The World's Largest Iceberg is Adrift

27 November, 2023

The world’s largest iceberg, with an area of nearly 4,000 square kilometers, has begun to drift again after being stuck for decades.

The world’s largest iceberg is adrift from Antarctica . Graphics: Johan Hallnäs

The huge iceberg, called A23a, broke free from the edge of Antarctica back in 1986. But it quickly ran aground in the Weddel Sea. And there it has been stuck until a few years ago.

– I noticed the first movement in 2020, says Andrew Fleming, researcher at the British Antarctic Survey, to the BBC.
The iceberg has an area larger than Gotland, whose area is closer to 3,200 square kilometers, and is about 400 meters thick.

– These large icebergs come from the huge ice shelves around Antarctica. The ice shelves are formed when the ice sheet flows towards the coast and the sea, says Nina Kirchner, docent in glaciology and director of the Tarfala research station at Stockholm University, to TT.

Started moving

In recent months, A23a has started to move a little faster due to currents and wind.

That the iceberg has started to move again after being stuck since 1986 is not so strange.

– Sooner or later they always come loose, even these mega-mountains. They are slowly breaking down, but it is a huge iceberg so it takes a long time, says Ola Kalén, oceanographer at SMHI, to TT.

He says that it is probably mainly the influence of the heat from ocean currents which causes the iceberg to erode from below and on the side which means that it has come loose now.

Melts eventually

The iceberg will now probably drift out into an area north of the Antarctic Peninsula where many icebergs gather. In that case, it is caught by a strong ocean current.

– It goes clockwise around Antarctica. There, they are transported further out and head towards warmer water, break up and melt over time, says Ola Kalén.

Another possibility is that A23a could get stuck again, but that depends on what the bottom conditions look like and how the currents are going.

Antarctica consists of both sea and land areas. The land area, which is approximately 14.2 million square kilometers, is covered to 98 percent by thick ice.
The huge ice caps are moving towards the sea at a speed of up to 300 meters per year. When the ice protrudes over the sea and settles in the water, so-called shelf ice is formed.
Source: The National Encyclopedia

Text: Fredrik Gunér/TT
Grafik: Johan Hallnäs

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