Antarctica is melting.
A rift in the Larsen C ice shelf, one of the largest ice shelves on the continent, has been growing since 2011. The rift suddenly grew by 20 km (12.5 miles) in December, according to a report by UK researchers—meaning that the ice shelf, slightly smaller than the US state of Delaware, is now hanging on by a thread, at least in geological terms.
The entire Larsen C ice shelf is about 350 meters thick (about 1,200 feet) and stretches for about 50,000 sq. km (about 19,000 sq. miles), making it slightly smaller than the size of Sri Lanka or the US state of West Virginia. The growing rift is likely to break away approximately 10% of the ice shelf.
“If it doesn’t go in the next few months, I’ll be amazed,” Adrian Luckman of Swansea University told BBC News. When it does, it’ll will be one of the 10 biggest ice shelf calving events in recorded history.
Researchers have been tracking the Larsen ice shelves, which are in different geographical locations, for years. Their observations took on added significance after Larsen A and Larsen B broke away in 1995 and 2002 respectively.
To put this in context, before breaking away, Larsen B ice shelf had been stable for more than 10,000 years. Since breaking away, the many glaciers held back by the ice shelf have accelerated their melting into the ocean, according to Adam Booth of the University of Leeds.
Larsen C is believed to have been stable for about the same 10,000 years, and it’s unclear what will happen to it after a huge chunk breaks away. One likelihood is that the remaining ice shelf will become less stable and start to collapse. If that happens, just like in the case of Larsen B, the glacier tributaries held back are likely to accelerate melting into the ocean. Estimates suggest that if all of Larsen C were to melt, global sea levels could rise by as much as 10 centimeters (about 4 inches). There are no penguin colonies on Larsen C that we need to worry about, Booth says.
These events have likely been accelerated by human-induced global warming, though scientists can’t yet be certain. The shelvings are spectacular when they occur. In the award-winning 2012 documentary Chasing Ice, photographer James Balog showcased striking footage of a glacier chunk the size of Manhattan breaking away, quite suddenly, from the Ilulisaat glacier in Greenland: