Understanding the mitigation potential of sustainable urban transport measures across income and gender groups

Highlights

• Impact of climate change mitigation policies for urban transportation on income-gender.

• Stricter policies with faster public transportation systems reduce emissions significantly.

• Emissions reduction from female groups is higher than male groups.

• Discussions on how analysis can influence transport planning and policy

Abstract

The global climate is going through a transformation due to increased GHG emissions. Urban transportation is one of the leading contributors to increased GHG emissions due to its dependency on fossil fuels. Mitigation measures are evaluated globally to reduce the emissions from the transport sector. These mitigation strategies have a disproportionate effect on the income-gender groups, and the emissions contribution is non-uniform across income levels and gender. It is imperative to understand the emissions contribution of these groups. In this study, the CO₂ and PM_2.5 emissions from a combination of eight income-gender groups together are estimated for four urban transport mitigation policy bundles. Further, the emission potential of each mitigation policy bundle for each income-gender group is calculated by comparing emissions from each policy bundle with respective BAU scenario emissions. For a better understanding, policy implication on each income-gender group's specific travel parameters like mode share, average trip length and vehicle kilometres travelled are also assessed. Bundle 4, which is a blend of planning, regulatory, economic and technological policy instruments, showed the highest mitigation potential across all income-gender groups. The study finds that the majority of the female groups showed the highest mitigation potential for both pollutants for 2030 and 2050.

Introduction

In recent decades, global warming, which has changed the earth's climatic system due to prolonged greenhouse gas (GHG) emissions, has become one of the most challenging issues (Finn, 2013). The continuous GHG emissions from various anthropogenic activities reaching the atmosphere caused irreversible changes to the climate (Intergovernmental Panel for Climate Change - IPCC, 2007; IPCC, 2014) and the environment (Guo et al., 2020). The scientific communities worldwide have acknowledged that climate change is a global threat that should be addressed seriously (Cook et al., 2016; Vajjarapu et al., 2019, Vajjarapu et al., 2020). Instances such as forming the United Nations Framework Convention on Climate Change (UNFCCC), Kyoto Protocol and the Paris agreement signify that climate change is being taken seriously (UNFCCC, 2020). In the pursuit of understanding the primary drivers for climate change, many studies have concluded that carbon dioxide (CO₂) emissions are one of the primary reasons for global climate change (Hao et al., 2016; Shindell et al., 2018; Huang et al., 2019; Withey et al., 2019; Peters et al., 2020). Additionally, the pivotal role of industries and the transportation sector in changing the global climate scenario is greatly acknowledged (Hensher, 2008; Satterthwaite, 2008; IPCC, 2014).

The transportation sector stands fourth among the leading contributors of GHGs after electricity, agriculture and industry due to its dependency on fossil fuels (IEA, 2014; IPCC, 2014). Due to rapid urbanization and expanded vehicle growth, the transportation sector shares about 23% of the global CO₂ emissions (IPCC, 2014). To reduce emissions, countries worldwide have resorted to emissions mitigation measures across all sectors, including transportation. Transportation is an essential component of any country's economic system as it helps in the movement of goods, people and information (Rodrigue and Notteboom, 2013). Despite the positive impact on the country's economy, many challenges are associated with this development, such as increased congestion, accidents, air and noise pollution and CO₂ emissions. The impacts of transportation and climate change have a disproportionate effect on gender and income groups (Islam and Winkel, 2017). The mitigation policies' trade-off between economic growth and the environment (Martens, 2006) may supplement the extant vulnerabilities and aggravate socio-economic inequalities (Arsenio et al., 2016). However, these social and economic inequalities are often less represented in the climate change mitigation policy framework, particularly in the transportation sector (Lucas and Pangbourne, 2014; Markkanen and Anger-Kraavi, 2019). The decision-makers should be well informed of the existing carbon inequalities to frame feasible climate change mitigation measures to reduce these socio-economic inequalities (Huang and Tian, 2021).

This paper attempts to develop a framework to evaluate climate change mitigation policies' impact on the urban transportation sector across various income-gender groups. The impacts of these policies on the change in the travel patterns such as modal shift, average trip length (ATL) and Vehicle Kilometres Travelled (VKT) across each income-gender group are studied. Further, the GHG emissions by each income-gender group for each policy are also evaluated to understand the carbon inequalities. This methodological framework and analysis will provide the policymakers with the necessary decision support to formulate equitable climate change mitigation policies for the urban transportation sector. Considering this background, the following are the objectives of the present study:

• To disaggregate the available data into a combination of income-gender groups.

• To evaluate the travel parameters such as mode share, vehicle kilometres travelled (VKT), and average trip length (ATL) for BAU and mitigation policy bundles.

• To estimate the CO₂ and PM_2.5 emissions for the business as usual (BAU) scenario and mitigation policy bundles for all income-gender groups

• Calculating the mitigation potential of each policy bundle across all income-gender groups.