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Performance determinants show European cities are delivering on climate mitigation


Cities are crucial climate change actors, developing largely voluntary action plans and emission reduction targets. There is limited evidence, however, of their impact through transnational climate initiatives and little empirical support linking mitigation strategies and emissions reductions. Here, we show that 60% of more than 1,000 EU Covenant of Mayors’ cities are on track to achieve their 2020 emission reduction targets. Assessments of cities’ mitigation outcomes and the determinants of performance show that on-track cities tend to have less-ambitious targets and higher baseline emissions and are in countries with more-ambitious national climate policies and greater realized emissions reductions than cities that are not on track. Automated textual analysis and a regression model find city emissions reduction is influenced by plan-level, city-level and country-level characteristics. Greater emissions reductions are associated with plans targeting energy efficiency. These results of city-level achievement provide empirical support for the theorized subnational actors’ contribution to global climate mitigation.

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Fig. 1: Map of emissions reduction performance calculated for 1,066 cities in Europe where sufficient data are available.
Fig. 2: Comparison of performance metrics between cities that are on track to achieve their state emission reduction goals (⍴ ≥ 1; n = 643) and those that are not (⍴ < 1; n = 423).
Fig. 3: Impact of ambition and climate actions on annualized percentage reduction in per capita emissions.
Fig. 4: Topic prevalences and key terms in the analysis.

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Data used to create figures are available at and on the Harvard Dataverse Network70 ( Source data are provided with this paper.

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This research was supported by a 2018 National University of Singapore Early Career Award to A.H. We thank R. Rauber and Z.Y. Yeo of Yale-NUS College for their assistance in data collection. We thank A. Weinfurter of the Data-Driven EnviroLab for assistance with the Supplementary Information. We thank S. McDaniel of the Global Covenant of Mayors for Climate and Energy and P. Bertoldi and N. Vetters of the EU Covenant of Mayors for their inputs and feedback on this paper.

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A.H. conceived and designed the study, collected data, conducted statistical analysis, made figures and wrote the paper. N.G. conducted background research and statistical analysis and contributed to the paper’s writing. Y.M.N. helped design the statistical model and conducted statistical analysis. J.T., W.T. and RV conducted the structural topic modelling.

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Correspondence to Angel Hsu.

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The authors declare no competing interests.

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Peer review information Nature Climate Change thanks Daniel Hoornweg, Stephen Jones, Albana Kona and Diana Reckien for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Additional information on EUCoM emission inventories and reporting requirements, Supplementary Figs. 1–3 and Tables 1–10.

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Hsu, A., Tan, J., Ng, Y.M. et al. Performance determinants show European cities are delivering on climate mitigation. Nat. Clim. Chang. 10, 1015–1022 (2020).

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