> Climate change may affect hundreds of millions and even so it is far away from an existential threat to humans.

So? WW2 was not an existential threat. Covid is not an existential threat. If you lose your job, your house, and spend the rest of your life as homeless, that's still not an existential threat to humanity. It's a meaningless criterion.

Humans are pretty resourceful; I expect we'll survive in some form or another. But climate change absolutely is an existential threat to ecosystems, biodiversity, food security, water security, political stability, etc. The fact that there will likely be humans somewhere on earth carving out an existence is not exactly comforting.