The chapters in this section need to be prefaced with several cautionary remarks. It is unlikely that the scientific and, even more, popular-scientific elaborations of environmental crisis reviewed below will remain unchanged over time. It is very possible that some elements of these elaborations will prove wrong. Given the extreme complexity of ecological processes, strict scientific certainty about always incomplete data is difficult to come by. Equally, the politicizing of science that is inevitable when scientists and others track environmental danger, damage, and risk in a context of social conflict leads to assertions that in hindsight may seem biased as well as prove untrue. All too easily, even serious projections and prophecies turn into quaint curiosities or even repugnant attitudes when viewed from the standpoint of a later time.