The deterioration of the environmental performance index that compares hazard management across cities and countries

Government entities play a critical role in designing and implementing effective mitigation and adaptation strategies to address climate change. At the same time, cities are key actors in applying local environmental policies. This paper evaluates and compares the environmental performance of urban areas and countries to identify the most effective level of governance. To achieve this, an innovative quantitative index is computed: the Deterioration of Environmental Performance Index (DEPI). This composite index offers valuable insights into the sustainability of territorial development strategies. The DEPI's annual evolution is examined for ten OECD countries and their respective urban areas over the period 2001–2020. Statistical analysis reveals that, in most cases, national-level environmental management outperforms urban areas. Specifically, all countries with non-ambiguous results exhibit lower DEPI scores (indicating better performance) than their corresponding urban areas, except for New Zealand. The results for Belgium, South Korea, and the United States of America are inconclusive. These findings highlight the vulnerability of cities to climate-related risks. In summary, national governments seem to demonstrate greater effectiveness than cities in managing five key environmental challenges: air pollution, river flooding, coastal flooding, wildfires, and heatwaves. AcknowledgmentWe thank Federica Daniele from the OECD for her valuable comments and remarks.