Developing Robust Conceptual Models in Climate Change and Health Research

Unpacking the relationship between climate change and health requires not only technical skills, but also a strong theoretical foundation. Climate change, health, and their relationships are all complex. Researchers begin by conceptualizing—for their specific questions—1) the nature of the climate event, 2) the details of the health outcome, and 3) the temporal and spatial relationships between the climate and health phenomena of interest.

Figure 1: Pathways of climate effects on health Available at: https://nca2018.globalchange.gov/chapter/14/¹

Beyond these three elements, contextual factors are crucial for identifying the complex causal pathways among climate change and health. Figure 1 illustrates how the pathway from a climate event, its manifestation in the environment, and its impact on various health outcomes is embedded within larger contexts. As suggested by the gray box on the right, individuals will be impacted by climate change in unique ways based on their demographic characteristics and social determinants that affect their lived experiences. The gray box on the left illustrates how environmental and institutional contexts will also influence relationships between climatic events and health. Contexts influence the impact of exposures on individuals as well as their mitigation and adaptation strategies in response to climate risks.

Building a conceptual model

Below, we provide the steps in creating a tailored conceptual model for climate change and health research.

1. Assessing the temporal and spatial nature of climate risk

Risks arising from climate change vary in their temporal and spatial scales. In terms of timing, risks may be acute or protracted. Acute risks arise when one-time exposure to a climate event is sufficient to trigger health outcomes, for example, when flooding makes water unsafe for drinking. Protracted risks, in contrast, arise from sustained exposure to climate phenomenon, such as the inhalation of dust over the course of enduring dry periods. The impact of climate change is also spatially variable. While some climate events affect wide areas, others’ scope is limited to discrete locations. Determining the type of risk depends on both the nature of the climate event and the health outcome studied. Identifying the temporal and spatial dimensions of risk provide the basis for decisions concerning temporal aggregation of climate data, as well as the length of expected lags between initial exposure to a climate event and the manifestation of the health outcome.

2. Incorporating social and behavioral context

Certain climate events are known to have deleterious effects on humans. For example, exposure to extremely high temperatures during the first trimester of pregnancy increases the risk of low birth-weight babies.² Basic biological truths such as this are insufficient, however, to fully assess the impact of climate events on individual health because individuals have dramatically different access to resources, opportunities, and constraints. A pregnant person who lives in an air-conditioned house will experience extreme temperatures very differently than a person who is houseless. Demographic characteristics, such as age, gender, wealth, and partnership status matter when assessing climate impacts.

Furthermore, the characteristics of societies (e.g., rural versus urban, gender roles, livelihoods) matter. Consider rising temperatures in nomadic versus other types of communities.³ For both, temperature change may make it harder to access water. In nomadic communities, the result could be men driving herds further from the community and thus staying away longer, while in other communities, the result could be that children tasked with collecting water find the task more physically demanding. Who and how individuals are affected by water shortages will vary depending on community norms and roles. Community characteristics will also affect the instigation and nature of mitigation and adaptation efforts. While analyses that map the nature of climate change over time provide a useful starting point, they cannot fully capture the individual- and community-specific impacts of climate change.³

3. Understanding environmental and institutional contexts

Environmental and institutional contexts are also influential in shaping causal pathways between climate change and health. The physical environment, such as altitude and the demarcation of seasons, can provide some level of protection from some climatic events. For instance, a small reduction in annual rainfall can have a devastating effect in an arid location where there is a close correspondence between a rainy season and agricultural production.⁴ The same reduction in rainfall might have only a minor impact in a location where annual precipitation is diffused throughout the year and is less closely tied to the agricultural season. Understanding such differences is important for selecting accurate measurements. In the former location, the rain shortfall might best be measured through the length of the rainy season. In the latter location, considering rainfall deviation from a monthly or annual average could be more appropriate.⁴

Institutional contexts include the built environment, such as the presence of roads, wells, and irrigation systems, as well as organizations designed to facilitate human capabilities, such as political, healthcare, and education systems. Local governments’ capacities to intervene to protect populations faced with climate risks can reduce negative health outcomes. Healthcare systems affect the accessibility of treatment (both physically and financially), while education systems provide individuals with the knowledge of when and how to respond to climatic events. Climate change and health research that fails to capture these contextual effects can lead to faulty conclusions.

Conclusion

Theorizing the core relationship among specific climate events and specific health outcomes is the first step in developing a conceptual model but is insufficient to fully capture complex causal pathways. Individual characteristics, social determinants of health, and environmental and institutional environments are also critical. Informed and clearly identified spatial and temporal measurement of climate exposures is necessary, and these exposures should be thoughtfully, appropriately, and explicitly linked to the particular health outcomes of interest. Community-focused expertise and stakeholder engagement is vital to fully understand and incorporate how broader contexts interact with local circumstances to uniquely influence how climate change is experienced.

For more information

To learn more about the technical modeling implications of climate-change-and-health conceptual models, see Dorélien and Grace (2023).⁴

To see a specific model of the impact of climate change on women’s reproductive health in Africa, see Grace (2017).³

For further delineation of the elements in climate-change-and-health models (in the U.S. context), see Balbus et al. (2016).⁵

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References

1. Ebi, K. L., Balbus, J. M., Luber, G., Bole, A., Crimmins, A., Glass, G., Shubhayu, S., Shimamoto, M. M., Trtanj, J., & White-Newsome, J. L. (2018). Human health. In D. R. Reidmiller, C. W. Avery, D. R. Easterling, K. E. Kunkel, K. L. M. Lewis, T. K. Maycock, & B. C. Stewart (Eds.), Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment (Vol. 2, pp. 539–571). U.S. Global Change Research Program. https://doi.org/10.7930/NCA4.2018.CH14

2. Grace, K., Verdin, A., Dorélien, A., Davenport, F., Funk, C., & Husak, G. (2021). Exploring strategies for investigating the mechanisms linking climate and individual-level child health outcomes: An analysis of birth weight in Mali. Demography, 58, 499–526. https://doi.org/10.1215/00703370-8977484

3. Grace, K. (2017). Considering climate in studies of fertility and reproductive health in poor countries. Nature Climate Change, 7, 479–485. https://doi.org/10.1038/nclimate3318

4. Dorélien, A., & Grace, K. (2023). Climate change-related demographic and health research: Data and approaches. In S. E. Ortiz, S. M. McHale, V. King, & J. E. Glick (Eds.), Environmental Impacts on Families (Vol. 12, pp. 43–66). Cham: Springer Nature Switzerland. https://doi.org/10.1007/978-3-031-22649-6_3

5. Balbus, J., Crimmins, A., Gamble, J. L., Easterling, D. R., Kunkel, K. E., Saha, S., & Sarofim, M. C. (2016). The impacts of climate change on human health in the united states: A scientific assessment. U.S. Global Change Research Program. https://doi.org/10.7930/J0VX0DFW