Air Freight vs Sea Freight Carbon Footprint (The Real Numbers in 2023)

How Much CO₂ Does a Cargo Ship Produce per KM? Is It Too Much?

A cargo ship produces 16.14 grams of CO₂ per metric ton of goods shipped per kilometer.⁸ On the other hand, container ships emit an average of 140 million metric tons of carbon dioxide annually, while bulk carriers emit 440 million metric tons of carbon dioxide.

There is a lot of potential in reducing the cargo freight carbon footprint that the sector leaves behind.

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There are a lot of technical and operational methods that you should use to reduce carbon footprints, such as the use of propulsion efficiency devices, weather routing, slow steaming, and contra-rotating propellers. In 2015, shipping emissions accounted for approximately 13% of the transport sector’s European Union greenhouse gas emissions. That percentage is significant.¹

Since then, the European Union has stepped up and added all the efforts to reduce greenhouse gas emissions.

The EU came up with the following strategies: monitoring, reporting, and verifying carbon dioxide emissions from bulk ships using European Union ports, setting out gas emissions targets for all ships, and setting up more short-term and long-term measures.

What Is Air Cargo Environmental Impact?

Civil aviation is among the rapidly growing global businesses. Like many other aspects of transport, aviation is liable for many adverse external effects that are unfriendly to the environment.¹ Some of the risks associated with air transport include air pollution, mainly greenhouse gasses, incidental water, soil pollution, noise pollution, and waste generation with high amounts of dangerous waste.

According to the European Union Emissions Trading system, all the flights operating in Europe must monitor, report, and verify their emissions. Every airline has a tradable allowance that covers a certain level of emissions from its activities annually. Air cargo leaves a large carbon footprint compared to sea freight.

Some of the future and contemporary environmental issues airlines must address are:

• Approach and takeoff noise
• Flyover noise from high altitudes in all quiet areas
• Fuel dumping and venting
• Emission of hydrocarbons and carbon monoxide in the airport area
• Sonic booms
• Depletion of the stratospheric ozone and potential for greenhouse effects
• Carbon dioxide emissions
• Contrail formation

Air Freight vs Sea Freight: Environment Positives

In 2021, air transport emitted 895 million tons of emissions. The number may look a lot, but is in in fact, only two percent of the 42 billion tons of greenhouse gasses generated from human activities annually. Though cargo has increased by 5% annually, aviation has managed to contain its emissions to approximately half that.¹

It has achieved this because of its massive investments in coordinated action and new technology to implement new infrastructural measures and operating procedures. Carbon dioxide is not the only greenhouse gas emitted by an airplane; the aircraft engine exhaust also emits average atmospheric nitrogen and oxygen.

The contrails (water vapor trails) created by an aircraft also create a net cooling effect. They can form cirrus clouds under some weather conditions, positively impacting climate change.

On the other hand, sea freight has traditionally been environmentally friendly and has avoided stringent environmental regulations on transport for many years. However, this has rapidly changed in the 21st century as the sector uses numerous environmental controls. The lion’s share of the environmental impacts has been reduced by removing unnecessary trips, decreasing cruising speed to reduce pollution and fuel consumption, and increasing the size of cargo batches.

Sea Freight vs Air Freight: Environment Cons

Ocean liners release their wastes either directly over or into the ocean, and these greenhouse emissions⁶ directly contribute to the acidification of the sea. Some of the greenhouse gasses emitted by these vessels include Sulphur dioxide, carbon dioxide, nitrogen oxides, etc. The gasses are formed in the combustion engines of the ship and are hazardous to the environment when released.

For instance:

• Hydrocarbons accumulate in the crops, soil, and food and pose a significant health risk
• Nitrogen oxides acidify the soil.
• Ozone formed by the interaction of other pollutants damages the root and leaves of crops, leading to lower crop yields.

Ships risk spreading alien organisms to vulnerable ecosystems, and the natural resources and energy used are considerable.²

While air freight accounts for less than one percent of global load, it continues to grow significantly. Air transport threatens the environment in three ways:

• During takeoff and landing, which contributes to global warming and conventional air pollution
• Emissions during flights contribute to global warming.
• Congestion, noise pollution, and other land-use matters pose risks to airports.

Sea Freight vs Air Freight Carbon Footprint: Which One?

When transporting cargo overseas, you have to choose one of the two. While speed and cost are factors to consider, the shipping method’s carbon footprint also plays a big role when deciding. Carbon footprint is another word for environmental impact.

Comparing air freight vs sea freight carbon footprint reveals that shipment by a liner has a significant advantage for planes. Long-haul flights emit 47 times more greenhouse gasses than ocean freight per ton a mile. In simple terms, flights generate 500 grams of carbon dioxide per kilometer. However, the full extent of air freight vs sea freight carbon footprint is cloudy.⁴

Although sea freight is better for the environment than air cargo, they release toxic greenhouse gasses directly over or into the ocean. These emissions significantly increase ocean acidification. When it comes to sensitive loads like pharmaceuticals, reliability and speed matter, as it makes it less likely to part ways with your cargo.

