In yet another blow to our ability to slow climate change has occurred in the highly vulnerable West Antarctica ice shelves. This iceberg is more than 100 miles in size — 4 times the size of Manhattan- and it broke off the Pine Island Glacier (PIG). PIG holds 1.7 feet of global sea level rise (SLR) and by adding the ice of Thwaites Glacier a gut wrenching SLR of 10 feet. This will only add more fury to powerful tropical storms creating even bigger human catastrophes that boggle the mind with their devastation to coastal cities throughout the world.
This break is not natural and it happens to be the fifth largest ice chunk loss from PIG since 2000. This crack had formed unnoticed at the very base of the ice shelf miles inland.
The Pine Island Glacier and, “the Thwaites Glacier, sit at the outer edge of one of the most active ice streams on the continent”. They provide a buttressing effect to the ice stream, by creating a backward stress that balances the downward stress of the ice trying to flow out to sea.
LOIZA, PUERTO RICO - SEPTEMBER 22: A resident wades through flood water days after Hurricane Maria made landfall, on September 22, 2017 in Loiza, Puerto Rico. Many on the island have lost power, running water, and cell phone service after Hurricane Maria, a category 4 hurricane, passed through. (Photo by Alex Wroblewski/Getty Images)This is not the first time an inland ice break has occurred at PIG. The AGU reported on a 2015 break that also had a similar result due to human caused warming, from fossil fuel emissions, of the Southern ocean.
“Rifts usually form at the margins of an ice shelf, where the ice is thin and subject to shearing that rips it apart,” he explained. “However, this latest event in the Pine Island Glacier was due to a rift that originated from the center of the ice shelf and propagated out to the margins. This implies that something weakened the center of the ice shelf, with the most likely explanation being a crevasse melted out at the bedrock level by a warming ocean.”
Another clue: The rift opened in the bottom of a “valley” in the ice shelf where the ice had thinned compared to the surrounding ice shelf.
The valley is likely a sign of something researchers have long suspected: Because the bottom of the West Antarctic Ice Sheet lies below sea level, ocean water can intrude far inland and remain unseen. New valleys forming on the surface would be one outward sign that ice was melting away far below.