ShIP to

The Larsen C Ice Shelf Collapse Is Just the Beginning—Antarctica Is Melting

by:COSCO     2019-08-14
From above, the Pine Island ice shelf is a slow
Train wreckage.
Its buckled surface is scarred by thousands of big cracks.
Its edge is torn by a mile of cracks every quarter.
At 2015 and 2016 a 225-square-
The mile-long part of it fell from the end and drifted to the Amundsen Sea.
Over the past few decades, the water has warmed more than 1 degree Fahrenheit, and the rate of ice melting and calving has quadrupled.
On the Antarctic Peninsula, the average temperature has risen by nearly five degrees.
That\'s why Delaware
The size of the iceberg has just fallen off the Larsen C ice shelf, why the smaller ice shelf on the peninsula has been completely disintegrated into the waters of the Weddell Sea.
But around the Amundsen Sea thousands of miles southwest of Antarctica\'s Pacific coast, glaciers are much larger and risky.
They affect the whole earth.
The Pine Island ice shelf is the floating end of the Pine Island Glacier and is one of several large glaciers flowing into the Amundsen Sea.
Together they drained a larger ice dome, called the ice sheet in the Western Antarctic, which was two and a half miles thick and covered twice as much as Texas.
Ice sheets cover a range of islands, but most of them are at the bottom of a basin 5,000 feet above sea level.
This makes it particularly vulnerable to ocean warming.
If, as researchers are increasingly convinced, all the fragile ice becomes unstable, broken into pieces and drifting away, it will raise sea levels by about 10 feet, flooding the shores of the world.
The ice is only blocked by ice racks on the edge, and floating dams that support isolated mountains and rocky ridges on the edge of the basin begin to fail.
They themselves do not add much to the sea level as they are already floating in the water.
But as the glaciers weaken, the glaciers behind them will flow faster to the sea, and the edges will retreat.
This is happening around the Amundsen Sea now.
Pine Island\'s ice shelf is about 1,300 feet thicker than most of its areas, a dramatic example: it has averaged 150 feet thinner from 1994 to 2012.
But even more worrying is the neighboring thwaite Glacier, which could disrupt stability in most parts of the Western Antarctic if it collapses.
These glaciers are the fastest retreating glaciers on the Earth\'s surface, said Eric rigno, an ice scientist at NASA\'s Jet Propulsion Laboratory in Pasadena, California.
Rignott, who has been using aircraft and satellite radar for more than 20 years in the region, believes that the collapse of the Southwest polar ice sheet is only a matter of time.
The question is whether humans need time to prepare in 500 or under the age of a hundred.
\"We have to get these numbers right,\" said Rignot.
But we must be careful not to waste too much time doing it.
Getting the right predictions requires only going to the ice to make the measurements.
In December 2012and-
A white Twin Otter plane flew low on the Pine Island ice shelf.
The pilot dragged the snowboard on the plane through the snow and then lifted it up and circled back to make sure he did not find any cracks.
After the plane landed, one person got off the ship.
He tied his rope and harness to the plane, and he used eight ropes to detect snow. foot rod.
Finally, the scout was satisfied: it was not possible to devour the burial cracks of the landing party.
More scientists get off the plane.
The team, led by the University of Alaska ice scientist Martin Truver, began building the camp.
Their plan is to stay on the ice rack for two months.
They will be the first people who don\'t even have one night.
Ice is considered too dangerous to visit.
But truffer\'s team wanted to drill holes all the time on the ice rack so they could measure heat from the seawater below.
When the researchers lay in the tent at night, in a 4,000-
There is no fixed outpost on a mile-long coastline, and they hear loud noises and loud noises from ice.
Every morning, they see new cracks that pass through its surface, one inch wide, and look like cracks without a bottom.
In their five-week study, the ice beneath the Boots was 7 feet thinner.
It took scientists a long time to realize how fast the ice melts in West Antarctica.
Part of the reason is that the most vulnerable glaciers are well protected.
In front of the Pine Island ice shelf, the floating end of the glacier freezes every winter.
In the summer, the broken sea ice is connected to the iceberg falling off the ice shelf, forming a changing fence that historically has left the ship at least a hundred miles from the ice shelf.
March 1994, United StatesS.
The icebreaker, Nathaniel B.
Palmer may be the second vessel to reach it.
Over the past few days, strong winds have separated the ice floes, creating a narrow and short passage for Palmer.
With no accurate maps to guide them, the crew on board watched the sonar monitor nervously.
It shows the chaotic bottom of the canyon and sharp ridges, including one that rises within 20 feet of the ship\'s keel.
