Abstract:

Urban systems play an important role in climate change mitigation. Chapter VIII of Working Group III (WGIII) contribution to the IPCC Sixth Assessment Report (AR6), ‘Urban Systems and Other Settlements’ provides a systematic and comprehensive assessment on how urban systems can help in the mitigation of climate change. It includes co-benefits and trade-offs of urban mitigation strategies, urban systems and greenhouse gas (GHG) emissions, urban mitigation options, governance, institutions and finance, and a roadmap of mitigation strategies for different urbanization types. The report shows that the growing concentration of people and activities by urbanization is an opportunity to simultaneously increase resource efficiency and decarbonize at scale. The urban share of global GHG emissions is substantive. It continues to increase, with much inter-region variation in the magnitude of the increase. In 2030, the construction of new, and upgrading of existing urban infrastructure will result in significant emissions. The increase in urban land areas will also create significant implications for future carbon lock-in. There is an urgent need to integrate urban mitigation strategies to address climate change, given the dual challenges of rising urban GHG emissions and more frequent extreme climate events. Deep decarbonization and systemic transformation are critical for cities to achieve net zero GHG emissions. Based on the report’s conclusions, China needs to pay more attention to climate change mitigation in urban systems. Three broad urban mitigation options can be used, including spatial planning and infrastructure, electrification urban energy systems, and enhancing carbon stocks through urban green and blue infrastructure, to achieve sustainable urbanization from a multi-dimensional and across-sectoral nexus perspective. In addition, China needs to develop urban-scale mitigation goals and carbon peaking pathways and strengthen cooperation and linkages between cities, in order to achieve climate change mitigation.

Key words: Urban systems, Greenhouse gas (GHG) emissions, Carbon lock-in, Climate change mitigation