The fingerprint of climate trends on European crop yields
- aEmmett Interdisciplinary Program in Environment and Resources,
- bCenter for Food Security and the Environment, and
- cDepartment of Environmental Earth System Science, Stanford University, Stanford, CA 94305
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Edited by Benjamin D. Santer, Lawrence Livermore National Laboratory, Livermore, CA, and approved January 9, 2015 (received for review May 23, 2014)
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Fig. 1.Patterns and time evolution of crop yields in Europe and the predicted impacts of climate trends. (A) Area-weighted yields of the four crops examined in this paper for the countries included in the study, 1960–2010 (SI Appendix, Table S1) (17). (B–E) Maps of the observed linear trend in yield in 1989–2009 for wheat (B), maize (C), barley (D), and sugar beet (E) (25). Maps of the expected change in yield based on growing-season temperature and precipitation trends in 1989–2009 (27, 28) and the yield response functions described by Moore and Lobell (8) (SI Appendix, Figs. S3 and S4) for wheat (F), maize (G), barley (H), and sugar beet (I). White shows areas not included in the study due to insufficient data.
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Fig. 2.Impacts of growing-season temperature and precipitation trends in 1989–2009 on European crop yields by country and for the whole region (Total). Impacts are weighted by regional production of the relevant crop in 1989–1994 (Methods). The black line shows impacts calculated using the regression point estimate (Table 1), and the colored bars show the 90% confidence interval obtained by inverting a two-tailed hypothesis test of size 10% (Methods). This distribution is skewed for wheat, maize, and sugar beet yields, which is why the bars are asymmetric around the point estimate.
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Fig. 3.Spatial fingerprint of trends in growing-season temperature and precipitation in 1989–2009 on wheat (A), maize (B), barley (C), and sugar beet (D) yields. The maps show the predicted trends in crop yield due to temperature and precipitation changes (Fig. 1 F–I) corrected by the regression coefficient
<mml:math><mml:mrow><mml:mover accent="true"><mml:mrow><mml:msub><mml:mi>β</mml:mi><mml:mn>1</mml:mn></mml:msub></mml:mrow><mml:mo stretchy="true">^</mml:mo></mml:mover></mml:mrow></mml:math>β1^(Table 1). White shows areas not included in the study due to insufficient data.
