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Freight is a significant contributor to climate change. Every year, billions of tons of cargo make their way across the planet on trucks, trains, ships, and planes. This adds up to 8% of global GHG emissions, and as much as 11% if warehouses and ports are included.
While many industries have begun to move towards greener alternatives, transport still has the highest reliance on fossil fuels of all sectors. Freight is forecast to double its emissions by 2050, fueled by economic growth in developing regions coupled with our increased appetite for ecommerce and home delivery. If we continue along our current path, by then freight will have taken the crown as the highest emitting sector.
Within freight, one mode of transport stands out with the highest emissions: road. At over 2.2 billion tons of CO2e released in 2020 alone, trucks account for about one-quarter of emissions across the entire transport sector. Electrification has the potential to decrease road emissions in a future where a larger percentage of energy comes from renewable sources.
Ships are often touted as the most sustainable freight method and transport three-quarters of the world’s cargo but most vessels still rely on fossil fuels, and many are outdated, making them significant polluters. Technological advancements over the last ten years have reduced the carbon emissions of modern cargo ships, but with 70% of vessels over ten years old, sea freight still weighed in at 657 million tons of CO2e emissions in 2020.
Moving freight by rail results in significantly lower emissions per tonne-kilometer than road and sea, particularly if the railway is electrified. Moving freight off the roads and onto trains is therefore a good way to reduce emissions and congestion (which increases emissions) and improve local air quality.
Air is by far the most carbon intensive transport method. The demand for air freight experienced a period of rapid growth during the COVID 19 pandemic which has continued ever since. In 2023, FedEx and UPS were responsible for almost 25% of aviation emissions, due in large part to the pressure for fast delivery through services such as Amazon Prime. Where air freight had previously been reserved for perishable goods or high-value items and transported in the belly of passenger planes, during the pandemic, the fleet of freight aircraft grew, placing its emissions at 155 millions tons of CO2e in 2020. Despite belly freight having returned to near pre-pandemic levels, this new freight fleet continues to operate.
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Every transport mode has a unique emissions profile, influenced by variables including engine efficiency, vehicle size, vehicle age and the type and quality of fuel used. It’s important to include not only direct emissions from fuel combustion but also indirect emissions from fuel production and distribution (well-to-wheel), as these typically add between 10% and 40% to total emissions.
What happens if the journey has multiple legs with mixed transport modes? Each leg must be calculated separately, increasing the resources needed for data collection and calculations.
Moreover, when shipments involve multiple carriers—each with their own operational practices, fleets, and emission standards—the complexity increases further. Different carriers use various types of vehicles with differing fuel efficiencies, maintenance schedules, and technologies, all of which influence emissions. They may also follow different reporting standards or provide data in inconsistent formats. This makes comparisons difficult. Coordinating and standardizing data from multiple carriers requires significant effort. If carriers are unable or unwilling to provide detailed emissions data, companies have to rely on generic estimates or assumptions that can distort their overall emissions assessments.
The efficiency of freight transport is also heavily influenced by load factors. Vehicles often return empty or partially loaded, known as ‘empty runs’, which increases emissions per unit of cargo transported. Accurately accounting for these variations requires data on cargo volumes and vehicle utilization.
Additional considerations must be made for certain modes.
For air transport, Radiative Forcing Factor accounts for fuel burn at high altitudes by airplanes. Including all variables ensures a more accurate emissions estimate—but also increases complexity.
For road vehicles, frequent braking, accelerating or driving in lower gears increases fuel consumption. These are influenced by the roads as well as the drivers: routes with steep inclines, declines, or sharp bends demand more braking and gear changes. Advanced tools like HERE Maps (used by Climatiq) factor in such route variances when estimating fuel emissions. Heavier traffic, driver behavior, or even the condition of the road surface can all contribute to higher emissions.
In a similar vein, hull biofouling—the buildup of microorganisms, plants, and algae—affects the drag of a vessel in the water and therefore its fuel efficiency. Estimates even suggest up to 9% of the shipping industry’s emissions are the direct result of biofouling.
There are further steps to consider outside of the transport itself. For example, between journey legs, cargo spends time in logistics hubs—the warehouses and ports where goods are processed and stored. There, it requires transport within the hub, electricity for operations, and possibly heating or cooling to maintain its temperature. All of these activities generate emissions, but methodologies for calculating energy emissions differ from calculating emissions for transport, and should be tailored to the hub’s location or energy mix.
Certain goods must be transported via a “cold chain”, the term used to describe temperature-controlled freight transport. This includes perishable food and beverages, pharmaceuticals, medical donations for transplantation, and industrial chemicals. Exposure to extreme heat or cold can spoil many of these products and make them unsuitable or unsafe to use—but maintaining the right temperature in the vehicles used to transport them can increase emissions.
Emissions aren’t only influenced by the goods; location also matters. The fuel mix of the local electricity grid is one factor. Some waterways restrict vessel types, forcing route changes. Seasonal and weather conditions further complicate emissions estimates: adverse weather can increase fuel consumption due to factors like increased air resistance or the need for heating and cooling systems.
These are just a few of the factors that complicate emissions estimates but are hard to account for on a case-by-case basis, especially for companies calculating emissions across multiple journeys or logistics activities.
Emissions estimates are only as good as the data they are based on. The input data required to calculate transport emissions is often incomplete, inaccurate, or inconsistent.
One significant challenge is the fragmented nature of supply chains, which makes high-quality data difficult to obtain. Activity data, like vehicle mileage or fuel consumption, is often scattered across various systems such as Transport Management Systems (TMS) and Enterprise Resource Planning (ERP) platforms, leading to data silos. Extracting, cleaning, and organizing this data to make it useful for emissions calculations can be highly labor-intensive.
The various emissions reporting standards and differing data formats across regions exacerbate the problem. For example, a shipment moved by truck across Europe might adhere to different reporting requirements than the same shipment moved by rail or sea across North America. This lack of global standardization makes it challenging to integrate emissions data consistently across each leg of a journey.
Proprietary information also poses a barrier to data availability. Many companies rely on third-party logistics (3PL) providers, and the transparency and granularity of data from these external partners can vary widely. In cases where a 3PL partner cannot provide precise details—like the type of vehicle or fuel used—companies must make assumptions. Common data gaps such as these make it difficult to accurately track, report, compare, and ultimately reduce transport-related emissions.
With so many aspects to consider, accurately calculating freight emissions can be highly complex—especially for ERP platforms or 3PL providers managing data for multiple customers. If you’re looking for a scalable solution that plugs into your existing software, you can explore Climatiq’s Freight emissions solution here.
