there isn't much of a conventional setting in this poem, unless you consider the vague concept of "apocalypse" or the "end of the world" to be a setting.
but, "fire and Ice" starts off with two images of the end of the world. In the first image, the world is a great bubbling mess of fire, lava, and explosions. cities are melting and trees are burning. In the second vision, the world is an ice cube/a ice sphere. a extremely large cloud looms above the earth, and temperatures are so low that life cannot survive.
from there we move to a discussion from the speaker- we now have the image of him "tasting" desire, like Eve biting into the fateful apple in the Garden of Eden. then he rewinds the end of the world somehow, as if this were a film.
In the second apocalypse, things run different. Ice carries the day, driven by the hatred of people.
