Massive icebergs threaten NIWA equipment


Massive icebergs threaten NIWA equipment 

NIWA may lose valuable scientific equipment after two massive icebergs broke off the Antarctic coastline over the weekend.

NIWA scientists have been monitoring satellite images of the Nansen Ice Shelf at Terra Nova Bay, about 285 km from Scott Base, as part of field work planning for next summer.

Yesterday NIWA oceanographer Dr Craig Stevens using NASA satellite images, spotted two separate icebergs had broken off the ice shelf. They are between 5 and 15km in length, up to 5km across, and could be as much as 100m thick.

The Nansen Ice Shelf is about 50km long and 30km wide. Ice shelves line the perimeter of Antarctica and regularly calve icebergs.  A small crack in the shelf was first spotted in December, 2013. Earlier this year NASA scientists noticed the crack had grown rapidly and had almost spread across the entire width of the ice shelf.

A NIWA mooring was deployed deep into Terra Nova Bay in December from the Korean ice breaker Aaron as part of a collaborative programme between New Zealand and Korea.  The mooring was into its second year of operation and contains sensitive and highly valuable scientific equipment that measures current, temperature and salinity to help understand the effects of climate change sea ice and ice shelves. There were plans to recover it early next year.

However, NIWA oceanographer Dr Mike Williams said today the icebergs that have broken off the ice shelf are so deep they could catch the top of the mooring and drag or break them if the icebergs drift over the mooring.  

“We won’t know until we go back next summer whether it is still there. We could lose a whole year of data. If that happens it will leave a gap in our research and that’s unfortunate.

“However, it is a risk we have to take – we could see the crack from satellite images but predicting when an ice shelf will calve is difficult. It could have happened any time in the next five years.”

The mooring is part of New Zealand’s contribution to the Southern Ocean Observing System, an international consortium to better observe changes in the Southern Ocean. A similar mooring, installed by the US is also at risk.  However, another NIWA mooring stationed to the south should be safe from these icebergs. The Koreans have a weather station now situated on one of the icebergs.


Chief Scientist - Oceans
Nansen ice shelf. [Craig Stevens]