Navigating within the planetary limits
A prospective life cycle environmental sustainability assessment in support of the energy transition in Swedish aviation
Time: Fri 2025-09-26 09.00
Location: Gradängsalen, Room 5703, Teknikringen 1, Campus, public video conference
Video link: https://kth-se.zoom.us/j/61851386411
Language: English
Subject area: Planning and Decision Analysis, Strategies for sustainable development
Doctoral student: Yat Yin Lai , Hållbar utveckling, miljövetenskap och teknik
Opponent: Professor Andreas Schäfer, University College London, England, UK
Supervisor: Professor Anna Björklund, Hållbarhet, utvärdering och styrning; Associate Professor Emrah Karakaya, Hållbarhet, Industriell dynamik & entreprenörskap
QC 20250819
Abstract
On December 17, 1903, the Wright brothers made the first controlled and sustained flight in human history, marking the beginning of aviation development. Aviation has since revolutionized mobility, strengthened international networks, facilitated cross-border trade, fostered cultural exchanges, and in the process, reshaped global society and economy. Despite its social and economic benefits, aviation is notoriously known for its impacts on the environment, particularly climate change. In 2023, direct emissions from aviation accounted for approximately 2% of global greenhouse gas emissions, and without intervention, they are projected to increase by two to fivefold compared to 2023 levels by mid-century.
To advance our knowledge of aviation sustainability and inform energy transition pathways, this thesis assesses the environmental sustainability of future air travel powered by alternative fuels and novel propulsion systems, using Sweden as a representative case. Due to its multi-dimensionality, aviation is conceptualized from a socio-technical system perspective, where the interplay between political, economic, social, technological, and ecological issues is considered. Using prospective life cycle assessment and absolute environmental sustainability assessment, the potential environmental performance of future air travel in Sweden is evaluated both in relative terms and from an absolute perspective. These different approaches seek to determine whether air travel supported by alternative fuels and novel propulsion technologies can offer environmental advantages over fossil kerosene, and if so, whether they can operate within the planetary limits.
The results suggest that while alternative fuels and novel propulsion systems can support air travel with a lower climate change impact than that of fossil kerosene, these travel alternatives may have a relatively higher potential to degrade the overall environment, demonstrating significant burden-shifting between environmental problems, across sectors, geographies, and time scales. When assessing future air travel in an absolute sense, the results indicate that the potential environmental impacts associated with Sweden’s projected air travel in 2050, even with advanced technologies, could overshoot the climate change and biodiversity loss thresholds by several orders of magnitude.
Although this research is subject to uncertainties associated with data limitations, methodological choices, and future projections, its indicative insights help identify opportunities for bringing Swedish air travel to environmentally sustainable levels while ensuring aviation continues to fulfill its societal role. Policymakers and stakeholders are recommended to adopt a systemic approach to guiding the aviation energy transition. This includes setting integrated environmental targets based on planetary limits and aligning them across aviation and interconnected industries. Given that the life cycle environmental performance of air travel is increasingly linked to the development of interconnected industries, a broader transition across multiple sectors may be necessary. Achieving this would require coordinated governance to prevent burden-shifting, as well as cross-sector collaboration to strengthen knowledge building, skills development, and financial investment in critical shared infrastructure. Finally, alongside technological advancements, effective demand-side management represents a complementary strategy that can potentially support a sustainable energy transition in aviation.