Vulnerability of California specialty crops to projected mid-century temperature changes

Authors: Kerr, Amber; DIALESANDRO, JAKE - New Mexico State University; Steenwerth, Kerri; LOPEZ-BRODY, NATHAN - New Mexico State University; Elias, Emile

Submitted to: Climatic Change
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2017
Publication Date: 9/7/2017
Publication URL: http://handle.nal.usda.gov/10113/5859844
Citation: Kerr, A.C., Dialesandro, J., Steenwerth, K.L., Lopez-Brody, N., Elias, E.H. 2017. Vulnerability of California specialty crops to projected mid-century temperature changes. Climatic Change. 148(3):419-436. https://doi.org/10.1007/s10584-017-2011-3.
DOI: https://doi.org/10.1007/s10584-017-2011-3

Interpretive Summary: This paper describes the temperature sensitivity and climate exposure of selected specialty crops grown in California. We used literature synthesis to create a sensitivity index (from 1 to 4) to changes in winter minimum and summer maximum temperature for the top 14 specialty crops. To estimate exposure, we used seasonal period change analysis of mid-century county level minimum and maximum temperature changes downscaled to county level from CMIP5 models. We described crop vulnerability on a county basis as (crop sensitivity index × county climate exposure × area of crop in county); individual crop vulnerabilities were combined to create an aggregate index of specialty crop vulnerability by county. We also created alternate vulnerability indices scaled by crop value rather than area, and normalized to total specialty crop area in each county. Our analyses yielded a spatial assessment highlighting seasons and counties of highest vulnerability. Winter and summer vulnerability are correlated, but not highly so. High-producing counties (e.g., Fresno County in the San Joaquin Valley) are the most vulnerable in absolute terms, while northern Sacramento Valley counties are the most vulnerable in relative terms, due to their reliance on heat-sensitive perennial crops. Scaling vulnerability by value rather than area highlights coastal counties growing high-value strawberries. Our results illustrate the importance of examining crop vulnerability from different angles in order to inform different policy responses. More physiological and economic research is needed to build a comprehensive picture of specialty crop vulnerability to climate change.

Technical Abstract: Increasing global temperatures are likely to have major impacts on agriculture, but the effects will vary by crop and location. This paper describes the temperature sensitivity and exposure of selected specialty crops in California. We used literature synthesis to create several sensitivity indices (from 1 to 4) to changes in winter minimum and summer maximum temperature for the top 14 specialty crops. To estimate exposure, we used seasonal period change analysis of mid-century minimum and maximum temperature changes downscaled to county level from CMIP5 models. We described crop vulnerability on a county basis as (crop sensitivity index × county climate exposure × area of crop in county); individual crop vulnerabilities were combined to create an aggregate index of specialty crop vulnerability by county. We also conducted analyses scaled by crop value rather than area, and normalized to total specialty crop area in each county. Our analyses yielded a spatial assessment highlighting seasons and counties of highest vulnerability. Winter and summer vulnerability are correlated, but not highly so. High-producing counties (e.g., Fresno County in the San Joaquin Valley) are the most vulnerable in absolute terms, while northern Sacramento Valley counties are the most vulnerable in relative terms, due to their reliance on heat-sensitive perennial crops. Our results illustrate the importance of examining crop vulnerability from different angles. More physi- ological and economic research is needed to build a comprehensive picture of specialty crop vulnerability to climate change.