The Antarctic Peninsula has been home to the Larsen C ice shelf, but it’s unclear for how much longer. Researchers have found a crack in the ice shelf that’s almost 200 kilometers long. Between May 25 and May 31 the crack grew by 17 kilometers. If another 13 kilometers are cracked, then the Larsen C ice shelf will become a 5,000 square kilometer iceberg.
The Larsen C Break
Adrian Luckman is a scientist at Swansea University and leader of the UK’s Midas project who has been monitoring the Larsen C ice shelf. He said that they’ve seen the rift turn towards the ice front, which suggests that the crack will move in a way that will cause the ice shelf to break off. If the Larsen C ice shelf breaks off, it would be the size of the state of Delaware or a quarter of the size of Wales.
The process of an ice shelf breaking is called calving. Luckman told the Guardian, “Like any fracture in something, the longer the fracture becomes the more pressure there is on the remaining part of it. So it is really only hanging by a thread here”. The 17 kilometer crack from May 25 to 31 was the longest crack observed this year. The loss of Larsen C would result in the total Larsen ice shelf to be 10% smaller, causing the landscape of the Antarctic Peninsula to change significantly.
After this recent crack in Larsen C, it’s unclear when and how the ice shelf will fully fracture. With the Antarctic’s remote location, scientists rely on satellite data and radar imaging systems to stay updated on the condition of the Antarctic ice shelves. With only 13 kilometers left before the ice shelf becomes an iceberg, Luckman could see it happening within months, weeks, or even days. But overall, the fate of Larsen C remains a mystery.
Ice Shelves and Climate Change
Although climate change may appear to be the likely culprit of the Larsen C rift, Luckman cautions us to look deeper into the geological structure of the shelf. “The rift has been there for decades; it might well have broken through at this moment, whatever had gone on. It could just be one of those cyclical factors in ice shelves – this is how they work, they grow and then they give birth to icebergs.” According to the National Snow and Ice Data Center, these ice shelves are permanent floating ice sheets connected to a landmass. If Larsen C breaks off, it will likely not contribute to sea level rise because it’s already floating.
However, it’s still important to study these ice shelves and icebergs because they act as the buffer for the glaciers that lay behind them. Without ice shelves, “ice [glaciers] can flow faster from the land to the ocean and contribute more quickly to sea-level rise,” says Luckman. For instance, 15 years ago the Larsen B ice shelf broke off and accelerated the flow of glaciers behind them. Larsen A also broke off in 1995. For the break off of Larsen A and B, increasing ocean and atmospheric temperatures are widely accepted as the cause for the early ice shelf breaks throughout the Antarctic Peninsula.
According to Luckman, “What happens to these ice shelves [of the Antarctic Peninsula] is in some ways a lesson for what might happen to the larger ice shelves that actually hold back ice from the main ice sheets – and that is potentially very significant into the far future”.