Understanding vulnerabilities associated with discrete events such as Katrina can illuminate more general vulnerabilities and associated adaptation options and constraints that are tied to long-term changes in climate. Climate change is expected to produce changes in patterns of precipitation and water availability (Figure 3.1), but it is unclear what vulnerabilities these changes may produce without first assessing how sensitive local populations are to such changes, and how effectively people may respond to the impacts of the changes. It is also important not to focus so much attention on climate events that we lose sight of how coupled human–environment systems may be vulnerable to nonclimate stresses or perturbations. A variety of natural occurrences and social processes can increase the vulnerability of peoples and places, including tsunamis, earthquakes, droughts, toxic waste spills, nuclear contaminations, economic globalization, deforestation, and HIV/AIDS. Complicating matters further is the fact that these developments do not necessarily operate in isolation, and that some of them (e.g., economic globalization) present potential benefits as well as pitfalls.
Since the 1980s, global environmental change has emerged as an important research area in many academic disciplines. Geographical scientists have played major roles in a variety of international and interdisciplinary environmental-change initiatives, and have taken a leading role in bringing vulnerability issues to the fore. Their research draws on a rich tradition of geographical work concerned with how humans are transforming Earth (Marsh, 1864; Sauer, 1925; Thomas, 1956; Glacken, 1967; Turner et al., 1990a). The approach of the “Chicago School of environmental risks and hazards” has been particularly influential. The Chicago School is based on the pioneering work of Gilbert White (e.g., White, 1945), who sought to explain why, in early 20th century United States, aggregate flood-related damages were rising, not falling, despite expanded technological interventions aimed at reducing flood damage. To answer this question, White focused on people’s decisions, asking what informational or psychological limitations led people to approach environmental risks and hazards in a way