Should We Walk or Take a Car for Minimum Greenhouse Gas Emissions? 2019-01-0996

This paper compares the greenhouse gas (GHG) emissions attributed to driving a popular production vehicle powered by an internal combustion engine (ICE), as well as a hybrid electric vehicle (HEV), with GHG emissions associated with walking, running and bicycling. The purpose of this study is to offer a different perspective on the problem of global warming due to anthropogenic causes, specifically on transportation and eating patterns. In order to accurately estimate emissions, a full life cycle of food has been considered coupled with energy expenditures of the aforementioned activities obtained from several different sources and averaged for more reliable results. The GHG emissions were calculated for Sweden, the UK, and the US. Depending on the availability of certain data, the methodology for different countries was altered slightly. The question whether walking, running or taking a bicycle is better for the environment than driving a car cannot be answered uniquely. This study demonstrates that the answer depends on several factors, such as diet composition, the number of people commuting, vehicle powertrain, as well as the country analyzed. The conclusion is that if one has an eco-friendly diet and travels alone the preferred modes of transport would be bicycling, walking and running, the cleanest of which by far is bicycling. However, if the diet has a higher CO2 footprint, as in the case of diets containing a large amount of meat and/or imported products, then the preference shifts towards cars, among which the most environmentally friendly are hybrid electric vehicles. The same conclusion applies to the cases where the number of people commuting together exceeds two-three persons.