When you lose such a product, the environmental cost of acquiring one is significantly greater than any greenhouse gas emission savings between air and ocean. Perhaps the most significant factor regarding carbon footprint is technology and vessel age. Older ships emit roughly five times more emissions than newer ones.⁴

Furthermore, most liners use bunker oil, the lowest grade fuel exceedingly high in Sulfur. Besides, older liners cannot filter or block emissions, including nitrogen oxide and particulates, and Sulfur. The good news is that the International Maritime Organization has put measures to reduce carbon emissions by at least 70% by 2050 and at least 40% by 2030.

Subsequently, in 2020 IMO effected a rule that placed limits on the amount of Sulfur⁷ each ship’s fuel should have. Some technology to help with sea freight’s carbon footprints includes investing in hydrogen fuel cells.

Ocean Freight vs Air Freight Carbon Footprint for Large Items: Which Is the Most Suitable?

So, what about air freight vs sea freight carbon footprint? Which one has a more negligible effect on the environment?

Airfreight leaves the most significant carbon footprint for large items compared to ocean freight. Flights emit 500 grams of carbon dioxide/metric tons of cargo per kilometer of transportation. However, ships emit only between 10 to 40 grams of carbon dioxide per kilometer.¹

The carbon footprint of airplanes is 20 to 30 times more than ships. For this reason, air freight produces a more carbon footprint for more significant items than the ocean freight.

There are various methods available to reduce the negative environmental impact of shipping products and one of them is taking advantage of shipping carbon offset programs.

Air Freight vs Ocean Freight Carbon Footprint for Small Items: Which One Should You Avoid?

For small items, air freight still produces more carbon footprint than the ocean freight. Although factors such as speed and cost vary, the carbon offset shipping amount remains constant.

The flight still makes 20 to 30 times more environmental impact than the ocean freight.²

Comparison of CO₂ Emissions by Different Modes of Transport

Every mode of transport presents its own environmental challenges. For example, even if every internal combustion engine on the planet was suddenly and miraculously powered by electricity, the electricity still has to be generated by methods that emit greenhouse gases.

Currently, however, measuring emissions by different modes of transport is possible, so the best solutions can be identified and then tree planting carbon offsets purchased to eliminate the emissions generated.

Air Freight vs. Sea Freight Comparison: What’s the Difference?

So, is air vs ocean freight better? When shipping, you need to decide if you want your cargo shipped cheap or fast. The simple answer is if you wish to go for speed, ship by air, and if you want cheap, ship by ocean. However, other factors complicate your overall decision, such as restricting hazardous goods, the environment, etc.³

As technology advances, ships get faster, and ocean freight is becoming quicker than it was decades ago. As a result, the express ocean shipping option is available. You can now get products from the factory to their destination through sea cargo in less than two weeks. Technological advancement has also enabled more efficient stock management and faster customs clearance on ships and ports.

However, express ocean freight comes with additional costs. Choosing this ocean freight option will make you pay at least 50% more than the standard shipping, but considering that it costs 3 to 5 times to ship with air freight, it is worth paying. Express sea freight is a good filing middle-ground for air freight and standard ocean shipping in terms of speed and cost.

Air Freight vs Sea Freight Cost Comparison? Which Is Better?

Air freight is the most expensive, while sea freight shipping is cost-effective. According to the World Bank, air freight is 13 to 17 times more expensive than ocean freight- and when your budget is millions of dollars, it makes a significant difference. You can also carry more items on a container ship than on a plane, saving extra costs.⁴

These products may also weigh more than a flight allows because planes limit the weight of your items when using air cargo. If you are shipping small but heavy objects, sea freight shipping will suit you best.

Carbon Footprint Ship vs. Plane? Which Affects the Least?

Planes produce more carbon footprint than ships. Research by the United Kingdom government indicated that airplanes create 44 times more carbon dioxide than ships when carrying the same cargo over the same distance. Ships are more environmentally friendly than planes, as greenhouse gasses emitted when using planes are much higher.⁵

Since planes emit these greenhouse gasses in the stratosphere, they considerably affect atmospheric chemistry. So, these plane emissions have a worse environmental impact than that of ships.

Air Freight vs. Land Carriage

With ground freight services, your products get transported overland using a truck. Two primary land carriage services include less-than-truckload freight shipping and full truckload freight shipping. FTL is the ideal land carriage if your items fill an entire truck, while LTL freight shipping is perfect when your items don’t.

• Land carriage is the most common mode of transportation, and people on all continents use it. You only need a single customs document, and you will have a seamless movement of items across various countries and states.
• Compared to air freight, the land carriage is cost-effective, flexible, and quick, and you enjoy scheduled delivery, allow for track and trace, and offer door-to-door delivery service. However, the smaller size vehicle means that the emissions are higher.

Thankfully, the best carbon offset programs are offering real solutions for eliminating the emissions generated by global transport. Simply use a footprint calculator to measure the emissions generated by air or sea transport, and then work to erase them using programs that will benefit both the climate and the environment.

The shipping method you choose depends on the item you are shipping. But when you care for the environment, you should weigh between air freight vs sea freight carbon footprint before deciding.

Frequently Asked Questions About Air Freight vs Sea Freight Carbon Footprint