Considering the growing interconnection between climate and health crises, two complementary conceptual frameworks are emerging in the humanitarian field. The “One health” approach integrates human, animal and ecosystem health into a unified vision of health issues, while the “Planetary health” approach has a more comprehensive view of the impact of human activities on the living world. These two approaches, despite their differences in implementation, share a systemic vision that enables us to respond to complex crises by promoting prevention and health equity, while preserving essential ecological balances.
Addressing climate impacts on health in complex humanitarian crises
The climate crisis is a health crisis. Alongside biodiversity loss and pollution (collectively forming the “triple planetary crisis”), climate-related disasters precipitate both physical and mental health issues and disrupt health services. Rising temperatures alter the distribution of disease vectors, thereby exposing populations to heightened outbreak risks. Climate changes significantly impact food security, potentially leading to increased rates of malnutrition. These factors may culminate in humanitarian crises and complicate aid efforts.[1] Médecins Sans Frontières and Lancet Countdown, Joint Brief, 2024. This situation further exacerbates health inequities that are systematic and avoidable, and unfair differences in health outcomes related to the social position of a particular group. For instance, people with disabilities are four times more likely to die during a disaster.[2]United Nations Office for Disaster Risk Reduction (UNDRR), Global Survey Report on Persons with Disabilities and Disasters, 2023. Which strategies and resources can humanitarian organisations count on when supporting communities against the dual threats of climate change and associated health risks?
One health
One health (OH) is an integrated, unifying approach to public health that seeks to sustainably balance and optimise the health of humans, animals and ecosystems, often represented by the well-known three-circle Venn diagram.
“One health (OH) is an integrated, unifying approach to public health that seeks to sustainably balance and optimise the health of humans, animals and ecosystems.”
The health community has recognised the interconnectedness of these health dimensions since at least one century (beginning with the “one medicine” con-cept, which later evolved into the “one world, one health” approach).[3]Jakob Zinsstag et al., “From ‘one medicine’ to ‘one health’ and systemic approaches to health and well-being”, Preventive Veterinary Medicine, vol. 101, September 2011, pp. 148-56. Recently, the COVID-19 pandemic emphasised the need for a comprehensive approach, and the value of encompassing both human and veterinary medicine has been demonstrated.[4]Jakob Zinsstag et al., One Health: the theory and practice of integrated health approaches, CABI, 2021. This led the Food and Agriculture Organization, the World Health Organization and the World Organisation for Animal Health, later joined by United Nations Environment Programme, to form the Quadripartite Collaboration for One Health for better prevention, prediction, detection and response to health threats like zoonosis (infectious disease transmitted by ani-mals).[5]Thomas C. Mettenleiter et al., “The One Health High-Level Expert Panel (OHHLEP)”, One Health Outlook, vol. 5, no. 18, 2023. This means, for instance, rein-forced community-based surveillance programmes targeting Mpox outbreaks in the Democratic Republic of the Congo[6]IFRC, “What is CBS?”, webpage, https://cbs.ifrc.org/what-cbs. or vaccination of dogs against rabies in Chad’s capital city, addressing a neglect-ed tropical disease.[7]Jakob Zinsstag et al., “Vaccination of dogs in an African city interrupts rabies transmission and reduces human exposure”, Science Translational Medicine, vol. 9, 2017. Multidisciplinary collaborations among service providers under the OH umbrella result in integrat-ed health services, such as the mobile, multi-sectoral taskforces in the Horn of Africa for addressing multiple needs of vulnerable pastoralists, their livestock and the rangeland ecosystems they de-pend on.[8]Siobhan M. Mor et al., “Community-Designed One Health Units as a Model for Integrated Service Delivery in Pastoralist Areas of Africa”, CABI Digital Library One Health Cases, 2024. Initially, these collaborations have been confined to veterinary and healthcare fields, raising concerns about a reductionist focus. Over time, this approach has incorporated a relational perspective[9]Julianne Meisner et al., “Relational One Health: A more-than-biomedical framework for more-than-human health, and lessons learned from Brazil, Ethiopia, and Israel”, One Health, vol. 18, June … Continue reading, creating a significant overlap with the concept of planetary health. Their simultaneous presence in the global health arena can lead to confusion when humanitarian practitioners blend these two frames, mixing up diverse expectations, areas of interest and levels of intervention. This paper aims to clarify the core principles of both approaches and their implications for humanitarian organisations.
