People felt that way in the 1970s. When my sister was born premature and died my mom was depressed, and later told me she ‘no longer believed in God’, and that the world was so bad there was no way she could have another child.<p>There as an environmental crisis back then too, inflation and numerous social crises.
"Climate anxiety" is an entirely reasonable reaction to the destruction of the natural world and the coming inhospitable planet. Not a mental illness.