A spatio-temporal analysis of agricultural vulnerability to climate change: The United States Great Plains, 1969--1992.

摘要

The process of agricultural land-use is both a cause and consequence of other environmental changes, such as climate change, that threaten the long-term well being of ecosystems and societies. This process is influenced by biophysical, economic and sociocultural factors that operate on a hierarchically ordered set of spatial scales and evolve over time and from place to place. Thus a central problem for researchers interested in the possible impacts of climate change on agriculture to characterize the conditions under which climate does and does not matter to agriculture. The objective of this dissertation is to examine the vulnerability of U.S. Great Plains agriculture to possible changes in climate, using a statistical framework capable of estimating region-wide trends alongside localized deviations, for the period 1969–1992.; There are three sets of important findings. First, the commonly studied factors that influence an important dimension of agricultural land-use—land values—are broadly applicable to the entire region. However, the importance of factors excluded from the statistical models (due to lack of data availability or inability to quantify) varies significantly between two sub-regions: the portion of the Great Plains overlying the Ogallala Aquifer and the rest of the region. Great Plains farmers with access to Ogallala groundwater for irrigation purposes are relatively insulated from swings in large-scale macroeconomic and environmental conditions. Compared to farmers without access to irrigation water, Ogallala farmers benefit less from improvements in these conditions, but they also suffer less from downswings (e.g., in commodity prices).; Second, there is strong evidence that for the region as a whole (i.e., without respect to the Ogallala), that land values—and by extension the variations in land uses that give rise to the differing land values—exhibit important localized clustering. The land uses of a given county are determined not only by characteristics of that county but also by characteristics of neighboring counties. This finding supports the longstanding theory supporting the between-farmer diffusion of agricultural practices, and suggests that a complete understanding of climate change impacts and policies designed to mitigate those impacts will need to account for and leverage social communication networks rather than assume that information is instantaneously accessible to all farmers everywhere.; Third, the economic importance of climate to Great Plains agriculture varies with the time at which the relationship is evaluated. (Abstract shortened by UMI.)