Urban scenario approaches with quartiles of benchmarked performance and co-benefits

Urban areas have a key role in mitigating climate change through decarbonisation and improving the lives of their inhabitants. This research work develops three scenario approaches that interface a multi-dimensional composite indicator with urban scenarios. First, urban emissions and the impact of urban growth on local biomes are analysed based on quartiles of benchmarked performance. Across 97 urban areas, the quartile of the challenged cities is projected to have 648.98 MtCO2eq of annual urban emissions in 2050 under a less ambitious green growth scenario. Those of the other quartiles are up to 159.98 MtCO2eq (solution-seeking), 121.61 MtCO2eq (transitioning), and 77.11 MtCO2eq (pioneering cities) in 2050. Based on cumulative urban emissions, challenged cities hold 69.39 % of the potential to avoid additional increments of global warming in 2050. Additionally, various convergence in the near-term or scenario-driven improvements in the multi-dimensional composite indicator provide other scenario possibilities. The index average for the 97 urban areas can increase to 41.490 when coupled with the more ambitious mitigation scenarios and 41.498 considering Monte Carlo simulations. Improved air quality can save 120,408 human lives as co-benefits for health. Illustrative cases from different regions are then discussed and the three scenario approaches are coded in modules to enable their broader application. The results are envisioned to support urban mitigation efforts and better align scenarios to realise co-benefits in a safer climate future.