A gigantic rifting event is entering its final phase on the Brunt Ice Shelf in Antarctica. Two enormous crevasses are predicted to intersect in the coming months. This will cause an ice berg measuring between 580 and 660 sq mi (1500 – 1700 sq km) and up to 820 feet (250 m) thick to break free from the Antarctic continent into the Weddell Sea. It will be largest ice berg to calve off the shelf since scientists started paying attention in 1915.
The first crack, called Chasm 1, had shown no movement in 35 years, but that changed in 2013. Since then, scientists have been watching Chasm 1 grow at a rate of about one to two miles (approximately 4 km) per year. Then in late October of 2016, a second crack appeared perpendicular to Chasm 1. The “Halloween Crack”—which could be called that as much for its jagged Joker-smile edge as for the timing of its discovery—extends east from the McDonald Ice Rumples. The two cracks are projected to meet in the next few months.
As soon as the Halloween Crack appeared, scientists at the Halley VI Research Station knew they would need to close up shop and head inland, again. First established in 1956 to study Earth’s atmosphere, the station has been moved several times due to ice instability and movement. The latest move, which involved hauling individual modules propped on “telescopic legs ending in giant skis,” one at a time, 14 miles inland, began in December of 2016 and was completed ahead of schedule in just over a year.
Now on the safe side of Chasm 1, scientists speculate about whether the calving event will have an impact on the stability of the remaining ice shelf. “The likely future loss of the ice on the other side of the Halloween Crack suggests that more instability is possible,” saysNASA/University of Maryland, Baltimore County (UMBC) glaciologist Chris Shuman, “with associated risk to Halley VIa.”
Professor Hilmar Gudmundsson of Northumbria University asserts that all this activity is to be expected as part of the natural life cycle of the Antarctic Ice Sheet: “Ice shelves just do this. They grow with time and eventually chunks break off…. So while what is happening now is new to us, for the ice shelf, this is most likely not a new thing, and it’s very plausible that something like this has happened in the past.”
We’ll soon find out whether the meeting of the Halloween Crack and Chasm 1 trigger an acceleration of calving events in Antarctica. If so, a team of specialized snow tractors rigged up like mechanized sled dogs will get busy hauling Halley’s futuristic research pods farther up the Brunt to less fractured ground.