Editing IPCC:AR6/WGIII/Chapter-8 (section)

=== 8.6.2 Mitigation Opportunities for Rapidly Growing Cities ===

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'''Rapidly growing cities with new and actively developing infrastructures can avoid higher future emissions through using urban planning to co-locate jobs and housing, and achieve compact urban form; leapfrogging to low-carbon technologies; electrifying all urban services, including transportation, cooling, heating, cooking, recycling, water extraction, wastewater recycling, and so on; and preserving and managing existing green a''' '''nd blue assets.'''

Rapidly growing cities have significant opportunities for integrating climate mitigation response options in earlier stages of urban development, which can provide even greater opportunities for avoiding carbon lock-in and shifting pathways towards net-zero GHG emissions. In growing cities that are expected to experience large increases in population, a significant share of urban development remains to be planned and built. The ability to shift these investments towards low-carbon development earlier in the process represents an important opportunity for contributing to net-zero GHG emissions at the global scale. In particular, evidence suggests that investment in low-carbon development measures and reinvestment based on the returns of the measures, even without considering substantial co-benefits, can provide tipping points for climate mitigation action and reaching peak emissions at lower levels while decoupling emissions from economic growth, even in fast-growing megacity contexts with well-established infrastructure ( [[#Colenbrander--2017|Colenbrander et al. 2017]] ).

At the same time, some of the rapidly growing cities in developing countries can have existing walkable urban design that can be maintained and supported with electrified urban rail plus renewable-energy-based solutions to avoid a shift to private vehicles ( [[#Sharma--2018|Sharma 2018]] ). In addition, community-based distributed renewable electricity can be applicable for the regeneration of informal settlements rather than more expensive informal settlement clearance ( [[#Teferi--2018|Teferi and Newman 2018]] ). Scalable options for decentralised energy, water, and wastewater systems, as well as spatial planning and urban agriculture and forestry, are applicable to urban settlements across multiple regions simultaneously ( [[#Lwasa--2017|Lwasa 2017]] ).

Rapidly urbanising areas can experience pressure for rapid growth in urban infrastructure to address growth in population. This challenge can be addressed with coordinated urban planning and support from enabling conditions for pursuing effective climate mitigation ( [[#8.5|Section 8.5]] and Box 8.3). The ability to mobilise low-carbon development will also increase opportunities for capturing co-benefits for urban inhabitants while reducing embodied and operational emissions. Transforming urban growth, including its impacts on energy and materials, can be carefully addressed with the integration of cross-sectoral strategies and policies.

Rapidly growing cities have entry points into an integrated strategy based on spatial planning, urban form and infrastructure (Figure 8.21). For rapidly growing cities that may be co-located and walkable at present, remaining compact is better ensured when co-location and mixed land use, as well as TOD, continues to be prioritised ( [[#8.4.2|Section 8.4.2]] ). Concurrently, ensuring that electricity and energy carriers are decarbonised while electrifying mobility, heating and cooling will support the mitigation potential of these cities. Along with an integrated approach across other illustrative strategies, switching to net-zero materials and supply chains holds importance ( [[#8.4.3|Section 8.4.3]] ). Cities that remain compact and walkable can provide a greater array of locational and mobility options to the inhabitants that can be adopted for mitigation benefits. Rapidly growing cities that may currently be dispersed and auto-centric can capture high mitigation potential through urban infill and densification. Conserving existing green and blue assets, thereby protecting sources of carbon storage and sequestration, as well as biodiversity, have high potential for both kinds of existing urban form, especially when the rapid growth can be controlled.

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