Alan Weisman's The World Without Us is based on the implausible premise that all human beings on the planet might suddenly and simultaneously disappear. What then? How much of what we have created will remain and for how long? As absurd as such a premise is, the inquiry sheds light on the ecological role of humans on the planet and how we have and have not irreversably changed it. Weisman writes that many of the non-native plants that we established in one place or another will, in time, lose ground to the native plants. Others will survive. Domesticated farm animals will be easy targets for a regenerated population of preditors. Dogs will not survive, but cats might.
Some of his most interesting passages describe the slow decay of buildings and their eventual complete decomposition. He compares the probable lifespan of specific artificial substances and comes to some rather interesting conclusions. For example, in time, little of Phoenix, Arizona will remain in a regenerated dessert but shards of glass and fire hydrants. The longest lasting materials will be plastics and nuclear waste. Both will continue to be deadly dangers to the remaining, recovering, or newly evolving species left behind.
Plastics will not retain their present form. Instead, they will decompose, but this will mean only that they will fragment into smaller and smaller peices. At first this seems benign, but Weisman points out that while we are familiar with birds and other animals that die because they mistakenly swallow plastic artifacts, the decomposition of these artifacts means that smaller and smaller animals will become the victims of our plastics. Plastic is the substance "that keeps on killing." The long-lived danger of nuclear waste is, of course, well known.
Among Weisman's more interesting observations is that much of the existing built world remains only because of constant maintanence by people. For example, without a constant supply of electricity, pumps that daily evacuate water from the New York subway system would fail, and much of system would flood. Water damage would cause widespread collapse of structures over and around the subway lines.
The World Without Us is not, however, a single coherent story. Weisman runs off on frequent tangents that make grasping the whole of the work difficult. After some of these tangents, he appears to recall that he is writing about the world without us and offers a tenuous link between his tangent and the main theme. Unfortunately, this hodge-podge structure is all too common in books I have read recently. It's as though authors don't quite have enough material on a subject to fill 250-300 pages, and are given the freedom by their editors to throw in whatever interesting padding they can vaguely relate to the book's subject. It makes me long for solid sustained treatments of a single subject.