NASA is monitoring a massive crack on the Brunt Ice Shelf in Antarctica. According to the space agency, if it breaks off, it will create an iceberg twice the size of New York City.

Scientists are unsure how the rest of the ice shelf, which houses scientific infrastructures and human researchers, would react if an iceberg breaks off.

Cracks Appear On Brunt Ice Shelf

The image obtained by the Operational Land Imager on Landsat 8 on Jan. 23 shows two massive cracks. On top of the image, called the Halloween crack, first appeared in late October 2016, hence the name. It grows from the area known as the McDonald Ice Rumples and headed east.

However, according to NASA, the more immediate threat is a crack visible on the center of the image. The crack has been stable for about 35 years, but it recently started accelerating as fast as 4 kilometers per year.

If the rift continues northward, it will meet the Halloween crack and an iceberg at least 1,700 square kilometers will break off.

While it sounds massive, it is not "terribly large" in Antarctic standards. NASA said it will not even make the top 20 list of the biggest icebergs in Antarctica. However, it will be the largest iceberg to break off of the Brunt Ice Shelf since observations started in 1915.

Uncertain Future

The growing cracks of the Brunt Ice Shelf have caused serious concerns for the researchers working in the area. Near both cracks is the Halley VIa Station, home of the British Antarctic Survey.

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

NASA said that calving, when an ice shelf sheds a smaller mass of ice, is a normal part of an ice shelf's life cycle. However, the recently observed changes are unfamiliar to the area.

Little has changed since the Brunt Ice Shelf was first explored by Ernest Shackleton in 1915, but the area is fast evolving in recent years.

"We don't have a clear picture of what drives the shelf's periods of advance and retreat through calving," added Chris Shuman, also a glaciologist from NASA. "The likely future loss of the ice on the other side of the Halloween Crack suggests that more instability is possible, with associated risk to Halley VIa."

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