After only 12 hours in front of the ice shelf, the Palmer was eroded by sea ice and forced to retreat north.
But this gives the crew enough time to lower the scientific instrument through the water column.
They made disturbing discoveries.
Near the surface, a stream of water flows from under the ice shelf, which is a little bit more salty than the surrounding water, because the melted ice is fresh. (
Ice is fresh because it originated from snow in western Antarctica. )
In the depths of 2,000 to 3,000 feet, the warm water flows through the underwater canyon under the ice.
Stan Jacobs, an oceanographer from Lamont
The Doherty Earth Observatory in New York soon learned what was going on.
The warm waters come from the South Pacific Ocean, more than 200 miles in the North Pacific.
It is heavily salted, followed by the bottom of an underwater canyon tilted towards a glacier.
The glacier itself carved the canyon thousands of years ago during the Ice Age, when it and other glaciers in western Antarctica moved hundreds of miles from where they are now --day positions.
Now, the same canyon is delivering warm water under the Pine Island ice shelf.
Somewhere dozens of miles inland, the warm waters discover the place where glaciers rise from the bottom of the sea and become ice floaters.
The warm water impacts the ice wall and erodes the ice wall, resulting in a steady stream of melted water. laden seawater.
Because it is colder and fresher, it is less dense, so it rises on the warm water surface, flows into the water, and then flows back to the sea under the shelf.
By measuring the amount of these fresh water, researchers can estimate how much ice is lost.
Adrian Jenkins, an ice scientist at the Cambridge British Antarctic Survey, said the melting rate was crazy.
According to his calculations, the ice shelf loses 13 cubic miles of ice every year from the lower side;
Back near the ground wire, the ice may become thinner by 300 feet each year.
\'The glaciers melt so fast that it\'s beyond our concept, \'Jenkins said.
Over the next 13 years, he and Jacobs have tried to return to Pine Island three times.
There is sea ice blocking every time.
When they finally returned to the Palmer in January 2009, they found that the melting rate increased by about 50%.
This time, they are equipped with a new tool: a yellow robot submarine called autos3.
Shaped like a torpedo, as long as it is a delivery truck, it can independently navigate under the ice rack, disengage with the ship, up to 30 hours at a time.
In the first three dives, Autosub3 found that the ice shelf was thin enough to be lifted from an undersea ridge spanning its width, which once supported and stabilized the ice shelf.
This opens a gap to allow warm water to flow into and melt the lower side of the ice more quickly.
The yellow robot almost died during the fourth dive.
When the crew pulled it out of the water, they found that its nose cone was broken and some exquisite internal equipment was damaged.
Technicians rebuilt what happened from the submarine\'s navigation data.
Thirty miles ago, under the ice shelf, Autosub3 strayed into a crack under the ice.
While looking for the way forward, it has been smashed and scraped on the wall of chasm, eventually rising by 500 feet into the maze-like interior of the ice rack.
In the end, it fell out and fled to the open waters.
At the same time, the submarine\'s sonar data reveals the stunning landscape it sailed through.
There is not only one channel at the bottom of the ice rack, but there are many channels, which are up to 600 feet.
The walls of these inverted ice canyons are carved into terraces, ledgers, and spires, extending a huge crack along the ceiling of each Canyon, and the cracks are even deep into the ice.
What is going on?
Jenkins recalled his thoughts when he first saw the sonar map.
What he and Jacobs realized was,
Below the canyon is carved by running water, like a rocky canyon on land.
Apparently, the melt from the ground wire is still warm enough to melt more ice.
It melts a lot as it flows dozens of miles along the lower side of the ice rack and returns to the public sea.
Today, ice is losing heavily in large parts of western Antarctica.
On the Antarctic Peninsula, warming is the most striking.
An invisible mountain range extending 700 miles to the top of South America.
Around Antarctica, strong winds and currents rotate constantly, and the peninsula is hit hard by warm air and water from farther north.
Since 1950, the average annual temperature on its west side has risen by nearly 5 degrees Fahrenheit, several times faster than the rest of the planet, and the winter has warmed by an astonishing 9 degrees.
Sea ice now forms only four months a year, not seven months.
Since 1988, four ice racks on the east side of the peninsula have disintegrated into fleets of icebergs. (
From Delaware, the Larsen C ice rack may do the same one day.
It\'s about to break a big block of ice. )
Warm air helps trigger these collapses by forming a water-melting pond on the surface of the ice rack;
The pond flowed into the cracks and squeezed them deep into the ice.
