image: Binghamton researchers are studying how ancient moisture patterns fueled Antarctic ice growth to better predict future sea level change.
Credit: Christopher Michel, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons
Warming of the ocean and air surrounding Antarctica is causing glacial ice mass loss and global sea level rise. To better predict future changes in sea level, an understanding of how Antarctic ice sheets will respond to warmer conditions is required. In a warmer world, enhanced moisture transport to the icy continent has the potential to increase snowfall over Antarctica, which compacts over time to create ice. Ice sheet growth from moisture transport and snow may offset some ice mass loss from marine-based sectors of Antarctic ice sheets.
Investigating how increased moisture transport to Antarctica, and under what temperatures and sea ice conditions moisture transport occurs, is required to understand the mechanisms that can lead to increased ice accumulation. This question is one that Binghamton researchers will address in the coming years.
Assistant Professor Adriane R. Lam and Postdoctoral Researcher Imogen M. Browne, both part of the Earth Sciences Department at Binghamton University, State University of New York have received funding from the National Science Foundation’s P4Climate (Paleo Perspectives on Present and Projected Climate) award, in part awarded under the Office of Polar Programs (OPP). This year alone, OPP’s budget was slashed by 88%, leading to the loss of several Antarctic field expeditions and grants; as of earlier this year, the P4Climate award has been archived.
“We are quite lucky to have been one of the last grants awarded under the P4Climate program,” said Lam.
Lam and Browne, along with their colleagues Assistant Professor Ruthie Halberstadt at the University of Texas at Austin and Research Assistant Professor Paul Acosta at George Mason University (all four are early-career researchers), will investigate moisture-driven mechanisms of ice sheet growth during the Miocene Climatic Optimum (17 to 14.7 million years ago). During the Miocene Climatic Optimum, atmospheric carbon dioxide levels reached at least 500 parts per million, global average temperatures warmed by 7–8°C above pre-industrial temperatures, and Antarctic ice sheets were smaller than modern. Warming was associated with volcanism, which spewed carbon dioxide and other greenhouse gases into the atmosphere. The Miocene Climate Optimum is considered an analog for future warming scenarios and is studied by geoscientists to understand how abiotic and biotic Earth systems will operate in warmer-than-present climates.
“Studying the Miocene is really interesting because Earth’s climate, hydrological cycle, and ocean circulation were different back then,” said Browne. “The Miocene climate records that we generate using marine sediment cores give us critical insight into how Earth’s climate system will respond to warmer and wetter conditions.”
The funding Lam, Browne and their colleagues obtained will allow them to use climate and ice sheet models, compared with numerical reconstructions of ice sheet volume, to test various hypotheses for moisture-driven ice sheet growth. Each model simulation tracks the geochemical composition of ice, generating a modeled chemical signal that can be compared directly against deep-sea geochemical records that tell researchers about ice volume.
To evaluate the feasibility of model simulations with different inputs for vegetation, ocean temperature, sea ice, and orbital parameters, the team will generate a new record of Antarctic ice sheet volume using the geochemistry of calcareous microfossils, called foraminifera, obtained from deep-sea marine sediment cores located in the path of very cold deep-ocean waters that are produced around Antarctica.
Data-model comparisons will evaluate how well each modeled mechanism can explain the observed ice volume and chemical changes across a major glaciation that occurred around 16 million years ago, right after the Miocene Climate Optimum. Specifically, investigators will explore the impacts of local mechanisms such as ice-proximal ocean warmth and sea ice cover as well as global mechanisms such as atmospheric carbon dioxide levels. Another factor that will be incorporated into the models are orbital forcings – the shape the Earth makes as it orbits around the sun (which changes every 100 and 400 thousand years), the degree of Earth’s tilt (which changes every ~41 thousand years), and the ‘wobble’ of Earth about its axis (which changes every ~19 thousand years) – as all of these orbital factors influence the amount of solar radiation hitting different parts of the Earth during the year and through geologic time. As such, orbital forcings have the power to greatly influence heat and moisture transport to Antarctica.
This is not Browne’s first time conducting research on or related to Antarctica. In 2018, she was a scientific participant on International Ocean Discovery Program Expedition 374, which drilled sediment cores from the Ross Sea region, a location where very cold, very deep-water masses are formed.
“Getting to sail with an international and interdisciplinary team of researchers and experiencing first-hand how sediment cores can be used to answer fundamental questions about Earth’s climate and ice sheet history was a formative experience in my career,” said Browne.
It was during this expedition, when Browne was a Ph.D. student, that she met and worked alongside Binghamton University Earth Sciences Associate Professor Molly Patterson. Browne began her postdoctoral work with Patterson at Binghamton in 2024, where she also began working alongside Lam. The NSF award to Lam, Browne and colleagues will allow Browne to continue her research as a postdoctoral researcher in the Earth Sciences Department.
“A grant like ours is special and important not just because of the science it will produce, but because it brings a group of researchers who have different skillsets together to work on a problem that has huge implications for society,” said Lam.
Ice volume data and model outputs will contribute to the international community synthesis effort and project results will provide critical context for understanding long-term trajectories in sea level.