Clinical relevance of loneliness in the treatment of depression: study protocol for a naturalistic prospective longitudinal study.

April 22 was designated as Earth Day in 1970, marking 57 years since its establishment. Globally, the frequency and intensity of extreme weather events (e.g., heat waves, prolonged droughts, wildfires, and floods) have been steadily increasing. In recent decades, the frequency of climate-related disasters has risen sharply, increasing from approximately 340 incidents per year in 2000 to 665 in 2023. Consequently, the public’s exposure to environmental stressors has also significantly increased (). Thus, climate change is no longer an uncertain threat in the distant future; it has transformed into a real-world disaster that directly threatens daily life and survival (). As humanity experiences natural disasters and extreme weather events, directly or indirectly, evidence has clearly demonstrated that the climate crisis not only affects physical health and socioeconomic foundations but also exerts severe negative impacts on mental health (). Consequently, awareness of and concern regarding climate change have also been increasing worldwide, and a significant number of people have experienced psychological anxiety due to the climate crisis. One of the most prominent psychological consequences of climate change is “climate change anxiety (CCA)” or “eco-anxiety”. The American Psychological Association defines it as a chronic fear of environmental catastrophe and describes it as a persistent state of anxiety stemming from the recognition of the irreversible impacts of climate change and concerns for future generations (). CCA has recently garnered global attention and emerged as a major mental health concern () CCA is a complex concept that extends beyond mere worry to encompass cognitive, emotional, and behavioral responses; it can be accompanied by persistent worry, feelings of helplessness, sleep disturbances, difficulty in concentration, and impaired functioning, among others (–). Alternatively, although anxiety can be interpreted as a normal and adaptive response to actual threats (, ), it can escalate to excessive or overwhelming levels due to the nature of a problem, which may be difficult to control and unlikely to be resolved through personal effort alone (). In these cases, it can trigger physical symptoms such as persistent worry, sleep disturbances, and changes in appetite, and may further cause serious impairment in an individual’s daily life and cognitive and social functioning. To date, research on CCA has primarily focused on the general adult population. According to previous studies, many people worldwide—including young adults and adolescents—report significant levels of anxiety and helplessness regarding climate change (, ). Scholars have reported that CCA exhibits significant positive correlations with depression, generalized anxiety disorder, suicidal behavior, and stress levels (–). However, studies that directly measure CCA and analyze its clinical characteristics among patients with mental disorders remain scarce.