How can climate adaptation policy enhance urban climate resilience? Empirical evidence from China

PLOS One | https://doi.org/10.1371/journal.pone.0335736 November 6, 2025 16 / 21 is the 10-year lagged PM2.5 air pollution index, denoted as L10_Pollution. Historically, cities with severe air pollution may have more substantial incentives to issue green bonds. However, historical pollution levels (represented by the 10-year lagged PM2.5 index) are theoretically unlikely to directly influence current urban climate resilience. Therefore, L10_Pollution as the instrumental variable for GB satisfies the relevance and exogeneity conditions. The results of the instrumental variable method are presented in Table 7. The results indicate that, based on the passing of the F-statistic and Hausman tests, the effect of the treated on GB and the effect of GB on Resilience remain significantly positive, consistent with the results of the aforementioned mediation mechanism tests. Therefore, the mediation mechanism test results in this study are highly reliable. On the other hand, we employed the event study method to conduct a parallel trend test on the TWFE estimate of the CACCP policy effect, with the results shown in Fig 8. The findings indicate that the TWFE estimates of the policy effects satisfy the parallel trend assumption. This result suggests that the triple difference (DDD) estimation used in the modera- tion mechanism test possesses some methodological robustness. Additionally, the fit of the moderation effect model in this study is highly satisfactory (0.9457, 0.9492, and 0.9377). Based on the above analysis, the moderation mechanism test results exhibit a high reliability.

5. Discussion and conclusions This paper focuses on China’s Climate-Adaptive City Construction Pilot Program (CACCP), utilizing panel data from 57 cities in the Yellow River Basin—a region characterized by ecological fragility—from 2010 to 2022. It employs Synthetic DID, stepwise regression, Sobel tests, and triple difference methods to empirically analyze the impact of the CACCP policy on urban climate resilience and its underlying mechanisms. The main research conclusions are: (1) Urban climate resilience is defined as a city’s comprehensive ability to adapt to long-term climate change trends, including stability, coor- dination, and transformation capabilities. Based on this, the study constructed an urban climate resilience assessment indicator system comprising 26 indicators. (2) Empirical results indicate that the CACCP policy significantly enhances urban climate resilience. This conclusion remains valid after a series of robustness tests. (3) Mechanism tests reveal that green bonds significantly mediate the CACCP policy’s enhancement of urban climate resilience; urban education and Table 7. Endogeneity test results. Variable treated GB GB Resilience L5_ERD -0.1755** (0.0782) treated 0.8003** (0.4038) L10_Pollution 0.2106** (0.0908) GB 0.2717** (0.1299) Constant 0.2382** (0.0946) −0.1465 (0.1209) −0.0057 (0.0485) 0.0612*** (0.0144) Controls YES YES YES YES City FE YES YES YES YES Year FE YES YES YES YES N 741 741 741 741 First-stage F-statistic 10.09*** 16.14*** Hausman 33.37*** 106.69*** https://doi.org/10.1371/journal.pone.0335736.t007