Bicycle use is an important, but by no means the only, explanatory factor in the relation between CO2 emissions per capita and mobility. Other important factors are urban planning characteristics, composition of the population and transport behaviour of residents. Goudappel Coffeng studied CO2 emissions per capita by using the mobility data from Mobiliteits Onderzoek Nederland (MON) and data on CO2 emissions per kilometre travelled by car, bicycle, bus or train. That led to a survey of average production of CO2 per capita by town. Among the towns of over 100,000 inhabitants Leiden (percentage of bicycle use 48%) , Amsterdam (38%), Haarlem (36%), Enschede (38%) and Rotterdam (26%) obtained high scores.
The fact that bicycle use is not always a decisive factor is demonstrated by Rotterdam. There most progress is made by an increase in public transport use and fewer journeys per person per day. And despite a high percentage of bicycle use (48%) Zwolle does not rank high, as do Emmen, Amersfoort and Almere.
The study leads to the conclusion that there are major differences among Dutch towns in the use of public transport and bicycles. This provides opportunities for local authorities to take action.