Totten ice front.  Esmee van Wijk

Totten Glacier is the largest glacier in East Antarctica and has the potential to make a significant contribution to global sea level rise. Lots of reports have shown that Antarctica’s Totten Glacier ice shelf is melting but is it a natural process? It is difficult to distinguishing between climate change effects and melting driven by natural processes. Relatively warm lakes have been discovered, and for whatever reason Totten will likely be contributing to global sea level rise in the future.

Between 2003 and 2008 the base of the glacier’s ice shelf was thinning at a rate of about 40 centimetres per annum. Over an 18-year timescale there are periodic 3-4 year fluctuations but no net change in the ice shelf’s thickness.

IMAS researcher Dr David Gwyther, has shown that “…we need to be able to distinguish between the impact of climate change and natural variability resulting from processes internal to the ocean, such as vortex-like eddies. Our modelling has shown that making this distinction is not a simple process. We found that intrinsic (natural) ocean processes accounted for 44 per cent of the variability in melting under the ice shelf over one to five years, and 21 per cent of the variability over a five to ten year period. Climate change accounted for variability of around the same magnitude”.

“This complex variability in the processes causing melting of the Totten ice shelf limits the conclusions that we can reach from short-term observations, as we are likely also monitoring natural variability, rather than solely climate change.

“Our study suggests that to fully understand and predict the behaviour of the glacier, we need to combine short term observations with data collected over a longer period and use modelling studies which can explore the long-term trends,” Dr Gwyther said.

This March IMAS did more study. Researchers drilled into the ice sheet and set off small explosives. These explosions sent out sound waves, which then echoed off different layers in the ice and bedrock. This led to the discovery of a network of lakes beneath the ice. Glaciologist Dr Galton-Fenzi said “a substantial amount of water” was contained in the subglacial lakes, which could impact the rate at which ice flows into the ocean.

While the Intergovernmental Panel on Climate Change (IPCC) estimates sea levels will rise by a metre by 2100, Dr Galton-Fenzi said those estimates did not factor in the increased discharge of Antarctic ice due to climate change. “The Totten Glacier drains an area of east Antarctica that contains about seven metres of sea level rise equivalent of ice,” he said. “We know there’s warm water present under the glacier, so we expect this is one of the regions in east Antarctica that’s going to change first.”

A study from NASA shows that smaller glaciers around Totten have lost significant amounts of ice in the last decade. Four glaciers in Vincennes Bay, west of Totten, have lost 9 feet of elevation since 2008. Glaciers in an area east of Totten called Wilkes Land have doubled their rate of melting since 2009 and are losing about .8 feet of ice per year.

Though those ice losses are relatively modest, it suggests the ice in East Antarctica is beginning to “wake up.” “The change doesn’t seem random; it looks systematic,” says Alex Gardner, a glaciologist with NASA’s Jet Propulsion Laboratory. “And that systematic nature hints at underlying ocean influences that have been incredibly strong in West Antarctica. Now we might be finding clear links of the ocean starting to influence East Antarctica.”