In July 2017, the “Larsen C Ice Shelf” on Antarctica collapsed, and a crack that stretched for hundreds of kilometers was marked on the “white continent”, forming an iceberg “A68” with an area of 6000 square kilometers (equivalent to Shanghai). . It slid into the sea, first in the shape of a boat-shaped sock, and then after splitting, it looked like an ill-intentioned “index finger”. It is the largest “moving body” in the world today, drifting northward with ocean currents.
An iceberg is nothing but a deserted place. It doesn’t seem to be a pity, but why do scientists in this field keep an eye on the trend of “A68”?
“White Continent” of Antarctica
Let me talk about Antarctica first. Antarctica is also known as the “white continent” because it has land masses that account for 1/10 of the world’s area and is covered with snow all year round.
Compared to other continents, Antarctica has many “world’s best”: the highest average elevation, the lowest average temperature (an average of minus 25 degrees per year), and the strongest average wind (common winds above 100 kilometers per hour).
Antarctica was officially written into human history, perhaps from the 1820s. It is also the latest new continent to be “discovered”. At that time, expeditions from Russia and Britain, as well as seal hunters from the United States, claimed to have seen the Antarctic continent. In the following decades, more and more countries “discovered” different areas of the Antarctic continent and declared their sovereignty in Antarctica.
In 1908, Britain declared its sovereignty over a piece of land in Antarctica for the first time, which immediately touched the sensitive nerves of other countries, and countries began to “enclose” in Antarctica. By the 1940s, 83% of the Antarctic land had been “divided” by Britain, France, Argentina, Chile, Australia, New Zealand, Norway and other countries, but the declared areas overlapped, and no one was allowed.
Until December 1, 1959, 12 countries, including the then powers of the United States and the Soviet Union, signed the Antarctic Treaty in Washington, banning all military operations and nuclear tests in Antarctica, ensuring that activities in Antarctica can only be done in peace. For the purpose, and freeze the territorial ownership claimed by all parties. Since then, the hustle and bustle of Antarctica has temporarily ended, and the “White Continent” does not belong to any country for the time being.
/ It is the largest “moving body” in the world today, and it is drifting northward with ocean currents. /
“Larson C Ice Shelf” and the split “A68”
The “crack” that caught the world’s attention in 2017 occurred on the “Larsen Ice Shelf”.
Seals of South Georgia
“Ice shelf” is also called “Ice Shelf”, which refers to a layer of ice floating on the sea beyond the range of land. There are ten main ice shelves in Antarctica. The largest are the Ross Ice Shelf and the Filchner-Lonny Ice Shelf. Sen A, Larsen B and Larsen C.
Whales in South Georgia
Because of the impact of global warming, Larsen A and Larsen B collapsed in 1995 and 2008, respectively. Although Larsen C has a much larger area than Larsen A and Larsen B, scientists predict Larsen C in the near future. Will also disappear. The “A68 iceberg” formed in 2017 accounted for 12% of the Larsen C ice shelf. It was also the world’s largest iceberg at that time and the third largest iceberg in history.
Many people see the iceberg bursting into the sea, and instinctively want to ask: Will the sea level rise?
Fortunately, because the ice shelf is originally in the sea, not on land, the A68 iceberg breaking away from the Larsen C ice shelf will not significantly affect the global sea level position. This is like melting ice cubes in a glass of water, and it doesn’t make the water surface rise. Therefore, for most people, the formation of A68 may be just a few minutes of news footage; however, for other creatures, it may be more than that.
At the end of 2020, the A68 iceberg, which had been drifting for more than three years, was once again on the news page.
In fact, for more than three years, the A68, which drifted northward into the Weddell Sea and gradually drifted towards the South Atlantic, has been continuously observed by satellites and has moved hundreds of kilometers so far.
With the northward drift and temperature rise, by November 2020, A68 has experienced several splits, from the original 175 kilometers long and 50 kilometers wide, to 158 kilometers long and 48 kilometers wide, and split into A68- B, A68-C two small icebergs.
At that time, A68-A, the “mother body” of A68, was only 500 kilometers away from South Georgia, home to 6 million penguins. Many experts worry that once the A68-A hits South Georgia, it will be a catastrophe to the local ecology.
