Separation of larger ice from an iceberg by a crack. An iceberg has broken off in Antarctica. One of the largest in history! Spotted from space

Illustration copyright BAS Image caption It is now the middle of winter in Antarctica. This crack that created the iceberg was filmed in the summer

One of the largest icebergs in history has just broken off from a glacier in Antarctica.

The area of ​​this giant ice field is approximately 6000 square meters. km. This is six times the size of “old” Moscow (before expansion in 2012) or four times the size of Greater London.

The iceberg was spotted by a US satellite flying over the Larsen S Ice Shelf on Wednesday.

Scientists have been waiting for this event: they have been watching the growth of a crack in the Larsen S glacier for more than ten years.

Since 2014, the progress of the crack has accelerated, and the birth of a new giant iceberg looked like a matter of near future.

The flat iceberg, about 200 meters thick, won't float far anytime soon, but you need to keep an eye on it: later, currents and winds could carry it north, where it could threaten shipping.

Spotted from space

The infrared sensor of the US Aqua satellite on Wednesday spotted a continuous strip of clear water between the ice shelf and the iceberg. This water is warmer than the surrounding ice and air.

"The rift has been barely visible in recent weeks, but there is now enough evidence to suggest it has widened significantly along its entire length," explains Professor Adrian Luckman, director of Project Midas at Swansea University in Wales. The participants in this project followed the birth of a new iceberg more closely than anyone else.

In recent hours, the European satellite system Sentinel-1 should also have received an image confirming the separation of the iceberg from the glacier. The radars of the two satellites of this system are capable of recording any displacement of the iceberg relative to the glacier.

Illustration copyright Air Force

The new iceberg may be one of the ten largest in history, although it does not compare with the most gigantic monsters spotted in Antarctica.

The largest iceberg in the Sputnik era was the iceberg that broke off the Ross Ice Shelf in 2000 - its area was about 11,000 square meters. km. This is larger than Lebanon, for example.

Six years later, fragments of this giant were still floating near New Zealand.

In 1956, it was reported that a US military icebreaker encountered an iceberg with an area of ​​about 32,000 square meters. km. This is larger than the area of ​​Belgium or, say, slightly smaller than the Tambov region. Unfortunately, there were no satellites at that time that could confirm this assessment.

The Larsen C glacier has also already given birth to giant icebergs. In 1986, a piece of about 9,000 square meters broke off from it. km.

The "offspring" of Larsen C can end up in the circular current of the Weddell Sea, but they can also be carried into the Southern Ocean and even into the southern part of the Atlantic Ocean.

A noticeable part of the icebergs from this area run aground near the British islands of South Georgia and gradually melt there.

The birth of a new giant iceberg in itself most likely does not mean anything special.

The Larsen C Ice Shelf is a mass of ocean-going ice formed by several glaciers that originate inland on the east coast of the Antarctic Peninsula.

The fact that the leading edge of ice floating in the ocean constantly breaks off is a completely natural process. On the continent, as a result of snowfalls, a mass of ice accumulates, slides into the ocean, floats away in the form of icebergs and melts - thus maintaining balance.

At the same time, scientists believe that the Larsen C glacier is now smaller than it has ever been in the last almost 12 thousand years, since the last ice age, and about a dozen more glaciers further north along the coast of the Antarctic Peninsula have either completely disappeared in recent decades. collapsed or shrank very much.

Looks healthy

The smaller glaciers closest to Larsen C, Larsen A and Larsen B, collapsed at the turn of the century. It is possible that global warming played a role in this.

However, Larsen S looks completely different from his brothers.

"We don't see the same signs here that we saw at the Larsen A and Larsen B glaciers," says Professor Helen Fricker of California's Scripps Institution of Oceanography. destroys the glacier."

"Most glaciologists are not yet particularly alarmed by what is happening with Larsen S. Normal processes," continues Professor Fricker.

