WASHINGTON — When it splits off, the Delaware-sized chunk of ice now barely clinging to one of Antarctica’s largest ice shelves will become one of the most massive icebergs in recorded history, scientists say.
For over two years, the U.K.-based /www.projectmidas.org/"}}" data-beacon-parsed="true">Project MIDAS has been monitoring a /www.the-cryosphere.net/9/1223/2015/tc-9-1223-2015.pdf"}}" data-beacon-parsed="true">large, fast-moving rift in the Larsen C ice shelf, located on the northern end of the Antarctic Peninsula. On Wednesday, researchers with the European Space Agency released a detailed analysis of the soon-to-be iceberg.
Data collected from ESA’s CryoSat satellite, which measures and monitors polar ice in Greenland and Antarctica, shows the iceberg will likely have an area of more than 2,500 square miles — larger than the island of Bali in Indonesia.
It’s expected to be about 620 feet thick and contain about 277 cubic miles of ice, according to ESA. Below the surface, the iceberg could reach a depth of nearly 700 feet.
“This is a single piece which is remarkable I guess because it’s of somewhat biblical proportions,” Mark Drinkwater, head of the mission science division at ESA’s European Space Research and Technology Centre, told Mashable.
In a post to Twitter, Drinkwater said the hype around the impending separation has given rise to the term “bergxit.”
Researchers warn the iceberg will likely be so large that it could pose a risk to maritime traffic.
“Whole or in pieces, ocean currents could drag it north, even as far as the Falkland Islands,” located east of South America’s southern peninsula, Anna Hogg of the University of Leeds said in a statement. “If so it could pose a hazard for ships in Drake Passage” ― a stretch of ocean between South America’s Cape Horn and Antarctica.
At 21,000 square miles, Larsen C is the largest ice shelf in the region. In recent years, however, what started as a small fracture has moved rapidly through the frozen structure, widening to more than 1,000 feet.
During the month of December, the rift grew by more than 10 miles, followed by another 6 miles in the first few weeks of January. Between May 25 and May 31, it grew by an astounding 11 miles — over 1.5 miles per day.
Today, the fissure is over 120 miles long, and only about three miles from reaching the ocean, according to ESA’s new analysis.
“The iceberg remains attached to the ice shelf, but its outer end is moving at the highest speed ever recorded on this ice shelf,” researchers with Project MIDAS wrote in a blog post last week. “We still can’t tell when calving will occur — it could be hours, days or weeks — but this is a notable departure from previous observations.”
Project MIDAS estimates the calving event will remove more than 10 percent of the Larsen C shelf, leaving the ice at “its most retreated position ever recorded.”
Along with fundamentally changing the Antarctic Peninsula, scientists worry a break-off could destabilize the entire shelf, meaning Larsen C could be headed for a similar fate as nearby Larsen A and Larsen B, which collapsed and disintegrated in 1995 and 2002, respectively.
Larsen B’s vanishing act is highlighted in the NASA video below:
In 2014, over a decade after Larsen B’s collapse, scientists determined the event was triggered by rising air temperatures.
Since ice shelves float on the ocean’s surface, the impending calving event won’t immediately raise sea levels. An event of this scale, however, could destabilize the entire shelf, resulting in its disintegration and the release of the glacier ice it holds back ― which ultimately would raise sea levels.
How long that process could take is difficult to pinpoint. But scientists estimate that if all the glaciers behind Larsen C ended up in the ocean, it would raise global sea levels by about 10 centimeters, or 4 inches.
CORRECTION: A previous version of this story stated the iceberg’s height above water was projected to be about 620 feet. In fact, that figure refers to its thickness.