influenced by Atlantic waters) tend to differ in their responses to climate change.

Since the first temperature and salinity measurements taken in the late 1800s, scientists have known that cold and relatively fresh water, which is lighter than salty water, floats at the surface of the Arctic Ocean. This fresh layer blocks the warmth of the deeper water from melting sea ice.

In the Eurasian Basin, that is changing. Abnormal influx of warm, salty Atlantic water destabilizes the water column, making it more susceptible to mixing. The cool, fresh protective upper ocean layer is weakening and the ice is becoming vulnerable to heat from deeper in the ocean. As mixing and sea ice decay continues, the process accelerates. The ocean becomes more biologically productive as deeper, nutrient-rich water reaches the surface.

By contrast, increased influx of warm, relatively fresh Pacific water and local processes like sea ice melt and accumulation of river water make the separation between the surface and deep layers more pronounced on the Amerasian side of the Arctic. As the pool of fresh water grows, it limits mixing and the movement of nutrients to the surface, potentially making the region less biologically productive.

The study also explores how these physical changes impact other components of the Arctic system, including chemical composition and biological communities.

Retreating sea ice allows more light to penetrate into the ocean. Changes in circulation patterns and water column structure control availability of nutrients. In some regions, organisms at the base of the food web are becoming more productive. Many marine organisms from sub-Arctic latitudes are moving north, in some cases replacing the local Arctic species.

“In many respects, the Arctic Ocean now looks like a new ocean,” said Polyakov.

These differences change our ability to predict weather, currents and the behavior of sea ice. There are major implications for Arctic residents, fisheries, tourism and navigation.

This study focused on rather large-scale changes in the Arctic Ocean, and its findings do not necessarily represent conditions in nearshore waters where people live and hunt.

The study stressed the importance of future scientific monitoring to understand how this new realm affects links between the ocean, ice and atmosphere.

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Co-authors of the paper include Matthew Alkire, Bodil Bluhm, Kristina Brown, Eddy Carmack, Melissa Chierici, Seth Danielson, Ingrid Ellingsen, Elizaveta Ershova, Katarina Gårdfeldt, Randi Ingvaldsen, Andrey V. Pnyushkov, Dag Slagstad and Paul Wassmann.

July 13, 2020 Posted by | ARCTIC, climate change, oceans, Reference | Leave a comment

Arctic heat, uncontrolled fires, crumbling permafrost – very bad climate news

July 6, 2020 Posted by | ARCTIC, climate change, Russia | Leave a comment

The Arctic’s climate disaster-Verkhoyansk goes from record cold to record heat

A Disastrous Summer in the Arctic, https://www.newyorker.com/news/annals-of-a-warming-planet/a-disastrous-summer-in-the-arctic?utm_source=nl&utm_brand=tny&utm_mailing=TNY_Daily_062720&utm_campaign=aud-dev&utm_medium=email&bxid=5bea00ac3f92a404693b7a69&cndid=46508601&hasha=c25c4ad8a3e4cbc8faed20a1376eed39&hashb=637cacb29baeeb67e63d66fee2c449133fb8087a&hashc=4df42b687b9cea804c58e24a5a8eb39e5e143c4b6f747bc38a3be837d323c31f&esrc=home&utm_term=TNY_Daily

The Record, 28 June 20,The remote Siberian town of Verkhoyansk, three thousand miles east of Moscow and six miles north of the Arctic Circle, has long held the record, with another Siberian town, for the coldest inhabited place in the world. The record was set in 1892, when the temperature dropped to ninety below zero Fahrenheit, although these days winter temperatures are noticeably milder, hovering around fifty below. Last Saturday, Verkhoyansk claimed a new record: the hottest temperature ever recorded in the Arctic, with an observation of 100.4 degrees Fahrenheit—the same temperature was recorded that day in Las Vegas. Miami has only hit a hundred degrees once since 1896. “This has been an unusually hot spring in Siberia,”  Randy Cerveny, the World Meteorological Organization’s rapporteur of weather and climate extremes, said. “The coinciding lack of underlying snow in the region, combined with over-all global temperature increases, undoubtedly helped play a critical role in causing this extreme.” Siberia, in other words, is in the midst of an astonishing and historic heat wave.