With the disappearance of the ice shelf, once stabilized glaciers flocked to the ocean and accelerated at twice, five or even nine times the original speed.
They are relatively small glaciers that do not raise sea levels, but their acceleration has exacerbated concerns that the same could happen to larger glaciers along the Amundsen Sea.
In July 12, the birth of an iceberg that fell off the Larsen C ice shelf, an area equivalent to Delaware, weighing about 1 trillion tons, was one of the largest icebergs in history.
This detachment may accelerate the collapse of the entire ice shelf.
A. Ice Shelf (
Collapsed on 1995)
Larsen B ice rack (
Collapsed on 2002)
2017 Larsen CIce ShelfLarsen CIce shelfbelingshausensea100 kmThe born IcebergWeddellSeaThe big piece of ice fell down, Larsen C cold ice July 12 is about 1 trillion tons of size and weight of Delaware, make it one of the biggest icebergs ever.
This detachment may accelerate the collapse of the entire ice shelf.
Larsen ice shelf (
Collapsed on 1995)
Larsen B ice rack (
Collapsed on 2002)
July 12, 2017 MAPAREALarsen C icebergDetached Larsen CIce ShelfSouth polleantaricalassen CIce shelfbelingshausenseawilkinsice Shelf100 kmThe Amundsen Sea is the peninsula to the south where the air is not cold in winter.
The biggest threat to glaciers is the mechanics Jacobs and Jenkins help discover: deep-sea canyons that deliver warm water from the North under ice racks, and deep inverted canyons that focus warmth on the underside of the ice.
Last year, led by Ted Scambos, an ice scientist at the Boulder national ice and snow data center in Colorado, a satellite survey of many Antarctic ice racks was conducted, according to Helen Frick of the San Diego Creek Institute of oceans, this melting Canyon is common.
They tend to fan out and guide warm water to the edge of the shelf.
The ice there is vital: it rubbed on the Still River banks, slowing the flow of the shelves and the glaciers behind them.
But ice is also thinner than other ice.
Scamambos said in early 2016 that it was something worth seeing.
Ian haut of the bird Polar and Climate Research Center in Columbus, Ohio, is another ice scientist who closely follows Pine Island.
On last November, he reported that two ominous new cracks had spread over the ice shelf, potentially trimming it to the shortest length ever.
When Howat reviewed the monthly satellite photos, he realized that the cracks were triggered by an unknown strange incident that occurred three years ago.
Torn strip
The ice that holds the ice shelf on its north shore suddenly falls off, indicating that it is melted and destroyed from below.
It exploded in just a few days and howhowhowat said, like a zipper, undid the side of the glacier.
It is not clear when the entire ice shelf may break up.
The \"warm\" water flowing from offshore waters is 4 to 6 degrees Fahrenheit higher than the freezing point.
But about 3,000 cubic miles of ice racks arrive each year, meaning they receive more heat than hundreds of nuclear power plants running 24/7 kilometers.
When Truffer and his team camped on the shelves in December 2012, they could feel how it was weakened.
When the melt goes deep into the ice from below, the ice without support sinks, causing the whole shelf to bend and twist.
Cracks burst along the stress line at the top and bottom of the ice.
The persistent organic pollutants and bangs that researchers have heard, as well as the emergence of new cracks every day, witness the gradual failure of ice in thinning and cracking.
With the weakening of the Pine Island ice shelf and the acceleration of glaciers, the ice extends inland from the coast and becomes thinner by 150 miles.
The effects of this instability spread to western Antarctica every year.
With a slight push, Truffer says, you\'ll find it hard to reverse decades of retreat behavior.
In fact, studies by Rigano and others over the past few years have shown that the collapse of several major glaciers flowing into the Amundsen Sea is now unstoppable.
Only between 2002 and 2009, the ice shelf in front of the Smith Glacier was thinner by 1,500 feet in some places, and the ice shelf in front of the Pope Glacier was thinner by 800 feet.
The ground line of the Amundsen Glacier has in some cases retreated dozens of miles, and now they are parked on the bottom of the sea that is tilted towards the center of the ice sheet.
Every time you add ice back, you will let the warm water reveal a larger ice surface.
It\'s a runaway process, and scientists are urgently trying to figure out how fast it\'s running.
Frick says the ice rack is a canary in the coal mine.
Because they are already floating, they do not raise sea levels themselves when they melt, but they send a signal that the rise is coming as the glaciers behind them accelerate.
Frick and her team found that the amount of ice that disappeared on all Antarctic ice shelves increased by 12-from 1994 to 2012-
Fold 6 cubic miles to 74 cubic miles per year.
