Wrenhaven scientists join survey tracking giant iceberg off West Antarctica

A team from the Wrenhaven Marine Institute has joined an international survey following one of the largest icebergs to break away from West Antarctica in recent years. The berg, about 1,100 square kilometres in area, split from the front of a fast-moving glacier and is now drifting slowly into open water.

Satellite images first showed a crack widening across the floating ice shelf last season. The final break came quickly, over less than two days, and the new berg has since rotated and moved about 40 km from its parent glacier. Scientists say calving on this scale is a natural process, but the rate of ice loss in the region has increased over recent decades.

Instruments on the ice

The survey, led by a polar research network of eleven universities, combines satellite radar with instruments dropped onto the berg by aircraft. They measure its thickness, speed and direction, and how quickly it melts from below. Wrenhaven's contribution is a set of floating sensors that record water temperature and salinity in the berg's wake.

An iceberg this size changes the ocean around it for months, stirring up nutrients and freshening the surface as it melts.

Dr Kaito Ferreira, a physical oceanographer at the institute, said the data would help improve models of how meltwater spreads around Antarctica. His colleague Dr Marit Solberg, who will join a research ship heading south, said the team also wants to understand what the berg's departure means for the glacier left behind, which no longer has as much ice holding it back.

• Area of the iceberg: about 1,100 square kilometres

• Distance drifted so far: about 40 km

• Sensors deployed by Wrenhaven: 12 floats

Getting instruments onto a moving iceberg is not straightforward. Aircraft fly low over the surface and drop sensor packages on small parachutes, aiming for flat areas away from crevasses. Some land in deep snow and stop transmitting within days, so the team deploys more than it needs. The floating sensors from Wrenhaven are lowered from a ship and drift alongside the berg, reporting their readings by satellite every six hours.

Icebergs of this size can survive for years, gradually breaking up as they are carried north by currents. Shipping in the Southern Ocean has been notified of its position, which will be updated weekly by the survey team.