Productivity and income in agriculture are heavily influenced by climatic conditions. Changes in temperature, precipitation, extreme events, water flows, and atmospheric content have a mixture of positive and negative implications for plant growth, livestock performance, and water supply, as well as for soil characteristics, pests, and diseases. Thus, this industry is likely to face changing conditions and may be at risk given the possible incidence of global climate change. This chapter examines the vulnerability of agriculture in Texas to global climate change. Estimation of the effects of climatic change on agriculture is difficult. Basically, there are three methods that could be used to make such an estimate. The first is based on observation, but it entails waiting for climate change conditions to develop fully, either globally or in representative regions. That is not now possible for the combination of carbon dioxide and climatic effects that we expect in the future. Second, one could turn to experimentation, by subjecting agricultural production systems to climatic change scenarios and observing the production implications. That is also not feasible, as the sites and systems to be investigated would render such an undertaking quite expensive. In addition, even if completed, the results would not reveal the effects on crop mix, markets, international trade, livestock herd size, and so on. That leaves the third, simulation-based approach, using models to simulate crop yields, crop mix choice, and market processes. This approach requires the adoption of scenarios regarding both climate effects and agricultural production and consumption conditions. It also necessitates the use of agricultural scenarios that are available, because the resources supporting this work do not permit reruns of the crop and hydrological simulations that are input. Thus the climate and associated agricultural and hydrological scenarios adopted are those resulting from the U.S. National Assessment (Reilly et al. 2001, 2002a,b). The first part of the chapter discusses how global climate change might influence agricultural processes. Second, results are presented from an assessment of the influence of climate change on crop yields and the agricultural economy under 2007 conditions. The 2007 base was used, as opposed to a future year, because experience has shown that the model variation introduced by assumptions about future technological progress, demand, exports, and other factors is far larger than the implications of most phenomena such as climate change. Third, we focus on a regional study in the area around San Antonio, examining agricultural effects in the face of nonagricultural and ecological competition. Copyright 2011 by the University of Texas Press. All rights reserved.