Planetary health
Planetary health (PH) is a solutions-oriented, transdisciplinary field and social movement focused on analysing and addressing the impacts of human biosphere depletion on human health and all life on Earth.
“Planetary health (PH) is a solutions-oriented, transdisciplinary field and social movement focused on analysing and addressing the impacts of human biosphere depletion on human health and all life on Earth.”
This broad concept, which has gained prominence since The Rockefeller Foundation–Lancet Commission’s report in 2015, emerged from a critical global health analysis about how health gains have been achieved by mortgaging the right to health of future generations and ecosystems.[10]Richard Horton et al., “From public to planetary health: a manifesto”, The Lancet, vol. 383, no. 9920, March 2014, p. 847. PH emphasises how, in the new geological epoch of the Anthropocene, human activities have destabilised Earth’s key life-support systems, infringing upon planetary boundaries.[11]Will Steffen et al., “Planetary boundaries: Guiding human development on a changing planet”, Science, vol. 347, 2015. Zooming out from interest in specific diseases, the PH narrative identifies the socio-economic processes and lifestyles of our society as etiological factors that jeopardise the conditions necessary for life.
As a methodology, PH provides a complex picture of climate-health links, offering multiple entry doors for intervention but lacking straightforward local-level actions, specific tools and indicators. As a framework, it unifies narratives about climate and health, facilitating trans-disciplinary collaborations and radical listening of local communities and indigenous knowledge.
Visually, PH expands upon the OH model by adding a fourth component, encom-passing the impact of the triple planetary crisis on mental health and well-being, planetary health equity (equitable good health in a stable Earth system)[12]Sharon Friel et al., “Governance for planetary health equity—the Planetary Health Equity Hothouse project”, The Lancet Planetary Health, vol. 8, April 2024., while raising ethical issues about the conflictive relationship humans have with nature.[13]United Nations Environment Programme, Making Peace with Nature: A scientific blueprint to tackle the climate, biodiversity and pollution emergencies, February 2021, … Continue reading PH advocates for a system-centred anal-ysis, scaling intervention from popula-tions to the human species and extending timescales to consider future generations.
While this broad framework faces a knowledge-to-action gap, systemic thinking in PH promotes integrated programmes. For example, a Sexual and Reproductive Health (SRH) project in the Lake Victoria Basin incorporated environmental and economic activities, ranging from clean cookstoves distribution to education and family planning, which are inter-twined from a PH perspective[14]Hilary Duff, Family Planning for People and Planet: A Population, Health, Environment Approach in the Lake Victoria Basin, Planetary Health Alliance 2018.. It is also interesting to note how Nature-Based Solutions (NBS) for health align with the PH concept that human health depends on a clean, sustainable, healthy environment.[15]OMS and UICN, Highlights Brief On WHO-IUCN Report On Designing Nature-Based Solutions For Human Health, 2023, … Continue reading NBS offers co-benefits related to climate adaptation and resilience, food security, health, and water, sanitation and hygiene (WASH).[16]The Friends of Ecosystem-based Adaptation (FEBA) network and The Partnership for Environment and Disaster Risk Reduction (PEDRR), Nature-based Solutions in Humanitarian Contexts, November 2021. Furthermore, PH’s fo-cus on social determinants of health cre-ates space to consider Mental Health and Psychosocial Support (MHPSS) not only in the aftermath of climate-related disasters but also in preventing distress related to the triple planetary crisis, despite limited shared cases from the Global South.[17]Siqi Xue et al., “Mental health and psychosocial interventions in the context of climate change: a scoping review”, npj Mental health Research, vol. 3, no. 10, 2024.
“OH and PH represent complementary approaches to addressing health risks exacerbated by the triple planetary crisis.”
In summary, OH and PH represent complementary approaches to addressing health risks exacerbated by the triple planetary crisis. OH primarily aims to improve health systems to address issues at the human-animal-ecosystem interface, while PH adopts a broader perspective, emphasising the interconnectedness of social, commercial and environmental determinants. Both help give priority to the environmental and climate impact on health, resulting in a paradigm shift in global health that promotes broad prevention. However, these concepts risk becoming overused buzzwords in humanitarian contexts if there is not a substantive dialogue among researchers, policymakers, donors, practitioners and local communities regarding the implications of adopting OH and PH lenses.
