Impact of East Antarctic glacial melt on sea-level rise

Totten glacier
Scientists will study the Totten Glacier in East Antarctica to better understand the impact of ice melt on sea level rise. (Photo: Esmee van Wijk)
The Aurora Australis icebreaker shipMelt water falling over ice cap

27th October 2016

The Australian Antarctic Program will study two glaciers, the Totten and Sørsdal, in East Antarctica this summer to better understand the impact ice melt is having on global sea-level rise.

The Totten Glacier, near Australia’s Casey research station, is the largest glacier in East Antarctica, and is showing signs that it is sensitive to warm ocean waters that can increase melt at the base of the ice shelf.

Australian Antarctic Division Glaciologist, Dr Ben Galton-Fenzi, said researchers want to better understand how much this glacial melt is driving sea-level rise.

“Since the 1900s the global sea-level has risen by around 20 centimetres and by the end of the century it’s projected to rise by up to one metre or more, but this is subject to high uncertainty,” Dr Galton Fenzi said.

“These estimates depend critically on understanding Antarctic glaciers, both how much and how fast they melt in a warming climate.

“We know there’s enough ice below sea level in the Totten Glacier, to raise global sea-levels by 3.5 metres, although this would likely take many centuries to occur,” he said.

This summer researchers will look at how warmer ocean water is melting glaciers and ice shelves from below.

“We will land helicopters on the Totten to deploy six GPS units to measure glacial flow speeds and surface elevation changes.

“We will also set up six Autonomous phase-sensitive Radio Echo Sounding (ApRES) instruments that can measure the glacier’s thickness up to 2 km below the surface and with millimetre precision,” Dr Galton Fenzi said.

The instruments will be put out at the beginning of the summer and left on site for up to six weeks.

Other instruments will be left on the glacier over winter and collected next season, streaming a compressed form of base melt rate estimates via satellite over the winter.

At the Sørsdal Glacier, near Australia’s Davis research station, melt ponds form on the top of the glacier in the warmth of summer.

University of British Columbia Glaciologist, Dr Christian Schoof, said as the air temperature around Antarctica warms an increase in melt pond formation could have serious consequences.

“These ponds drain down through the ice until the water reaches bedrock, where it acts as a lubricant, causing the ice flow to speed up,” Dr Schoof said.

Dr Schoof and Australian colleagues’ work on Sørsdal Glacier will be the first attempt to monitor the effect of surface ponds on the flow of ice in East Antarctica.

“We will deploy cameras to take photos every 2–3 hours, put out pressure sensors to measure how the melt ponds fill and drain.

“We will also take temperature measurements on the surface of the glacier and use GPS antenna to determine if the ice flows faster in summer,” Dr Schoof said.

This year the Australian Antarctic Program will support 95 projects in Antarctica, the Southern Ocean and on sub-Antarctic Macquarie Island.

More than 500 expeditioners will travel south over the summer season on the Airbus A319 and C-17A Globemaster III, and on Australia’s icebreaker Aurora Australis, which departs Hobart today.

[Video]

Impact of East Antarctic glacial melt on sea-level rise

Video transcript

[Dr Ben Galton-Fenzi, Glaciologist]

We’ve got six weeks of time down there early in the season and we’re going to be flying out and deploying autonomous, phase-sensitive radio echo-sounding instruments and GPS on the surface of the Totten to measure the flow of the Totten, how fast it’s melting and hopefully how that’s going to be evolving over a season.

The Totten Glacier is one of the biggest glaciers in Antarctica. It drains the Aurora sub-glacial basin. A substantial proportion of that is grounded below sea level. It holds about 3.5 metres of potential sea-level rise.

Recent satellite observations have shown that the Totten Glacier has been changing. The surface elevation of it has actually been lowering over time and we now also understand that it’s very sensitive to oceanic conditions and so what we want to try to do is get a baseline understanding about how fast the glacier is flowing, what that variability is and then therefore we can project forward in time about how we expect it to change into the future.

[end transcript]