Scientists observing the rift in the Larsen C Ice Shelf in West Antarctica have reported dramatic cracking over the past week. The rift has grown a startling 11 miles (17 km) over the last seven days, bringing it to within eight miles (13 km) of breaking off and producing one of the largest ever recorded icebergs.

A UK-based research team called Project MIDAS has been studying the growing rift on the Larsen C Ice Shelf for several years now, but over the past few months it has recorded significant new cracking. The Larsen C Ice Shelf is set to follow its neighbors, Larsen A and B, which splintered in 1995 and 2002, respectively, but this iceberg is set to be larger than the two resulting from those two events.

Because these ice shelves are already floating on water their release will not directly contribute to a global sea level rise, but they do represent dramatic land mass shifts occurring at a rapid pace in West Antartica. The Project MIDAS researchers raise concerns over the secondary effects caused by a major event such as this.

"Ice shelves hold back the glaciers which feed them," the team writes on a blog that has been documenting this growing ice rift. "When they disappear, ice can flow faster from the land to the ocean and contribute more quickly to sea level rise."

Studies on the previous Larsen B Ice Shelf event in 2002 showed that the feeding glaciers accelerated their melting following the shelf break. The Larsen C Ice Shelf rift is the largest fissure observed to date in the region and highlights the overall vulnerability of the West Antarctic Ice Sheet.

A report published last year by the National Snow and Ice Data Center ominously signaled the potential "catastrophic" scenario that could result if the West Antarctic Ice Sheet continued to deteriorate. It estimated a complete collapse of the region would raise the global sea level by more than 10 ft (3.3 m) in the next few decades or centuries depending on the rate of thinning.

It's yet to be seen what the overall consequences of this event will be, but the speed of the cracking is certainly unexpected, and when this massive iceberg eventually breaks off, the Larsen Ice Shelf will lose 10 percent of its total area. In the words of the Project MIDAS team, this will "fundamentally change the landscape of the Antarctic Peninsula."

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