IPCC Climate Change 2022 report discusses amongst other things (in a 3000 page document) the importance of how we build our cities and the change to modes of transport can greatly increase our emissions as a society. Cycling has, apart from walking, the lowest emission of any transport mode. To make cycling for transport work, we need to build our city to support it. Here are highlights relating to these topics.
In the city of Lisbon, Portugal, improvements in cycling infrastructure and bike-sharing system resulted in 3.5-times more cyclists within 2 years.
In Copenhagen, the cost of cycling (0.08 €/km) is declining and is about 6 times lower than car driving (0.50 €/km).
In addition, participants were willing to cycle 1.84 km longer if the route has a designated cycle track and 0.8 km more if there are also green surroundings.
Build it and they will come. IPCC 2022 Full Report, 8-70, 8-71
Chapter 8 Urban Systems and Other Settlement, IPCC 2022 Full Report
Executive Summary
Integrated spatial planning to achieve compact and resource-efficient urban growth through co-location of higher residential and job densities, mixed land use, and transit-oriented development could reduce GHG emissions between 23-26% by 2050 compared to the business-as-usual scenario (robust evidence, high agreement, very high confidence). Compact cities with shortened distances between housing and jobs, and interventions that support a modal shift away from private motor vehicles towards walking, cycling, and low-emissions shared and public transportation, passive energy comfort in buildings, and urban green infrastructure can deliver significant public health benefits and have lower GHG emissions. {8.2, 8.3.4, 8.4, 8.6}
IPCC 2022 Full Report, 8-6
Compact city policies and interventions that support a modal shift away from private motor vehicles towards walking, cycling, and low-emission public transport delivers significant public health benefits (Creutzig 2016; Ürge-Vorsatz et al. 2018). Trade-offs associated with compact development include the marginal health costs of transport air pollution (Lohrey and Creutzig 2016) and stress from traffic noise (Gruebner et al. 2017) (Section 8.4.2.2).
IPCC 2022 Full Report, 8-23
Measures from different sectors that can provide both mitigation and adaptation benefits involve urban planning (see Section 8.4.2), buildings (Sections 8.4.3.2 and 8.4.4), energy (Section 8.4.3), green and blue infrastructure (Section 8.4.4), transportation (Section 8.4.2), socio-behavioural aspects (Section 8.4.5), urban governance (Section 8.5), waste (Section 8.4.5.2), and water (Section 8.4.6). In addition to their energy-saving and carbon-sequestration benefits, many measures can also enhance adaptation to climate threats, such as extreme heat, energy shocks, floods, and droughts (Sharifi 2021). Existing evidence is mainly related to urban green infrastructure, urban planning, transportation, and buildings. There has been more emphasis on the potential co-benefits of measures, such as proper levels of density, building energy efficiency, distributed and decentralised energy infrastructure, green roofs and facades, and public/active transport modes.
IPCC 2022 Full Report, 8-25
8.4.2 Spatial planning, urban form, and infrastructure 43
Urban form is the resultant pattern and spatial layout of land use, transportation networks, and urban design elements, including the physical urban extent, configuration of streets and building orientation, and the spatial figuration within and throughout cities and towns (Lynch 1981; Handy 1996).
IPCC 2022 Full Report, 8-54
Compact and walkable urban form has many co-benefits, including mental and physical health, lower resource demand, and saving land for AFOLU. In contrast, dispersed and auto-centric urban form is correlated with higher GHG emissions, and characterised by separated land uses, low population and job densities, large block size, and low intersection density.
IPCC 2022 Full Report, 8-54
Dispersed and auto-centric urban form is strongly correlated with high GHG emissions, and characterised by separated land uses, especially of housing and jobs, low street density, large block sizes, and low urban densities. Separated and low densities of employment, retail, and housing increase average travel distances for both work and leisure, and make active transport and modal shift a challenge. Since cities are systems, urban form has interacting implications across energy, buildings, transport, land use, and individual behaviour. Compact and walkable urban form enables effective mitigation while dispersed and auto-centric urban form locks-in higher levels of energy use.
IPCC 2022 Full Report, 8-55
Greenways support stormwater management to mitigate water runoff and urban floods by reducing the water volume (e.g., through infiltration) and by an attenuation or temporal shift of water discharge (Fiori and Volpi 2020; Pour et al. 2020). Using green infrastructure delays the time to runoff and reduces water volume but depends on the magnitude of floods (Qin et al. 2013).
