Collapse_ How Societies Choose to Fail or Succeed - Jared Diamond [304]
CHAPTER 16
The World as a Polder: What Does It All Mean to Us Today?
Introduction ■ The most serious problems ■ If we don’t solve them . . . ■ Life in Los Angeles ■ One-liner objections ■ The past and the present ■ Reasons for hope ■
The chapters of this book have discussed why past or present societies succeed or fail at solving their environmental problems. Now, this final chapter considers the book’s practical relevance: what does it all mean to us today?
I shall begin by explaining the major sets of environmental problems facing modern societies, and the time scale on which they pose threats. As a specific example of how these problems play out, I examine the area where I have spent most of the last 39 years of my life, Southern California. I then consider the objections most often raised to dismiss the significance of environmental problems today. Since half of this book was devoted to ancient societies because of the lessons that they might hold for modern societies, I look at differences between the ancient and the modern worlds that affect what lessons we can draw from the past. Finally, for anyone who asks, “What can I do as an individual?” I offer suggestions in the Further Readings section.
It seems to me that the most serious environmental problems facing past and present societies fall into a dozen groups. Eight of the 12 were significant already in the past, while four (numbers 5, 7, 8, and 10: energy, the photosynthetic ceiling, toxic chemicals, and atmospheric changes) became serious only recently. The first four of the 12 consist of destruction or losses of natural resources; the next three involve ceilings on natural resources; the three after that consist of harmful things that we produce or move around; and the last two are population issues. Let’s begin with the natural resources that we are destroying or losing: natural habitats, wild food sources, biological diversity, and soil.
1. At an accelerating rate, we are destroying natural habitats or else converting them to human-made habitats, such as cities and villages, farmlands and pastures, roads, and golf courses. The natural habitats whose losses have provoked the most discussion are forests, wetlands, coral reefs, and the ocean bottom. As I mentioned in the preceding chapter, more than half of the world’s original area of forest has already been converted to other uses, and at present conversion rates one-quarter of the forests that remain will become converted within the next half-century. Those losses of forests represent losses for us humans, especially because forests provide us with timber and other raw materials, and because they provide us with so-called ecosystem services such as protecting our watersheds, protecting soil against erosion, constituting essential steps in the water cycle that generates much of our rainfall, and providing habitat for most terrestrial plant and animal species. Deforestation was a or the major factor in all the collapses of past societies described in this book. In addition, as discussed in Chapter 1 in connection with Montana, issues of concern to us are not only forest destruction and conversion, but also changes in the structure of wooded habitats that do remain. Among other things, that changed structure results in changed fire regimes that put forests, chaparral woodlands, and savannahs at greater risk of infrequent but catastrophic fires.
Other valuable natural habitats besides forests are also being destroyed. An even larger fraction of the world’s original wetlands than of its forests has already been destroyed, damaged, or converted. Consequences for us arise from wetlands’ importance in maintaining the quality of our water supplies and the existence of commercially important freshwater fisheries, while even ocean fisheries depend on mangrove wetlands to provide habitat for the juvenile phase of many fish species. About one-third of the world’s coral reefs