Anthropogenic climate change is causing the Arctic to heat up twice as fast as the rest of the planet. Climate models had predicted this phenomenon, known as Arctic amplification, but they did not predict how fast the warming would occur. Although Verkhoyansk has seen hot temperatures in the past, Saturday’s 100.4-degree record follows a wildly warm year across the region. Since December, temperatures in western Siberia have been eighteen degrees above normal. Since January, the mean temperature across Siberia has been at least 5.4 degrees Fahrenheit above the long-term average. As the meteorologist Jeff Berardelli reported for CBS, the heat that has fallen on Russia in 2020 “is so remarkable that it matches what’s projected to be normal by the year 2100, if current trends in heat-trapping carbon emissions continue.”  By April, owing to the heat, wildfires across the region were larger and more numerous than they were at the same time last year, when the Russian government eventually had to send military aircrafts to battle vast blazes. The scale of the current wildfires—with towering plumes of smoke visible for thousands of miles on satellite images—suggest that this summer could be worse. Because of the coronavirus pandemic, they will also be more complicated to fight.

Toward the end of May, as the sun stopped dropping below the horizon, the heat continued. In the town of Khatanga, far north of the Arctic Circle, the temperature hit seventy-eight degrees Fahrenheit, or forty-six degrees above normal, topping the previous record by twenty-four degrees. The heat and fires are also hastening the dissolution of Siberian permafrost, perennially frozen ground that, when thawed, unleashes more greenhouse gases and dramatically destabilizes the land, with grave consequences. On May 29th, outside Norilsk, the northernmost city in the world, the thawing ground buckled, causing an oil-storage tank to collapse and spew more than a hundred and fifty thousand barrels, or twenty-one thousand tons, of diesel fuel into the Ambarnaya River.   The spill was the largest to ever occur in the Russian Arctic.

Norilsk, which was constructed in the nineteen-thirties by prisoners of a nearby Gulag camp, Norillag, was already one of the most polluted places in the world. Most of its hundred and seventy-seven thousand residents work for Norilsk Nickel, the company that owns the collapsed oil tank. Its massive mining and metallurgy complex alone is worth two per cent of Russia’s G.D.P. The city contributes a fifth of the global nickel supply and nearly half of the world’s palladium, a metal used to make catalytic converters. Factories billow clouds of sulfur dioxide incessantly, and the resulting acid rain has turned the city and its surroundings into an industrial wasteland, with no green space or parks, just dirt and dead trees. Life expectancy in Norilsk is twenty years shorter than it is in the United States. The last time the town made the news, before the oil spill, was exactly a year ago, when an emaciated polar bear, a refugee from its melting home, was photographed rummaging through the city dump.

Norilsk Nickel’s executives have tried to skirt responsibility for the oil spill by blaming the thawing permafrost—or, as a press release stated, “a sudden sinking of the storage tank’s pillars, which served accident-free for more than thirty years.”

But the thaw did not happen unexpectedly, out of nowhere. Buildings in Norilsk have collapsed because of the sagging ground. Russian and international experts have been aware of the risks that rapidly thawing permafrost represents for more than a decade. A 2017 report from an Arctic Council working group said that “communities and infrastructure built on frozen soils are significantly affected by thawing permafrost, one of the most economically costly impacts of climate change in the Arctic.” They found that thawing permafrost could contaminate freshwater, when previously frozen industrial and municipal waste is released, and that the bearing capacity of building foundations has declined by forty to fifty per cent in some Siberian settlements since the nineteen-sixties. They also noted that “the vast Bovanenkovo gas field in western Siberia has seen a recent increase in landslides related to thawing permafrost.” The authors of a 2018 paper, published in Nature Communications, found that “45% of the hydrocarbon extraction fields in the Russian Arctic are in regions where thaw-related ground instability can cause severe damage to the built environment.” The paper continued, “Alarmingly, these figures are not reduced substantially even if the climate change targets of the Paris Agreement are reached.”

In early June, President Vladimir Putin declared a national emergency, and scolded local authorities for their slow response to the spill. The Kremlin allegedly found out about the spill two days after the fact, from pictures of a crimson river posted on social media. Although the Russian prosecutor general’s office agreed, in a preliminary finding, that the thawing permafrost was a contributing factor to the spill, investigators also said that the fuel-storage tank had needed repairs since 2018. They arrested four employees of the power plant on charges of violating environmental regulations. Norilsk Nickel denied the accusations but said that the company is coöperating with law-enforcement agencies and has launched “a full and thorough investigation.” “We fully accept our responsibility for the event,” the company said in a statement provided to the Guardian. Vladimir Potanin, the president of Norilsk Nickel and the richest man in Russia, said that the company will pay for the full cost of the disaster, which he estimated at ten billion rubles, or a hundred and forty-six million dollars. (A Russian environmental watchdog, Rosprirodnadzor, put the cost at around one and a half billion dollars.) Putin, meanwhile, publicly lambasted Potanin for the disaster, emphasizing that it was his company’s negligence that led to the spill. “If you replaced them in time,” Putin said, in a video call in early June, referring to the aging oil-storage tank, “there wouldn’t have been the damage to the environment and your company wouldn’t have to carry such costs.”

The company’s initial response efforts—floating booms to contain the spill—largely failed. By June 9th, the oil had entered the forty-three-mile-long Lake Pyasino, which borders a nature preserve and flows into the Pyasino River. “Once it enters that river system, it can’t be stopped,” Rob Huebert, an Arctic expert at the University of Calgary, said. “The oil could then make its way to the Arctic Ocean.” On June 11th, Russia’s investigative committee charged Norilsk’s mayor with criminal negligence, for his botched response to the disaster. Last Friday, in another video call, Putin’s emergencies minister reported that response teams had collected 3.6 million cubic feet of polluted soil and 1.1 million cubic feet of contaminated water. The company will construct a pipeline to pump the contaminated muck to unspecified disposal sites. But the region will remain toxic. Diesel oil seeps into river banks. Even if the oil is contained to the lake, the contamination can never be fully removed. Some of it will make its way through the food chain. Wildlife—fish, birds, reindeer—could suffer for decades. “You can’t ever really clean a spill up,” Huebert said. Putin, in the call, emphasized that work must continue until the damage is remedied. “Obviously, the disaster has brought dire consequences for the environment and severely impacted biodiversity in water bodies,” he said. “It will take a lot of time to reclaim and restore the environment.”

Putin, however, is not known for his environmentalism. His anger and concern about the Norilsk oil spill might have more to do with how much it exposed his government, making visible the overwhelming economic and environmental risks facing oil, gas, and mineral development in Siberia if temperatures there continue to rise. “The Russians’ continued development of oil and gas in the central Arctic region is their economic future,” Huebert said. “The Russians’ interest in all this is to keep the oil flowing, whatever it takes.” But sixty per cent of Russia is permafrost. Although much of the newest oil and gas infrastructure in the Far North has been engineered with climate change in mind, temperatures are currently on track to far exceed projections. Perhaps that is why the Kremlin did, finally, officially ratify the Paris accord last October. And yet the Kremlin continues to incentivize increased oil and gas development in eastern Siberia and the Arctic, which will lead to more greenhouse-gas emissions, which will continue speeding up the permafrost thaw.

