A crack in an Antarctic ice shelf is creating an iceberg size of Delaware

A rapidly advancing crack in Antarctica’s fourth-largest ice shelf is getting close to a full break, according to scientists. It has accelerated this year in an area already threatened by warming temperatures, and is now only about eight miles from the edge of the ice shelf.

The crack in Larsen C is more than 120 miles long, and some parts of it are as wide as two miles. Once the crack reaches all the way across the ice shelf, it will create one of the largest icebergs ever recorded, according to Project Midas, a research team from Swansea University and Aberystwyth University that has been monitoring the rift since 2014.

Because of the amount of stress the crack is placing on the remaining eight miles of the shelf, the team expects the break to happen soon.

The glaciologist Eric J Rignot, a professor at the University of California, Irvine, and a senior scientist at the NASA Jet Propulsion Laboratory, says the rift’s recent turn toward the shelf is a strong sign of when the full break could occur.

“In my experience, when the rift takes a 90 degree turn like this is, it will happen in the next few weeks, no more than that,” he said.

Ice shelves, which form through runoff from glaciers, float in water and provide structural support to the glaciers that rest on land. When an ice shelf collapses, the glaciers behind it can accelerate toward the ocean. Higher temperatures in the region are hastening the ice shelf’s retreat. If it breaks at the crack, Larsen C will be at its smallest size ever recorded.

The ice front would also be left much closer to the ice shelf’s compressive arch, a line that scientists say is critical for structural support. If the front retreats past that line, the northernmost part of the shelf could collapse within months. It could also significantly change the landscape of the Antarctic peninsula.

“At that point in time, the glaciers will react,” Rignot said. “If the ice shelf breaks apart, it will remove a buttressing force on the glaciers that flow into it. The glaciers will feel less resistance to flow, effectively removing a cork in front of them.”
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