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)
Significance
Agriculture is one of the economic sectors most exposed to climate change impacts, but few studies have statistically connected long-term changes in temperature and rainfall with yields. Doing so in Europe is particularly important because yields of wheat and barley have plateaued since the early 1990s and climate change has been suggested as a cause of this stagnation. Here, we show that the impact of climate trends can be detected in the pattern of long-term yield trends in Europe. Although impacts have been large in some areas, the aggregate effect across the continent has been modest. Climate trends can explain 10% of the slowdown in wheat and barley yields, with changes in agriculture and environmental policies possibly responsible for the remainder.
Abstract
Europe has experienced a stagnation of some crop yields since the early 1990s as well as statistically significant warming during the growing season. Although it has been argued that these two are causally connected, no previous studies have formally attributed long-term yield trends to a changing climate. Here, we present two statistical tests based on the distinctive spatial pattern of climate change impacts and adaptation, and explore their power under a range of parameter values. We show that statistical power for the identification of climate change impacts is high in many settings, but that power for identifying adaptation is almost always low. Applying these tests to European agriculture, we find evidence that long-term temperature and precipitation trends since 1989 have reduced continent-wide wheat and barley yields by 2.5% and 3.8%, respectively, and have slightly increased maize and sugar beet yields. These averages disguise large heterogeneity across the continent, with regions around the Mediterranean experiencing significant adverse impacts on most crops. This result means that climate trends can account for ∼10% of the stagnation in European wheat and barley yields, with likely explanations for the remainder including changes in agriculture and environmental policies.
Footnotes
- ↵1To whom correspondence should be addressed. Email: fcmoore{at}stanford.edu.
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Author contributions: F.C.M. and D.B.L. designed research; F.C.M. performed research; F.C.M. analyzed data; and F.C.M. and D.B.L. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
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This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1409606112/-/DCSupplemental.
