International team launch second attempt to drill deep for Antarctic climate clues

Antarctic Science Platform climate researchers are part of an ambitious mission to recover critical geological records to help forecast future sea-level rise. The first team members have embarked on a 1128 km journey across the Ross Ice Shelf to set up camp on the edge of the West Antarctic Ice Sheet.

The vast West Antarctic 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 Amundsen Sea, due to the presence of warm water next to it. In contrast, water underneath the large Ross Ice Shelf remains 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.

Understanding what temperature will trigger unavoidable melt of the Ross Ice Shelf, and the subsequent collapse of the West Antarctic Ice Sheet, is critical for all of humanity. This is the challenge driving the scientists, drillers and Antarctic field specialists from 13 countries to come together as part of the SWAIS2C (Sensitivity of the West Antarctic Ice Sheet to 2°C) project, and why the “on-ice” team of 27 will camp at the KIS3 drilling site this Antarctic summer.

The team is seeking insights contained in sediment layered in the seafloor under the Ross Ice Shelf. To obtain this record they must melt a hole through around 580 m of the ice shelf, pass through a 55 m ocean cavity, and use a custom-designed drilling system to retrieve a sediment core from up to 200 m deep 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.

“We were making the first ever attempt to obtain a core this deep so far from a base and so close to the centre of the West Antarctic Ice Sheet,” says Prof Richard Levy, SWAIS2C Co-chief Scientist, from GNS Science and Te Herenga Waka – Victoria University of Wellington.

“Cutting-edge Antarctic frontier science is challenging, and we learned valuable lessons. We’re heading back this year to finish what we started, with an even greater sense of urgency – the climate warning signs are only getting louder.”

“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,” says Levy.

The coveted core is expected to reach back hundreds of thousands of years, potentially 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. If the researchers find marine algae, indicating open ocean conditions, it’s likely the ice sheet retreated.

The team calls SWAIS2C “the discovery for our lifetime” and hopes the results will guide plans to adapt to unavoidable sea-level rise, while amplifying the imperative to mitigate global greenhouse gas emissions.

“Retrieving this sample from such a remote location will help us build a clearer picture of how the West Antarctic Ice Sheet will respond to future warming, which parts will melt first and which parts will remain. We’re using the past to help us prepare for our future,” says Prof Tina van de Flierdt, SWAIS2C Co-chief Scientist, from Imperial College London.