Climate Change Impacts on One Health Systems: A Narrative Review of Empirical Evidence and Policy Responses.

Background: Climate change poses critical threats to human, animal, and environmental health, yet evidence on integrated One Health responses remains fragmented. Although numerous studies highlight climate-driven health risks, many climate adaptation frameworks still underrepresent cross-sectoral interactions and the needs of low-resource settings. Objective: This study aims to identify and operationalize key governance mechanisms, surveillance strategies, and collaborative approaches that can be implemented to support health-adaptive policies. Methods: A comprehensive search of peer-reviewed literature and international reports (March 2020-June 2025) was conducted across Scopus, PubMed, Web of Science, the World Health Organization (WHO), WHO African region (AFRO), European Centre for Disease Prevention and Control (ECDC), the Food and Agriculture Organization (FAO), and the European Public Health Association (EUPHA) repositories. A narrative synthesis approach was adopted to integrate findings across heterogeneous study designs and contexts. Results: Climate change intensifies vector-borne diseases, heat-related illness, food insecurity, biodiversity loss, and environmental degradation, disproportionately affecting low- and middle-income countries. Evidence suggests that implementing a One Health approach through effective, evidence-based actions such as fostering collaborative engagement, using a common operating picture for community-based surveillance, and strengthening resilient food and livestock production systems that are adaptable to a changing climate could enhance surveillance capacity and accelerate preparedness and early warning processes. Conclusion: Significant opportunities exist to improve One Health governance by, among other things, establishing coordinated surveillance systems, flexible policy approaches, an ecosystem-based perspective, and inter-sectoral engagement. Currently, policies fail to fully consider environmental and animal health aspects, which could pose significant risks.