Runaway iceberg that's bigger than Delaware is on the move again

In July 2017, an iceberg weighing about 1 trillion tons broke off of Antarctica’s Larsen C ice shelf, but it’s hard to put that event into perspective. NASA scientists finally got the chance to see this behemoth berg in person a few months later, and they took some stunning shots for the scrapbook.

Stretching some 2,240 square miles — or about 259 square miles larger than Delaware — Iceberg A-68 defied the expectations of NASA Earth Observatory science writer Kathryn Hansen:

“I was aware that I would be seeing an iceberg the size of Delaware, but I wasn’t prepared for how that would look from the air. Most icebergs I have seen appear relatively small and blocky, and the entire part of the berg that rises above the ocean surface is visible at once. Not this berg. A-68 is so expansive it appears if it were still part of the ice shelf. But if you look far into the distance you can see a thin line of water between the iceberg and where the new front of the shelf begins.”

The edge of the Larsen C ice shelf and the western edge of Iceberg A-68 in the distance The edge of the Larsen C ice shelf (left) and the western edge of Iceberg A-68 in the distance (right). (Photo: Nathan Kurtz/NASA)

The team that Hansen accompanied did more than just snap photos of the iceberg, however. To get some sense of the terrain below the ice, including the depth of the water, scientists used a gravimeter and radar to take those measurements.

Researchers with the British Antarctic Survey have also been studying the adventures of A-68, and in February 2018 released this video footage of the enormous iceberg recorded via helicopter:

[embedded content]

In September 2018, researchers announced that after 13 months of shuffling back and forth, A-68’s southern tip rotated 90 degrees and is caught up in ocean currents pushing the iceberg north.

[embedded content]

“Until recently, the iceberg was hemmed in by dense sea-ice in the east and shallow waters in the north,” Adrian Luckman from Swansea University told BBC News. “Now, a strong foehn wind blowing eastwards off the ice shelf in early September has pushed the southerly end of the iceberg out into the Weddell Gyre. This persistent clockwise drift of ocean waters and floating sea-ice flowing north past the Larsen Ice Shelf has rotated A-68 out into the Weddell Sea.”

A-68 isn’t an immediate risk to raising sea levels — after all, it was floating in the ocean already before it broke off from Larsen C — but any seafaring craft in the area should probably be aware of it, though it might be hard to miss something that’s roughly 1 million times the size of an American football field. That being said, A-68’s very existence does serve as a reminder of the fragility of Larsen C. A diminishing Larsen C could speed up the flow of ice into the sea, and that in turn will contribute to sea level rise.

Also on MNN: 7 strange ice formations

Editor’s note: This article has been updated since it was originally published in November 2017.


(Visited 283 times, 1 visits today)

Leave a Reply