As an adult, I can see the badness of this film that was way above my head when I saw it as a child. It's ambitiously bad.
The entire premise is ridiculous, since it rests upon the assumption that global temperatures could rise to over 130 degrees F for
weeks and there would still be anyone left alive. No, by the time the Seaview launched its missile to end the threat, there would be no one left.
Forget the abominably slow pacing. Forget the questionable struggles of deciding whether to follow a commander who may be losing his mind. Forget the debate over destiny and self-determination. None of that matters. Based on the premise, the world died before the crew of the Seaview even knew what was happening.
I may need to write a full review of this at some point.