HOUSTON – (April 25, 2022) – Rice University geobiologist Jeanine Ash is on an Antarctic mission that aims to recover the first direct evidence that can answer one of the biggest questions about climate change of the 21st century: how much will the sea level rise and how fast?
Ash is part of a US effort funded by the National Science Foundation (NSF) called the Sensitivity of the West Antarctic Ice Sheet to 2°C, or SWAIS 2C, project, which is part of a larger international mission of the same name. Managed by Antarctica New Zealand, the mission involves more than 75 scientists from a dozen nations.
Ash, who studies the isotopic signatures of organic compounds, hopes to be selected for the SWAIS 2C ice contingent which will use specialized geologic and hot water drilling systems to drill through up to 1,000 feet of ice at two outlying locations. of the Ross Ice Shelf, a floating platform of ice the size of France.
“Our main goal while we’re there is to get the sediments that are under the pack ice, but the science part of my group is acquiring and recording what we call ‘ephemeral properties,'” she said. declared. “These are things that will start to change as soon as these sediment cores are at Earth’s surface temperatures, pressures and oxygen concentrations.”
Tiny bubbles of air, methane and other gases trapped in the muddy sediment for hundreds of thousands of years will begin to fizz, like the bubbles from a freshly opened soda bottle, as soon as the sediment cores are drilled will be lifted above the ice. .
“We also want to take samples of the microbial communities that live in the sediment and preserve them so we can work on them in labs back home,” Ash said. “These kinds of things absolutely have to happen the moment these nuclei appear.”
Scientists expect Earth’s climate to warm by 2 degrees Celsius over the next few decades. The team’s goal is to recover sediments that will tell the story of how the West Antarctic Ice Sheet behaved when global temperatures were this warm in the past.
Earth has gone through at least 12 ice ages in the last million years. In each, ice sheets grew, covering up to a third of the planet, then melted and retreated in a period of interglacial warming like the one Earth is experiencing today.
At the hottest point of Earth’s last interglacial, about 125,000 years ago, global sea levels were about 20 to 30 feet higher than today. Melting ice from Antarctica may have contributed most of the water for these increases, but scientists aren’t sure that’s the case. And the extent of their uncertainty is a reflection of what is lacking in the scientific record: direct, fossil and sedimentary evidence of what happened in West Antarctica at this time and others like it.
Today, West Antarctica is covered in enough ice to raise ocean levels by more than 14 feet. But much of the land beneath the ice is thousands of feet below sea level. During a number of interglacials the ice retreated from West Antarctica and it was a shallow sea. Sediments deposited on the seafloor during these times likely contain evidence of how sea level responded during interglacial periods when the climate warmed by 2 degrees Celsius.
To retrieve the sediment, the SWAIS 2C team must drill through the ice at sites on the Siple coast of the Ross Sea that were ice-free in the past. They will focus on one site during each of the two Antarctic summers 2022-23 and 2023-24.
Ash, the team’s lead geomicrobiologist, is one of the few early career researchers to hold an international leadership position on the project.
“The sediment cores we get, we can use them to answer different questions,” she said. “We can use them as paleoclimatic archives. But there is also a living community in this archive, and there are microbial ecologists and genomics people who are only interested in the insects that live there today, because it is a strange and extreme environment. It is totally dark. It’s under pressure. It’s in the coldest place in the world. There is so little carbon. Like, what do they even eat? How are they metabolized?
“And we want to know because when we get to the point of going to places like (Jupiter’s moons) Europa and Enceladus, and we’re drilling under the ice there, we’re going to be looking for insects that have strategies to life very similar to anything that lives under the West Antarctic Ice Sheet,” she said.
As a geochemist, Ash said she stands at the intersection of scientific communities to probe the paleoclimatic history and microbiology of the ice sheet.
“I’m not a trained microbiologist,” she said. “But I’ve been on a lot of these types of expeditions. I use a geochemical perspective to observe what these metabolisms do, how they transform carbon. It makes me close enough to where the microbiologists feel safe to let me take their samples.
Ash hopes to spend 4-6 weeks at the drill site each season, collecting and cataloging ephemeral data and preparing core samples to ship to labs back home. She said the paleoclimatic and microbiological spheres sometimes overlap.
“In the genetics of this living microbial community, there are also records,” she said. “If at any point this area was free of ice and I was a happy little phytoplankton that died and was buried, some of my genetic information is still there under all that ice. And using very high-precision metagenomics and transcriptomic techniques, we can kind of unravel that information, obviously the microbes 150 meters below the seafloor are not photosynthesising right now, but if they have the machinery to do so , so at one point it was open water, so that’s a way for the microbiological side to contribute to the paleoclimatic side.
Ash said it was exciting to be able to contribute something that probes fundamental questions, like: What are the qualities of water under the ice sheet? Where is the most vulnerable ice? And what happens when warm ocean water reaches the bedrock beneath the West Antarctic Ice Sheet?
“These are unresolved questions,” Ash said. “By recovering these sediments, we can test various models for West Antarctic ice sheet retreat and hopefully inform vulnerable coastal communities of what may be in store.”
The NSF is providing $680,000 in SWAIS 2C Drilling, Aviation and Field Operations Support and $2.9 million in grants (2035035, 2034719, 2034990, 2034996, 2034999, 2035029, 2034883) to Rice and d other participating US universities, including Binghamton University, Colgate University, Columbia University, Northern Illinois University, University of Nebraska-Lincoln and Central Washington University. The project is also supported by New Zealand, Germany, Australia, the United Kingdom and South Korea.
“Collaborative Research: Sensitivity of the West Antarctic Ice Sheet to 2° Celsius (SWAIS 2C)”, NSF Office of Polar Programs
CAPTION: Jeanine Ash (Photo by Jeff Fitlow/Rice University)
CAPTION: A New Zealand scientific expedition crossing the Ross Ice Shelf in late 2017. (Photo courtesy of www.neilsilverwood.com)
CAPTION: Using a specialized hot water drilling system, scientists from the West Antarctic Ice Sheet Sensitivity to 2C, or SWAIS 2C, project scientists will drill through hundreds of feet of ice in West Antarctica to recover the first direct fossil evidence of what previously happened to the West Antarctic Ice Sheet when average global temperatures reached or exceeded predicted levels over the next two decades. (Image courtesy of GNS Science)
CAPTION: To reach their drill sites, scientists from the West Antarctic Ice Sheet Sensitivity to 2C, or SWAIS 2C, project will start on the coast at New Zealand’s Scott Base and traverse approximately 750 miles of the Ross Ice Shelf in caravans of tracked vehicles. (Image courtesy of GNS Science)
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