Scientists took a particularly close look at this glacier some time ago, when it was not clear where the crack that appeared near the Gipps Glacier Rise would go. There was a possibility that it would pass behind another key point, the Boden Glacier Rise. In this case, the glacier's slide into the ocean would significantly accelerate.

But the crack reached the water south of the Boden Hill, and now scientists do not expect a significant acceleration of the glacier's movement.

Next, scientists will focus in particular on a strip of “warm,” soft ice that runs across the ice shelf from west to east and out to the ocean about 100 kilometers north of Gipps Rise, in the area where the iceberg calved.

Illustration copyright Air Force

This strip was called the “Yorga suture (tectonic suture)” and a whole series of cracks abuts against it, without spreading further.

“The fact that an iceberg has broken off from a glacier does not in itself increase the likelihood that cracks will overcome the Jörg suture,” says Chris Burstad from the University Center of Spitsbergen.

"We don't know at this stage whether there is some large-scale weakening of this zone going on - for example, whether the ocean is eroding the ice shelf from below - or whether the current rift was just an episode that was bound to happen, sooner or later," says Chris Burstad.

“We know that faults periodically widen and lead to the formation of large, flat icebergs even in the absence of climate change,” the scientist recalls.

In the north-west of Antarctica, an iceberg with an area of ​​almost 6 thousand square meters broke off from the Larsen C ice shelf. km and weighing a trillion tons - one of the largest in the history of observations, reports the BBC.

— Project MIDAS (@MIDASOnIce) July 12, 2017

The thickness of the Larsen Glacier reaches approximately 350 meters. It keeps all of Antarctica's internal glaciers from draining into the ocean, which could also begin to separate from the continent. The detachment of the iceberg resulted in the loss of a tenth of the entire glacier.

The formation of an iceberg is not related to global warming. Unlike thin layers of sea ice, Larsen is an ice shelf, which is a mass of ice floating in the ocean.

“There is enough ice in Antarctica to raise sea levels by 60 meters if everything melted or even just poured into the ocean,” Martin Siegert, professor of geology at Imperial College London and co-director of the Grantham Institute for Climate Change and the Environment, explained to The Guardian newspaper.

The birth of a huge iceberg will not lead to a rise in sea levels. "It's like an ice cube in your glass of gin and tonic - it's already floating, and even if it melts, it doesn't change the volume of water in the glass very much," Siegert compared.

According to scientists, in the near future the iceberg will move quite slowly, but it needs to be monitored: sea currents can carry it to a place where it will pose a danger to ship traffic.

The Larsen Glacier originally consisted of three - Larsen A, Larsen B and Larsen C. Over the past half century, temperatures on the Antarctic Peninsula have increased by 2.5 degrees Celsius. Climate change led to the fact that in 1995 Larsen A with an area of ​​4000 square meters. km was completely destroyed. In the early 2000s, an iceberg with an area of ​​more than 3 thousand square meters broke off from Larsen B. km.

In December 2016, NASA received images from aircraft that showed that a giant crack had appeared in Larsen C, 112 kilometers long, about 100 meters wide and about 500 meters deep. This year it grew rapidly and by July had increased to 200 kilometers in length. The mass of ice here can reach a trillion tons.

The largest recorded iceberg, B-15, measured 295 x 37 km, had an area of ​​11,000 sq km and weighed three trillion tons. It broke off from the Ross Ice Shelf in March 2000, near Roosevelt Island, and then broke into smaller pieces in 2000, 2002, 2003. Six years later in 2006, several large pieces were spotted in New Zealand.

In 1965, it was reported that an American icebreaker discovered an object with an area of ​​32,000 square meters. km - larger than the area of ​​Belgium, but at that time there were no satellites with which to confirm this information.

Agence France-Presse, citing scientists who have been monitoring a growing crack in the ice for months, reports that part of Antarctica's largest ice shelf, the western Larsen C glacier, has separated, forming one of the largest icebergs on record.

