What is the author's tone in the nonfiction book, Underland?

As a first person narrator, MacFarlane has a light touch and betrays few political opinions. Instead, he favors sensory description and reveals the intense feelings that the landscapes he visits bring up. For example, when he and his friends witness a huge calving event in Greenland, he writes: "(O)ur shouts turned from awe to something like horror as that shining black pyramid lurched up out of the water, sea streaming from it. My stomach lurched too as the ice came up: the sublime displaced by a more visceral response to this alien display" (381).