Also known as "eco dread" and probably a fair few other terms besides.
This feeling of anxiety is highly prevalent among young people. I have friends for whom the topic of the environment is not considered suitable for extended conversation with their pre-teens, because it can become so upsetting. I contrast this with the wonder, awe and hope I used to feel in the 90's lying on my bedroom floor reading about nature.
This write up is focused on the feeling itself, rather than the politics, economics or science of biodiversity collapse. I could get into the phenomenology of nature itself, and maybe I will, but not here.
Ecological dread is not felt by everyone. Many people feel confident that everything is going to be alright and that the planet will survive, which of course it will.