June 30, 2020 Posted by | ARCTIC, climate change, Reference | Leave a comment

Need for action on global heating – It’s 38°C in Siberia

June 27, 2020 Posted by | ARCTIC, climate change, Russia | 1 Comment

Record breaking heat in Verkhoyansk, north of the Arctic Circle

June 22, 2020 Posted by | ARCTIC, climate change, Russia | Leave a comment

Raising dangerously radioactive Russian submarines from the bottom of Arctic oceans

Russia plans to raise radioactive wrecks in the Arctic    https://bellona.org/news/nuclear-issues/2020-05-russia-plans-to-raise-radioactive-wrecks-in-the-arctic

By 2030, the Russian government will raise seven pieces of radioactive debris – including two nuclear submarines – from the bottom of Arctic oceans, where they were intentionally scuttled during the Soviet era, documents received by Bellona confirm.  May 12, 2020 by Charles Digges

By 2030, the Russian government will raise seven pieces of radioactive debris – including two nuclear submarines – from the bottom of Arctic oceans, where they were intentionally scuttled during the Soviet era, documents received by Bellona confirm.

The documents identify this debris as the most dangerous of the items the Soviet Union discarded in polar waters, and say that six of them contain more than 90 percent of the radioactivity to be found on the Arctic seabed.

Of particular importance, the documents say, are the K-159 and K-27 nuclear submarines, the nuclear reactors of which were still full of nuclear fuel when they went down.

Both submarines, say experts, are in a precarious state. In the case of the K-27, which was scuttled intentionally in 1982, the sub’s reactor was sealed with furfural, before it was sunk. But experts say this seal is eroding. The K-159, which sank while it was being towed to decommissioning in 2003, poses similar threats. Some 800 kilograms of spent nuclear fuel remained in its reactor when it went down in some of the most fertile fishing grounds in the Kara Sea.

In both cases, experts fear that a nuclear chain reaction could occur should water leak into the submarines’ reactor compartments.

Russian scientists have kept a close eye on the K-159, launching regular expeditions to monitor for potential radiation leaks. According to their data, should the submarine depressurize, radionuclides could spread over hundreds of kilometers, heavily impacting the local fishing industry.

Anatoly Grigoriev, who heads up the international programs department of Rosatom, Russia’s state nuclear corporation, says that raising the wrecks will cost some €123 million.

“Should the K-159 depressurize, it could cause €120 million of damage per month,” Grigoriev told Bellona at an earlier meeting.

Both submarines, say experts, are in a precarious state. In the case of the K-27, which was scuttled intentionally in 1982, the sub’s reactor was sealed with furfural, before it was sunk. But experts say this seal is eroding. The K-159, which sank while it was being towed to decommissioning in 2003, poses similar threats. Some 800 kilograms of spent nuclear fuel remained in its reactor when it went down in some of the most fertile fishing grounds in the Kara Sea.

In both cases, experts fear that a nuclear chain reaction could occur should water leak into the submarines’ reactor compartments.

Russian scientists have kept a close eye on the K-159, launching regular expeditions to monitor for potential radiation leaks. According to their data, should the submarine depressurize, radionuclides could spread over hundreds of kilometers, heavily impacting the local fishing industry.

Anatoly Grigoriev, who heads up the international programs department of Rosatom, Russia’s state nuclear corporation, says that raising the wrecks will cost some €123 million.

“Should the K-159 depressurize, it could cause €120 million of damage per month,” Grigoriev told Bellona at an earlier meeting.

The majority of this debris was left in the eastern bays of the Kara Sea near the Novaya Zemlya Archipelago. Still, the exact location of some of these sunken objects is still unknown. The whereabouts of the reactor compartment from the K-140 nuclear submarine remains unaccounted for.

And there are other radiation hazards that are farther afield. The K-278, or Komsomolets, nuclear submarine lies at the bottom of the Norwegian Sea.

“A quarter of all the radioactive waste that has been sunk in the oceans belongs to us,” says Sergei Antipov, director of strategic planning and project management at the Nuclear Safety Institute of the Russian Academy of Sciences.