Implications for humanitarian organisations
While there is no shared roadmap for OH and PH in humanitarian settings, significant efforts have been made. The University of Geneva surveyed over 400 humanitarian organisations in thirty-five climate-vulnerable countries to assess OH and PH integration. The results were subsequently discussed in a workshop involving thirty-eight experts from six countries, representing twenty-one organisations, at the Geneva Health Forum 2024, and through a global online consultation. The One Sustainable Health network continues this work by hosting a multidisciplinary group committed to operationalising these approaches in humanitarian settings. This process culminated in a policy brief providing guidance for humanitarian efforts to simultaneously protect people, animals, plants and ecosystems in interrelated crises.[18]Valeria Marino et al., Humanitarian Action in the Planetary Crisis, Policy Brief, 2025 , … Continue reading What key steps have been identified for translating OH and PH into humanitarian action?
Operational research
Animal health, particularly zoonoses, re-mains the most prominent OH research area, whereas PH research focuses more on climate change and social de-terminants of health.[19]Rafael Ruiz de Castañeda et al., “One Health and planetary health research: leveraging differences to grow together”, The Lancet Planetary Health, vol. 7, no. 2, February 2023, pp.109-111. Examples of the former include meteorological data analysis for prevention of infectious dis-ease in Central Africa[20]Alexandra Heaney et al., “Meteorological variability and infectious disease in Central Africa: a review of meteorological data quality”, Annals of the New York Academy of Sciences, vol. 382, no. … Continue reading and assessment of the effect of snakebite on health and socioeconomic factors in Nepal.[21]Sara Babo Martins et al., “Assessment of the effect of snakebite on health and socioeconomic factors using a One Health perspective in the Terai region of Nepal: a cross-sectional study”, The … Continue reading
Examples of PH-related research include research aiming to prevent 5.1 million excess deaths per year attributable to ambient air pollution from fossil fuel use,[22]Jos Lelieveld et al., “Air pollution deaths attributable to fossil fuels: observational and modelling study”, BMJ, vol. 383, November 2023, … Continue reading quasi-experimental studies to evaluate the health impacts of agro-forestry in Tanzania,[23]Todd S. Rosenstock, “A planetary health perspective on agroforestry in Sub-Saharan Africa”, One Earth, vol. 1, no. 3, November 2019, pp. 330–344. a study of con-sequences of sea-level rise and salinity intrusion in Bangladesh’s coastal region that expose women and adolescents to hygiene risks, including skin disease and reproductive health problems,[24]Sinha Susmita et al., “The Impact of Saline Water on Women’s Health in the Coastal Region of Bangladesh: Special Attention on Menstrual Hygiene Practices”, Cureus, vol. 16, no. 8, August 2024. and an assessment of the effectiveness of heat adaptation for vulnerable populations.[25]Christopher Burman, Assessing the effectiveness of Heat Adaptation & Heat Reduction Interventions for vulnerable population in urban and rural settings of a low- and middle- income country, … Continue reading
In both cases, operational research could equip humanitarian organisations with methods and tools for better cross-sectoral collaborations and evidence on the incremental benefits of these collaborative efforts.
Financial support
OH is a pillar of the Pandemic Fund, hosted by the World Bank, which provides multi-year grants to prevent future pandemics. Similarly, the Agence Française de Développement supports and finances an OH approach in Low and Middle Incomes Countries.
PH discourse offers value-based advoca-cy for networks like the Planetary Health Alliance, dedicated think-thanks or the health workforce.[26]Mariam Haq et al., “Advocating for planetary health is an essential part of advocating for children’s health”, Pediatric Research, vol. 96, November 2024, pp. 1494–1502. However, few donors are explicitly committed to supporting this ap-proach in the field. For instance, PH is men-tioned in addressing the impact of climate change on public health in the Dutch Global Health Strategy 2023-2030, but, overall, it seems that OH is a more accepted and insti-tutionalised approach, while PH still faces different barriers in policymaking.[27]Danielle Brady, Planetary Health: A holistic vision for people and the planet, European Policy Centre, 19 September 2023.
To address the latter, donors should recog-nise the complexity and diversity of public health and livelihood issues, allocating more funds to break silos of vertical programmes and investing in localised pilot projects.[28]Valeria Marino et al., Humanitarian Action…, op. cit.
