The Totten glacier in Antarctic. Image: Paul Brown

Warm ocean water is melting the largest glacier in East Antarctica from below, Australian scientists have found.

The team of 23 scientists and technicians from the Australian Antarctic Division, the Antarctic Climate and Ecosystems CRC , the University of Tasmania’s Institute for Marine and Antarctic Studies and CSIRO Oceans and Atmosphere Flagship, returned to Hobart today on Australia’s icebreaker Aurora Australis, after taking the first water samples collected alongside the Totten Glacier.

Steve Rintoul, Voyage Chief Scientist, say that until this voyage no oceanographic measurements had been made within 50 kms of the glacier.

At 120 km long and more than 30 km wide the Totten Glacier is one of the world’s largest and least understood glacial systems.

It drains 538,000 square kilometres of East Antarctica, an area more than twice the size of Victoria. 70 billion tonnes of ice flow out of it every year, enough to fill Sydney Harbour every two and a half days.

“It was thought that glaciers on the East Antarctic ice sheet were relatively immune to the kind of melting taking place on the much smaller West Antarctic ice sheet,” says Dr Rintoul.

“But satellite data show that the Totten has been thinning faster than other glaciers in East Antarctica and until now we have not known why.”

The researchers used new instruments, including autonomous floats and gliders, to sample the ocean beneath sea ice.

As warm ocean waters melt the Totten and other floating glaciers around the edge of Antarctica, more glacial ice can flow into the ocean, raising sea level.

This study will help address one of the biggest questions concerning future sea level rise: how will warming of the ocean affect the Antarctic ice sheet?

The Totten Glacier alone has an amount of ice equivalent to 6 metres of global sea level rise.

Glaciers grounded on bedrock below sea level, like the Totten, are vulnerable to changes in ocean temperature and currents, because the ocean can penetrate deep under the glacier.

A key part of the voyage was the recovery of US and Australian instruments moored on the sea bed for up to two years at six different locations adjacent to the Totten glacier. The Australian instruments are part of the national Integrated Marine Observing System.

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