Fire and Ice
The speaker brings us into the middle of an argument between people who think the world will come to a fiery end and people who think the world will freeze. He could be talking about the literal end of the world, but he's also talking about the power that human beings have to harm or "destroy" one another.
The speaker's experience with romantic desire has taught him that passionate or "hot" emotions like love and lust would probably have the power to turn the earth into a big fireball. But he has also experienced the other extreme, and he knows that colder emotions like hate have great destructive power. Love gets all the publicity, but hate is the silent killer. It may not have the same grandeur as the fireball ending, but it'll do the trick.