“Residents” on South Georgia
South Georgia Island is one of the largest marine protected areas in the world, and is famous for the huge settlements of coastal creatures such as king penguins, macaroni penguins, and seals. Its area is about 3592 square kilometers, which is much smaller than the A68 iceberg that just split from the Larsen C ice shelf. Although A68 splits several times and melts slightly as it leaves the Antarctic Circle, it is still larger than South Georgia.
A68 is called an iceberg, but in fact it is a white “ice platform”. And it is just like what we know as the “Iceberg Theory” said that compared to what we see on sea level, a larger part of the iceberg is actually below sea level.
Experts estimate that the underwater part of the A68 iceberg may be more than 200 meters deep. If it is too close to South Georgia Island, or even directly hits, it will cause the seabed creatures around South Georgia Island to be crushed and underwater ecology suffer. Damage, and the large amount of fresh water contained in A68 will also change the pH of the local ocean and test the adaptability of aquatic organisms.
And if A68 directly hits South Georgia Island and gets stuck on the continental shelf, the livelihoods of the “residents” on the island will also be greatly impacted-the foraging paths of penguins and seals will be obstructed by A68 and forced to change.
For young children of penguins and seals, adequate feeding is very important. If penguins and seals have to detour to find food, causing the feeding interval to be too long, their babies may become malnourished or even starve to death.
South Georgia, home to 6 million penguins
/ The “A68 iceberg” formed in 2017 accounted for 12% of the Larsen C ice shelf. /
In terms of the size of A68, if this huge iceberg is really “stuck” on South Georgia, it may take more than ten years to disappear. The largest iceberg in history is the “B15” iceberg that split from the Ross Ice Shelf in 2000. Its area is about twice the size of A68. It took 18 years for it to break away from the ice shelf to completely melt away. How will the animal inhabitants of South Georgia face and adapt to such drastic and long-term changes?
In December 2020, A68-A split into smaller icebergs A68-D, A68-E, and A68-F, and the “parent” A68-A was once again reduced slightly. But the most important thing is that on January 28 this year, A68-A “cracked” again more than 100 kilometers south of South Georgia, and this time it was almost divided in half to form A68-G. Will the two icebergs part ways? Is there any piece still heading towards South Georgia? Or will South Georgia be lucky enough to escape?
Winter is not coming, winter is coming
In fact, Antarctica has been cracking and melting.
It is hard to imagine that Antarctica, which has always been snow-white and cold, will actually have a fever. On February 9, 2020, the “Major Ferras Antarctic Scientific Research Station” set up in Brazil measured the highest temperature since the Antarctic temperature began to be observed in 1961: 20.75 degrees Celsius. The temperature is higher than Guangzhou that day.
Scientists integrated data from 20 Antarctic observatories from 1989 to 2018 and found that the average temperature of Antarctica increased by 1.8 degrees Celsius, while the global average temperature rose by 0.5 to 0.6 degrees Celsius over the same period. The temperature rise in Antarctica has almost tripled.
In 2018, a research report by Nature pointed out that between 1992 and 1997, Antarctica melted about 49 billion tons of glaciers each year, but from 2012 to 2017, Antarctica’s melting rate was extremely fast, exceeding 200 billion tons per year.
Scientists have also warned against this: If the rate of global warming is not changed, by 2070, one-quarter of Antarctic ice will disappear; sea level will be 50 cm higher than in 2000; global average temperature will be Rise 3.5 degrees Celsius.
For humans, low-lying areas will be submerged, causing a large number of people to migrate; extreme weather increases, in addition to frequent disasters, crop yields in various places may also decline… However, the first thing to do is to live around Antarctica for generations. Penguins, seals, whales and other creatures.
Winter is not coming, winter is not coming.
A68 briefly attracted the attention of the world with its “huge”, but it is just a microcosm. After the lower layer of the ice shelf in Antarctica flows into the higher-temperature ocean currents, cracks will be formed, and gradually cracked away, forming icebergs, floating towards us one by one. At the same time, however, “Antarctica” seems to be gradually leaving us.
What humans create will eventually fall back to humans. Winter is coming, winter is coming.