This book is a massive and highly entertaining thought experiment. The motivating questions are, “What happens to everything we have built in this world, the human infrastructure, the cities, the power plants, the roads, the pipelines, etc., should humanity suddenly collapse and leave the Earth without us? What remnants of our dominant species’ civilization will be recognizable after 200 years, a thousand years, after a cycle of ice ages, after geologic time (millions of years) has elapsed?” 

Alan Weisman considers first what happens to our cities, perhaps the our most proud and massive accomplishment, and how long it might take before there is nothing left. And by “nothing left” he means, either ruins, an etching into the fossil record, or no easily discernible evidence that these huge constructions ever existed. He discusses the human infrastructure that teeters on the edge of global calamity even with our constant monitoring and adjusting, and which, after we are gone and no longer around to manage, may cause damage to the planet that will last for eons. He also assesses those aspects of our culture that will last the longest as a testament to our existence. Weisman arrives at his projections through interviews with experts in the fields of anthropology, ecology, forestry, waste disposal, and many others.

The author does digress into deep analysis of past injustices done to the planet as well as the history of topics like the development of fertilizer and the storage of chemical and nuclear waste and the effect all this has on the planet. He describes the hole in the ozone layer, the timeline of discovery, and causes. Though much of what he has to say about history is instructive, sometimes the details are well known and it feels like filler. This is too bad, because majority of the information is fascinating and instructive. However, on balance, I think the pages dedicated to this ambitious thought experiment were worth the occasional digression.