A massive iceberg is very close to splitting off from one of the largest ice shelves in Antarctica, after a fast-growing crack stretched to within 13km of the open ocean this week.
Aerial observations last week showed the crack had shifted toward the edge of the ice sheet and the open ocean, leading scientists to estimate that an iceberg more than 300,000 times the size of the one that sunk the Titanic could calve off as soon as (the northern) summer.
The formation of the iceberg fits within a broader trend of shrinking ice shelves in the region, which scientists believe is linked to global warming.
The crack has grown an additional 17 kilometres in the last week, according to observations released on Wednesday by Project MIDAS, a European research group that has been monitoring the region, making the iceberg's separation imminent.
"I would expect it to occur quite rapidly, within days or weeks," Dan McGrath, a scientist with the US Geological Survey who has studied the ice sheet extensively, said on Thursday in a phone interview.
The 5,000-square-kilometre chunk of ice has nearly completely broken off the Larsen C ice shelf, the fourth largest in Antarctica.
Scientists from Project MIDAS warned in 2015 that the loss of such a large mass of ice would create a "significant risk" of the shelf as a whole becoming unstable and breaking up, although McGrath cautioned that the larger outcome is not guaranteed.
While the generation of such a large iceberg is striking, McGrath said, it is less worrisome than other processes scientists have recently observed in the Antarctic, most of which are thought to be tied to climate change.
"If Larsen C were to collapse, it would be concerning for its own reasons, but the contribution to global sea level rise would be very small, something in the centimetres," McGrath said.
Continued destablisation and eventual break up of the larger masses of ice in Western Antarctica, by comparison, would likely raise sea levels by around a metre or more, he added.