Since the early 2000s, massive projects to decommission Soviet-era nuclear submarines have been ongoing with the assistance of numerous western partners. Moscow has shared information about these radioactive hazards with nations of the G-7 and has worked with the European Bank of Reconstruction and Development and other donors.

This international cooperation has brought significant results. Military bases have been cleared of most radioactive contamination and nearly 200 rusted-out nuclear submarines have been safely dismantled, as a review of the last 25 years of Bellona’s work clearly shows.

Russia, moreover, has the necessary infrastructure to deal with whatever discarded radiation hazards are brought to the surface of Arctic waters. And while Russia lacks the necessary vessels for such undersea rescues, the international partners it has developed while cleaning up other pieces of the Soviet nuclear legacy certainly do.

Next year, Russia assumes the rotating chairmanship of the Arctic Council, and we hope that Moscow will be able to announce upon the first meeting that these projects are underway. Bellona, which is already involved in discussing this important work, has high hopes.

May 16, 2020 Posted by | ARCTIC, Russia, wastes, weapons and war | Leave a comment

An Arctic island is warming SIX times faster than the global average

May 1, 2020 Posted by | ARCTIC, climate change | Leave a comment

Arctic marine life threatened as a result of Alaskan sea ice disappearing

Disappearing Alaskan sea ice is significant for Arctic marine ecosystem, Science Daily , April 22, 2020, University of Maryland Center for Environmental Science

Summary:
A new study shows that plant materials originating in Arctic sea ice are significantly incorporated into marine food webs that are used for subsistence in local communities of the greater Bering Strait region. The research has the potential to demonstrate the importance of sea ice ecosystems as a source of food in Arctic waters in Alaska and beyond.

A new study shows that plant materials originating in Arctic sea ice are significantly incorporated into marine food webs that are used for subsistence in local communities of the greater Bering Strait region.

The study led by scientists from the University of Maryland Center for Environmental Science traced persistent biological compounds that are uniquely generated by microscopic plants in sea ice and found that the compounds are present throughout the base of the food web. The research has the potential to demonstrate the importance of sea ice ecosystems as a source of food in Arctic waters in Alaska and beyond.

“It is widely thought that the loss of sea ice habitat will have far-reaching implications for Arctic ecosystems,” said lead author Chelsea Wegner Koch, a graduate research assistant and the University of Maryland Center for Environmental Science.

“As sea ice breakup occurs earlier and forms later each year, the open water period is expanding and the sources of food are shifting away from sea ice and towards greater proportions of open water production. This production in the absence of sea ice differs in the quality, quantity, and timing of delivery to the seafloor,” she said.

Efforts to account for the proportional shifts in contributions of ice algae have been incomplete due to the lack of a specific tracer that can be definitively assigned to ice algae rather than open-water phytoplankton. The compounds reaching the seafloor that were studied are associated with food for a range of seafloor animals that in turn provide food for ecologically and culturally important organisms, such as the bearded seal, Pacific walrus, gray whale and spectacled eider that forage on the shallow sea floor. …… https://www.sciencedaily.com/releases/2020/04/200422151134.htm
 

April 23, 2020 Posted by | ARCTIC, climate change, environment | Leave a comment

North pole soon to be ice free in summer 

April 21, 2020 Posted by | ARCTIC, climate change | Leave a comment

Big European bank offers to help Russia retrieve 1000s of radioactive junk from the Arctic sea

CTY Pisces – Photos of a Japanese midget submarine that was sunk off Pearl Harbor on the day of the attack. There’s a hole at the base of the conning tower where an artillery shell penetrated the hull, sinking the sub and killing the crew. Photos courtesy of Terry Kerby, Hawaii Undersea Research Laboratory. August 2003.

