One of the largest icebergs in the world, the famous A-23a, turned blue a few days ago. This color would be a sign of the beginning of its disappearance after 40 years of drifting in the ocean.
When one of NASA’s satellites captured the A-23a iceberg on December 26, a bright blue color was visible on the top of the iceberg. “Blue corresponds to areas where water has warmed and accumulated in linear formations [les fissures de la glace] says Walter Meier, senior research scientist at the US National Snow and Ice Data Center, in an interview with Duty.
He specifies that the linear patterns which alternate between blue and white are linked to streaks which were created when the piece of ice was still part of the Antarctic ice sheet, hundreds of years ago. The water thus accumulates in the cracks to flow to the edge of the ice shelf, which ends up breaking, specifies the expert.
“This clearly indicates that the iceberg is melting significantly and is nearing the end of its life cycle, where it will completely break up,” says Meier.
Iceberg A-23a broke away from the Filchner-Ronne Ice Shelf in 1986. It was located along a massive crack, called “the Great Chasm” by scientists who first noticed it in the 1950s.
This immense expanse of ice is known to be one of the largest icebergs in the world and one of the oldest ever tracked by scientists.
When it was detached in 1986, it covered approximately 4,000 square kilometers, almost ten times the island of Montreal. At the beginning of January, its area reached 1,032 square kilometers, according to data from the United States National Ice Center, after losing several significant chunks last July, August and September.
Near the end
For 30 years, the “mega-iceberg” remained stranded in the same place in the shallow waters of the Weddell Sea, in Antarctica. “Staying in the same place for more than 30 years is quite unusual, and the fact that it has survived this long is quite remarkable,” says Mr. Meier.
Since 2020, the A-23a iceberg has been moving with the currents of the Southern Ocean. It is currently moving northeast across the Southern Ocean towards the South Atlantic.
“It’s fast approaching the end,” Mr. Meier says. “It keeps breaking into smaller pieces. » The glacier expert estimates that the end of the iceberg can be counted in days or weeks, and that in any case it will not survive the summer.
Its melting will not have an impact on sea levels since the glacier is already in the ocean and always has been. What influences sea level is rather the melting of terrestrial glaciers.
The speed of glacier melting is an indicator of the evolution of climate change. According to a study published in February 2025 in the international scientific journal Natureup to half of the world’s ice could evaporate by 2100, depending on global greenhouse gas emissions.
