I'm a sci-fi writer. I try to keep my science real. Lately I've had occasion to research 'extinction events' (earth has had at least five and possibly as many as twenty) When Toba blew (many gigaton) it was no big deal....compared to one of the extinction events.

People don't seem to have any idea of scale. The biosphere of earth is as relatively thick as a film of water on an apple. (about ten miles vs about 8K miles)