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A new global assessing early warning systems (EWS) for extreme-weather events in large cities finds that while many urban centers report efforts to protect their populations, significant gaps remain—particularly in low- and lower middle-income countries. Led by associate professor Mary Fox, PhD, MPH, and Mary Sheehan, PhD, MPH at the Johns ��ѻ��ý Department of Health Policy and Management and published in May in the online Bulletin of the World Health Organization, the research highlights the uneven distribution of urban EWS and the underutilization of public health expertise in climate adaptation strategies.

The study, Large City Extreme-Weather Early Warning and Public Health Engagement: A Global Assessment, analyzed climate adaptation actions reported by 182 cities with populations exceeding one million. These cities submitted data to the Carbon Disclosure Project (CDP) adaptation database between 2021 and 2023. Using the United Nations’ ‘Early Warnings for All’ framework, the research team examined how cities integrate risk knowledge, hazard monitoring, warning communication, and preparedness to protect their populations from climate-related disasters.

“The findings suggest that while many cities recognize the importance of early warning systems for extreme-weather events, too few are fully implementing these systems across all necessary pillars,” said Fox.

“Of equal concern, few city EWS cover multiple hazards, and public health agencies are not consistently engaged in these efforts, despite their critical role in disaster preparedness and response,” added Sheehan.

Key Findings

• Limited implementation of comprehensive early warning systems: Among the 182 cities analyzed, only 71 (39%) reported implementing actions that covered all four essential EWS pillars. Cities in higher-income countries were three times more likely to report fully developed EWS than those in lower-income countries.
• Public health’s role is underutilized: While over 80% of cities stated that health protection was a goal of their EWS, only 41% explicitly reported involvement from public health departments. This engagement was more prevalent in cities with multi-hazard early warning systems (MHEWS) and those in wealthier nations.
• Multi-hazard systems are more effective, but rarer: Nearly half of the cities with EWS had MHEWS, which address hazards such as heatwaves, floods, and vector-borne diseases. However, these were primarily found in high-income regions, leaving many vulnerable populations without sufficient protection.
• Disparities in access and readiness: Cities in Africa, Southeast Asia, and the Eastern Mediterranean were the least likely to have robust EWS. These regions also contain some of the world’s largest urban populations, often in informal settlements that are disproportionately exposed to climate risks.

Implications for Policy and Practice

The study underscores the urgent need for scaling up urban early warning capacities particularly in lower-income regions. Researchers recommend the development of a city-specific framework for multi-hazard EWS that prioritizes public health integration and cross-sector collaboration. Strengthening partnerships between meteorological agencies and health departments could enhance disease surveillance, risk communication, and targeted preparedness efforts.

Additionally, the researchers highlight promising practices in cities that have successfully integrated public health into their climate adaptation strategies. For example, Taipei has implemented a comprehensive multi-hazard alert system, while cities like Phoenix and Barcelona have developed heat-health action plans that actively involve public health authorities.

“Extreme-weather events are increasing in frequency and severity due to climate change, and urban populations—especially those in vulnerable communities—are on the front lines,” said Fox. “Ensuring that all large cities have robust, multi-hazard early warning systems with strong public health engagement is not just an adaptation strategy; it’s a public health imperative.”