A fissure that has been steadily growing across the Larson C ice shelf off of the Antarctic Peninsula has been a concern for scientists since it began extending through the ice between 2011 and 2015. The Larsen C ice shelf, described by the British Antarctic Survey as “slightly smaller than Scotland,” is Antarctica’s northernmost shelf, and is the sole remaining of the three Larsen shelves: Larsens A and B broke up in 1995 and 2002, respectively.
Having just recently come out of the perpetual night that affects the region south of the Antarctic Circle during the southern hemisphere’s winter, Larson C’s crack had lengthened by 22 kilometers (13.7 miles), bringing its full length to 130 km (80.8 miles). It has also widened dramatically too, from 200 meters (656-feet), to 350 meters (1,150 feet) wide — more than a fifth of a mile, a chasm as wide as the ice shelf itself is thick.
“We previously showed that this will remove between nine and twelve per cent of the ice shelf area and leave the ice front at its most retreated position ever,” explains Project MIDAS team members Adrian Luckman, Daniela Jansen, and Martin O’Leary. “The trajectory of the rift now implies that the higher of these two estimates is more likely.”
This means that the breakup of the Larson C shelf is continuing unabated. While the shelf itself won’t contribute much to ocean level rise — the bulk of the ice is already in the water — researchers are concerned that the removal of this ice will cause a domino-like effect that will loosen the land-bound glacial ice that feeds the ice shelf, pouring large volumes of ice and fresh water into the ocean.
“If this will calve off in the next, say two or three years, the calving front will be retreated very far back, further than we’ve seen it since we were able to monitor this,” says Daniela Jansen, a researcher with Germany’s Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research. “And our theory in this paper was basically that the calving front might become unstable. Once the iceberg has calved off completely, there might be a tendency for the ice front to crumble backwards.”