I think it is fairly obvious to any reader of this excellent short story that Jack London is an author who knows his material well, and has not just researched it but has lived it. Jack London himself in his teens and twenties advetured extensively on sea and ice, prospecting for gold in the Yukon Territory and therefore new first hand the dangers of venturing out in sub-zero conditions and the kind of risks such people took. If we examine the story, it is full of small details that clearly indicate the way that the author's personal experience shaped his fiction. Consider the following example:
The sight of the dog put a wild idea into his head. He remembered the tale of the man, caught in a blizzard, who killed a steer and crawled inside the carcass, and so was saved. He would kill the dog and bury his hands in the warm body until the numbness went out of them. Then he could build another fire.
It is clear that this reference is based on factual knowledge, and indeed this practice was very common among Arctic explorers. Such details and the realistic description again and again reinforces the way that London wrote not from the comfort of his armchair alone but based on the experiences that he himself endured as part of his adventuring days.