End-to-end shipping is a complex process, included is the decision on what modes of transport that will be used for a shipment. Several factors are included in this decision-making process, such as the type of cargo, shipping location, and destination, costs, but with increasing regulation around sustainable transports, carbon footprint is a growing determining factor. Though CO2-emissions is the measure most commonly cited, it is not the only environmental impact of transport.
In this article, we will take a closer look at the environmental impact of:
There are too many variables to give you an exact CO2 emission-number that will be the same for every truck, every rail journey and so on. So with that, keep in mind that we speak about averages for each freight transport option.
Additionally, of course, with every transport option, there is a question about how new or old the transport vessel is. Whether it is an older truck, ship, locomotive, or airplane, it will be less environmentally friendly and efficient than a newer model.
Air freight environmental impact
Certain cargo, like perishable goods, is time sensitive, which means air freight is practically your only option. Because of its speed and security, it is also a popular option for goods that could easily be transported by other means of transport.
Air cargo shipments offer the smallest load capacity compared to the other alternatives. Aircraft also release the highest number of CO2. This results in the highest levels of CO2-emissions per load transported, on average 500 grams of CO2 per metric ton of freight per kilometer of transportation.
Though it is true that aviation fuel emits less carbon dioxide and air pollutants than fossil fuels, it still emits significant levels of CO2 and harmful chemicals. Planes release emissions directly into the upper atmosphere, causing a greater impact on atmospheric chemistry.
Air transports largely contribute to air pollution, but also incidental water, soil pollution, noise pollution, and waste generation with high amounts of dangerous waste. Air pollution causes damage to humans, the World Health Organization estimates 4.2 million people die yearly from outdoor air pollution, but it also gravely affects our biosphere, soil, water, and buildings.
One positive impact does come from air transport, the water vapor trails created by an airplane create a net cooling effect and can form cirrus clouds under some weather conditions.
Road freight environmental impact
Unimodal trucking, when road freight trucking is the single mode of transport for the entire freight journey, often seems like the easiest option, especially within Europe, but it entails a heavy environmental impact. Road transport relies on fossil fuels and produces fine particles that pollute the outside air, which is dangerous to humans and ecosystems.
A truck emits ca. 60 to 150g of CO2 per ton and a kilometer of transportation. But it is not only about the truck itself, but contributing to road traffic congestion, which increases fuel consumption of the affected cars and trucks and in return, also CO2 emissions and air pollution. According to a European Commission Statistical Pocket 2021 report, road freight transport accounted for 27.2 % of greenhouse gas emissions in 2019.
Diesel trucks are known as air pollutants first and foremost, but they also produce notable noise pollution. Noise pollution is not only bothering people, but also local wildlife. Studies show noise pollution makes it harder for animals to survive because it affects their ability to use sound for navigation, find food, mate, and avoid predators.
We will not escape trucking with first and last mile, but we can limit these distances by embracing combined transport. That would mean a bigger opportunity to use alternative and more sustainable fuels already for the shorter trucking distances and not wait for more efficient options in the future.
Rail freight environmental impact
Unfortunately, customers have traditionally faced high barriers in accessing rail-freight and then later struggle with service below expectations. These factors have lead to an underutilized rail network despite being generally considered to have a lower environmental impact than air or road transport, especially in terms of CO2-emissions.
The CO2 emission emitted by rail freight varies depending on whether electric or diesel locomotives are being used. If the rail network is electrified, the CO2 emissions are lower, and there is potential for a green energy source. On average, a modern freight train emits 30 to 100g of CO2 per ton and a kilometer of transportation.
Noise pollution and the vibrations from the moving train are of the bigger effects of rail freight transport, especially if high-speed rail is in use. Train lines often run through both countryside and communities that are disturbed greatly by the loud noise that ensues. Noise pollution can lead to habitat loss if the local wildlife no longer uses the area on the other side of the tracks, and behavioral changes if the noise is perceived as a risk.
Building new railways is necessary for rail transport to be able to manage higher volumes of cargo and reach more destinations. Expanding the railway network does cause both physical and behavioral barriers to wildlife, like habitat fragmentation. However, studies have also shown that for certain bat species and butterflies, the clearing a railway adds actually improves their conditions. We can therefore not say that railways are always negative for all the local wildlife.
