Optimal Pathway for Decarbonizing Canada's Maritime Transport: Short-Term (2025–2035), Medium-Term (2035–2050), and Long-Term (2050 and beyond)

Decarbonizing Canada's maritime transport sector is a priority driven by climate commitments and the need to cut shipping emissions. While most studies focus on individual technologies or single criteria, this research applies the Multi-Criteria Decision-Making (MCDM) Analytic Hierarchy Process (AHP) framework to assess multiple decarbonization strategies across economic, environmental, technological, and regulatory factors. It identifies key criteria, evaluates strategies, and explores their interactions, including the financial sector's role in supporting the transition. Environmental Impact (28%) ranks as the most critical criterion, followed by Economic Viability (20%), Technological Feasibility (13%), Scalability and Flexibility (9%), and Energy Security (9%). Additional factors include Life-Cycle Analysis (5%), Infrastructure Requirements (4%), Social and Political Feasibility (4%), Safety and Risk Management (4%), and Implementation Timeline (4%). The evaluation ranks Energy Efficiency Improvements (S7) as the most effective strategy (0.753) due to its feasibility and economic benefits. Liquefied Natural Gas (LNG) (S1) follows (0.698), but it is limited by methane emissions. Biofuels (S2) and Electrification (via Battery-Powered Ships) (S8) score 0.563, as they are facing sustainability and battery constraints, respectively. Green Hydrogen (S3), Green Ammonia (S4), and Synthetic Fuels (or e-Fuels) (S5) score 0.483, offering long-term potential but also being hindered by infrastructure challenges. Ocean-Based Fuels (S6) rank lowest (0.403) due to their early stage development. These findings suggest that the optimal decarbonization pathway follows a phased approach: prioritizing energy efficiency and transitional fuels (LNG, biofuels) in the short term (2025–2035); scaling up green hydrogen, ammonia, and synthetic fuels in the medium term (2035–2050); and advancing full electrification and ocean-based fuels beyond 2050 (supported by policy, investment, and infrastructure). In this way, the study provides insights for policy-makers, industry, and financial institutions by helping prioritize investments and policy measures while highlighting the need for public–private partnerships, regulatory incentives, and green financing. However, the MCDM-AHP approach involves subjective weighting, and it thus requires validation through case studies and quantitative modelling. Future research should also explore nuclear propulsion, which could be a high-energy-density solution for long-distance shipping, and carbon capture technologies, which could capture CO2 emissions from ships and help to reduce their environmental impact.