A chunk of ice bigger than the US state of Delaware is hanging ‘by a thread’ from the West Antarctic ice shelf, satellite images revealed Wednesday.
When it finally calves from the Larsen C ice shelf, one of the biggest icebergs in recorded history will be set adrift—some 6,600 square kilometres (2,550 square miles) in total, according to the European Space Agency (ESA).
The iceberg’s depth below sea level could be as much as 210 metres (almost 700 feet), or about 60 storeys, it said.
‘The crack in the ice is now around 200 kilometres (125 miles) long, leaving just five kilometres between the end of the fissure and the ocean,’ the ESA said in a statement.
‘Icebergs calve from Antarctica all the time, but because this one is particularly large its path across the ocean needs to be monitored as it could pose a hazard to maritime traffic.’
Scientists tracking the berg’s progression expect it to break of within months.
The Larsen C shelf will lose more than 10 percent of its total surface area.
The massive ice cube will float in water and by itself will not add to sea levels when it melts.
The real danger is from inland glaciers.
Ice shelves float on the sea, extending from the coast, and are fed by slow-flowing glaciers from the land.
They act as giant brakes, preventing glaciers from flowing directly into the ocean.
If the glaciers held in check by Larsen C spilt into the Antarctic Ocean, it would lift the global water mark by about 10 centimetres (four inches), researchers have said.
The calving of ice shelves occurs naturally, though global warming is believed to have accelerated the process.
Warming ocean water erodes the underbelly of the ice shelves, while rising air temperatures weaken them from above.
Icebergs calve from Antarctica all the time, but because this one is large, the ESA says its path across the ocean needs to be monitored as it could pose a hazard to maritime traffic.
This graphic shows how the large crack in the Larsen C Ice Shelf has progressed over time
Dr Anna Hogg, an ESA Living Planet Fellow and researcher at the University of Leeds said: ‘As for this new Larsen C berg, we are not sure what will happen.
‘It could, in fact, even calve in pieces or break up shortly after.
‘Whole or in pieces, ocean currents could drag it north, even as far as the Falkland Islands.
‘If so it could pose a hazard for ships in Drake Passage.’
The nearby Larsen A ice shelf collapsed in 1995, and Larsen B dramatically broke up seven years later.
The ESA is keeping an eye on Larsen C with its Copernicus and CryoSat Earth orbiters.
The rift in the Larsen C Ice Shelf grew suddenly by around 18 kilometres (11 miles) in December 2016, leaving a vast iceberg more than 5,000 square kilometres (1,900 square miles) ‘hanging by a thread’.
The main rift continued to grow early this year and satellite data revealed a second branch of the rift, some nine miles (15 km), was moving towards the edge of the ice.
Researchers have warned the ice shelf will be less stable after the iceberg calves, and could follow the example of its neighbouring ice shelf Larsen B, which completely disintegrated in 2002 after a similar event.
Man-made global warming has already lifted average global air temperatures by about one degree Celsius (1.8 degrees Fahrenheit) since pre-industrial levels.
Antarctica is one of the world’s fastest-warming regions.
The world’s nations undertook in the Paris Agreement, inked in 2015, to cap average global warming at ‘well under’ 2 C.
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