Final answer:
The word 'gripping' in the excerpt conveys a tone of respect for the intensity of the cold weather in Alaska, rather than any optimism, sympathy, or sarcasm.
Step-by-step explanation:
The author's use of the word gripping to describe the cold snap in Alaska contributes to the tone of the passage by emphasizing the severity and overwhelming nature of the cold. It does not imply optimism, sympathy for Erickson, or sarcasm towards her perceived weakness. Instead, the word gripping suggests a sense of respect for the raw power of the frigid weather, almost as though it has the ability to seize and hold the attention or even the physical well-being of those affected by it.