Stanford Scientists Discover Crucial Missing Component of Sea-Level Rise

Computational modeling is frequently used by scientists to analyze the effects that melting Antarctic ice will have on the planet's waters. Their most recent efforts have concentrated on the geometry, fracturing, and surface melting of ice sheets—processes that may cause or hasten the mass loss of ice sheets. The thawing of the bed, also known as basal thaw, at the interface of the land and the miles-thick ice sheet above it has now been noted by researchers as another process that could have a similarly major impact on the future of the ice sheet.

The new analysis reveals regions that, if they thawed, might rival some of the biggest drivers to sea-level rise, such Thwaites Glacier, despite not currently losing a lot of mass. The size of Antarctica, which is 14,200,000 km2 (5,500,000 sq mi), is about 45% greater than that of the United States. The vulnerable areas cover a larger area than California. The study will be released in the journal Nature Communications today, September 14, 2022.

According to senior research author Dustin Schroeder, "you can't necessarily assume that everywhere that's currently frozen will stay frozen." He teaches geophysics as an associate professor at Stanford Doerr School of Sustainability. These areas can be overlooked as potential contributions.

The simulations were based on recent theoretical work showing that basal thaw might occur over brief timescales. The co-authors of the study explored theories regarding whether the start of such thawing could result in major ice loss within a century using numerical ice sheet models. They found that thawing caused mass loss in parts of the ice sheet that are not typically linked to instability and contributions to sea level at that time scale.

According to lead study author Eliza Dawson, a PhD student in geophysics, "there actually has been little to no continental-wide work that looks at the onset of thawing - that transition from frozen ice to ice near the melting point, when a tiny bit of water at the bed can cause the ice to slide." We were curious to find out how much of an impact melting would have and which parts of the ice sheet might be most vulnerable.

The adjustments in friction brought about by the ice sheet moving over the ground underneath it were utilized by the scientists to estimate temperature changes at Antarctica's base. The simulations showed that the Enderby-Kemp and George V Land regions in East Antarctica, which is now thought to be more stable than West Antarctica, would be more vulnerable to thawing at their beds. They also emphasized the Wilkes Basin in George V Land as having the potential to contribute significantly to sea level rise in the event of thawing; this feature is comparable in size to the fast changing and most likely unstable Thwaites Glacier in West Antarctica.

Schroeder, who is also an associate professor of electrical engineering, stated that Thwaites is the subject of intense attention from the entire community at the moment. However, some of the locations that are typically associated with significant, lasting alterations aren't the most provocative and significant ones in this study.

Information on the ice sheet is scarce because of the ice sheet's position in Antarctica and the region's harsh climate. Even less is known about the country hidden below its ice-covered exterior.                                                                        

We have the technology to measure the bed in these far-off locations, but finding the right position often requires years of planning, field camps, and specialized equipment, according to Schroeder. It's challenging and pricey.

The physics of how ice slides, or how variations in temperature affect how the ice sheet moves and evolves, was used by the scientists to fill in knowledge gaps. The authors intend to create and use radar-based analysis techniques in subsequent work to investigate the temperature of the ice sheet bed in these crucial regions.

The transformational contribution of Eliza's study, according to Schroeder, is that "you need to identify the locations where it matters." It poses the following general queries: Does this matter? If it matters, where, exactly? With this strategy, we intend to help the community prioritize where to search and why, helping them to avoid taking the wrong path.

In the potentially vulnerable places revealed in this study, scientists do not yet know what factors are most likely to cause thawing at the bed, nor do they know when they might be able to. Changing ocean conditions, which are seen everywhere in Antarctica, could be one potential reason.

Despite being close by, Schroeder noted that warm ocean water "may not necessarily reach certain East Antarctica regions as it does in sections of West Antarctica." "Near-term thawing of the ice-sheet bed seems like a considerably easier switch to flick than we'd expected," says recent theoretical work indicating that thermal processes at the bed can be easily activated, even spontaneously.

As a result of processes that have the potential to change the behavior of enormous ice sheets like Greenland and Antarctica, the study shows how crucial it is to measure, comprehend, and model the temperature at the base of ice sheets in order to understand our future. This is because the biggest source of uncertainty in projections for sea-level rise is this factor.

To examine these places more closely, Dawson stated that "follow-on investigation will be needed." The community has to comprehend and start paying attention to the process of mass loss from the ice sheet as a result of bed melting, particularly in these potentially susceptible places.

Schroeder is a center fellow at the Stanford Woods Institute for the Environment and a faculty affiliate of the Institute for Human-Centered Artificial Intelligence (HAI). The University of Tasmania, Georgia Institute of Technology, and Dartmouth College all contributed to the work as co-authors.

By STANFORD UNIVERSITY