While everyone knows that active transportation is good for you, there has been little data on exactly how much carbon emissions are lowered by walking, biking or taking public transit.

A new study published in Elsevier looked at the climate change impact of daily commuting using active travel. By gathering travel activity information in seven European cities  this study found that car travel contributed seventy percent to CO2 emissions across different modes and cycling contributed to just one percent.

Christian Brand at Oxford University and twenty other researchers concluded that if a car driver or passenger changed from a car to a bicycle they decreased “life cycle” CO2 emissions by 3.2 kilograms of CO2 daily.

This study looked at data from several cities instead of just one, and also took into account “full life cycle impacts” of both active and vehicular travel. Using life cycle analysis cycling is not “zero-carbon” emissions because of the creation, maintenance and eventual trashing of bikes, and any associated batteries and motors. The researchers did note that life cycle emissions for passenger vehicle travelled are ten times higher than that of cyclists.

The researchers looked at “short to medium sized trips, ” typically 2 km for walking, 5 km for cycling and 10 km for e-biking ” It is these short trips that “contribute disproportionately” to emissions when conducted by vehicle because of cold engine starts.