Rail freight is still more efficient in terms of tons of goods moved per liter of fuel compared to air and road freight options. Especially comparing to road freight, rail freight offers more efficient land use, less air pollution, and less congestion and wear and tear on roads. In terms of noise pollution, a report by the European Environment Agency (EAA) states that ca. 5 times as many people are affected by road traffic noise above 55 dB compared to railways.
Water transportation environmental impact
Both cargo ships and barges can hold very large volumes of goods. One barge holds approximately 15 times more than one rail car and 60 times more than one semi-trailer. They also require less fuel to transport their cargo. This means that they are most efficient in terms of cargo transported per liter of fuel.
The environmental impact of sea freight
Ballast water is water brought on to manage the ship’s weight and level. This is a very old practice to steady the ship, but it poses a real environmental threat. Releasing ballast water that has been collected in a very different environment carries many risks for the destination port’s microbiome. In the ballast water, there could be foreign bacteria, microbes, organisms, larvae, etc., of various species that may now become invasive species and cause significant damage to the local ecosystem.
To battle the ballast water problem, many countries have adopted regulations on how to treat ballast water before disposal. One type of treatment is chemical, to kill the organisms effectively and quickly strong chemicals are used, but they may create a toxic byproduct that is released instead. The best option environmentally would be to treat the ballast water using a mechanical treatment or using UV radiation to kill the organisms. Another possibility is to look at ships that do not release ballast water all by using alternative systems.
Sinking ships and oil spill disasters can have irreversible consequences on the ecosystem of oceans and sea coasts. A smaller oil spill can happen when a ship re-fuels, but even a smaller spill may still cause serious environmental harm by contaminating water and soil. Larger oil spills may also cause explosions and fires, harm wildlife, and contaminate seafood at large.
When ships are abandoned in the ocean or sink, they inevitably impact the surrounding environment. When large vessels sink, they scrape the seafloor, causing damage to a sizeable ocean habitat. Additional environmental damage is caused if the vessel is then left abandoned, as metals, chemicals, and oil will leak into the water.
Looking at CO2-emissions, container ships emit on average 10 to 40 grams of CO2 per kilometer. The European Commission established that international shipping produces less greenhouse gases for every ton transported per kilometer than road or air transport.
However, when it comes to container ships the main problems relate to their release of emissions either into or directly over the ocean, and those can contribute directly to ocean acidification.
The environmental impact of inland waterways transportation
Transportation via inland waterways has been on the decline since the modernization of trucks due to its lack of flexibility in routes and unreliable conditions. However, the known environmental impact, in terms of for example noise pollution, is low.
Inland waterways freight transportation also requires well-maintained waterways, which is the case for established canal systems and popular rivers, but it is not extensive. Extending waterways is often associated with a decline in water quality and a burden on the natural environment.
Traditional barges are without engines or motors, meaning the barge itself did not use any fuel for transportation; however, the tug vessel would, of course, require fuel. These days self-propelling barges have become increasingly common, meaning they would consume fuel, but they are still very fuel-efficient and can move cargo more than four times as far as trucks on the same amount of fuel.
Barge transport is associated with fewer emissions due to strict national regulations regarding water quality values. In the cases of international rivers, an agreement is made between the nations where the river flows, and most often, the most strict value is adhered to.
Intermodal transports environmental impact
So unfortunately, there is no one golden solution to more sustainable transport as there is not one option that will suit all goods and all transport needs. However, integrating rail or barge more efficiently in freight transports can lead to 60-90% reduction in CO2-emissions compared to a truck only option.
Thus, the potential of intermodal transportation when the main leg of the journey is via rail or inland waterways is monumental. As you have learned, these transportation options carry the least environmental impact, also looking at pure CO2-emissions. That means the longer you are able to make the main leg with one of these options, the greater your CO2-savings will be and the smaller the environmental impact of the cargo transport will be.
When you are not relying on one mode of transport, your transport network and supply chain also become more resilient. If the last couple of years have taught us anything, it is the importance of a resilient supply chain.
The best way forward is to look at intermodal transportation, combining different modes, to find the most efficient route for your needs and at a reasonable cost. Optimize your route planning with the help of a freight management system, like rouvia, and with the click of a button get an overview of available options with their price, ETAs, and CO2-emissions data.