Nearly 40% of all maritime freight tonnage — roughly 4,500 million tons out of a global total of 11,000 million tons — is fossil fuel cargo: coal, oil, gas, and petrochemicals, according to Quartz. That figure carries a layered irony the shipping industry has long lived with: the sector moves the world's hydrocarbons while burning them, and the two dependencies reinforce each other in ways that make decarbonization structurally harder than in almost any other transport mode.

On the consumption side, IEA data shows oil products have historically constituted over 99% of total energy demand for international shipping, with fossil fuels accounting for roughly half of freight shipping energy consumption despite comprising only 40% of its tonnage — a reflection of the energy intensity of bulk and tanker operations. In 2023, the sector's oil consumption reached 4.2 million barrels per day, up 5% year-on-year, according to the IEA. International shipping as a whole accounted for approximately 2% of global energy-related CO2 emissions in 2022 — modest as a share of the total, but concentrated in a sector with very few near-term substitution options.

The alternative fuel picture is starkly thin. Biofuels met less than 0.5% of global maritime shipping energy demand in 2022. As of the most recent fleet data available, only 8% of world shipping tonnage is equipped to use alternative fuels at all, per UNCTAD. Those two numbers together — sub-0.5% energy share, 8% capable tonnage — suggest that even the ships built or retrofitted for alternatives are not yet running on them at scale.

The Demand Trajectory and the Transition Gap

The IEA's scenario work projects that bioenergy, hydrogen, and hydrogen-derived fuels could grow from under 1% of combined shipping and aviation energy today to roughly 15% by 2030 and 80% by 2050, per a 2023 IEA report. That trajectory is steep — and the gap between the 2030 target and today's sub-1% baseline is not a gradual ramp. It requires compounding annual deployment rates that the current order book and bunkering infrastructure do not yet support.

Worth flagging here: the 2030 figure is a projection within a net-zero-aligned scenario, not a forecast of what current policy settings are likely to deliver. The distance between the two is where the real policy and investment question lives.

Near-term shipping volumes add a further complication. Ocean freight volumes are projected to decline approximately 6% in October 2025 compared to the same period in 2024, according to C.H. Robinson's October 2025 freight market update. Softening demand typically compresses operator margins, and compressed margins historically slow fleet investment — including investment in alternative-fuel newbuilds. The timing is inconvenient for a transition that depends on accelerating capital formation.

What the Numbers Actually Mean

The sector's structural bind is not hard to describe. Shipping moves fossil fuels because the global economy still demands them in enormous volumes; shipping burns fossil fuels because alternatives are expensive, bunkering infrastructure is sparse, and the technology options — green ammonia, methanol, LNG as a bridge, hydrogen — each carry meaningful trade-offs in energy density, safety handling, or supply chain maturity. A vessel with a 25-year operational life ordered today will likely still be at sea in 2050. Fleet turnover alone cannot close the transition gap within the IMO's net-zero timeline.

The 8% alternative-fuel-capable share of world tonnage is perhaps the most actionable single number in this dataset. It tells you where the transition currently sits in physical terms: at the very early-adopter stage, well short of the inflection point where infrastructure investment becomes self-reinforcing. The PC era saw a similar dynamic in the mid-1980s, when software availability and hardware penetration were each waiting for the other to move first. Shipping's version involves far heavier capital commitments and sovereign energy policy, which makes the coordination problem considerably harder.

That said, the sector is not static. Regulatory pressure — particularly the IMO's revised GHG strategy and the EU's inclusion of shipping in its Emissions Trading System from 2024 — is beginning to price carbon into voyage economics in ways that were absent five years ago. Whether that price signal arrives at sufficient magnitude, soon enough to redirect the investment decisions being made in shipyards today, is the question the next several years will answer.