Systemic change and decarbonisation are not possible without behavioural change (Capstick et al. 2014; Nelson and Allwood 2021; Huckebrink and Bertsch 2021). The Intergovernmental Panel on Climate Change (IPCC) and the United Nations Environment Programme (UNEP) highlight the significant mitigation potential of behavioural shifts, particularly in transport (UNEP 2020; Jaramillo et al. 2023). Yet, the majority of nationally determined contributions (NDCs) do not explicitly incorporate behavioural mitigation strategies (Parkin et al., 2024). This gap suggests that behavioural interventions have yet to be systematically quantified and operationalised within national climate policy frameworks, underscoring the need for robust estimates regarding their mitigation potential if behavioural change is to be treated as a measurable lever for global emission reduction to achieve the objectives of the Paris Agreement. In this context, India’s Mission Lifestyle for Environment (LiFE), announced at COP26 in 2021, and the subsequent G20 High Level Principles on Lifestyles for Sustainable Development of 2023, have set the stage for global coordination on demand-side mitigation.
This study estimates the potential for lowering emissions in G20 countries by altering passenger transport behaviour, grouping countries into developing countries and developed countries + China to account for the uneven distribution of emissions within the G20 (UNEP 2025). G20 members account for 84% of the global GDP, 60% of the world’s population (World Bank 2026), and, as of 2024, 78% of the global CO2 emissions (Crippa et al. 2025). Developed nations and China, just 34% of the world’s population, were responsible for over 60% of global road transport emissions that year (Crippa et al. 2025). Motor vehicle ownership follows a similar pattern: 860 per 1,000 people in the USA, 704 in France, 223 in China, and 33 in India (OICA 2024), reflecting how economic levels, infrastructure, and lifestyle shape mobility demand across nations.
This study uses the Global Change Analysis Model (GCAM) V8.2 to model three behavioural interventions in passenger transport: (1) hybrid work, (2) shared mobility, and (3) increased bus ridership, chosen for being system-wide, scalable, easy to quantify, and consistently highlighted in global assessments due to their measurable impacts across diverse national contexts. The scenarios model these levers separately and in combination, recognising that multiple behavioural measures are likely to be pursued concurrently in practise.
The paper can be accessed here.
(The views expressed are personal)
This paper is authored by Rohini Dikshit, Chetna Arora, Pallavi Das, and Vaibhav Chaturvedi, CEEW.