Antarctic rocks reveal glacial retreat – Australian Antarctic Program (News 2022)
Antarctica is a long way to pick up a bag of rocks.
But that’s exactly what Australian scientists have done to try to measure the impact of climate change on a glacier in East Antarctica.
As part of the Securing Antarctica’s Environmental Future (SAEF) research partnership, the Monash University team took their tools to the Browning Peninsula, home to the Vanderford Glacier.
Dr Felicity McCormack said the region that feeds Vanderford Glacier, known as the Aurora subglacial basin, is rapidly thinning and contributing to sea level rise.
“Vanderford Glacier is at substantial risk of rapid retreat as the ocean warms in response to climate change,” Dr McCormack explained.
“A recent study has shown that patches of deep, warm ocean water are entering the cavity beneath the Vanderford ice shelf, which could lead to thinning of the ice shelf as the climate warms.”
This change has scientists wanting to learn more about the history of the Vanderford Glacier, but rocks, rather than ice, may hold the key.
Secrets of stone
Rocks can rise on glaciers as they move slowly from the interior towards the coast, tearing the rock below.
Glaciers can retreat but they leave the rocks they pushed forward.
Dr Richard Jones said rocks contain chemical isotopes, special types of atoms that are produced in rocks when exposed to the sky and bombarded by cosmic radiation.
“By analyzing these isotopes, we can build a picture of how the Vanderford glacier has retreated and advanced during past episodes of climate change over the past few thousand years,” said Dr Jones.
This information will help researchers better predict how the Vanderford Glacier will behave in future climates.
Here is the exercise
To search for the necessary geological clues, the team used a special ‘corer’ to drill into the bedrock.
Looking and sounding a bit like a jackhammer, it allowed the group to drill into bedrock to trace the glacier’s previous path.
The rest of the mission was devoted to locating the perfect outcrop.
“After taking some observational measurements, we used an angle grinder and scissors to collect Snickers bar-sized rock samples for analysis,” Dr Jones said.
In total, the transport totaled 130 kilograms from 30 separate sites around the peninsula.
“We sometimes had to carry samples in our backpacks or drag them in sleds, but there was nothing too strenuous!”
With collection complete, the team now has the task of processing the samples in the lab.
“We crush the rock first, then we dissolve it, and finally we use the magic of geochemistry to extract specific isotopes,” Dr Jones said.
“The isotopes measured from these rock samples will be used to determine when the Vanderford Glacier retreated and thinned, before modern observations, and whether it has ever advanced over the past millennia.”
Field observations, satellite remote sensing and ice sheet models will also be used.
This season has been the first year of field work for the team, supported by the nearby Casey Research Station and exceptionally mild Antarctic weather.
“Most of all, we had time to enjoy the breathtaking scenery, beautiful wildlife and stunning views of the incredible Vanderford Glacier,” said Dr McCormack.
SAEF is a special research initiative of the Australian Research Council.