Maybe the point of the book is the opposite, people have ignored environmental impacts on history for a long time, here are some examples. As you say, it is jus

Maybe the point of the book is the opposite, people have ignored environmental impacts on history for a long time, here are some examples. As you say, it is just one part of the puzzle, then why make a point of being wary of the part of the puzzle that was already ignored. It seems that people for a long time were so wary of it that it was unknown, no need to be even more wary.