These spheres are completely connected, and some constant exchanges occurred between each of them.
J.R Mc Neill describes and explains how and why changes occurred in these spheres. Telling us how and why such changes occurred, showing us the various consequences of such changes on our cities, our seas, our lakes, our way of life ., explaining us that environmental degradation « could be sometimes » reversible, the author invites readers to make their own evaluation of the environmental alterations he discusses.
Sometimes, he tries to show us the positive side of changes. Much of the change results from economic development and projects that have improved human living standards; for example, artificial fertilizers allow perhaps an extra 2 billion people to eat'; and sometimes he reminds us that the different technological changes have eased pressure on some resources.
He also tells us about the story of Thomas Midgely who discovered that adding lead to gasoline made it burn better and in this way, who indirectly did more damage to the Atmosphere than any other human being, and how did Japan transform itself from a polluter's paradise to a country of clean air without sacrificing economic performance. There are other numerous historical « little stories » and facts in the book. We learn for example that mining efforts in France uprooted people, shifted land and poured smoke and noxious gases into the Atmosphere, that the growth of US railroad (made of wood) threatened to chew up American's forests at the turn of the twentieth century.
The interesting thing we can notice in this book, is that Mc Neill places his environmental history' in a social, economic and political context, which strengthen his analysis.
Everyone (maybe each in a different way) is concerned about our environmental history'. The environment is subjected to different natural degradations, such as earthquakes, volcanic eruption, floods or droughts.