Over the past two and a half million years there have been dramatic changes in the level of the sea. At the end of the last interglacial period, about 10,000 years ago, the ocean was 400 feet lower than it is today, and as we are finally beginning to take in, the sea level is still rising. “[I]nundations,” writes John R. Gillis, author of “The Human Shore: Seacoasts in History,” “are capable of inducing massive population movements and radical changes in ways of life.” His examples include the Netherlands, swamped in 1170, 1362, 1703, 1916, and 1953; Japan; the Maldives; and, somewhat eerily, Long Island.
It was strange to read this book in the wake of both Hurricane Sandy and the presidential election. Today, half the world’s population lives within 120 miles of the sea, and anyone who watched the election returns and saw the count coming in from the big states — California, New York, Texas, Florida — can grasp how true this is for the United States. More than half the American population now lives within 50 miles of a coast.