March 19, 2020 Posted by | ARCTIC, Russia, wastes | Leave a comment

Polar ice melting at an accelerating rate

Polar ice caps melting six times faster than in 1990s  https://www.theguardian.com/environment/2020/mar/11/polar-ice-caps-melting-six-times-faster-than-in-1990s

Losses of ice from Greenland and Antarctica are tracking the worst-case climate scenario, scientists warn  Damian Carrington Environment editor @dpcarrington,Thu 12 Mar 2020   The polar ice caps are melting six times faster than in the 1990s, according to the most complete analysis to date.

The ice loss from Greenland and Antarctica is tracking the worst-case climate warming scenario set out by the Intergovernmental Panel on Climate Change (IPCC), scientists say. Without rapid cuts to carbon emissions the analysis indicates there could be a rise in sea levels that would leave 400 million people exposed to coastal flooding each year by the end of the century.

Rising sea levels are the one of the most damaging long-term impacts of the climate crisis, and the contribution of Greenland and Antarctica is accelerating. The new analysis updates and combines recent studies of the ice masses and predicts that 2019 will prove to have been a record-breaking year when the most recent data is processed.

The previous peak year for Greenland and Antarctic ice melting was 2010, after a natural climate cycle led to a run of very hot summers. But the Arctic heatwave of 2019 means it is nearly certain that more ice was lost last year.

The average annual loss of ice from Greenland and Antarctica in the 2010s was 475bn tonnes – six times greater than the 81bn tonnes a year lost in the 1990s. In total the two ice caps lost 6.4tn tonnes of ice from 1992 to 2017, with melting in Greenland responsible for 60% of that figure.

The IPCC’s most recent mid-range prediction for global sea level rise in 2100 is 53cm. But the new analysis suggests that if current trends continue the oceans will rise by an additional 17cm.

“Every centimetre of sea level rise leads to coastal flooding and coastal erosion, disrupting people’s lives around the planet,” said Prof Andrew Shepherd, of the University of Leeds. He said the extra 17cm would mean the number of exposed to coastal flooding each year rising from 360 million to 400 million. “These are not unlikely events with small impacts,” he said. “They are already under way and will be devastating for coastal communities.”

Erik Ivins, of Nasa’s Jet Propulsion Laboratory, in California, who led the assessment with Shepherd, said the lost ice was a clear sign of global heating. “The satellite measurements provide prima facie, rather irrefutable, evidence,” he said.

Almost all the ice loss from Antarctica and half of that from Greenland arose from warming oceans melting the glaciers that flow from the ice caps. This causes glacial flow to speed up, dumping more icebergs into the ocean. The remainder of Greenland’s ice losses are caused by hotter air temperatures that melt the surface of the ice sheet.

The combined analysis was carried out by a team of 89 scientists from 50 international organisations, who combined the findings of 26 ice surveys. It included data from 11 satellite missions that tracked the ice sheets’ changing volume, speed of flow and mass.

About a third of the total sea level rise now comes from Greenland and Antarctic ice loss. Just under half comes from the thermal expansion of warming ocean water and a fifth from other smaller glaciers. But the latter sources are not accelerating, unlike in Greenland and Antarctica.

Shepherd said the ice caps had been slow to respond to human-caused global heating. Greenland and especially Antarctica were quite stable at the start of the 1990s despite decades of a warming climate.

Shepherd said it took about 30 years for the ice caps to react. Now that they had a further 30 years of melting was inevitable, even if emissions were halted today. Nonetheless, he said, urgent carbon emissions cuts were vital. “We can offset some of that [sea level rise] if we stop heating the planet.”

The IPCC is in the process of producing a new global climate report and its lead author, Prof Guðfinna Aðalgeirsdóttir, of the University of Iceland, said: “The reconciled estimate of Greenland and Antarctic ice loss is timely.”

She said she also saw increased losses from Iceland’s ice caps last year. “Summer 2019 was very warm in this region.”

