A newly published study spearheaded by Dartmouth scientists has provided a pivotal and alarming look into the future of the Antarctic Ice Sheet. Offering the first multi-century, multi-model projections of ice sheet evolution, the research draws from an ensemble of 16 models and demonstrates the escalating risk of sea-level rise.
The findings serve as a wake-up call: while current emissions are causing a gradual ice loss in the 21st century, the real threat lies in the rapid acceleration of ice melt after 2100, with significant implications for global sea levels and coastal communities.
The Dartmouth-led study, published in Earth’s Future, modeled various emission scenarios and tracked the resulting changes in Antarctica’s ice sheet across 300 years. Projections under high-emission scenarios predict up to 4.4 meters of sea level rise by 2300, a dramatic increase compared to the 0.28 meters expected by 2100. The study highlights several critical areas, notably the Bungenstock Ice Rise (upstream of the Ronne Ice Shelf), the Siple Coast (upstream of the Ross Ice Shelf), and the Amundsen Sea sector, where the models predict the most substantial ice loss.
One of the most notable aspects of the research is the variability in model outcomes for the Amundsen Sea sector. Some models simulate a near-total collapse by 2300, while others suggest a more moderate retreat. The discrepancy underscores the complexity of ice sheet behavior and the importance of bedrock topography, a key factor driving the speed and extent of ice retreat.
A significant takeaway from the study is the growing divergence between low- and high-emission scenarios after 2100. While the 21st century sees relatively similar outcomes under both scenarios, the period after 2100 could see the difference magnify sharply. Hélène Seroussi, the study's lead author and associate professor at Dartmouth’s Thayer School of Engineering, notes:
"Our study shows that beyond 2100, the long-term impacts for regions vulnerable to sea-level rise become amplified, emphasizing the critical importance of reducing carbon emissions immediately."
This finding is echoed by other studies as well. A 2020 report by the National Snow and Ice Data Center highlights that sea-level rise from ice sheets, particularly in Antarctica, could contribute up to 2.5 meters of rise by 2100 in the worst-case scenarios, compared to much lower contributions under emissions-reduction pathways.
The Dartmouth study also draws attention to the increasing role of ice shelf collapse in amplifying ice loss post-2100. While ice shelf disintegration is limited through the 21st century, it becomes a significant driver of rapid mass loss beyond 2100, mainly under high-emission scenarios. Ice shelves act as buttresses, slowing the movement of glaciers into the sea. Once they collapse, the underlying glaciers lose their support, accelerating the retreat and dramatically increasing sea-level rise.
Studies by the British Antarctic Survey have shown that warming ocean waters are already thinning critical ice shelves like Pine Island and Thwaites Glacier. These glaciers are often referred to as the "doomsday glaciers" due to their potential to trigger runaway ice loss. According to research published in Science Advances, Thwaites alone could eventually contribute up to 3 meters of sea-level rise if they fully collapse.
The Dartmouth study underscores a key challenge facing scientists: while models provide essential insights, there is considerable uncertainty when projecting long-term ice loss. The Amundsen Sea sector exemplifies this, with simulations ranging from gradual retreat to near-total collapse. As Seroussi notes:
"The exact timing of significant collapses remains unknown, but once the process starts, it’s difficult—if not impossible—to slow down."
This has led to increased collaboration among the global climate science community, allowing researchers to refine their models. By comparing outputs from multiple models, scientists can better pinpoint areas where improvement is needed. A recent initiative, led by the Intergovernmental Panel on Climate Change (IPCC), emphasizes the need for more interactive ice sheet coupling in global climate models, which would improve projections and help reduce uncertainty, especially for regions like West Antarctica.
The message is clear—future generations are at risk unless meaningful action is taken. Mathieu Morlighem, a coauthor of the Dartmouth study, emphasizes:
"The divergence in outcomes between high- and low-emission scenarios grows rapidly after 2100. These results highlight the critical need to cut carbon emissions now to protect future generations."
Policymakers worldwide are increasingly recognizing the need for long-term planning beyond 2100. While much of the conversation around sea-level rise has focused on this century, studies like this shift the lens to the more profound threats awaiting after 2100. While setting 2100 as a critical target for carbon neutrality, the Paris Agreement may need to extend its timelines further, given the long-term projections of ice loss and the consequent rise in global sea levels.
The multi-century projections from the Dartmouth study highlight a stark reality—Antarctica’s ice sheet is seriously threatened by rising emissions, with consequences that will extend for centuries. The research emphasizes the urgency of immediate global action to curb carbon emissions but also calls for continued collaboration and refinement of models to better understand the future of one of Earth’s most critical climate regulators.
As the world focuses on solutions to the climate crisis, this study adds a crucial layer to the conversation: the long-term stability of Antarctica’s ice sheet and the far-reaching impacts of sea-level rise that could reshape coastlines and communities across the globe.
