Beneath the Ice: Revealing Antarctica’s past to safeguard the future
ANZIC Expeditioner, Dr Linda Armbrecht, is part of an international team probing the sensitivity of the West Antarctic Ice Sheet.
An international team is heading to Antarctica this summer to drill through – and beneath – the mighty Ross Ice Shelf for precious samples to help understand how sensitive the West Antarctic Ice Sheet is to a warming climate.
The ambitious project, dubbed SWAIS2C (Sensitivity of the West Antarctic Ice Sheet to 2°C of warming) will drill through nearly 600 metres of ice and then into the seafloor beneath for the critical geological records, in one of the world’s most remote locations.
ANZIC Expeditioner, Dr Linda Armbrecht from the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS), is one of the on-ice team of 27 specialists. She hopes to peer back in time at ancient organisms and ecosystems, hunting for clues in ancient DNA layered in the sediments that are the target of the expedition.
“This is the opportunity of a lifetime – getting these samples from underneath the ice sheet,” Linda says with obvious excitement. “My goal is to work out what organisms lived here during various phases of the Earth’s past, what the ecosystem looked like, and how that changed when the climate was warmer, or cooler, or changing.”
“To me, it’s a big discovery project – and our collective results will be important for humanity.”
But obtaining the precious samples will take Linda well out of the comfort zone.
“We’ll be living in tents. On the Ice. In the Antarctic weather for six weeks. I’ve never done anything like it before!”
“This only works with a lot of trust in the team, the local experts, and the specialist training,” she says.
Studying the ecosystems of the past, through tell-tale DNA fragments left in sea-floor sediments, will allow the SWAIS2C team to map what happened to the West Antarctic Ice Sheet in the past – its retreat and advance, growth and melting over time.
“Antarctica should provide good conditions for preserving DNA, so we should be able to look back a long time – to maybe millions of years ago. This means we can study changes to the ice sheet during several warm phases in the past.”
Other members of the team will use other techniques to study the sediment cores.
“There’s lot of interdisciplinary work in this project,” Linda says. “Geophysicists, sedimentologists, oceanographers, geochemists and paleoclimate experts. Everyone brings their own specialist expertise to examine the samples and understand the condition of the ice sheet in the past”.
“When we put all of that together, what we learn from the past will help us build a picture of how the West Antarctic Ice Sheet will respond in the near future as we transition to a warmer climate – which parts will melt first and which parts may hold on,” Linda explains.
Understanding what temperatures will trigger melting of the Ross Ice Shelf, and the subsequent collapse of the West Antarctic Ice Sheet, is critical. The Ice Sheet holds enough ice to raise sea level by 4-5 m if it melts completely.
Research has found a collapse might be inevitable for some parts of the West Antarctic Ice Sheet, such as the area around the ‘Doomsday Glacier’ (Thwaites Glacier) in the neighbouring Amundsen Sea, due to the presence of warm water. In contrast, water underneath the large Ross Ice Shelf is still cold.
“The Ross Ice Shelf serves as a stabilising buttress to the inland ice of other areas of the West Antarctic Ice Sheet. But we lack direct evidence if, and when we will lose it.” Linda says.
This urgency is driving the scientists, drillers and Antarctic field specialists as they head out to the ice this summer. To obtain the critical sediment core samples containing the biological and climatic clues, the team must melt a hole through around 580 m of the ice shelf, descent a 55 m ocean cavity, and use a custom-designed drilling system to drill up to 200 m into the seabed.
This is no easy task – something the team knows all too well. Due to technical difficulties, their efforts to do so last year were scuppered after reaching the seafloor.
Professor Richard Levy, SWAIS2C Co-Chief Scientist from GNS Science and Te Herenga Waka – Victoria University of Wellington, says they’re headed back this year to finish what they started, but with an even greater sense of urgency.
“The climate warning signs are only getting louder,” Prof Levy says. “Since our last deployment we’ve seen global temperatures reach record highs across the world. Last year, the average increase in Earth’s annual surface temperature exceeded the 1.5°C target of the Paris Agreement for the first time since we started routinely measuring temperature with instruments. While this increase may be temporary, we are well on track to permanently cross this threshold in the next 5 to 10 years.”
The coveted core is expected to reach back hundreds of thousands of years, potentially even millions of years. Such a record would include the last interglacial period 125,000 years ago, when Earth was around 1.5°C warmer than pre-industrial temperatures – similar to the temperatures we’ve approached this year due to human-caused climate change.
The sequence of rocks and mud will reveal how the West Antarctic Ice Sheet behaved during this past time of warmer temperature. For example, if researchers like Linda find evidence of photosynthesising marine algae – which need light to live and so indicate open ocean conditions – it’s likely the ice sheet retreated.
The SWAIS2C team hopes the results will guide plans to adapt to unavoidable sea-level rise, while amplifying the imperative to mitigate global greenhouse gas emissions.
Learn more
Details of the projects can be found on the SWAIS2C website and media release.
Stay up-to-date with the team during their Antarctic summer with SWAIS2C on Instagram , Facebook, LinkedIn and X (formerly Twitter).