Some say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
Rhyme
The rhyme scheme is : aba abc bcb with ice repeated twice and also contained within twice/suffice. This clever twist on the terza rima rhyme means that the initial opening fire gradually fades as the poem progresses, with ice taking over.
Meter (Metre in British English)
Overall the poem is a mix of iambic tetrameter and iambic dimeter, the long lines having eight syllables and four stresses, the shorter four syllables and two stresses. This gives the poem a rising feel as each word at line end is stressed. That familiar daDUM daDUM steady beat is maintained, one of Frost's most popular.
Some say / the world / will end / in fire, (spondee+3 iambs)
Some say / in ice. (spondee+iamb)
From what / I’ve ta / sted of / desire (4 iambs)
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is al / so great (2 iambs)
And would suffice.
So note the spondees that open the first two lines giving a spurt of energy with a double stress to the alliteration. And line seven scans a little differently as the reader has to naturally pause at the end of destruction, before the word ice continues the meaning into the final two lines via enjambment.