The climate change mitigation effects of daily active travel in cities

Christian Brand,Sonja Kahlmeier,Mailin Gaupp-Berghausen,Arnout Standaert,Francesco Iacorossi,Elisabeth Raser,Luc Int Panis,David Rojas-Rueda,Michelle Laeremans,Francesca Racioppi,Simona Sulikova,Thomas Götschi,Sandra Wegener,Evi Dons,Regine Gerike,Audrey De Nazelle,Esther Anaya-Boig,Anna Clark,Erik Stigell,Juan Pablo Orjuela,Mark Nieuwenhuijsen ,Mireia Gascón ,Ione Ávila-Palència

doi:10.1016/j.trd.2021.102764

Abstract

Active travel (walking or cycling for transport) is considered the most sustainable form of personal transport. Yet its net effects on mobility-related CO2 emissions are complex and under-researched. Here we collected travel activity data in seven European cities and derived life cycle CO2 emissions across modes and purposes. Daily mobility-related life cycle CO2 emissions were 3.2 kgCO2 per person, with car travel contributing 70% and cycling 1%. Cyclists had 84% lower life cycle CO2 emissions than non-cyclists. Life cycle CO2 emissions decreased by −14% per additional cycling trip and decreased by −62% for each avoided car trip. An average person who ‘shifted travel modes’ from car to bike decreased life cycle CO2 emissions by 3.2 kgCO2/day. Promoting active travel should be a cornerstone of strategies to meet net zero carbon targets, particularly in urban areas, while also improving public health and quality of urban life.

Highlights

Transport has been one of the most challenging sectors for reducing its significant impacts of fossil energy use and associated greenhouse gas (GHG) emissions since the 1990s (Sims et al, 2014)
The observed cycling trip share for our sample was between 17% in Barcelona and 54% in Antwerp (Supplementary Table S1), i.e. somewhat higher than cycling shares reported for the cities (EPOMM, 2020) and a direct result of purposively oversampling cyclists
We found statistically significant associations between life cycle CO2 emissions and the main modes of travel according to daily distance travelled (Table 3b): when compared to using a bike as the main mode, using the car or public transport increased CO2 while walking decreased CO2

Summary

Introduction

Transport has been one of the most challenging sectors for reducing its significant impacts of fossil energy use and associated greenhouse gas (GHG) emissions since the 1990s (Sims et al, 2014). Beyond a net reduction in travel demand, one of the more promising ways to reduce transport carbon dioxide (CO2) emissions[1] is to promote and invest in active modes of transport (e.g. walking, cycling, e-biking) while ‘demoting’ motorized modes that rely on fossil energy sources (Bearman and Singleton, 2014; Castro et al, 2019; de Nazelle et al, 2010; ECF, 2011; Frank et al, 2010; Goodman et al, 2012; Keall et al, 2018; Neves and Brand, 2019; Quarmby et al, 2019; Sælensminde, 2004; Scheepers et al, 2014; Tainio et al, 2017; Woodcock et al, 2018) This could reduce CO2 emissions from road transport more quickly than technological measures alone, in urban areas (Beckx et al, 2013; Creutzig et al, 2018; Graham-Rowe et al, 2011; Neves and Brand, 2019). This may become even more relevant considering the vast economic effects of the COVID-19 pandemic, which may result in reduced capacities of individuals and organizations to renew the rolling stock of vehicles in the short and medium period, and of governments to provide incentives to fleet renewal

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