Nature’s power right on cue

ANTARCTIC researchers watched as a segment of the Sorsdal Glacier ice shelf broke off into the Southern Ocean this month, in what scientists have said is a rare sighting.

The team of four engineers and two scientists who observed the event — called calving — were testing the capability of the nupiri muka, an Autonomous Underwater Vehicle that went beneath an ice shelf for the first time just before the event.

Marine glaciologist David Gwyther, who witnessed the event, said although ice shelf calving was natural, climate change was likely to increase the frequency.

“As such, this event will provide an invaluable baseline against which we can assess future changes,” Dr Gwyther said.

The chunk that broke off measures about 6km by up to 1km.

Associate Professor Guy Williams, from the Australian Maritime College’s Autonomous Maritime Systems Laboratory, said it was “serendipitous” that the calving happened where the research team was testing the AUV, which is in its first deployment to Antarctica to test its capability ahead of missions to more globally significant ice shelves.

Prof Williams said the timing of the event would lead to better understanding ice sheet change.

“The AUV is used to explore the sea floor and the structure of the cavities under Antarctic ice shelf with a view to understanding the melting that is occurring in those zones and how that relates to rising sea levels,” he said.

Prof Williams said the team chose this glacier because it was close to Davis Station and the calving was timely.

“To have it measured just before it broke is really interesting,” he said. “It was able to measure that region immediately before the event.”

Institute for Marine and Antarctic Studies PhD student Eleri Evans had been monitoring the ice shelf since December and said although the calving was predicted, it was unusual for people to see these events in Antarctica.

“The data from the photographic images taken at the site will be critical to improving our understanding of how the Sorsdal Glacier produces icebergs,” Ms Evans said.

Nupiri muka means “eye of the sea”. Prof Williams said the name cuts to the heart of what the AUV will be used for, taking observations researchers can’t get in any other way.