Glaciologists have discovered that warm ocean water is penetrating several kilometers beneath the solid ice of Thwaites Glacier in West Antarctica. These discoveries indicate that current climate models might not accurately predict how ocean and ice interactions will affect future sea level rises.
A research team led by the University of California, Irvine utilized advanced satellite radar data to uncover evidence of warm, high-pressure seawater moving deep underneath the grounded ice of Thwaites Glacier in West Antarctica.
In a study released today in Proceedings of the National Academy of Sciences, the researchers explained that extensive contact between ocean water and the glacier – a phenomenon seen across Antarctica and Greenland – triggers “intense melting” and may necessitate a reevaluation of predictions concerning global sea level increases.
The glaciologists utilized information collected from March to June 2023 by Finland’s ICEYE satellite mission. The ICEYE satellites operate in a “constellation” formation in polar orbit, employing InSAR – interferometric synthetic aperture radar – to continuously observe changes on the Earth’s surface. Multiple passes of the spacecraft over a specific region provide comprehensive data. In this study, it illustrated the rising, falling, and bending of Thwaites Glacier.
“The ICEYE data offered a continuous series of daily observations that align closely with tidal cycles,” stated lead author Eric Rignot, a professor of Earth system science at UC Irvine. “In the past, we had sporadic data, which made it difficult to see the overall picture. Now, with ongoing time series data that we can compare to tidal cycles, we’re witnessing how seawater enters at high tide, recedes, and sometimes even moves further underneath the glacier, becoming trapped. Thanks to ICEYE, we are able to observe this tidal dynamic for the first time.”
Michael Wollersheim, the ICEYE Director of Analytics and co-author of the study, emphasized, “Previously, some of the most active natural processes could not be observed with adequate detail or frequency. Using satellite radar images to monitor these processes with precision daily represents a major advance in research.”
Rignot noted that this project enabled his team to better comprehend how seawater behaves beneath Thwaites Glacier. He explained that seawater entering the glacier’s base, coinciding with the freshwater from geothermal activity and friction, accumulates and must flow out. Water flows through natural channels or gathers in cavities, increasing pressure and raising the ice sheet.
“In certain areas, the water pressure almost equals that of the ice above. A slight additional pressure can elevate the ice,” Rignot explained. “This pressure is sufficient to lift a column of ice more than half a mile high.”
This isn’t just any seawater; Rignot and his colleagues have documented how climate change affects ocean currents that carry warmer seawater to the Antarctic coastline and other polar regions. Circumpolar deep water is salty and has a lower freezing point, which means while freshwater freezes at 0 degrees Celsius, saltwater freezes at around -2 degrees, a small difference that significantly contributes to the “intense melting” of basal ice observed in this study.
Co-author Christine Dow, a professor at the University of Waterloo in Ontario, Canada, commented, “Thwaites is the most unstable area in Antarctica and contains enough ice to contribute 60 centimeters to sea level rise. We are concerned that we may be underestimating the glacier’s rate of change, which could have disastrous effects on coastal communities worldwide.”
Rignot expressed hope that the findings from this project would encourage further investigation into the conditions beneath Antarctic glaciers, including projects involving autonomous robots and more satellite surveillance.
“The scientific community is very eager to explore these remote polar areas for data collection and to enhance our understanding of the situation, yet funding is not keeping pace,” he remarked. “We are working with the same budget in 2024, after adjusting for inflation, as we had in the 1990s. We need to expand the network of glaciologists and physical oceanographers to tackle these observation challenges sooner rather than later; right now, it feels like we are trying to climb Everest in tennis shoes.”
In the near future, Rignot – who is also a senior project scientist at NASA’s Jet Propulsion Laboratory – opined that this study will provide enduring advantages to the ice sheet modeling community.
“Integrating these ocean-ice interaction insights into ice sheet models should allow us to replicate the developments of the past 25 years more accurately and, in turn, bolster our confidence in predictions,” he stated. “If we can incorporate the processes described in our paper, which are typically absent from most current models, the reconstructions should align better with observations. Achieving that would be a significant success.”
Dow emphasized, “Right now, we lack sufficient data to determine how much time remains before the seawater intrusion becomes irreversible. By refining models and concentrating our research on these crucial glaciers, we aim to clarify timelines for decades rather than centuries. This work will assist communities in adapting to rising sea levels while also highlighting the importance of reducing carbon emissions to avert dire consequences.”
Rignot, Dow, and Wollersheim collaborated with Enrico Ciraci, a UC Irvine assistant specialist in Earth system science and NASA postdoctoral fellow; Bernd Scheuchl, a researcher from UC Irvine; and Valentyn Tolpekin from ICEYE. The research was funded by NASA and the National Science Foundation.
