The ignorance of the man in "To Build a Fire" is our ignorance: the ignorance of the human race with respect to nature. London's use of dramatic irony gives us an omniscient perspective on things, allowing us to take a step back and see not just the man's delusions with regards to his immediate surroundings, but also the lack of awareness and understanding we often show towards our own natural environment.

Right from the start we're painfully aware of the man's delusions. When the "old-timer" warns him against travelling alone, the man scoffs at him for being "womanish." Even without knowing what subsequently happens, we sense the danger. Scientific evidence is also blithely ignored by the man. He thinks that 50 degrees below zero is cold and uncomfortable, but that's all; he thinks he can get through it with thick socks, ear muffs, and warm moccasins. Though the man chooses to remain ignorant, this is still an example of situational irony, as we know something he doesn't know or care to know.

Dramatic irony creates suspense in the story because we sense that something unpleasant is going to happen to the man, but we don't know quite what. Maybe he'll go through several terrifying ordeals before emerging victorious in the end—cold, frostbitten and hungry, but much wiser, and crucially, still alive. Even if we've never read the story, and even if we don't know the ending, we know something the man doesn't—the old-timer was right all along. Unfortunately for the man, he only comes to realize this when it's far too late.

London uses dramatic irony to great effect in his story "To Build a Fire." In the story, a man is walking from one camp to the next through the Alaskan wilderness, accompanied only by a dog, in extreme cold. The man thinks it might be more than fifty degrees below zero; in fact, London's narrator tells us in paragraph 6, "it was not merely colder than 50 below zero; it was colder than 60 below, than 70 below. It was 75 below zero. Because the freezing point is 32 above zero, it meant that there were 107 degrees of frost."  By telling his reader that it is far colder than the man thought it was, London is simultaneously highlighting how "green" the man is and creating suspense: the reader knows that the man is in a life-threatening situation; even the dog "was worried by the great cold. It knew that this was no time for traveling." As the story progresses, more and more is made of the difference between what the reader knows and what the man does not; the man's analysis of his situation often is limited to his thinking "It certainly is cold!" As it becomes clear that the man will die, the dramatic irony of the story causes the reader to feel pity for the man and also becomes the basis for an object lesson on man's insignificance in the face of the raw power of nature.