Sea levels are on track to rise significantly by the end of the century, with a projected increase of 0.5 to 1.9 meters under a high-emissions scenario.
This startling estimate, from a study led by Nanyang Technological University (NTU) in Singapore, surpasses United Nations Intergovernmental Panel on Climate Change (IPCC) projections by up to 90 centimeters.
Published in Earth’s Future, the study introduced a cutting-edge “fusion approach” that combines multiple models with expert assessments.
This method bridges a critical gap in sea-level science, providing a “very likely range” of outcomes with a 90% probability, compared to the IPCC’s 66% probability for its “likely range.”
New lens on projections
“By combining these different approaches into a single fusion projection, we were able to estimate the uncertainty associated with future sea-level rise and quantify the very likely range of sea-level rise,” explained Dr. Benjamin Grandey, Senior Research Fellow at NTU’s School of Physical and Mathematical Sciences (SPMS) and lead author of the study.
The innovative method integrates data from the IPCC’s Sixth Assessment Report, accounting for both medium- and low-confidence projections.
It also considers less understood but potentially catastrophic processes, such as abrupt ice sheet collapses, to provide a more comprehensive picture.
Higher stakes for high emissions
Under a high-emissions pathway, the NTU model projected that global sea levels could surge by as much as 1.9 metres by 2100.
This far exceeds the IPCC’s top-end projection of 1.0 metres, raising the alarm over previously underestimated risks.
“Our new very likely projections highlighted just how large the uncertainties were when it came to sea-level rise,” said Dr. Grandey.
“The high-end projection of 1.9 metres underscored the need for decision-makers to plan for critical infrastructure accordingly. More importantly, these results emphasised the importance of climate mitigation through reducing greenhouse gas emissions,” he added.
Implications for coastal communities
The projections paint a dire picture for coastal areas. Rising seas threaten to inundate communities, disrupt infrastructure, and wreak havoc on ecosystems.
Co-author Professor Benjamin Horton, Director of the Earth Observatory of Singapore at NTU, described the findings as a “significant breakthrough in sea-level science.”
“By estimating the probability of the most extreme outcomes, it underscored the severe impacts of sea-level rise on coastal communities, infrastructure, and ecosystems, emphasising the urgent need to address the climate crisis,” Horton stated.
Tool for action
The NTU team stressed that their work provides actionable insights for urban planners and policymakers.
“By appropriately combining the best available knowledge of sea-level information at different confidence levels into a single fused probability distribution, we developed a novel way to project the full uncertainty range of future sea-level rise,” said Professor Chew Lock Yue from NTU’s School of SPMS.
The implications extend beyond sea-level projections. Associate Professor Justin Dauwels of TU Delft added, “Our new method for projecting the full uncertainty range of future sea-level rise could also be applied for other climate projections and beyond, including coastal flooding risk assessments, infrastructure vulnerability analysis, and economic impact forecasts.”
The study underscored the urgency of mitigating greenhouse gas emissions while preparing for worst-case scenarios.
Supported by Singapore’s National Research Foundation and the National Environment Agency, the research highlights the necessity for robust global policies to counteract climate threats.
