A substantial part of international trade goes through shipping routes, which has made it a challenging sector to decarbonize. A new study involving CMCC researchers identifies potential pathways for decarbonizing global shipping with low carbon fuels.

Decarbonizing the shipping industry has been a growing policy goal as the sector accounts for approximately 3% of global CO2 emissions. Furthermore, a 2020 study by the International Maritime Organization, predicts that this share of emissions could increase by as much as 130% of 2008 emissions by 2050 if left unchecked. This has made a reduction in the shipping industry’s emissions an important piece of global mitigation efforts, particularly as international trade of goods and services is expected to continue to grow, placing further onus on ensuring emission reductions.

A new study, involving an international team of researchers including CMCC’s Johannes Emmerling and Laurent Drouet, investigates how the global shipping industry could reduce its carbon emissions in line with climate goals. The research, published in the journal Nature Climate Change, uses advanced modeling to project different scenarios for shipping emissions through 2100.

International shipping CO2 emissions. a, International shipping activity level between 2020 and 2100 across scenarios, indexed to 2020; b, Variation of the annual CO2 emissions from international shipping in 2050 when compared with 2020 across scenarios; c, Variation of the annual CO2 emissions from international shipping in 2070 when compared with 2020 across scenarios. Source: Müller-Casseres et al, 2024.

Under ambitious climate scenarios, the study shows how shipping emissions could be reduced by up to 86% by 2050 compared to 2020 levels. This would be achieved primarily through a shift to low-carbon fuels like biofuels, renewable alcohols, and green ammonia, whereby models that included an emphasis on these low-carbon fuel options tended to show a deeper decarbonization potential.

“This is one of the first studies to use multiple integrated assessment models to analyze decarbonization pathways specifically for the shipping sector in the context of global climate goals,” says senior scientist at CMCC and co-author of the study Johannes Emmerling – who believes that the research provides a more comprehensive view on shipping’s role in climate mitigation efforts.

Emmerling and Drouet contributed to the study through their work with the WITCH integrated assessment model, a dynamic global model that integrates the most important elements of climate change in a unified framework. In this application, the model provided key projections on shipping demand, emissions, and fuel use under different scenarios.

“Shipping has been a challenging sector to decarbonize, but our research shows there are viable pathways to dramatically reduce emissions by mid-century,” says Emmerling. “The key will be developing and scaling up production of alternative low-carbon fuels that can power large vessels.”

More information:

Müller-Casseres, E., Leblanc, F., van den Berg, M. et al. International shipping in a world below 2 °C. Nat. Clim. Chang. 14, 600–607 (2024). https://doi.org/10.1038/s41558-024-01997-1