A crack more than 100 miles long in one of Antarctica’s largest ice shelves grew another 6 miles in a little more than two weeks this month, British scientists reported Thursday. That’s on top of an 11-mile growth that occurred in the second two weeks of December — representing a 17-mile total advance in not much more than a month.

The extension of the rift in the Larsen C ice shelf ran roughly parallel to the ocean-terminating front of the floating ice shelf, and so, did not bring it any closer to breaking off a large piece — 12 miles of ice still connect the emerging ice island to the larger shelf. But the parallel growth may ensure that the iceberg, when it does break off, will be somewhat larger.

Here’s an image showing the growth of the rift recently from Project MIDAS, a research consortium located at Swansea University and Aberystwyth University in Wales that is monitoring the crack by satellite:

The researchers reiterated a statement they released earlier this month, signaling their suspicion that this will lead to the breakoff of a nearly Delaware-size piece of ice and “leave the ice front at its most retreated position ever recorded; this event will fundamentally change the landscape of the Antarctic Peninsula.” They fear that the break could speed up the flow of the ice seaward and potentially destabilize the shelf, which holds back enough ice above sea level to raise oceans by 4 inches. But not every scientist agrees that will be the outcome.

Either way, the advancing rift continues to suggest that a very large break could be coming. “Every advance would seem to bring the end closer,” said Adrian Luckman, a researcher with Swansea University who heads up the project.

“However,” Luckman continued, “the rift has now entered the softer suture zone ice originating from Cole Peninsula, which we believe to be more substantial than elsewhere, so it is still impossible to make predictions.”

Cole Peninsula is the knob-shaped out-jutting of land in the image above landward of the current location of the end of the rift. A “suture zone” is a region of softer and more flexible ice that’s less likely to crack, and that exists between streams of ice flowing from glaciers, in effect stitching them together. Still, the current rift has crossed suture zones before.

So scientists will have to continue to track the rapidly growing rift. Meanwhile, their data show that it is growing faster and faster:

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