Projections of future food production necessarily rely on models, which must themselves be validated through historical assessments comparing modeled to observed yields. Reliable historical validation requires both accurate agricultural models and accurate climate inputs. Problems with either may compromise the validation exercise. Previous studies have compared the effects of different climate inputs on agricultural projections, but either incompletely or without a ground truth of observed yields that would allow distinguishing errors due to climate inputs from those intrinsic to the crop model. This study is a systematic evaluation of the reliability of a widely-used crop model for simulating U.S. maize yields when driven by multiple observational data products. The parallelized Decision Support System for Agrotechnology Transfer (pDSSAT) is driven with climate inputs from multiple sources – reanalysis, reanalysis bias-corrected with observed climate, and a control dataset – and compared to observed historical yields. The simulations show that model output is more accurate when driven by any observation-based precipitation product than when driven by un-bias-corrected reanalysis. The simulations also suggest, in contrast to previous studies, that biased precipitation distribution is significant for yields only in arid regions. However, some issues persist for all choices of climate inputs: crop yields appear oversensitive to precipitation fluctuations but undersensitive to floods and heat waves. These results suggest that the most important issue for agricultural projections may be not climate inputs but structural limitations in the crop models themselves.
Areas of Focus: Climate Change, Climate Science, Environment
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Climate Change
Climate change is an urgent global challenge. EPIC research is helping to assess its impacts, quantify its costs, and identify an efficient set of policies to reduce emissions and adapt...
Definition
Climate Science
EPIC’s interdisciplinary team of researchers is contributing to a cross-cutting body of knowledge on the scientific causes of climate change and its social consequences.
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Environment
Producing and using energy damages people’s health and the environment. EPIC research is quantifying the social costs of energy choices and uncovering policies that help protect health while facilitating growth.