This research explores the complex interplay between climate change, health risks, and migration in the Republic of the Marshall Islands (RMI). Climate change is projected to significantly alter migration patterns globally, a trend already observed in various regions. Human health, influenced by climate exposure and access to social services, acts as both a driver and consequence of migration. Isolating the specific effects of climate change on health and migration is challenging due to various confounding factors. The heterogeneity of climate change impacts on migration and health necessitates nuanced research to guide effective policy interventions. The RMI, highly vulnerable to climate change impacts, faces direct (e.g., injuries from extreme events), indirect (e.g., disease outbreaks), and diffuse (e.g., reduced physical activity due to heat) health consequences. Mental health is also significantly impacted, encompassing stress, depression, and solastalgia. Migration within and outside the RMI may serve as an adaptation strategy to mitigate these risks. Existing research on climate-related migration in the Pacific Islands has addressed displacement, risk and vulnerability, agency and decision-making, and adaptation mechanisms. However, limited research focuses on the interplay between climate stressors, health impacts, and migration decisions, underscoring the need for further empirical evidence. This study uses data from a 2017 household survey in the RMI to analyze the relationships between climate stressors, health impacts, and migration intentions, aiming to identify vulnerable populations and inform policy interventions promoting equitable adaptation.

Previous research on climate-related migration in the Pacific Islands has mainly focused on displacement, vulnerability, agency, decision-making processes, and policy responses. Studies highlight the displacement of populations due to rising sea levels and other climate-related disasters. Risk and vulnerability assessments have identified populations disproportionately affected by climate change. Research also explores the agency of individuals and communities in deciding to migrate, examining the factors influencing their decisions. Policy and adaptation strategies have also been investigated to address the challenges of climate-related migration. However, limited research integrates climate stressors, health impacts, and migration decisions. This study aims to fill this gap by analyzing existing survey data to explore these relationships in the RMI.

This study employed a secondary analysis of household survey data collected in the RMI in 2017. The survey, administered to 199 households across three islands (Majuro, Maloelap, and Mejit), assessed household experiences with climate stressors (drought, heatwaves, storm surge, typhoons, king tides), their direct and indirect impacts on household health (food, water, land, crops, housing, safety, disease, injury), and perceptions of the severity trends of these stressors. Migration history and future expectations were also documented, alongside reasons for migration or non-migration. The study sites were chosen to represent the RMI’s diverse geographies and population densities (urban and rural). The data analysis comprised two parts: logistic regression and hierarchical clustering. Logistic regression assessed the relationship between climate stressors, health impacts, and the expectation to migrate (a binary outcome based on responses of "Yes/Maybe" or "No"). The regression analysis also examined the associations among climate stressors, health impacts, and demographic variables. Hierarchical clustering grouped respondents based on climate stressor experiences, perceptions of natural resource status and trends, and ranked problems associated with climate stressors. This approach aimed to identify groups with distinct vulnerability profiles and explore non-linearities in the data.

The study found that while all respondents experienced climate stressors, no significant correlations existed between climate stressors, health impacts, and the expectation to migrate in the overall sample. However, hierarchical clustering revealed distinct groups based on climate stressor experiences, wealth, and migration expectations. One group reported low stressors, high wealth, and low migration expectations, showing a statistically significant relationship between climate-related health impacts and migration. The other group experienced very high climate stressors, low wealth, and high migration expectations. In this group, climate stressors were significantly associated with proximate determinants of health (e.g., food and water security), but not directly with migration decisions. This suggests that for the high-stress, low-wealth group, the indirect impacts of climate change on health and well-being are significant but migration is not necessarily the immediate response. The findings highlight the heterogeneity of climate vulnerability and adaptive responses within the RMI population.

The study's findings highlight the complex and multifaceted nature of climate vulnerability in the RMI. While all households experienced climate stressors, their impacts and responses varied significantly based on socioeconomic status and access to resources. The lack of a direct correlation between climate stressors and migration intentions in the aggregate suggests that migration decisions are influenced by a complex interplay of factors beyond immediate climate impacts. For households with low wealth and high climate stress, the focus is on immediate health and well-being, while for wealthier households, climate-related health impacts may be more directly tied to migration plans. This emphasizes that policies promoting equitable adaptation must address both the direct and indirect consequences of climate change on health and well-being, focusing on improving economic opportunities, expanding access to education and healthcare, and enhancing resilience to climate stressors.

This study underscores the importance of understanding the heterogeneous nature of climate vulnerability and adaptation strategies in the RMI. The findings highlight the need for multifaceted policies that address the socioeconomic disparities influencing migration decisions and promote equitable adaptation outcomes. Future research could explore the long-term impacts of climate change on migration patterns and health outcomes, examining the effectiveness of interventions designed to enhance resilience and reduce vulnerability.

The study's reliance on self-reported data might introduce biases in respondents' perceptions of climate stressors and health impacts. The cross-sectional nature of the data limits the ability to establish causal relationships between climate stressors, health impacts, and migration decisions. The sample size, while substantial, may not fully capture the diversity of experiences across the entire RMI.