A comparison of carbon dioxide emissions associated with motorised transport modes and cycling in Ireland

Cycling is widely viewed as a transport mode with marginal environmental impacts. However, such a view fails to take account of such factors as the increase in carbon dioxide exhaled as a result of increased physical activity or the emission embodied in the manufacture of the bicycle. This paper presents estimates of emission factors for various forms of commuter transport in Ireland that allow comparison against emissions from cycling. When indirect energy is taken into account, the results presented here indicate that a cyclist commuting an equivalent distance to work releases an almost equal amount of carbon dioxide as that attributed to a passenger of an electrically propelled train at full occupancy during peak service times. Travel by bicycle is much less carbon intensive when compared to passengers travelling at off-peak times. Transport by car and sports utility vehicle is the most carbon intensive of the commuter modes of transport studied, however, travelling in a fully occupied car has an emission factor approaching that of off-peak bus transport.