Reducing greenhouse gas (GHG) emissions from the maritime sector will be a crucial component of climate mitigation toward meeting the Paris Agreement targets. Therefore it is essential to identify decarbonization pathways for the maritime industry that are feasible, efficient, and avoid carbon-intensive lock-in, while still supporting the movement of goods needed for human well-being. To study how these pathways may interact with broader socio-economic conditions, we developed an open-source maritime gravity demand model that incorporates a wide range of SSP-differentiated measures for an interdisciplinary set of phenomena, that enables maritime activity projections to vary in a complex manner with socio-economic and -cultural futures.
We begin with a large historical dataset on shipped goods and combine it with several SSP-specific projectionsdrawn from interdisciplinary sources. The combined dataset allows us to draw a holistic picture differentiated across shipping market segments like oil, container, and bulk dry. Based on regression coefficients of historical data for the respective parameters, we extrapolate trade flows by multiplying them with future projections—drawn from recent literature—of the respective parameters. This process yields trade flows in monetary units, which we then translate into cargo tonnage by mapping them with geo-spatial data of actual port calls in a base year. The final product is projected maritime demand for different ship types and SSPs. While rich in their own right, these projections will also be used (beyond the YSSP) to parametrize an improved version of the shipping representation in the MESSAGEix-GLOBIOM/MESSAGEix-Transport global integrated assessment model. The added detail in this model will allow it to cover demand/activity for maritime shipping of all commodities.
The gravity model results per seshow vast differences in future maritime demand projection across both SSPs and countries. We project that some countries will significantly increase maritime activity while that of industrialized countries will eventually saturate. The level of maritime activity in the future heavily depends on the chosen parameters for the respective ship segment and its future projections. Overall, the work demonstrates a successful combination of interdisciplinary datasets into one analysis yielding improved maritime demand projections and improved representation of SSP narratives, reflective of socio-economic factors that are usually omitted from sector-focused analyses.