The University of Swansea (Wales) reported that the iceberg calved between Monday and Wednesday (that is, between July 10 and 12), when part of the Larsen C glacier, whose area is 5.8 thousand square kilometers, finally separated.

It should be noted that previously scientists warned that if the iceberg breaks away, this will entail the loss of about a tenth of the entire glacier.

Initially, the Larsen Glacier consisted of three parts - Larsen A, B and C. On the Antarctic Peninsula, temperature indicators over the past five decades have increased by 2.5 degrees Celsius. Climate change led to the fact that Larsen A, whose area was four thousand kilometers, was completely destroyed in 1995. An iceberg, whose area reached about three thousand square kilometers, separated from the Larsen B glacier in the early 2000s. In the winter of 2016, the NAA received photographs from airplanes, which clearly showed that a large crack had formed in the third glacier, the length of which was 112 kilometers, the width was about one hundred meters, and the depth was approximately 500 meters. Throughout 2017, it rapidly increased and by the beginning of July its length was already 200 kilometers. Here the mass of ice can be about a trillion tons.

According to Adrian Luckman of Swansea University, who led the research in Antarctica, scientists cannot predict what might happen to the iceberg in the future. It may remain intact, but it is more likely that it will crack. Some of the debris may remain in the same area for decades, while some may float into warmer waters.

In addition, the scientist also noted that there is no consensus among researchers regarding the fate of the shelf. Some experts are convinced that it will gradually increase, others, on the contrary, are confident that new icebergs will continue to separate from it, and ultimately this will lead to its complete destruction.

Scientists from Britain believe that in the future the shelf will become less stable, but this process will take many years in any case.

According to glaciologist Martin O'Leary, a member of the research team, the new iceberg will not provoke an immediate rise in sea levels, but if the shelf continues to decrease, it could cause glaciers to wash away the shores on their way to the ocean . Over time, this ice may affect sea levels, although only slightly.

Speaking about the reasons for the appearance of the giant iceberg, Alexey Kokorin, head of the Russian climate program WWF, pointed out that the iceberg broke off from the ice shelf because it was being washed away from the bottom by ocean waters. Scientists note that water temperatures in the surface layer of the ocean, which is hundreds of meters deep, have increased slightly. This is what global warming is.

As the scientist notes, at present it is too early to say that an iceberg, even a gigantic one, can affect the rise in water levels in the World Ocean. Currently, this level is rising by three millimeters every year. However, it can still make some contribution to the rise in level and the cooling process of the ocean.

According to Vasily Smolyanitsky, head of the world sea ice data center (Arctic and Antarctic Research Institute), an iceberg of gigantic size does not pose a threat to shipping, since it will drift in the waters of the Southern Ocean for a long time. However, the process of melting will take decades.

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According to Swansea University professor and head of the MIDAS Antarctic project Adrian Luckman, a huge iceberg with an area of ​​5,800 sq. km, 350 m thick and weighing more than 1 trillion tons, which broke off from Antarctica on July 12, can last for several decades.

Professor Adrian Luckman stated:

"This iceberg is one of the largest in history, and its future is difficult to predict. It may remain in one piece, but it is more likely that it will break up into fragments. Some of the ice may remain in the area for decades, other parts may drift north, to warmer waters".

Scientists plan to monitor the movement of the broken iceberg. According to scientists, it provides the connection of all the ice shelves of Antarctica; later they may begin to separate from the ice continent.

The main reason for the destruction of the Antarctic ice sheet is the flooding of its base by warm ocean water.

"What happened today is a consequence of natural causes. We know nothing about the possible impact of human-induced global warming on these processes. However, the ice shelves now find themselves in a very precarious position. The Antarctic ice has now retreated to its furthest distance in recorded history. We will be monitoring very closely for potential signs of instability across all ice shelves.", said Swansea University glaciologist Martin O'Leary.

Swansea University staff suggest that the new iceberg will not lead to a rise in sea levels and will not be associated with global warming.

