The poem "Fire and Ice" by Robert Frost explores the idea of the world ending either in fire or ice as a metaphor for the human emotions of desire and hatred.  One possibility for the Earth's demise is the expansion of the sun. In about 5 billion years, the sun will exhaust its hydrogen fuel and expand into a red giant, engulfing the inner planets, including Earth. This scenario is in line with the "fire" mentioned in the poem.

Another possibility, though less likely, is that the sun could undergo a process that would cause it to cool down, making the Earth uninhabitable. This scenario could be associated with the "ice" mentioned in the poem. However, it is worth noting that the sun cooling down to such an extent is not considered a probable outcome based on our current understanding of stellar evolution.

There are other potential threats to the Earth's existence, such as asteroid impacts, gamma-ray bursts, or even human-induced catastrophes. While it is impossible to predict the exact course of events, it is important for humanity to continue to study and understand the universe to better prepare for potential challenges.

a. The poem is "Fire and Ice" by Robert Frost.
b. In this context, fire represents strong emotions, especially desire and passion.
c. The poetic device used in the first line is alliteration. ‘Some say’ and ‘world will’ are the words where it has been used.
d. The contradiction in the first two lines is that some people believe the world will end in fire, while others believe it will end in ice. These are two opposite elements.
e. Ice and fire are similar in the sense that they both have the power to cause destruction and can symbolize different human emotions, such as desire and hatred.
f. The poet agrees with those who favour fire.
g. The poet uses 'some' instead of 'I' to emphasize that he is presenting different perspectives and not just his own opinion.
h. The rhyme scheme is ABA ABC BCB.