Three decades after breaking free from the Filchner Ice Shelf in 1986, the colossal iceberg A23a, one of the world’s largest, appears to be moving beyond Antarctic waters after being grounded for more than three decades according to reports from the British Antarctic Survey.
aving been firmly grounded in the Weddell Sea for over 30 years, the iceberg, boasting a size three times that of New York City and more than twice the size of Greater London, measuring approximately 4,000 square kilometers (1,500 square miles), is now adrift beyond Antarctic waters.
Remote sensing expert Andrew Fleming, affiliated with the British Antarctic Survey, shared insights with the BBC, revealing that the iceberg began its gradual drift about a year ago. Recent observations indicate that it has accelerated its movement, passing the northern tip of the Antarctic Peninsula, propelled by the combined forces of wind and ocean currents.
Icebergs play a key role in ocean dynamics. For example, as icebergs melt they release freshwater and nutrients into the ocean, affecting primary productivity, ocean circulation and the formation and break-up of sea ice. Icebergs also present hazards to ships, so accurate, up-to-date knowledge of where icebergs are, and how big they are, is critical.
… British Antarctic Survey said.
Intrigued by the sudden shift, Fleming sought opinions from colleagues, exploring the possibility of changes in shelf water temperatures triggering the iceberg’s movement. However, the consensus among experts was that the time had simply come for A23a to relinquish its grounded state and embark on a new trajectory. “It was grounded since 1986, but eventually it was going to decrease (in size) sufficiently was to lose grip and start moving,” explained Fleming.
The first signs of A23a’s movement were noted by Fleming in 2020. Now, as it continues its journey, the iceberg has successfully ungrounded and is navigating along ocean currents toward sub-Antarctic South Georgia, marking a significant event in the natural rhythm of Antarctica’s icy landscapes.
Researchers at British Antarctic Survey are using a new AI tool to detect icebergs in the Southern Ocean. This is the first step towards scientists being able to track the complete life cycle of most icebergs across Antarctica from satellite data.