\'I think it\'s time for American scientists to stop being so cautious about communication risks,\' she said.
The retreat and bleeding of these glaciers will accelerate over time, and the rig Glacier agrees with the Rignot.
Maybe in the next 30 to 40 years you don\'t care much about this, but things can get really bad from 2050 to 2100, and it doesn\'t matter to listen to scientists at this point
However, they will still get worse after things get really bad.
Since the beginning of the 19 th century Industrial Revolution, most of the heat generated by our fossil fuel emissions has entered the ocean.
However, most of the heat that now reaches the Antarctic ice shelf comes from another effect of climate change: strong polar winds and ocean currents allow warm sea water to flow from the sea into the continental shelf and under floating ice.
Even if we start to reduce emissions, more ocean warming has not yet arrived.
There is more heat on the way to Antarctica.
Scientists pay special attention to the thwaite Glacier, which in itself can raise the global sea level by 4 feet;
Last fall, the UK and the US science foundation announced a coordinated field event costing between $20 million and $25 million, which will deploy ships, planes, satellites and underwater robots to assess the glacier starting in 2018.
At present, the best estimates suggest that Antarctica will shed enough ice to raise the global sea level by 1. 5 to 3.
5 feet by 2100, depending on the rate at which humans continue to emit greenhouse gases.
Coupled with rapidly melting glaciers in Greenland and around the world, sea levels are likely to rise by 3 to 7 feet, up 2100.
But this is not the worst case: sea level will not stop rising at 2100.
The Earth\'s past provides worrying clues about what might be brought about by a more distant future.
Geologists studying ancient coastlines concluded that 125,000 years ago, when the earth was only a little warmer than it is today, the sea level was 20 to 30 feet higher.
About 3 million years ago, the carbon dioxide in the last atmosphere was as high as it is today, the temperature was about the level of 2050, and the sea level was up 70 feet from today.
However, the collapse of Greenland and the Western Antarctic ice sheet will only raise sea levels by 35 feet.
So in order to consider the worst, scientists have to turn their eyes to the east of Antarctica, where there are more than three homes --
The fourth of all the ice on Earth.
January in the pastpropeller DC-
Flight 3 takes off from Casey Station, Australia, on the east coast of Antarctica.
Built in 1944, the plane was equipped with modern scientific equipment.
When it flew over the Toten Glacier, the radar recorded the thickness of the ice.
Another instrument records a slight change in the gravitational field of the Earth, a clue to the underwater terrain under the glacier floating ice shelf.
From time to time, a crew member opened the back door of the plane, knelt on a windy opening and threw a torpedo --shaped object.
When the device splashed into water, it was divided into two parts: one floating, sending a radio signal to the aircraft, and the other moving down along the 2,600 feet wire to measure the water temperature all the way down.
Until recently, it has been considered safe for ice fields in eastern Antarctica;
Unlike the West of Antarctica, it is located in the Highlands.
But make a map with ice
Low Penetration Radar Display
The lying area, cut by a glacier-carved passage, drops to 8,500 feet below sea level, perfect for guiding warm sea water to the center of the ice sheet.
The Toton Glacier is the largest coastal outlet in the region.
If it collapses, the global sea level could rise by 13 miles, almost equivalent to the entire west of Antarctica, rigonot noted.
Only one glacier.
On January 2015, the Australian icebreaker Aurora Australia became the first ship to arrive in front of Toten.
Like Palmer on Pine Island in 1994, it found deep, warm water flow under the ice shelf at a speed of 4.
Five cubic miles a day.
From the Antarctic point of view, glaciers have lost several cubic miles of ice each year.
But the University of Texas ice scientist Donald brankenshipp, who is in charge of the aviation investigation, fears it will explode.
In 2016, his team reported evidence from the cornerstone that torden had repeatedly retreated 100 to 200 miles inland from his current location, meaning it might help explain why 3 million
The blancenhepp survey also found two deep-enough underwater grooves to allow warm water under totenhepp\'s ice shelf.
In last January, the team was refining these maps of the sea floor.
Totten\'s ice will melt at a slower rate than in western Antarctica.
The worst that has emerged from Antarctica seems to be going on for centuries.
But that means giving up many of the world\'s largest cities, including New York, Los Angeles, Copenhagen, Shanghai and dozens of others, and they don\'t look so crazy all the time.
The fuse is lit, says Blankenship.
We just ran around on the map, where all the bombs were.
Custom message
Chat Online 编辑模式下无法使用
Leave Your Message inputting...