由 caicai8478 Average carbon emissions: 0.01-0.05 kg CO₂/ton-kilometer (large container ships are most efficient).
Example: Transporting 1 ton of cargo from Shanghai to Los Angeles (about 10,000 kilometers) emits about 100-500 kg CO₂.
Advantages: Large cargo capacity of ships (such as 200,000-ton container ships), extremely low unit emissions; slow sailing (economic speed) can further reduce emissions.
Air transport:
Average carbon emissions: 0.5-1.5 kg CO₂/ton-kilometer (the belly cargo efficiency of passenger flights is low).
Example: Also from Shanghai to Los Angeles, 1 ton of cargo by air emits about 5,000-15,000 kg CO₂, which is 10-100 times that of sea transport.
Disadvantages: Jet fuel (kerosene) has a high carbon content, and the nitrogen oxides (NOₓ) and condensation trails emitted at cruising altitudes exacerbate the greenhouse effect.
- Key influencing factors
Carrying efficiency:
Seagoing ships can carry 10,000 tons of cargo, while the maximum load of a Boeing 747 freighter is only about 140 tons.
Fuel type:
Ships mainly use heavy fuel oil (high sulfur content, but IMO 2020 new regulations limit sulfur) or liquefied natural gas (LNG); aircraft rely on high-purity jet fuel.
Speed and distance:
Air transport is suitable for high-value, time-sensitive goods, but carbon emissions increase linearly over long distances; sea transport is suitable for bulk goods, and the emission advantages of medium and short distances (such as within Asia) are weakened.
- Environmental policies and technological progress
Shipping emission reduction measures:
Use shore power (turn off the engine when docked) and install scrubbers to reduce sulfur emissions; pilot hydrogen fuel or ammonia powered ships.
The International Maritime Organization (IMO) aims to reduce carbon emissions by 50% by 2050 compared to 2008.
Air transport innovation direction:
Sustainable aviation fuel (SAF), electric aircraft (short-haul feeder), optimizing routes to reduce contrails.
The International Air Transport Association (IATA) has pledged to achieve net zero emissions by 2050, but it is difficult to achieve technological breakthroughs.
- Industry selection recommendations
Scenarios for priority sea transport:
Bulk commodities (ores, grain), storable commodities (electronic products), and time-insensitive trade.
Scenarios for choosing air transport:
Fresh food, pharmaceutical vaccines, emergency supplies and other high value-added goods.
- Data reference
According to the International Transport Forum (ITF), sea transport accounts for more than 80% of global cargo transportation, but only contributes 2-3% of carbon emissions in the transportation industry; although air transport accounts for a small proportion (<1% of cargo volume), carbon emissions account for more than 10%.
Conclusion
The carbon emission efficiency of sea transport is significantly better than that of air transport, especially in long-distance bulk transport. However, air transport is irreplaceable and still needs to be used in certain areas. In the future, through clean energy transformation and operational optimization, the carbon intensity of both is expected to decrease, but sea transport will still be the core choice for low-carbon logistics. For enterprises, balancing timeliness and carbon footprint needs to be included in supply chain strategic planning.