If ice shelves stop holding back the flow of the inner parts of Antarctica's glaciers into the ocean, then the level of the world's oceans could rise by 10 cm, and this is a significant amount by scientific standards.

Leading researcher at the Institute of Geography of the Russian Academy of Sciences, Candidate of Geographical Sciences Andrei Glazovsky gave an interview to Sputnik radio and explained the ongoing processes in Antarctica:

“This is not the fault of global warming, this is a natural process: Antarctica is losing its mass this way. Snow falls on the continent, accumulates in the form of a gigantic mass - this is the ice sheet of Antarctica, and then such large pieces break off from it, mostly icebergs. Now Antarctica is in In general, it loses a little - and not “plus or minus”, but absolutely loses - about 150 cubic kilometers in pure form. That is, more flows out of it than comes in. By the way, this is not the largest iceberg in Antarctica, it is one of the ten largest. There were much more icebergs that were observed - there was a “piece” of about 11 thousand square kilometers in 2000.”, - said Andrey Glazovsky.

According to the scientist, the iceberg will not affect the level of the World Ocean, but may create problems for shipping:

“It’s not like the iceberg floated somewhere, it separated from the floating plate and became independent. Then its fate is this: it will slowly crawl away from Antarctica, go north. Then it can go to an area where shipping is observed, and there they may there will be trouble. Now it’s difficult to say where it will go. There is a circular current, and it can spin a little and go further. I’ll tell you right away: it will not affect the level of the World Ocean, because it broke away from the floating plate. But if it crawled on. continent, then the ocean level would rise by about three millimeters. This is very decent. Now the level of the World Ocean is rising by about three millimeters per year, but this is the contribution of all the glaciers of Antarctica and Greenland.", - explained Andrei Glazovsky.

It is difficult to predict where the iceberg will move; at the moment it has sailed 13 kilometers from the continent.

Since it became dangerous to be on the glacier, scientists left it in the spring of 2017. And then they will watch the iceberg from space

Melting Antarctica:

Scientists have been monitoring the stability of this ice shelf for several years. Thomas Zurbuchen, a Swiss-American astrophysicist who has been appointed Deputy Administrator of NASA's Science Mission Directorate since October 2016, published an image of the new iceberg on July 12, 2017, taken by NASA's Terra and Aqua satellites:

The blue color represents a warm surface - this is seen between a new iceberg and an ice shelf, as well as in areas of open ocean and where the water is covered with thin ice. Lighter blue tones indicate pristine or thicker ice.

“A careful analysis of the increase in the number of natural disasters, extreme weather events around the world, as well as statistical indicators of space and geophysical parameters in recent years has shown an alarming trend towards a significant increase in a short period of time. These data indicate that the assumptions made by a number of scientists that the Earth’s climate change over the course of 100 years or more will be gradual are incorrect, since in fact this process is happening much more dynamically.These are processes that humanity is currently unable to influence, so their consequences, possible risks and difficulties for people in connection with future events on Earth cannot be underestimated; we need to prepare for these events ». Quote from d salary of the ALLATRA SCIENCE community of scientists« » .

The area of ​​this giant ice field is approximately 6000 square meters. km. This is 6 times larger than “old” Moscow (before expansion in 2012) or 4 times larger than Greater London.
The iceberg was spotted by a US satellite flying over the Larsen S Ice Shelf on Wednesday.

Scientists have been waiting for this event: they have been watching the growth of a crack in the Larsen S glacier for more than ten years.
Since 2014, the progress of the crack has accelerated, and the birth of a new giant iceberg looked like a matter of near future.
The flat iceberg, about 200 meters thick, won't float far anytime soon, but you need to keep an eye on it: later, currents and winds could carry it north, where it could threaten shipping.

