Spinning Ice
Iceberg A23a, Antarctica 12-20-23 (credit: NASA)
A monster iceberg in Antarctica, labeled A23a, covers an area of 1,700 square miles or nearly 4 times the size of New York City. The trillion-ton block of ice began moving north from the region late last year.
According to NASA, in November 2023 an instrument on the Terra Earth monitoring satellite, MODIS, captured an image of the iceberg since it had originally broken off from the Filchner ice shelf. That day, the berg was drifting past islands at the tip of the Antarctic Peninsula, nearly 1,000 miles from its origin. In 1986, it had first broken free but became stuck on a shallow section of seafloor in the Weddell Sea and stayed anchored in place there for 37 years. A23a has now been observed spinning in the Southern Ocean beyond the peninsula.
A23a is perhaps the largest berg currently moving in the world’s polar oceans. Previous masses of such huge sizes eventually escape the Southern Ocean circulation and move into the Drake's Passage, a turbulent body of water between the tip of South America and Antarctica. In this region, the icebergs typically melt quickly in the warmer waters. Since A23a was once part of a floating ice shelf, its melting will not affect sea level rise.
However, danger from a moving and spinning block of ice to wildlife like nesting penguin colonies or migrating whales while feeding, not to mention passing ships, cannot be dismissed. WHB