Uncertainties in predicting rice yield by current crop models under a wide range of climatic conditions

TLDR

Predicting rice yield under future climates is crucial for food security, yet ecophysiological crop models combined with climate outputs still have largely unquantified uncertainties. The study aimed to determine whether using an ensemble of crop models can reduce these uncertainties. We evaluated 13 rice models against multi‑year experimental data from four diverse Asian sites, comparing their predictions and exploring how different physiological process representations affect yield uncertainty and sensitivity to temperature and CO₂. Individual models performed inconsistently and produced larger uncertainty at extreme temperatures, but the mean of all 13 models matched experimental yields within 10 % and an ensemble of eight or five calibrated models reduced uncertainty to field‑experiment levels, while sensitivity analysis shows a need to improve biomass and harvest‑index predictions under rising CO₂ and temperature.

Abstract

Abstract Predicting rice ( Oryza sativa ) productivity under future climates is important for global food security. Ecophysiological crop models in combination with climate model outputs are commonly used in yield prediction, but uncertainties associated with crop models remain largely unquantified. We evaluated 13 rice models against multi‐year experimental yield data at four sites with diverse climatic conditions in Asia and examined whether different modeling approaches on major physiological processes attribute to the uncertainties of prediction to field measured yields and to the uncertainties of sensitivity to changes in temperature and CO 2 concentration [ CO 2 ]. We also examined whether a use of an ensemble of crop models can reduce the uncertainties. Individual models did not consistently reproduce both experimental and regional yields well, and uncertainty was larger at the warmest and coolest sites. The variation in yield projections was larger among crop models than variation resulting from 16 global climate model‐based scenarios. However, the mean of predictions of all crop models reproduced experimental data, with an uncertainty of less than 10% of measured yields. Using an ensemble of eight models calibrated only for phenology or five models calibrated in detail resulted in the uncertainty equivalent to that of the measured yield in well‐controlled agronomic field experiments. Sensitivity analysis indicates the necessity to improve the accuracy in predicting both biomass and harvest index in response to increasing [ CO 2 ] and temperature.