What is the carbon footprint of transport?
Transport emitted about 8.4 billion tonnes of CO₂e in 2024, around 16% of the world’s greenhouse gas emissions excluding land use (EDGAR) and nearly a quarter of the CO₂ from energy (IPCC). Road vehicles produce about 70% of it, aviation 12%, shipping 11% and rail 1%. Per kilometre, a domestic flight emits about 229 g of CO₂e per passenger and a petrol car driven alone about 162 g, against about 31 g for a train (UK government factors, 2026).
How much carbon a journey or a shipment produces depends as much on how it travels as on how far. This page brings together the government emission factors for every common way of travelling and moving goods, and the two main estimates of what transport adds up to worldwide, with the sources and assumptions behind each figure.
Carbon per passenger-kilometre
| How you travel | kg CO₂e per km | g CO₂e per km |
|---|---|---|
| Domestic flight (with warming effects at altitude) | 0.22928 | 229 |
| Diesel car, one person | 0.17265 | 173 |
| Petrol car, one person | 0.16152 | 162 |
| Taxi | 0.14861 | 149 |
| Hybrid car, one person | 0.12961 | 130 |
| Ferry, with a car | 0.12933 | 129 |
| Short-haul flight, economy (with warming effects) | 0.12576 | 126 |
| Long-haul flight, economy (with warming effects) | 0.11704 | 117 |
| Motorbike | 0.11367 | 114 |
| Local bus | 0.10151 | 102 |
| Coach | 0.03948 | 39 |
| National rail | 0.03092 | 31 |
| Electric car, one person (UK grid) | 0.02951 | 30 |
| Tram or light rail | 0.02121 | 21 |
| Ferry, on foot | 0.01871 | 19 |
| London Underground | 0.01549 | 15 |
| Eurostar (international rail) | 0.01135 | 11 |
Car and motorbike figures are per vehicle, so they apply to one person travelling alone: two people sharing a petrol car emit about 81 g each, less than a local bus at its average occupancy (102 g). Bus, rail, ferry and flight figures already share the emissions among the average number of passengers. The flight figures include DEFRA’s allowance for the extra warming that aircraft cause at altitude through contrails and nitrogen oxides; without it a domestic flight is about 136 g per passenger-km (see radiative forcing). The electric car figure uses the UK grid’s 2026 factor, so it is higher in countries whose electricity comes mostly from coal.
Swapping a domestic flight for the train cuts the emissions of the journey by about 87%, and a coach is almost as good as rail. The train vs plane vs car calculator works out a specific journey, and the guides to flying, cars and cruise ships go into each in more detail.
Moving goods: carbon per tonne-kilometre
| Mode | kg CO₂e per tonne-km | g CO₂e per tonne-km |
|---|---|---|
| Air (long-haul, in passenger planes’ holds) | 0.9360 | 936 |
| Lorry (North American average, mixed loads) | 0.1000 | 100 |
| Rail (EU average) | 0.0184 | 18.4 |
| Ship (Panamax bulk carrier) | 0.0052 | 5.2 |
Flying a tonne of goods a kilometre emits about 180 times as much as shipping it in a bulk carrier, and about nine times as much as a lorry. Each figure is one representative case from the GLEC Framework: the lorry figure is the North American average for mixed loads, the rail figure the EU average, and the ship a dry-bulk carrier of 60,000–99,999 deadweight tonnes burning heavy fuel oil. Container ships are measured per container rather than per tonne. Real shipments vary with load, route and fuel; the ISO 14083 standard sets out how companies should calculate them, and the transport and logistics calculators apply it.
Transport’s share of global emissions
| Measure | Figure | Source |
|---|---|---|
| Transport emissions, 2024 | 8.44 billion t CO₂e | EDGAR 2025 |
| Share of global emissions (excluding land use), 2024 | 15.9% | EDGAR 2025 (our calculation) |
| Transport emissions, 2019 | 8.7 billion t CO₂e | IPCC AR6 |
| Share of energy-related CO₂, 2019 | 23% | IPCC AR6 |
| Share of all greenhouse gases, 2019 | about 15% | IPCC AR6 |
| Transport emissions, 1990 | 4.71 billion t (EDGAR); 5.0 billion t (IPCC) | EDGAR 2025; IPCC AR6 |
Transport emissions have grown by about 79% since 1990 on EDGAR’s figures, and the IPCC notes that since 2010 they have grown faster than those of any other end-use sector, at an average of 1.8% a year. The IPCC ranks transport as the fourth-largest source of greenhouse gases, after electricity and heat, industry, and agriculture and land use. Its 2019 total is given as 8.7 billion tonnes in the chapter summary and 8.9 billion in the chapter itself; EDGAR’s figure for the same year is 8.43 billion, from different data and an older set of warming values for methane and nitrous oxide. Almost all of it is carbon dioxide from burning fuel.
Road, air, sea and rail
Share of direct transport emissions by mode, 2019. Source: IPCC AR6 WGIII, Chapter 10. The four add up to 94%; the IPCC does not itemise the rest, such as pipelines.
Cars, vans, lorries, buses and motorbikes produce most transport emissions. Aviation and shipping are smaller but, the IPCC notes, still growing fast. International flights and shipping, which fall outside any one country’s total, emitted about 619 million and 704 million tonnes of CO₂e in 2024 on EDGAR’s figures.
What these figures count
- Direct emissions only, mostly. The DEFRA passenger factors count the fuel burned, or for electric cars and trains the electricity generated; they leave out producing and delivering the fuel (well-to-tank) and building vehicles and roads. The GLEC freight factors include fuel production (well-to-wheel), so they are not directly comparable with the passenger figures.
- UK averages. DEFRA’s factors reflect UK vehicles, occupancy and electricity. A fuller bus, a newer plane or a cleaner grid changes the numbers.
- Sector totals. The global figures count fuel burned in vehicles, ships and planes, not making vehicles or building roads and railways, which count under other sectors such as industry.
Frequently asked questions
About 8.4 billion tonnes of CO₂e in 2024, around 16% of global greenhouse gas emissions excluding land use, according to the EU’s EDGAR database. The IPCC puts transport at 23% of energy-related CO₂ in 2019. Road vehicles produce about 70% of it.
Walking and cycling, then rail. In the UK government’s 2026 factors, national rail emits about 31 g of CO₂e per passenger-km, a coach about 39 g and Eurostar about 11 g, against about 162 g for a petrol car with one person and 229 g for a domestic flight.
Per passenger-km, a domestic flight (about 229 g CO₂e including warming effects at altitude) emits more than a petrol car driven alone (about 162 g). A car with two or more people, or an electric car, comes out well ahead. Long-haul flights emit less per km than domestic ones but cover far greater distances.
Road vehicles, including cars, vans, lorries, buses and motorbikes, produced about 70% of direct transport emissions in 2019, according to the IPCC. Aviation produced 12%, shipping 11% and rail 1%.
By sea. A bulk carrier emits about 5 g of CO₂e per tonne-km in the GLEC Framework, rail about 18 g, a lorry about 100 g and air freight about 936 g, so moving goods by air emits around 180 times as much as by ship.
Sources: DEFRA/DESNZ, Greenhouse gas reporting: conversion factors 2026; Smart Freight Centre, GLEC Framework v3.2; Jaramillo, P. et al. (2022), “Transport”, in Climate Change 2022: Mitigation of Climate Change, IPCC AR6 Working Group III, Chapter 10; Crippa, M. et al. (2025), GHG emissions of all world countries, JRC/IEA (EDGAR_2025_GHG). Related: transport and logistics emissions · DEFRA emission factors · train vs plane vs car calculator