Toward a Unified Framework for Climate and Health Research: Gaps in Exposure Metrics and Health Outcomes.

As the health impacts of climate change become increasingly evident, research on climate-related exposures and health outcomes has grown. However, a disproportionate focus on certain exposures and health outcomes persists, and substantial inconsistencies remain in the definitions and measurement methods used across studies, hindering the integration of findings and the development of comprehensive public health strategies. To address this gap, we assessed epidemiological literature, identifying uneven research distribution and highlighting areas requiring further investigation. We conducted a literature search in PubMed, the Cochrane Library, and Embase using key terms related to climate change and health. A total of 611 original studies on human populations, published in English from January 2000 to June 2024, were included. Significant heterogeneity was evident in the definitions of climate-related exposure metrics. The focus areas of climate-related exposure were narrow, primarily limited to temperature and temperature-related hazards (n = 526), precipitation (n = 88), and air pollution (n = 39), while research on extreme weather events was scarce. Similarly, the scope of health outcomes studied was largely confined to all-cause mortality (n = 249), cardiovascular disease (n = 159), and communicable diseases (n = 148). In contrast, relatively few studies have addressed the impacts of climate change on neurodegenerative diseases (n = 8), endocrine disorders (n = 4), or hematologic diseases (n = 3), indicating a critical need for broader investigation into these underrepresented health outcomes. Future research should prioritize the transparent reporting of both context-specific and standardized exposure definitions to improve cross-study comparability and broaden its scope to encompass more diverse climate-related exposures and health outcomes.