Assessing the impacts of the recent California drought on crop production

Wednesday, April 22, 2015
Kaiyu Guan, Stanford University, Stanford, CA, United States, Steven J Davis, University California Irvine, Irvine, CA, United States and Shraddhanand Shukla, University of California Santa Barbara, Santa Barbara, CA, United States
California is in the midst of its one of the most severe droughts in the past several hundred years. Agricultural irrigation accounts for more than 80% of total water use in California, and the state’s agriculture in turn accounts for more than 30% of US crop production by dollar value. Thus, the current drought led to agriculture losses of roughly $1.5 Billion in 2014. We combine crop statistics and climate data for a 25-year period (1980-2014) to investigate the current drought impacts on agriculture production. Focusing on 12 major California crops: wine grapes, lettuce, almonds, strawberries, table grapes, hay, oranges, cotton, tomatoes, walnuts, avocados, and pistachios, we decompose the drought’s impacts on crop production into two factors: crop yield and crop area. We find that the drought-induced heat stress is the primary cause of reductions in crop yield, but that most of the overall reduction in crop production (more than 70%) is the result of decreases in crop area. Human decisions to fallow land during the recent drought relate to increases in the cost of groundwater pumping, tightly linked with the severe water deficit. Our study provides a comprehensive analysis to understand the water-food nexus challenge under the current California drought, with important implications for management of agriculture during future droughts.