Climate anxiety is a phenomenon that is gaining importance due to the general public’s increased awareness of the worsening climate crisis. At present, climate anxiety is not operationalized consistently across the existing literature. It is important to gain more consensus on the definition and operationalization of climate anxiety to facilitate reliable and generalizable research and to further develop interventions. Content analysis can contribute to this by providing insight into the overlap in the content of climate anxiety measures. With a systematic search, this study identified and analyzed 12 distinct scales measuring climate anxiety. The 119 items covered a total of 57 disparate symptoms. Jaccard indices showed that the mean overlap between symptoms of different climate anxiety scales was generally very low, as was the overlap between pairwise comparisons of climate anxiety scales. These results highlight the lack of uniformity in assessing climate anxiety and the need to properly define and operationalize this concept. The potential reasons for low overlap and how this might impact the reliability and validity of existing measures is discussed. It is critical that future work aims at finding consensus on the definition of climate anxiety (e.g., through a Delphi study) and psychometrically comparing the different questionnaires.