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Here's how that weird, rectangular-looking iceberg came to be

Image: Operation Icebridge
Operation IceBridge, NASA's longest-running aerial survey of polar ice, captured this image of a very sharp-angled, tabular iceberg floating among sea ice just off of the northern Antarctic Peninsula. Copyright Jeremy Harbeck NASA
Copyright Jeremy Harbeck NASA
By Shoshana Wodinsky with NBC News Tech and Science News
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These bergs are actually more common than you may think.


This past week, an aerial photo of an iceberg as flat, square and smooth as a sheet cake set the internet aflame with rumors of alien visitors and chainsaw-wielding glaciologists.

The picture was snapped on Oct. 16 by scientists working with Operation IceBridge — a NASA mission that monitors the ways polar regions are responding to climate change. The researchers saw the rectangular berg floating off the coast of northern Antarctica during a survey of the region's polar ice.

Despite its usual appearance, "tabular icebergs" like these are actually completely natural, Kelly Brunt, a NASA glaciologist and an associate research scientist at the University of Maryland said in an interview with Live Science. She added that these flat-topped and angular ice sheets are typically wider than they are deep, and can span hundreds of miles across.

Though the iceberg in the photo hasn't been measured, Brunt estimates that it's about one mile across — though, she added, like all icebergs, only about 10 percent of it is visible above the water line, meaning most of its square-shaped bulk lies underwater.

"Icebergs detaching from the edges of these ice shelves are like corners of a sheet of office paper getting cut with a pair of ocean-scissors," said Timothy Bartholomaus, a glaciologist with the University of Idaho. "Right after the cut, when the iceberg detaches, the edges will often be perfectly square."

We rarely see those perfect edges, he added, because of the "rough and tumble lives" of typical icebergs. As these tabular bergs float out to sea, any sharp corners are quickly ground down in collisions with other icebergs, or they melt over time. Because the recently photographed iceberg was still sharp around the edges, NASA scientists said it's likely that this berg was cleaved off not too long ago.

The yet-to-be-named iceberg snapped off the Larsen C ice shelf, which calved an iceberg the size of Delaware last year. That event raised concerns that the entire shelf was on the verge of crumbling, as both the Larson A and B ice shelves did in 1995 and 2002, respectively.

Scientists are concerned about how ice at Earth's poles will fare with warming temperatures, and how melting ice will affect sea levels around the world, but Bartholomaus is hesitant to draw direct links to climate change.

But, he added that "the presence of icebergs like these are a sign of increased calving."

Figuring out exactly how climate change affects Antarctic ice, though, remains challenging, according to Bartholomaus.

"Humans are warming the climate," he said. "Globally, we see very clear increases in air temperature that can only be explained through human-caused carbon emissions. In Antarctica, the specifics are more murky."

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