New research led by Dartmouth offers a beacon of hope amidst climate concerns, showing that the worst-case scenarios of Antarctic ice sheet collapse and consequent sea-level rise are highly unlikely. The study emphasizes accurate physics for coastal planning while urging ongoing climate action.
In a climate landscape often dominated by alarming news, a Dartmouth-led study brings a glimmer of hope by disputing one of the most catastrophic predictions about sea-level rise. The study, published in Science Advances, contends that the dire forecasts of sea levels rising dramatically due to Antarctica’s ice sheets collapsing are highly improbable in the near term. This reassurance comes even as polar ice loss remains a critical concern.
The groundbreaking study scrutinizes a prediction from the United Nations’ Intergovernmental Panel on Climate Change (IPCC), which suggested that the collapse of Antarctic ice sheets could propel global sea levels to rise by up to 50 feet by 2100. This projection, which was deemed a “low likelihood” scenario, prompted alarm due to its drastic implications, such as the submergence of large parts of Florida.
However, the Dartmouth-led research team, utilizing high-resolution models, focused on the Thwaites Glacier — dubbed the “Doomsday Glacier” for its rapid melting and potential sea-level impact. Their simulations reveal that the Marine Ice Cliff Instability (MICI) mechanism — underpinning the extreme IPCC forecast — does not accurately represent the physics of ice sheet dynamics.
Instead, even the vulnerable Thwaites Glacier is unlikely to experience the swift collapse suggested by MICI within this century.
“These projections are actually changing people’s lives. Policymakers and planners rely on these models and they’re frequently looking at the high-end risk. They don’t want to design solutions and then the threat turns out to be even worse than they thought,” Mathieu Morlighem, a professor of earth sciences at Dartmouth and the study’s corresponding author, said in a news release.
He emphasized the importance of reliable models for coastal planning and policy-making.
The research team, which includes experts from Dartmouth, the University of Michigan and several UK institutions, performed extensive simulations that accounted for the complexities of ice sheet behavior.
They found that the contested cliff collapse scenario is not as imminent or straightforward as previously feared.
“Everyone agrees that cliff failure is real — a cliff will collapse if it’s too tall. The question is how fast that will happen,” added Morlighem.
By using more refined models, the team demonstrated that ice cliff instability would not occur on the rapid timescales posited by earlier simulations. This considerably moderates the anticipated sea-level rise for the 21st century, providing a more nuanced outlook.
While this analysis provides some relief, it does not negate the ongoing threat of ice sheet retreat and resulting sea-level rise.
“We’re not reporting that the Antarctic is safe and that sea-level rise isn’t going to continue — all of our projections show a rapid retreat of the ice sheet,” Morlighem added.
Rather, the findings underscore the need for accurate projections based on sound physical principles.
In particular, the study raises doubts about the MICI process while reaffirming other instabilities like Marine Ice Sheet Instability (MISI) that contribute to polar ice loss.
“We’re not calling into question the standard, well-established projections that the IPCC’s report is primarily based on,” Hélène Seroussi, co-author and associate professor at Dartmouth’s Thayer School of Engineering, said in the news release. “We’re only calling into question this high-impact, low-likelihood projection that includes this new MICI process that is poorly understood. Other known instabilities in the polar ice sheets are still going to play a role in their loss in the coming decades and centuries.”
Dan Goldberg, a glaciologist at the University of Edinburgh and study co-author, added, “While we did not observe MICI in the 21st century, this was in part because of processes that can lead to the MISI. In any case, Thwaites is likely to retreat unstably in the coming centuries, which underscores the need to better understand how the glacier will respond to ocean warming and ice-shelf collapse through ongoing modeling and observation.”
As the world continues to grapple with the impacts of climate change, this study provides a more hopeful yet cautious perspective on future sea-level rise, reinforcing the critical role of accurate scientific modeling in addressing environmental challenges.