Recent science has shown that it is inevitable that the warming Southern Ocean will speed up the melting of parts of the West Antarctic Ice Sheet (WAIS) regardless of our future carbon dioxide emissions. The WAIS holds enough ice to raise sea level by 5 m if completely melted.
While we are committed to sea level rise, we aren’t yet certain how much and how fast the ice in West Antarctica will melt. Whereas sectors of the WAIS appear highly vulnerable, it remains unclear as to when and under what climatic conditions we will lose the large buttressing ice shelves that stabilise the ice inland. To help answer this question, we have to turn to the geological record and recover sediment from regions near the centre of West Antarctica that were deposited during past times when it was warmer than today.
These sediments hold environmental information that is key to our future but, until now, has been impossible to obtain.
"We know more about the rocks and composition of the moon than we do about the land beneath the West Antarctic Ice Sheet,” said Richard Levy, Co-Chief Scientist of the SWAIS2C project.
Astronauts have collected over 2,400 rock and mineral samples from different locations on the moon since the first landing in 1969. However, there are only 13 locations beneath the ice blanketing West Antarctica where scientists and researchers have recovered geological samples. That’s about to change as an international team of researchers and drillers leave Christchurch for Antarctica on the 16 November.
The Sensitivity of the West Antarctic Ice Sheet to Two Degrees of Warming (SWAIS2C for short) international research project is designed to determine whether the Ross Ice Shelf and West Antarctic Ice Sheet will melt as Earth’s average surface temperature approaches 2°C above those that characterised our planet before the industrial era.
“It is the goal of the Paris Agreement to keep global warming to well below 2°C. Yet we do not know whether the West Antarctic Ice Sheet will lose most of its ice at 1, 2, or 3 degrees of warming, committing us to several metres of sea level rise,” said Tina van de Flierdt, Co-Chief Scientist of the SWAIS2C project.
To understand more about Antarctica’s potential contribution sea-level rise, a team of drillers, engineers, and researchers will travel ~800 km via traverse and airplane to the southeast margin of the Ross Ice Shelf and drill up to 200 m below the seafloor to recover a geological record of changing rock types that reflect environmental conditions at the time they formed. The hope is that these records will provide key insights into West Antarctica’s past and the Earth’s future.
“We will use a custom-built hot water drill to melt a 35-cm diameter hole through 590 m of ice to access the 50-m thick ocean cavity near where land ice begins to float and form an ice shelf,” said Richard Levy.
“We will then position a special sediment coring system over the hole, lower a diamond-studded hollow drill bit to the ocean floor, and drill down to obtain a long sedimentary record from well-below the seafloor of West Antarctica,” said Darcy Mandeno, the Drilling Operations Manager for SWAIS2C.
Antarctic field operations are scheduled to begin in November 2023 on the Kamb Ice Shelf and will continue through 2024. A second field season will begin in November 2024 at the Crary Ice Rise co-led by Molly Patterson and Huw Horgan.
More than 120 people from around 35 international research organisations are collaborating on the SWAIS2C project, including around 25 early-career researchers. SWAIS 2C brings together researchers from New Zealand, the United States, Germany, Australia, Italy, Japan, Spain, Republic of Korea, the Netherlands, and the United Kingdom.
Total project operations and logistics will cost US$5.4 million. Significant additional funding and in-kind contributions have been provided by the Natural Environment Research Council, Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research, Federal Institute for Geosciences and Natural Resources, National Science Foundation (NSF-2035029, 2034719, 2034883, 2034990, 2035035, and 2035138), German Research Foundation (grants KU 4292/1-1, MU 3670/3-1, KL 3314/4-1), Istituto Nazionale di Geofisica e Vulcanologia, Korea Polar Research Institute, National Institute of Polar Research (Japan), Antarctic Science Platform (ANTA1801), Leibniz Institute for Applied Geophysics, AuScope, and the Australian and New Zealand IODP Consortium. This project is the first in Antarctica for the International Continental Scientific Drilling Program (ICDP), and follows on from other successful international Antarctic research programmes such as ANDRILL.
Logistical support comes from Antarctica New Zealand (K862A-2324, K862A-2425) in collaboration with the United States Antarctic Program. Drilling is funded and supported by the ICDP. The SWAIS2C Project Manager is GNS Science and the Drilling Services Provider is Te Herenga Waka—Victoria University of Wellington.
The team calls SWAIS2C “the discovery for our lifetime” and hopes that results will guide plans to adapt to unavoidable sea level rise, while amplifying the imperative to mitigate global greenhouse gas emissions.
“Our approach to drilling is novel and not without risk, but it’s the only way we are going to get those critical samples. If we are successful and prove that this new drilling system will work, it will open up new opportunities to obtain key records of environmental change and ice sheet dynamics at other remote locations across Antarctica,” said Richard Levy.
“Retrieving samples from such remote locations in Antarctica will allow us to build a much better picture of how Antarctic ice will respond to future warming, which parts will melt first, and which parts will remain. We will use the past to learn about the future. This knowledge is critical as humanity grapples with the unavoidable challenge of sea level rise,” said Tina van de Flierdt.
“Whatever we recover and discover on this trip will be new to humankind and important in understanding future sea-level rise,” said Richard Levy.
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Background
Earth’s average surface temperature has warmed by 1.2°C since the Industrial Revolution (1850) due to human activities that include burning of fossil fuels (coal, oil, and natural gas). At the same time, sea level has risen an average 20 cm across the world, primarily due to the expansion of the ocean as it absorbs heat and melting of our planet’s glaciers, land-based ice caps, and ice sheets.
We can expect further warming of between 1.4° to 4.4°C by 2100—the size of the increase depends on what socio-economic decisions society makes about our greenhouse gas emissions. An additional 30 cm of sea level rise is unavoidable regardless of our emissions decisions, but the increase may be as much as 1 or 2 m if we follow a high-emissions pathway and potential instabilities in Antarctica’s ice sheets play out.
Just how sensitive Antarctica’s large ice shelves—and the marine ice sheets that sit behind them—are to warming between 1.5° and 2°C is a key element of research that will help better predict when and how much the polar ice sheets might melt.
Scientists can look to the past for answers to that important question. Geological reconstructions from around the world indicate that sea levels were 6 m higher than today during the last interglacial, 125,000 years ago. Earth’s average surface temperature was 1 to 1.5°C warmer than pre-industrial at that time. These data suggest that parts or all of the West Antarctic Ice Sheet may have collapsed, which highlights a potential sensitivity to temperatures that we have already reached, and will certainly experience in the coming decade. This project aims to obtain robust, direct evidence for potential ice collapse under different environmental conditions.
