Abrupt and Persistent Declines in Regional Precipitation Patterns: Societal Implications and Geographic Patterns

Abrupt and persistent changes in regional climate patterns have happened in the past, and according to models, may happen again in the future. These sudden and prolonged shifts have negatively impacted the well being of people and can compromise the ability of societies to sustain into the future in a desirable way. It is therefore important to determine which places might be vulnerable to abrupt changes in precipitation patterns the future, as well the impacts that such shifts have had in the past. Understanding this should help to focus management efforts. Using an analysis of twentieth century gridded station data, this research investigates the impact that sudden and prolonged declines in annual precipitation had for three socialecological systems: northern Mexico in the 1950s and 1960s, parts of the Former Soviet Union in the 1920s and 1930s, and southern Africa in the 1980s and 1990s. A literature review was carried out to determine the effects that the abrupt changes had on the socialecological systems under consideration. In addition, the geography, climate, and land use practices of the regions were investigated using both literature and analyses of average precipitation, crop cover, and potential vegetation datasets. Comparisons of the events were made in an attempt to elucidate patterns that could be studied further. Savanna and grassland/steppe potential vegetation zones were found to be particularly vulnerable to the sudden and prolonged shifts in precipitation patterns. In addition, agricultural productivity was determined to be a central component of each of the social-ecological systems considered. For this reason, it is recommended that management efforts in regions vulnerable to abrupt and persistent changes in precipitation concentrate on improving the resilience of their agricultural systems. Political were also found to be an important determinant of the impact that the shifts had on the social-ecological systems studied. Lastly, this research demonstrates the importance of integrating disciplines when studying the dynamics of abrupt climate change.