I’m honestly wondering if we should deliberately reject all the existing terminology and try to start again, since a) as you say, many organisations use these terms inconsistently with each other, and b) the terms aren’t etymologically intuitive. That is, ‘existential catastrophes’ needn’t either threaten existence or seem catastrophic, and ‘global’ catastrophes needn’t affect the whole globe, or only the one globe.
I’m honestly wondering if we should deliberately reject all the existing terminology and try to start again, since a) as you say, many organisations use these terms inconsistently with each other, and b) the terms aren’t etymologically intuitive. That is, ‘existential catastrophes’ needn’t either threaten existence or seem catastrophic, and ‘global’ catastrophes needn’t affect the whole globe, or only the one globe.