Fossil cargoes drive 50% of maritime fuel use despite 40% tonnage share

UNCTAD Review of Maritime Transport 2023 records 11.1 billion tonnes of seaborne trade with coal, crude oil and LNG forming the dominant bulk flows. Rebaselined energy models show these cargoes generate roughly twice the transport work per tonne compared with short-sea scrap or container trades because average voyage distances exceed 8,000 km for energy commodities versus under 2,000 km for most other dry bulk. The resulting fuel share reaches 50% even before port and auxiliary consumption is added. IEA World Energy Outlook 2023 and the Nature Energy short-sea electrification study together quantify the denominator effect. Coal trade falls 40% by 2035 under stated policies while crude and product tanker demand contracts 25-30% under net-zero pathways. Iron-ore volumes remain exposed to steel decarbonisation but shift toward regional electric-arc routes, trimming another 15% of long-haul bulk work. These reductions remove the highest-energy-intensity segments first. Remaining demand concentrates on shorter, higher-frequency routes suited to battery-hybrid and shore-power systems. Inland and coastal segments already demonstrate 60-80% electrification potential in European and East Asian pilots. The operational implication is a sharply smaller pool of molecules required for deep-sea ammonia or methanol propulsion once fossil and raw-ore baselines decline. Efficiency gains and modal shifts further compress the residual fuel requirement. Fleet slow-steaming and wind-assist retrofits cut energy intensity 15-20% on the surviving long-haul trades. The net maritime fuel task therefore contracts faster than gross tonnage projections imply.