1. Large Ensemble Exploration of Global Energy Transitions Under National Emissions Pledges.
- Author
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Wessel, Jacob, Iyer, Gokul, Wild, Thomas, Ou, Yang, McJeon, Haewon, and Lamontagne, Jonathan
- Abstract
Global climate goals require a transition to a deeply decarbonized energy system. Meeting the objectives of the Paris Agreement through countries' nationally determined contributions and long‐term strategies represents a complex problem with consequences across multiple systems shrouded by deep uncertainty. Robust, large‐ensemble methods and analyses mapping a wide range of possible future states of the world are needed to help policymakers design effective strategies to meet emissions reduction goals. This study contributes a scenario discovery analysis applied to a large ensemble of 5,760 model realizations generated using the Global Change Analysis Model. Eleven energy‐related uncertainties are systematically varied, representing national mitigation pledges, institutional factors, and techno‐economic parameters, among others. The resulting ensemble maps how uncertainties impact common energy system metrics used to characterize national and global pathways toward deep decarbonization. Results show globally consistent but regionally variable energy transitions as measured by multiple metrics, including electricity costs and stranded assets. Larger economies and developing regions experience more severe economic outcomes across a broad sampling of uncertainty. The scale of CO2 removal globally determines how much the energy system can continue to emit, but the relative role of different CO2 removal options in meeting decarbonization goals varies across regions. Previous studies characterizing uncertainty have typically focused on a few scenarios, and other large‐ensemble work has not (to our knowledge) combined this framework with national emissions pledges or institutional factors. Our results underscore the value of large‐ensemble scenario discovery for decision support as countries begin to design strategies to meet their goals. Plain Language Summary: Most countries have pledged to significantly reduce greenhouse gas emissions over the next few decades. These emissions primarily come from burning fossil fuels for electricity, heat, energy for industrial processes, and transportation fuel. Converting to cleaner forms of energy requires transforming the energy system. However, decision makers must consider the countless, unpredictable ways the future could unfold. Modelers address this "deep uncertainty" by running computer simulations many times and computing how impactful various inputs are on the outcome. We explore different ways countries may meet emissions reduction goals and how impacts vary regionally, considering 11 sources of uncertainty with 5,760 simulations. We find larger economies and developing regions experience the most severe economic outcomes consistently across our wide range of inputs. Further, removing carbon dioxide from the air through engineered and natural solutions allows some flexibility to continue emitting during the transition, but the role of different options varies regionally, and is subject to future costs and the way emissions are priced. Previous work has typically focused on representative scenarios, rather than a "large ensemble," and has not combined this framework with modeling national emissions pledges. These findings are helpful for decisionmakers as countries design strategies to meet their goals. Key Points: Energy transition costs can, by multiple metrics, unevenly impact larger economies, and developing regions under a wide range of futuresRegional investment risk has global implications for mitigation pathways, robust to broad uncertainties and with strong relative impactsThe relative role of different carbon dioxide removal options in meeting decarbonization goals varies across regions and scenario pathways [ABSTRACT FROM AUTHOR]
- Published
- 2024
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