Transport emissions, mode by mode
Per-passenger-km emissions for every mode you might choose for a given trip. The same 500 km journey can be 20× more or less carbon-intensive depending on what you take.
CO2 per passenger-kilometre
| Mode | kg CO2e / passenger-km | Relative |
|---|---|---|
Petrol car (alone) DEFRA, average | 0.171 | |
Flight (short-haul) <1500 km | 0.158 | |
Taxi (per passenger) DEFRA | 0.150 | |
Flight (medium-haul) 1500-5000 km | 0.149 | |
Flight (long-haul) DEFRA, with radiative forcing | 0.146 | |
Hybrid (alone) DEFRA | 0.121 | |
Bus (per passenger) DEFRA | 0.105 | |
Plug-in hybrid (alone) DEFRA | 0.084 | |
Petrol car (4 passengers) per-person split | 0.043 | |
Rail (per passenger) DEFRA, average | 0.041 | |
Metro (per passenger) DEFRA | 0.029 |
What actually shifts your transport number
- One long-haul flight typically dwarfs every other transport choice for the year combined.
- Carpooling halves a car's per-person emissions. Two people in a petrol car beat a half-empty bus.
- Trains are nearly always cleanest on European-style high-speed networks. The factor is < 50 g CO2/passenger-km even on dirtier grids.
- Walking and cycling are zero on the marginal trip (lifecycle emissions of bikes/shoes are negligible at any reasonable use rate).