The study, published in the scientific journal Earth's Future, provides a 90 percent probability range for sea-level rise under a high-emissions scenario, complementing the Intergovernmental Panel on Climate Change (IPCC) reports that primarily offer projections with a 66 percent probability. This enhanced approach addresses uncertainties and extends risk management tools for policymakers.
Existing sea-level rise projections depend on various methods to simulate climate processes. These include well-understood mechanisms like glacier melting and less predictable phenomena such as abrupt ice shelf collapses. The resulting variability in these models has limited the IPCC's ability to provide very likely ranges for future sea levels.
To tackle this challenge, NTU researchers developed a new "fusion" projection method. This innovative approach integrates established models with expert assessments, delivering a clearer picture of potential sea-level rise.
Dr. Benjamin Grandey, lead author and Senior Research Fellow at NTU's School of Physical and Mathematical Sciences (SPMS), explained, "Our new approach tackles a key issue in sea-level science: different methods of projecting sea-level rise often produce widely varying results. By combining these different approaches into a single fusion projection, we can estimate the uncertainty associated with future sea-level rise and quantify the very likely range of sea-level rise."
This approach incorporated projections with both medium and low confidence, supplemented by expert input to address uncertain processes like rapid ice sheet changes. By applying a weighting system, the model prioritized reliable medium-confidence data while accounting for less certain projections to address extreme scenarios.
The results highlight significant differences compared to IPCC assessments:
- Low-emissions scenario: NTU's model projects a very likely range of 0.3 to 1.0 meters, compared to the IPCC's likely range of 0.3 to 0.6 meters.
- High-emissions scenario: The NTU model forecasts a very likely range of 0.5 to 1.9 meters, surpassing the IPCC's likely range of 0.6 to 1.0 meters.
These broader ranges suggest that earlier estimates may have underestimated the potential for extreme outcomes, particularly under high-emissions pathways.
Dr. Grandey emphasized the implications of the findings: "Our new very likely projections highlight just how large the uncertainties are when it comes to sea-level rise. The high-end projection of 1.9 meters underscores the need for decision-makers to plan for critical infrastructure accordingly. More importantly, these results emphasize the importance of climate mitigation through reducing greenhouse gas emissions."
The study's interdisciplinary approach has broad applications. Co-author Professor Chew Lock Yue from NTU's SPMS explained, "By appropriately combining the best available knowledge of sea-level information at different confidence levels into a single fused probability distribution, we have developed a novel way to project the full uncertainty range of future sea-level rise."
Associate Professor Justin Dauwels from TU Delft's Department of Microelectronics added, "Our new method for projecting the full uncertainty range of future sea-level rise can also be applied for other climate projections and beyond, including coastal flooding risk assessments, infrastructure vulnerability analysis, and economic impact forecasts."
Research Report:Fusion of Probabilistic Projections of Sea-Level Rise
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