Trillion tons of ice
One of the biggest icebergs in recorded history just broke loose
Scientists announced Wednesday that a much-anticipated break at the Larsen C ice shelf in Antarctica has occurred, unleashing a massive iceberg that is more than 2,200 square miles in area and weighs a trillion tons.
In other words, the iceberg — among the largest in recorded history to splinter off the Antarctic continent — is close to the size of Delaware and consists of almost four times as much ice as the fast melting ice sheet of Greenland loses in a year. It is expected to be given the name “A68” soon, scientists said.
“Its volume is twice that of Lake Erie, one of the Great Lakes,” wrote researchers with Project MIDAS, a research group at Swansea and Aberystwyth Universities in Wales that has been monitoring the situation closely by satellite.
The break was detected by one NASA satellite instrument, MODIS on the Aqua satellite, and confirmed by a second, they said. The European Space Agency also confirmed the break.
The iceberg contains so much mass that if all of it were added anew to the ocean, it would drive almost 3 millimeters of global sea level rise. In this case though, the ice was already afloat so there won’t be a substantial sea level change.
The Project MIDAS group said Wednesday that the effect of the break is to shrink the size of the floating Larsen C ice shelf by 12 percent. While they
can’t be certain, they’re concerned that this could have a destabilizing effect on the remainder of the shelf, which is among Antarctica’s largest.
“The iceberg is one of the largest recorded, and its future progress is difficult to predict,” said Adrian Luckman, the lead MIDAS researcher and an Antarctic scientist at Swansea University, in a statement. “It may remain in one piece but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters.”
There is no expected immediate effect on shipping, Luckman said by email.
“Icebergs from this region occasionally make it out beyond the tip of the Antarctic Peninsula, but it will take a while for that to happen to this iceberg or its fragments, and there is not a lot of shipping in the area that I am aware of,” he explained.
The change is large enough that it will trigger a redrawing of the Antarctic coastline, according to Ted Scambos, senior research scientist with the National Snow and Ice Data Center.
Indeed, it means that the Larsen C ice shelf, previously the fourthlargest of its kind in Antarctica, is now probably only the fifth- or sixth-largest, Scambos said.
Even larger icebergs than this have broken off of Antarctica in the past, however, including an over 4,000-square-mile berg, famously dubbed B15, in 2000. That was almost twice the size of this one and broke off the Ross Ice Shelf, Antarctica’s largest floating ice body. It was the biggest iceberg ever recorded.
Larsen C also lost an even larger piece in 1986, Scambos said, but that occurred in considerably different circumstances. It came after the shelf had grown considerably and extended much farther out into the Weddell Sea than it does now.
“This calving is a little bit different, because it makes the ice shelf so much smaller,” Scambos said.
Indeed, the front of Larsen C ice shelf has retracted back farther than ever previously observed, according to Eric Rignot, a glaciologist with NASA and the University of California-Irvine.
“The ice front is now almost 40 km farther back,” said Rignot by email. “A similar evolution was seen on Larsen A and B before they collapsed in 1995 and 2002 respectively,” he added, referring to Larsen C’s now missing northern cousins.
If you add together all the ice lost from the various Larsen ice shelves since the 1970s, it is around 7,350 square miles, according to figures provided by Rignot. That is a little bit smaller than the state of New Jersey.
Scientists will now proceed to track the iceberg using satellite imagery, and should be able to get a chance at regular glimpses even in Antarctic night, due to the use of radar and thermal imaging.
This is how the growing chasm in the Larsen C ice shelf looked in February. The sheet of ice, almost the size of Delaware, has broken away and become a massive iceberg, scientists said Wednesday.