Toward a unified understanding of climate anxiety: Examining measures of climate and eco-anxiety

In sum, both previous studies and the current work have identified a lack of comprehensive definitions of the core con- structs [10,11]; floor effects and restricted variance in the outcome variable (e.g., [6,7,12,29]); a lack of clarity in the factor structure [20]; reservations about whether the emotional core of climate anxiety is captured, especially in the Climate Anxiety Scale [9]; and finally, the insight that the two existing measures cover the same overarching construct.

PLOS One | https://doi.org/10.1371/journal.pone.0339562 December 29, 2025 15 / 19 To advance the field, we propose the following to improve the measurement of climate anxiety. First, it is essential to begin with clear and refined definitions of the constructs being measured, including greater conceptual explicitness regarding their temporal stability. A particularly promising approach is to distinguish between affective and appraisal reac- tions to climate change, on the one hand, and the resulting impairments in quality of life, on the other [62]. While the CAS and HEAS already capture aspects of impairment, further refinement of these scales could enhance sensitivity for clinical or otherwise vulnerable populations, enabling more precise assessment and validation of the consequences of climate anxiety. At the same time, this distinction will help avoid variance restrictions when measuring affective and appraisal reactions and will facilitate the development of an instrument that effectively captures the emotional basis of climate action in the general population. Additionally, such an approach will reinforce the non-pathologization of climate anxiety, a topic frequently discussed in the literature [4,7–9]. Moreover, differentiating these aspects of climate anxiety will enable more precise validation efforts, ensuring that measures of impairment undergo validation in clinical samples, while emotional experiences are appropriately studied in the general population.

To ensure replicability of future scales’ factor structures and avoid challenges related to multicollinearity, it is important to recognize that the emotional core of climate anxiety is empirically difficult to separate from other climate-related emo- tions. Studies have shown high correlations, especially between climate anxiety, climate anger, and climate sorrow (e.g., in the Inventory of Climate Emotions [8,73]). Given these overlaps, future research could benefit from a measure that con- siders a broader spectrum of emotions and their shared role in promoting climate action. By refining conceptual distinc- tions and overlaps and improving measurement tools, future research can provide a more comprehensive understanding of climate-related emotions and their impact on individual and collective action. Limitations Some limitations of this study should be considered. Both the CAS and HEAS were developed in high-emitting countries (e.g., the US, Australia, New Zealand) with relatively advantaged populations. In many contexts where climate change impacts are already a daily reality—despite only little emissions coming from these contexts (e.g., less advantaged countries in sub-Saharan Africa or Pacific Island states)—emotional responses may differ qualitatively and quantitatively. To fully understand climate anxiety across diverse cultural and socio-economic settings, future research should test and adapt measures contextually, taking into account local experiences of climate-related impacts and vulnerabilities. Further,

the study was cross-sectional and correlational, meaning that causal claims cannot be made regarding the relationships between the overarching climate anxiety factor and other constructs. The sample included only adults, limiting the gener- alizability of our findings to children and adolescents, although they might be a particularly relevant group for experiencing impairments due to climate anxiety [74]. Furthermore, investigating the causal relationships between climate anxiety and measures of political participation, acceptance of climate policies, and individual pro-environmental behaviors, as well as the role of self-efficacy, remains an important direction for future research. Understanding causal relations could be espe- cially interesting in populations that rally for more climate protection. Longitudinal studies spanning longer time periods could provide deeper insights into these dynamics. However, given the identified limitations of the current measures, we recommend improving the measures before applying them in experimental or longitudinal studies. Conclusions The current work addressed the complexity of measuring climate and eco-anxiety. It emphasized the challenges posed by vague definitions, partial clinical operationalizations, variance restrictions in the measures through floor effects, and proposed different measures of climate and eco-anxiety. The study provided a thorough validation of the frequently used measures of CAS and HEAS. A joint model of climate and eco-anxiety showed that CAS and HEAS presumably capture

the same overarching construct: climate anxiety. Validation efforts in a nomological network of climate anxiety not only enhance our understanding of the construct but also position climate anxiety as a pivotal focus for future research. This

PLOS One | https://doi.org/10.1371/journal.pone.0339562 December 29, 2025 16 / 19 could elucidate variance in climate activism and become increasingly relevant when climate health risks aggravate and become a greater mental health threat in the future. Before advancing future research, it is crucial to refine climate anxiety measures to prevent jangle fallacies and variance restrictions—starting with precise definitions that distinguish between emotional responses and impairments related to climate change and ensuring that refined measures are validated within their specific target groups. Acknowledgments PACE is a joint project of the University of Erfurt, the Robert Koch Institute (RKI), the Federal Centre for Health Education (BZgA), the Leibniz Institute of Psychology (ZPID), the Science Media Center (SMC), and the Bernhard Nocht Institute for Tropical Medicine (BNITM). The authors are grateful to all members of the PACE team for conducting this joint project. Author contributions Conceptualization: Lisa Marie Hempel, Mattis Geiger, Cornelia Betsch. Data curation: Lisa Marie Hempel, Mattis Geiger. Formal analysis: Lisa Marie Hempel, Mattis Geiger. Funding acquisition: Cornelia Betsch. Methodology: Lisa Marie Hempel, Mattis Geiger. Project administration: Cornelia Betsch. Resources: Cornelia Betsch. Supervision: Mattis Geiger, Cornelia Betsch. Writing – original draft: Lisa Marie Hempel. Writing – review & editing: Lisa Marie Hempel, Mattis Geiger, Cornelia Betsch. References

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