March 14, 2020 Posted by | ANTARCTICA, ARCTIC, climate change, Reference | Leave a comment

Arctic ice melt is changing ocean currents 

February 10, 2020 Posted by | ARCTIC, climate change, Reference | Leave a comment

Permafrost thawing -“fast and dramatic, affecting landscapes in unprecedented ways

 

February 6, 2020 Posted by | ARCTIC, climate change, Reference | Leave a comment

Why Arctic glaciers are melting away at an accelerating rate

How the ocean is gnawing away at glaciers, https://www.sciencedaily.com/releases/2020/02/200203114350.htm

Date:
February 3, 2020
Source:
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
Summary:
The Greenland Ice Sheet is melting faster today than it did only a few years ago. The reason: it’s not just melting on the surface — but underwater, too. AWI researchers have now found an explanation for the intensive melting on the ice’s underside, and published their findings in the journal Nature Geoscience.

The glaciers are melting rapidly: Greenland’s ice is now melting seven times faster than in the 1990s — an alarming discovery, since climate change will likely intensify this melting in the future, causing the sea level to rise more rapidly.

Accordingly, researchers are now working to better understand the underlying mechanisms of this melting. Ice melts on the surface because it is exposed to the sun and rising temperatures. But it has now also begun melting from below — including in northeast Greenland, which is home to several ‘ice tongues’. Each tongue is a strip of ice that has slid down into the ocean and floats on the water — without breaking off from the land ice. The longest ice tongue, part of the ’79° North Glacier’, is an enormous 80 km long. Over the past 20 years, it has experienced a dramatic loss of mass and thickness, because it’s been melting not just on the surface, but also and especially from below.

Too much heat from the ocean

A team led by oceanographer Dr Janin Schaffer from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Bremerhaven has now identified the source of this intense underwater melting. The conclusions of their study, which the experts have just released in the journal Nature Geoscience, are particularly unsettling because the melting phenomenon they discovered isn’t unique to the 79° North Glacier, which means it could produce similar effects elsewhere. For the purposes of the study, the researchers conducted the first extensive ship-based survey of the ocean floor near the glacier, which revealed the presence of a two-kilometre-wide trough, from the bottom of which comparatively warm water from the Atlantic is channelled directly toward the glacier. But that’s not all: in the course of a detailed analysis of the trough, Janin Schaffer spotted a bathymetric sill, a barrier that the water flowing over the seafloor has to overcome. Once over the hump, the water rushes down the back of the sill — and under the ice tongue. Thanks to this acceleration of the warm water mass, large amounts of heat from the ocean flow past the tongue every second, melting it from beneath. To make matters worse, the layer of warm water that flows toward the glacier has grown larger: measured from the seafloor, it now extends 15 metres higher than it did just a few years ago. “The reason for the intensified melting is now clear,” Schaffer says. “Because the warm water current is larger, substantially more warmth now makes its way under the ice tongue, second for second.”

Other regions are also affected

In order to determine whether the phenomenon only manifests at the 79° North Glacier or also at other sites, the team investigated a neighbouring region on Greenland’s eastern coast, where another glacier, the Zachariæ Isstrøm, juts out into the sea, and where a large ice tongue had recently broken off from the mainland. Working from the surface of an ice floe, the experts measured water temperatures near the ocean floor. According to Schaffer: “The readings indicate that here, too, a bathymetric sill near the seafloor accelerates warm water toward the glacier. Apparently, the intensive melting on the underside of the ice at several sites throughout Greenland is largely produced by the form of the seafloor.” These findings will ultimately help her more accurately gauge the total amount of meltwater that the Greenland Ice Sheet loses every year.

Story Source:

Materials provided by Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research. Note: Content may be edited for style and length.

February 3, 2020 Posted by | ARCTIC, climate change, oceans | Leave a comment

America Almost Stockpiled Nuclear Weapons In Iceland

December 30, 2019 Posted by | ARCTIC, USA, weapons and war | Leave a comment

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