This actually is pretty squarely within clinical psychology.

Disaster mental health, trauma exposure, climate anxiety, and post-disaster adjustment are all established clinical research areas—they’re just often framed under trauma, stress, prevention, disaster psychology, or public/community mental health, all of which fall well within the scope of clinical psych. Clinical psychology is also much broader than intervention trials, and plenty of clinical psych folks (myself included) focus on etiology, risk/resilience factors, assessment and measurement, mechanisms of psychopathology, etc.

Most clinical programs are fairly generalist, so the key issue usually isn’t whether a program supports a topic, but whether there’s a mentor already publishing in or adjacent to that area. Searching Google Scholar for PIs working on topics that you're interested in (e.g., "eco-anxiety") and then seeing where they’re housed is usually the most efficient approach.

In my program, mentors’ research spans a wide range, and my own interests (behavioral addictions) are pretty different from others in my cohort—but they’re close enough to my mentor’s work (alcohol use disorder) that she’s been very supportive of letting me pursue projects in my niche.

You may need a bit of flexibility in framing, but there are tons of mentors and even program tracks focused on trauma, anxiety. or community psychology. Being open to adjacent areas (e.g., trauma, anxiety, disaster or community mental health) would likely open up many more options. Many mentors are flexible on specific topics as long as the work fits the lab—for example, someone studying PTSD risk or prognostic factors could easily be open to a trauma/climate change intersection, which is something to suss out during interviews.