Grams of CO2 produced for every passenger per kilometre travelled.
Air (domestic) – 316
Air (short haul) – 260
Air (long haul) – 210
Car (1 passenger) – 200
Car (1.56 passengers) – 128
Motor Bike
Cycle
Bus – 70
Coach – 25
Sea Ferry – 45
Train – 22
Taxis – 600 (1 passenger)
Reference 1: http://www.defra.gov.uk/sustainable/government/
“Green guide for buyers – Climate change (action sheet)”