IPCC 2022 Full Report, 8-55
Providing a connected system of greenspace throughout the urban area may promote active transportation (Nieuwenhuijsen and Khreis 2016), thereby reducing GHG emissions. Soft solutions for improving green infrastructure connectivity for cycling is an urban NBS mitigation measure, although there is low evidence for emissions reductions. In the city of Lisbon, Portugal, improvements in cycling infrastructure and bike-sharing system resulted in 3.5-times more cyclists within two years (Félix et al. 2020). In Copenhagen, the cost of cycling (Euro 0.08/km) is declining and is about six times lower than car driving (Euro 0.50/km) (Vedel et al. 2017). In addition, participants were willing to cycle 1.84 km longer if the route has a designated cycle track and 0.8 km more if there are also green surroundings. Changes in urban landscapes, including through the integration of green infrastructure in sustainable urban and transport planning, can support the transition from private motorised transportation to public and physically active transportation in carbon-neutral, more liveable and healthier cities (Nieuwenhuijsen and Khreis 2016; Nieuwenhuijsen 2020). Car infrastructure can be also transferred into public open and green space, such as in the Superblock model in Barcelona’s neighbourhoods (Rueda 2019). Health impact assessment models estimated that 681 premature deaths may be prevented annually with this implementation (Mueller et al. 2020) and the creation of greenways in Maanshan, China has stimulated interests in walking or cycling (Zhang et al. 2020).
IPCC 2022 Full Report, 8-70, 8-71
8.4.5 Socio-behavioural aspects
Transport emissions can be reduced by options including telecommuting (0.3%), taking closer holidays (0.5%), avoiding short flights (0.5%), using public transit (0.7%), cycling (0.6%), car sharing (1.1%), and carpool commuting (1.2%); all reduction estimates reflect cumulative per capita emission savings relative to baseline emissions for the period 2011–2050, and assume immediate adoption of behavioural changes (van de Ven et al. 2018). Cities can support voluntary shift to walking, cycling, and transit instead of car use through changes to urban form, such as TOD (Kamruzzaman et al. 2015), increased density of form with co-location of activities (Ma et al. 2015; Ding et al. 2017; Duranton and Turner 2018; Masoumi 2019), and greater intersection density and street integration (Koohsari et al. 2016). Mechanisms such as providing financial incentives or disincentives for car use can also be effective in reducing emissions (Wynes et al. 2018) (see Section 8.4.2).
IPCC 2022 Full Report, 8-71
8.4.5.1 Increasing locational and mobility options
Spatial planning, urban form, and infrastructure can be utilised to deliberately increase both locational and mobility options for socio-behavioural change in support of urban mitigation. The mitigation impacts of active travel can include a reduction of mobility-related lifecycle CO2 emissions by about 0.5 tonnes over a year when an average person cycles one trip per day more, and drives one trip per day less, for 200 days a year (Brand et al. 2021). Urban areas that develop and implement effective 15/20-minute city programs are very likely to reduce urban energy use and multiply emission reductions, representing an important cascading effect.
IPCC 2022 Full Report, 8-72
Accessibility as a criterion widens the focus beyond work trips and VMTs, paying attention to a broader set of destinations beyond workplaces, as well as walking and biking trips or active travel. It holds promise for targeting and obtaining greater reductions in GHG emissions in household travel by providing access through walking, biking, and public transit. Accessibility as a criterion for urban form has been embedded in neighbourhood form models since at least the last century and in more recent decades in the urban village concept of the New Urbanism (Duany and Plater-Zyberck 1991) and TODs (Calthorpe 1993). However, accessibility did not gain much traction in urban planning and transportation until the last decade. The experience of cities and metropolitan areas with the COVID-19 pandemic has led to a further resurgence in interest and importance (Handy 2020; Hu et al. 2020), and is becoming a criterion at the core of the concept of the 15/20-minute city (Moreno et al. 2021; Pozoukidou and Chatziyiannaki 2021). Initially, neighbourhoods have been designed to provide quality, reliable services within 15 or 20 minutes of active transport (i.e., walking or cycling), as well as a variety of housing options and open space (Portland Bureau of Planning and Sustainability 2012; Pozoukidou and Chatziyiannaki 2021; State Government of Victoria 2021). Community life circles strategy for urban areas have also emphasised walking access and health (Weng et al. 2019; Wu et al. 2021). The growing popularity of the 15/20-minute city movement has significant potential for reducing VMT/VKT and associated GHG emissions.
IPCC 2022 Full Report, 8-72
8.6.4 COVID-19 and cities
A promising transformation that has been observed in many cities is an increase in the share of active travel modes such as cycling and walking (Sharifi and Khavarian-Garmsir 2020).
IPCC 2022 Full Report, 8-96
Cities could seize this opportunity to provide better infrastructure to further foster active transportation. This could, for example, involve measures, such as expanding cycling networks and restricting existing streets to make them more pedestrian- and cycling-friendly contributing to health and adaptation co-benefits as discussed in Section 8.2 (Sharifi 2021).
IPCC 2022 Full Report, 8-96
References
Brand, C. et al., 2021: The climate change mitigation impacts of active travel: Evidence from a longitudinal panel study in seven European cities. Glob. Environ. Chang., 67, 102224, doi:10.1016/j.gloenvcha.2021.102224.
Félix, R., P. Cambra, and F. Moura, 2020: Build it and give ‘em bikes, and they will come: The effects of cycling infrastructure and bike-sharing system in Lisbon. Case Stud. Transp. Policy, 8(2), 672–36 682, doi:10.1016/j.cstp.2020.03.002.
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