Is Climate Change Really an Existential Risk?

I'm generally skeptical of climate change as an X-Risk. I think it's plausible that at four degrees Celsius increase, which is within the so like climate models predict, given virtually no action to decarbonize. Right now, we are not really putting an effort to decarbonized. Will climate change result in human extinction? I don't think that you can assign it infinite negative disvalue just because of that. That creates a problem in ethical reasoning where yeah, anything can be justified to prevent that outcome regardless of how unlikely it is. But going back to climate, why I think climate is an existential risk is because it risks the deaths of 10% to 20% of humanity