Existential threat means things can’t get worse (you just stop existing).
Ignoring the potential of geoengineering implies you are sure that we have a better solution which will work. I hope we don’t have to use geoengineering but I am certain the status quo of hoping renewables and batteries in the 1st world will save us is not going to work.
Threat is not certainty. If somebody is out there to kill you, you are under an existential threat, until they are caught. It's not a reason to start playing Russian roulette, saying "I'm already in danger, cannot get worse than that!"
>The same logic applies to shutting down oil and gas production: if we are not certain, then why risk the downsides?
You are conflating the cost of not extracting a fraction of a fraction of current production capacity with the risk ending human existence through changing systems we do not have anything close to a full understanding of nor precise control over.
Degrees of risk matter, in fact they are the whole point of GPs logic.
Ignoring the potential of geoengineering implies you are sure that we have a better solution which will work. I hope we don’t have to use geoengineering but I am certain the status quo of hoping renewables and batteries in the 1st world will save us is not going to work.