Pilot programmes
OH and PH offer exciting opportunities in the humanitarian-development-peace (HDP) nexus, where climate-related disasters, food insecurity, livelihood challenges, migration, violence and health are interconnected and amplify each other. Both OH and PH approaches offer valuable strategies for health prevention and environmental sustainability, albeit with distinct implementation modes. OH focuses on strengthening health systems, for instance, by enhancing disease surveillance, investing in capacity-building of the health workforce for infectious diseases and antimicrobial resistance, inviting veterinary experts for health risk assessment, and integrating animal health considerations into livelihood programmes.
In contrast, PH advocates for a whole-of-society transformation, primarily through restructuring governance and coordination mechanisms, promoting education and communication initiatives, and transforming business practices to align with planetary boundaries.[29]Planetary Health Alliance, Planetary Health roadmap and action plan, 2024, https://www.planetaryhealthalliance.org/roadmap In practice, PH promotes, among other things, use of meteorological data in the health information system for climate-disaster preparedness, highlights the value of qualitative data and communities’ lived experiences, invites social scientists in the design of climate and health programmes, and intentionally aims for co-benefits for health and the environment. PH implementation includes climate mitigation efforts applied to the health system, simultaneously enhancing the climate resilience of health facilities. This approach is exemplified in Chad through the piloting of the Climate Vulnerability and Capacity Assessment.[30]Climate Action Accelerator, Health Service Level – Climate Vulnerability and Capacity Assessment, June 2024, https://climateactionaccelerator.org/wp-content/uploads/2024/06/VCA-06_2024.pdf Overall, the op-erationalisation of PH presents particular challenges due to its emphasis on systems thinking, long-term perspectives and the complexities associated with measuring co-benefits for climate and health.
In conclusion, both approaches urge hu-manitarian organisations to acknowledge the interdependence between the health of people, domestic and wild animals, plants, and ecosystems in complex crisis settings, promoting actions based on evidence and transdisciplinary collaborations to protect and promote health, livelihoods and ecosystem services, while contributing to the global transforma-tional movement that addresses the roots of health inequities and climate injustice.
“The parallel development of OH and PH may generate confusion and potentially discourage humanitarian practitioners from incorporating these approaches into their work.”
The parallel development of OH and PH may generate confusion and potentially discourage humanitarian practitioners from incorporating these approaches into their work. While merging those two approaches could be viewed as an opportunistic and pragmatic choice, we contend that OH and PH serve complementary purposes for humanitarian action.
OH provides technical guidance for national policies and specific integrated projects that address health issues at the intersection of human health, animal health and environmental determinants of health. This approach could be mainstreamed to increase the quality and effectiveness of health programmes, including those in humanitarian settings.
PH, on the other hand, functions as a nomadic concept, a heuristic tool for exchanging understandings of the tri-ple planetary crisis across disciplinary, professional and cultural boundaries[31]Manuela Rossini, Nomadic concepts, Swiss Academies of Art and Sciences, 2020, which helps navigate wicked prob-lems[32]David Weaver, “Taming the wicked problem of climate change with ‘virtuous challenges’: An integrated management heuristic”, Journal of Environmental Management, vol. 347, December 2023, p. … Continue reading. The triple planetary crisis and its health impacts, which follow a social gradient, exemplify such problems due to their complexity and interconnectedness and the multitude of stakeholders involved in seeking solutions. PH’s added value for the humanitarian community lies in its potential to reinvigorate systemic analysis, promote foresight exercises, potentially develop innovative practices and sustain a crucial debate about the systemic root causes of poor health across the fields of humans, animals and ecosystems.
Both approaches aim for prevention, both adopt a systemic view that helps work on the weak spot of complex issues and both increase the cost-effectiveness of health actions.
In light of these considerations, we call upon experts and practitioners who are curious about, and committed to, both approaches to bridge their knowledge and efforts, to join innovative partnerships and to build PH and OH awareness, capacity-building, guidance and pilot programmes in humanitarian settings to address the intertwined risks and impacts of climate and health.
For more information:
Valeria Marino, Isabelle Bolon, Davide Ziveri, Katherine Urbáez, Jakob Zinsstag, Karl Blanchet and Rafael Ruiz de Castañeda, Humanitarian action in the planetary crisis. 4 recommendations and 28 actions for humanitarians, researchers, policy makers and donors to protect people, animals, plants and ecosystems, Policy brief, 2025, https://genevahealthforum.com/wp-content/uploads/2025/02/GHF-Policy-Brief-2025-1.pdf
Corresponding author
rafael.ruizdecastaneda@unige.ch
Picture Credit : © Catalina Martin-Chico / Agence Vu’ pour Action contre la Faim
