It’s no revelation that sea levels are rising. The melting of ice sheets and the expansion of ocean water are two consequences from human-caused climate changes. What’s happening inside Earth will also shape future shorelines. Jacky Austermann tries to understand these inner dynamics.
A geophysicist at Columbia University’s Lamont-Doherty Earth Observatory, Austermann didn’t always know she would end up studying climate. Her fascination with math from a young age coupled with her love of nature and the outdoors — she grew up hiking in the Alps — led her to study physics as an undergraduate, and later geophysics.
As Austermann dug deeper into Earth’s geosystems, she learned just how much the movement of hot rock in the mantle influences life on the surface. “I got really interested in this entire interplay of the solid earth and the oceans and the climate,” she says.
Big goal
Much of Austermann’s work focuses on how that interplay influences changes in sea level. Since 1880 the average global sea level has risen by more than 20 centimeters per year. The annual rise is also increasing. However, local sea levels can fluctuate, with different shorelines experiencing changes in their level. Austermann states that the solid earth also plays a part.
“We think about sea level change generally as ‘ice is melting, so sea level is rising.’ But there’s a lot more nuance to it,” she says. “A lot of sea level change is driven by land motion.”
Understanding this nuance could allow for more accurate climate models to predict sea level rise in future. This research should inform practical solutions for coastal communities at high risk.
Austermann has been developing computer models that can reconstruct sea level fluctuations over the last few millions of years. Her models incorporate data on how the creeping churning of the mantle and other geologic phenomena have altered land and sea elevation, particularly during interglacial periods when Earth’s temperatures were a few degrees higher than they are today.
Standout research
Previous studies had suggested that this churning, known as mantle convection, sculpted Earth’s surface millions of years ago. “It pushes the surface up where hot material wells up,” Austermann says. “And it also drags [the surface] down where cold material sinks back into the mantle.”
Austermann, along with his colleagues, were the first ones to show that topographic changes caused by mantle intrusions in 2015 Antarctic ice melted because of this.Over the past 3 million years. Near the ice sheet’s edges, ice retreated more quickly in areas where the land surface was lower due to convection.
What’s more, mantle convection is affecting land surfaces even on relatively short time scales. Mantle convection has been a major factor in the interglacial period from around 130,000 to 115,000years ago. An ancient coastline that has been damagedHer team reported that she was able to increase the distance by several meters. Science AdvancesIn 2017.
The It is possible for the solid earth to be deformed by melting or growing of ice sheet., Austermann says. The weight of the accumulating ice causes land to sink, causing sea levels to rise. Water also falls as the land lifts up where the ice melts. This, along with the tugging effect of the ice sheets on the water surrounding it, is changing local sea levels all around the globe. It’s very relevant to coastal areas who are planning their defenses in this climate crisis.
These geologic processes are important in improving models of sea level rise. Austermann’s team is gathering more data from the field, scouring the coasts of Caribbean islands for clues to what areas were once near or below sea level. These clues include fossilized corals, water ripples in stone and tiny chutes in rock that indicate that air bubbles once rose through the sand at ancient beaches. The work is “really fun,” Austermann says. “It’s essentially like a scavenger hunt.”
Douglas Wiens from Washington University in St. Louis, a seismologist, stated that her efforts placed the solid earth at a forefront of research into sea level rises. Before, “a lot of those factors were kind of ignored.” What’s most remarkable is her ability “to span what we normally consider to be several different disciplines and bring them together to solve the sea level problem,” he says.
Building community
Austermann believes that the best part of her job, and her students and postdocs, is her interaction with them. Austermann wants to foster a healthy, happy and motivated research group. “It’s really rewarding to see them grow academically, scientifically, come up with their own ideas … and also help each other out.”
Roger Creel, a Ph.D. student in Austermann’s group and the first to join her lab, treasures Austermann’s mentorship. He said that Austermann sets realistic and transparent expectations and provides prompt and thoughtful feedback. They also meet for regular check ins. “Sometimes I think of it like water-skiing, and Jacky’s the boat.”
Oana Dumitru, a postdoctoral researcher in the group, appreciated the gentle push she received to write and submit a grant application on her own. “I thought I was not ready for it, but she was like, you’ve got to try,” Dumitru says.
Austermann prioritizes her group’s well-being, which fosters collaboration, Creel and Dumitru say. That sense of inclusion, support and community “is the groundwork for having an environment where great ideas can blossom,” Austermann says.
You would like to nominate someone on the next SN 10 List? Please send your name, affiliation, and a few sentences about yourself and your work to sn10@sciencenews.org.
