An integrated analysis of climate change mitigation strategies for the maritime sector

Abstract

The International Maritime Organization (IMO) has recently revised its GHG strategy, setting an unprecedented ambition for international shipping to achieve net-zero greenhouse gas emissions by or around 2050. To meet this target and other intermediate goals in the coming decades, it is essential to have a comprehensive understanding of potential demand scenarios for shipping, fuel pathways for the sector, and their associated emissions. While Life-Cycle Assessments (LCAs) and sectoral models provide valuable insights for specific case studies, additional modelling approaches are needed for a more holistic assessment of the sector. Thus, linking bottom-up shipping emission models can aid in exploring the heterogeneity of emissions across the shipping fleet, while Integrated Assessment Models (IAMs) can integrate the shipping sector with the global energy system. Providing more detailed modelling frameworks can be crucial for hard-to-abate sectors like shipping, especially in the context of deep mitigation scenarios. To address that, the MariTeam model has been developed leveraging highresolution spatial data collected from the Automatic Identification System (AIS) to build present-day and future emission inventories. Results from this approach are linked to the IAM MESSAGE-ix to produce mitigation scenarios for the shipping sector including aggregated representations of the energy and land-use systems. To date, no studies have combined bottom-up shipping energy demand with life-cycle emissions in a framework that links sectoral and global energy systems, nor have they been evaluated in light of the new IMO targets. Consequently, the literature might offer only a partial view of the solution space. This work addresses this gap and is structured around five publications of increasing scope. By focusing on modelling energy demand and potential adoption of alternative fuels, this thesis expands on energy demand scenarios for the sector within different decarbonization trajectories. The findings underscore the critical role of alternative fuels, along with energy efficiency improvements, in reducing emissions from the international maritime sector over the coming decades.