Britain Needs to Move Its Antarctic Base Because the Ice Shelf Is Cracking

As winter sets in for the Northern Hemisphere, it's summertime on Earth's southernmost continent. For Antarctic researchers, that means another window of opportunity for fieldwork. But summer or not, the risks of the cold environment remain, and there's one particular natural hazard that is currently preoccupying British Antarctic researchers: a crack in the ice near their research base that could eventually snap it off into the sea atop a free-floating iceberg.

You can't stop nature, so there's only one thing for it: the British Antarctic Survey (BAS) is setting up to relocate Halley VI, the latest version of the Halley Research Station, which was opened on the Brunt Ice Shelf in 2013 and looks like a giant metal tardigrade.

"There's a crack that has formed in the ice shelf, and it's growing in a direction roughly towards the station," explained BAS glaciologist Hilmar Gudmundsson. "It's growing at about 1.7 km a year, and if this growth continues over the next few years in the same way as it has over the last three years, then eventually the crack will be upstream of the research station on the Brunt Ice Shelf."

What that means is that the station could eventually become cut off from the shelf so it's free-floating on an iceberg. But Gudmundsson and deputy project manager Adam Bradley assured us there's no immediate danger to the base or its inhabitants: this is a precautionary measure to bring the station further inland and keep it accessible.

In fact, while this particular chasm was not foreseen, the base was built with similar eventualities in mind. It's on hydraulic legs mounted on giant skis, ready to be pulled across the ice into a new position by bulldozers.

"The station was the first Antarctic research station that's designed to be fully relocatable, and so we know the station's capable of this, but this will be the first time we've actually tried to do it," said Bradley.

He explained that they will have to decouple each module, lower them on their hydraulic legs, and hook them up to heavy vehicles that will simultaneously push and pull each one across the ice shelf. At least one of the modules weighs over 200 tonnes, and they'll be moved at around 2-3 km per hour. "It could potentially take quite a lot of time to get to the destination, but slow and steady is what it's all about," said Bradley.

The researchers haven't yet decided on the exact new site and the move itself won't happen until next summer season in 2016-2017. For now, BAS is taking all of the equipment it will need for the relocation down to the base, as well as two temporary camps with their own power and water generation that will be erected for researchers to continue their work while Halley VI is making its journey. The cargo will go over in three ship journeys this season.

Gudmundsson explained that the crack in question is actually part of a larger chasm that has been in the ice shelf for decades. Chasm 1 is one of three major cracks identified as a risk on the Brunt Ice Shelf but it only recently started growing again. BAS monitors the ice using various data sources including satellite imaging. "The crack is big enough that we can see it quite clearly from space," said Gudmundsson.

They also take in-situ measurements using a GPS network on the ice shelf that transmits data to BAS in Cambridge. "We have two GPS units on both sides of the crack and they collect data every day and send it back so we can see the development of the crack and how it widens with time," Gudmundsson said. Current data shows that at that point the crack is widening by about 10 cm a day, which is caused by the natural calving of the ice shelf.

They also use ground-penetrating radar in order to see more detail of the crack below the surface of the ice. The crack cuts all the way through the ice shelf, which Gudmundsson said is around 250 m thick in that region (though there's a lot of variation).

While the crack was unexpected—Gudmundsson compared the natural phenomenon to an earthquake in terms of unpredictability—the team is prepared to put its moveable station to the test. Previously, Halley would have had to be rebuilt.

Meanwhile the researchers continue to expect surprises. Bradley said the biggest challenge to the relocation project would be the Antarctic conditions, as the summer season in the region is short. "That's my biggest concern—if it's an unusually bad-weather season, for instance, then we will lose a lot of time," he said.

A lot of the work will require being outside, so cold temperatures and high winds (by Antarctic standards) could cause problems for personnel.

Bradley, who is currently on his way to Antarctica and spoke to me just before he left, was sanguine about the project. "This is the nature of life on an ice shelf: the fact that it will always chuck up surprises sometimes," he said.