Climate change isn't the only culprit behind massive ice shelf crack in Antarctica

A crack running along the Antarctic ice shelf has scientists on alert, but this time the changing climate isn't to blame.

A massive fissure is moving at an accelerated rate across Larsen C, an ice shelf on the northern peninsula in Antarctica. While the knee-jerk reaction for many may be to blame such a crack on climate change, it's just one of several possible reasons as to why the ice shelf is separating.

"The driving force for the crack is all about geometry and stresses in the ice. Climate change could be playing a role," said Heidi Sevestre, a glaciologist at University of St. Andrew's in Scotland.

Sevestre spent six weeks down on the ice shelf in 2015, living in a tent with other scientists as they studied the icy environment.

According to Sevestre, cracks in the ice are part of the natural life of an ice shelf. They're a normal response to geometric stresses in the ice, depending on how fast the ice is moving.

However, this crack is breaking at a faster rate than most do, and it's raised some eyebrows as to what it might mean for Larsen C. The reason for its accelerated breaking remains, so far, undetermined.

"If they didn’t fracture and calve off of icebergs, they would just be getting bigger," said Dan McGrath, a glaciologist at Colorado State University. "So it’s a very natural part of the process that we’re witnessing here."

McGrath spent several seasons on the Antarctic Peninsula, specifically on Larsen C in 2011.

"It by itself... this potential calving event is not directly tied to climate change," McGrath said. "It’s not directly tied to warming atmospheric temperatures in the atmosphere of the peninsula."

"There is this big iceberg forming," Sevestre said. "It is not quite an ice shelf because it is still attached to the ice shelf, but it’s only attached by about 20 kilometers of ice, which is very, very small."

Ice shelves work as barriers from the ice on the mountains to the ocean, Sevestre explained. Once there is no longer something preventing the ice from the mountains flowing into the ocean, ice can flow right into the waves and add to sea-level rise.

"All the ice is contained in these glaciers and is suddenly being discharged or dumped into the ocean," Sevestre said.

As the ice melts, the glaciers will start to speed up, contributing to further ice falling into the sea water, Sevestre explained. More recently, some glaciers have accelerated to five to ten times faster than previously seen.

One ice shelf has already mostly disappeared from the region. Larsen B is almost entirely gone after it became too unstable, collapsing in 2002.

Larsen B was also part of the Antarctic Peninsula. Due to warm winds from the mountains, lakes and ponds developed on the surface of the ice sheet. Suddenly, the water from the bodies of water seeped through the ice. Larsen B disappeared almost completely in a matter of months.

According to Sevestre, early signs of similar lakes are already forming on Larsen C.

"Climate change could be playing a role," Sevestre said. "It’s hard for us to draw a direct link between how the crack is behaving at the moment and climate change."

For now, glaciologists are watching the activity in the ice intently.

"We’re trying to understand Larsen C and the properties that are leading to this rift growth," said McGrath, "in order to understand the stability of the much larger ice shelves that are in the Antarctic ice sheet."

"Even if Antarctica looks like something that is very, very far away," Sevestre said, "it is important to remember what is currently happening in Antarctica will impact us in the future and is already impacting us."

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