Spotted from space

The infrared sensor of the US Aqua satellite on Wednesday spotted a continuous strip of clear water between the ice shelf and the iceberg. This water is warmer than the surrounding ice and air.
"The rift has been barely visible in recent weeks, but there is now enough evidence to suggest it has widened substantially along its entire length," explains Professor Adrian Luckman, director of Project Midas at Swansea University in Wales. The participants in this project followed the birth of a new iceberg more closely than anyone else.
In recent hours, the European satellite system Sentinel-1 should also have received an image confirming the separation of the iceberg from the glacier. The radars of the two satellites of this system are capable of recording any displacement of the iceberg relative to the glacier.



The new iceberg may be one of the ten largest in history, although it does not compare with the most gigantic monsters spotted in Antarctica.
The largest iceberg in the Sputnik era was the iceberg that broke off the Ross Ice Shelf in 2000 - its area was about 11,000 square meters. km. This is larger than Lebanon, for example.
Six years later, fragments of this giant were still floating near New Zealand.
In 1956, it was reported that a US military icebreaker encountered an iceberg with an area of ​​about 32,000 square meters. km. This is larger than the area of ​​Belgium or, say, slightly smaller than the Tambov region. Unfortunately, there were no satellites at that time that could confirm this assessment.
The Larsen C glacier has also already given birth to giant icebergs. In 1986, a piece of about 9,000 square meters broke off from it. km.
The “offspring” of Larsen C can end up in the circular current of the Weddell Sea, but they can also be carried into the Southern Ocean and even into the southern part of the Atlantic Ocean.


A noticeable part of the icebergs from this area run aground near the British islands of South Georgia and gradually melt there.
The birth of a new giant iceberg in itself most likely does not mean anything special.
The Larsen C Ice Shelf is a mass of ocean-going ice formed by several glaciers that originate inland on the east coast of the Antarctic Peninsula.
The fact that the leading edge of ice floating in the ocean constantly breaks off is a completely natural process. On the continent, as a result of snowfalls, a mass of ice accumulates, slides into the ocean, floats away in the form of icebergs and melts - thus maintaining balance.
At the same time, scientists believe that the Larsen C glacier is now smaller than it has ever been in the last almost 12 thousand years, since the last ice age, and about a dozen more glaciers further north along the coast of the Antarctic Peninsula have either completely disappeared in recent decades. collapsed or shrank very much.

Looks healthy

The smaller glaciers closest to Larsen C, Larsen A and Larsen B, collapsed at the turn of the century. It is quite possible that global warming played a role in this.
However, Larsen S looks completely different from his brothers.
“We don't see the same features here that we saw at the Larsen A and Larsen B glaciers,” says Professor Helen Fricker of the Scripps Institution of Oceanography in California. “We don’t see that kind of melting, and we don’t see any evidence of a large volume of meltwater on the surface that is eroding the glacier.”
“Most glaciologists are not yet particularly alarmed by what is happening with Larsen S. Normal processes,” continues Professor Fricker.
Scientists took a particularly close look at this glacier some time ago, when it was not clear where the crack that appeared near the Gipps Glacier Rise would go. There was a possibility that it would pass behind another key point, the Boden Glacier Rise. In this case, the glacier's slide into the ocean would significantly accelerate.
But the crack reached the water south of the Boden Hill, and now scientists do not expect a significant acceleration of the glacier's movement.
Next, scientists will focus in particular on a strip of “warm”, soft ice that runs across the ice shelf from west to east and out to the ocean about 100 kilometers north of Gipps Rise, in the area where the iceberg calved.

This strip was called the “Yorga suture (tectonic suture)” and a whole series of cracks abuts against it, without spreading further.
“The fact that an iceberg has broken off from a glacier does not in itself increase the likelihood that cracks will overcome the Jörg suture,” says Chris Burstad from the University Center of Spitsbergen.
"We don't know at this stage whether there is some large-scale weakening of this zone going on - for example, whether the ocean is eroding the ice shelf from below - or whether the current rift was just an episode that was bound to happen, sooner or later," says Chris Burstad.
“We know that faults periodically widen and lead to the formation of large, flat icebergs even in the absence of climate change,” the scientist recalls.
Jonathan Amos, BBC Science Correspondent

 

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