It turns out that Primack knew very little about Henry David Thoreau, but he eventually learned that throughout the 1840s Thoreau kept extensive records about the first day of "ice-out," the first day ice no longer covers most of the water, the first buds and flowerings of certain trees and flowers, and bird sightings. So Primack replicated that for several years in the 2000s. (Spoiler: Climate change has impacted both flora and fauna in this area of Massachusetts.)
As a social scientist, I found the methods Primack used to be super interesting. He spent years looking for historical records on things like fish, insects, and amphibian life in the area and the joy in his rare victories comes off the page so infectiously I occasionally threw my raised fist up in the air to celebrate with him.
His writing style is absolutely accessible to non-biology oriented people. I, for one, don't know a proboscis from a stamen, but this book did not make me feel in any way that I had to go read a textbook to catch up. I didn't find it patronizing, either, so it carefully walked a line between an entry in an encyclopedia for children and a botanical journal meant to be read only by people with doctorates in obscure branches of plant biology. It was also quite funny at times. Consider the following passage:
"Despite working on plants in Concord from 2003 to 2006, an despite our many contacts and friends within the community of birders, on the one hand, and Thoreau scholars, on the other, no one had told us that Thoreau had kept a detailed record of bird arrival times in Concord! WE found out only later that many of them knew about Thoreau's bird records. I only learned about the records because of a brief reference to them in a book that I was reading." (page 101)
I laughed so hard at this. Of course everyone assumed that Primack knew everything there was to know about Thoreau, while, in fact, he knew virtually nothing about Thoreau.
Anyway, this book is engaging and witty and terrifying all at the same time. I recommend it to all.