NASA worried iceberg twice the size of New York City may break off

Feb. 25 (UPI) -- NASA researchers are concerned an enormous iceberg may break off from Antarctica's Brunt Ice Shelf, potentially jeopardizing future research expeditions in the region.

Since first noticing the eastbound crack in 2016 -- it runs from an area on the shelf known as McDonald Ice Rumples -- the researchers have also observed a crack heading northward at about 2.5 miles per year.

When the two cracks intersect, scientists caution, about 660 square miles of ice will break from the shelf. That would represent the largest break from the shelf since 1915.

"The near-term future of Brunt Ice Shelf likely depends on where the existing rifts merge relative to the McDonald Ice Rumples," Joe MacGregor, a glaciologist at NASA's Goddard Space Flight Center, said in a news release. "If they merge upstream (south) of the McDonald Ice Rumples, then it's possible that the ice shelf will be destabilized."

The rumples form along with the ice flow underwater. Their rocky formation blocks the flow of ice, which creates pressure waves and cracks that grow at the surface.

Break offs occur during the normal life cycle of an ice shelf, but these recent shifts are uncommon in the area, researchers say. Until recently, the McDonald Ice Rumples area had remained relatively stable.

Now, this event could present a safety concern for scientists working at the British Antarctic Survey's Halley Station, which runs year-round to perform atmospheric and space science research.

"We don't have a clear picture of what drives the shelf's periods of advance and retreat through calving," said Chris Shuman, a glaciologist at NASA/University of Maryland at Baltimore County.