Antarctica Sheds Trillion-Ton Iceberg, But Scientists Aren't Blaming Climate Change
By: Eric Mack
A trillion-ton iceberg the size of Delaware has calved off of Antarctica, permanently reshaping the Antarctic Peninsula.
A 5,800 square km section of the Larsen C ice shelf split off the continent sometime between Monday and Wednesday, according to a release from Project Midas, which has been keeping an eye on it. The iceberg's split has been expected for quite some time, and although it's certainly a big chunk, it doesn't set the record for biggest 'berg to break free from Antarctica – an 11,000 square km block seen calving from the Ross Ice Shelf by satellites in 2000 holds that title.
The newly liberated chunk of ice, which will probably be known as A68, has volume equal to two Lake Eries, but was already floating in the ocean and will have no immediate impact on sea levels worldwide. However, last month Dr. Thomas Wagner, a NASA scientist who studies the cryosphere explained to my colleague Marshall Shepherd that loss of ice shelves can lead to a sort of domino effect:
"Ice shelves buttress glaciers around Antarctica. Their break up causes the rapid flow of glacial ice into the sea. This process is considered the number one potential trigger of rapid sea level rise."
Wagner adds that Larsen C does not look to be in a position to trigger the loss of glacial ice itself, but could provide scientists an opportunity to study the process.
Updated #Sentinel1 InSAR sequence shows final branching at the rift tip as it reaches within 4.5 km (2.8 miles) of breaking through to calve pic.twitter.com/6F1Bs8Zmkv
— Adrian Luckman (@adrian_luckman) July 6, 2017
However, according to Project Midas, this week's calving event reduces the size of Larsen C by 12%, and there was research published in 2015 that shows the newly reduced ice shelf could be less stable. The neighboring Larsen B shelf disintegrated in 2002 following a similar rift in 1995 and Adrian Luckman, a Swansea University researcher and lead investigator for Project Midas, says it's worth keeping a close eye on Larsen C.
“In the ensuing months and years, the ice shelf could either gradually regrow, or may suffer further calving events which may eventually lead to collapse – opinions in the scientific community are divided. Our models say it will be less stable, but any future collapse remains years or decades away.”
He says this week's calving event can't simply be blamed on climate change, as he explained in a separate editorial on Wednesday:
"...in satellite images from the 1980s, the rift was already clearly a long-established feature, and there is no direct evidence to link its recent growth to either atmospheric warming, which is not felt deep enough within the ice shelf, or ocean warming, which is an unlikely source of change given that most of Larsen C has recently been thickening. It is probably too early to blame this event directly on human-generated climate change."
As for the new iceberg itself, Luckman says it is likely to break into fragments and some of the ice could hang around its origin, while other parts could drift to warmer waters to the north.