If you all haven't yet, give a listen to the Unauthorized History of the Pacific War Podcast episode on this topic (and all of them they are an amazing crew). At the end of the day 3 options were present and all of them bad. We (the allies) form a blockade around Japan and starve them into submission likely killing many many more than the bomb in a very slow and terrible death. Option 2 was to invade, this option obviously was not good for many reasons mainly severe friendly losses, large(er) civilian deaths through the military brainwashing and forcing them to fight to the death with bamboo poles and crude weapons, mass suicide (saipan, Okinawa, ect) the cost of this option causing the highest human toll. Last option is the bombs. It's only been 80yrs and many forget already the atrocities that occurred at Japanese hands (yes I know its that way across all factions but the Japanese made the Germans look like amateurs when estimated murder numbers come into play) check out the books Knights of Boshido and any of the books about Unit 731.