Big, beautiful and — blue. But this 40-year-old iceberg is about to disappear forever
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A 40-year-old iceberg that was once the world’s largest is floating in the South Atlantic Ocean, where it will soon melt into water.
But it goes out in style.
IA-23a, as it is known, emerged from Antarctica in 1986 and has captured the attention of scientists ever since.
But the world’s eyes are now on the behemoth berg because of its stunning blue pattern, seen in NASA satellite images taken just after Christmas.
The bright color, however, is a sign that A-23a is in its dying days, as it moves through what scientists call an “iceberg graveyard,” some 2,800 kilometers from where it broke up. Here’s what you need to know about the life and legacy of the A-23a.
They are more than 1 trillion tonne
IA-23a was once part of the Filchner Ice Shelf of Antarctica, east of the Antarctic Peninsula that reaches South America.
In 1986, a 4,000-square-kilometer block broke off, or grew, to form an iceberg — basically a flat sheet of ice about the size of Rhode Island and weighing more than a million tons.
But it didn’t stay away from home for long.
It stayed at the bottom of the Weddell Sea until 2020, when it began its dangerous journey north of the Antarctic peninsula. Now, after several more bases, it is drilling near the island of South Georgia.
IA-23a is now much smaller. According to the US National Ice Center, it has shrunk to about 781 square kilometers as of Friday after parts of it came in warmer waters.
Chris Schuman, a retired scientist, told the NASA Earth Observatory that A-23a is unlikely to survive the Southern Hemisphere summer.
The world’s largest iceberg, known as A23a, is on its way to open water after being stuck in the ocean since the 1980s. It is drifting off the coast of Antarctica and could be dangerous to wildlife if it hits the uninhabited South Georgia Islands.
A good death
Icebergs of any shape and size are visible. But what people find amazing about the A-23a is that variety of blue color on its face.
Ted Scambos, a senior research scientist at the University of Colorado at Boulder, told the NASA Earth Observatory that areas with green trees likely have meltwater that accumulates on top of the ice as it gradually breaks down.
“You have the weight of the water sitting inside the cracks in the ice and forcing them open,” he said.
The resulting pattern appears to be lines, parallel lines formed in the ice over time that “direct the flow of meltwater,” National Snow and Ice Data Center senior research scientist Walt Meier told NASA.
International weather reporter Susan Ormiston embarked on Canada’s first expedition to Antarctica with 15 climate scientists and the crew of HMCS Margaret Brooke. He dives into the world’s conflicts in the remote South Pole, explaining what is happening in the region and what is at stake.
Outside of the sky
White and blue might be the colors you expect to see on an iceberg. But what about green? Yellow? I mean black?
Scientists investigating why some icebergs in the Weddell Sea have turned a bright emerald or jade color say this may be because the ice reflects the color of phytoplankton in the water.
The yellow icebergs, according to a 2019 article from National Geographic, may be the result of dust rich in iron oxide, which was picked up as the ice cap moved over Antarctica’s rock.
“The ice filters out the red light, and the iron oxides filter out the blue light, so the green is what’s left as the refracted sunlight is reflected off the ice,” Steve Warren, professor emeritus at the University of Washington, told the publication.
Then there’s the unusual black ice seen last spring off the coast of Labrador.
Local man Hallur Antoniussen told CBC Radio’s Labrador Morning that it wasn’t just the black color that was amazing – but also its diamond-like shape.
It is not clear if this color was created.
But Lev Tarasov, a physicist and glacial earth systems modeller at Memorial University in St.
The ‘deadly’ chance of icebergs
It should come as no surprise that distant icebergs from this area of Antarctica will approach warmer waters and begin to break up in what is often called the “iceberg graveyard.”
The Weddell Sea gyre is a wave that rotates clockwise and pulls the icebergs northward from this part of Antarctica, in the same direction that A-23a followed, and into the Scotia Sea and the Drake Passage.
“The water at this latitude – about 54 degrees south – is generally warmer than the Southern Ocean and is fatal to ice caps,” said the NASA Earth Observatory. IA-23a is located at about that latitude.
A satellite view of the iceberg seen Wednesday on NASA Worldview appears to show a significant chunk of the A-23a breaking off.
As ocean warming and circulation patterns change, a Canadian scientific team is scrambling to collect water and soil samples around Antarctica that they hope will hold clues to Earth’s past and what may happen to the climate in the future.
