PS 23-57
The sensitivity of crop yields to temperature in China: A meta-analysis
The influence of global warming on crop yields in China has been widely analyzed through various climatic-crop model simulations, but the direction and magnitude of the temperature effect still remains uncertain. Understanding the sources of this divergence is central to building a more robust picture of temperature changes’ likely impacts. With 270 observations collected among 40 studies, our meta-analysis evaluated the temperature sensitivity of crop yields (the relative yield change for a temperature increase of 1°C) at national and regional scales. A literature review was performed, distinguishing two simulations methods: process-based models and statistical models. For the process-based models, the sensitivity test was made by increasing the daily mean temperature during the growing season, holding other climatic and non-climatic factors the same as the baseline condition. The temperature sensitivity was estimated as the simulated relative yield change obtained for a temperature increase of 1°C. For the statistical models, historical data on crop yields and growing season weather (such as mean temperature, precipitation or other climatic factors) were used to calibrate relatively simple multiple regression equations. The regression coefficients of temperature were then deemed as the temperature sensitivity.
Results/Conclusions
Because few information about temperature sensitivity of crop yields are found in the literature review for Maize and Soybean, the following analyses mainly focus on wheat (N=104) and rice (N=121). At the national scale, most results obtained with the process-based models reveal that crop yields significantly decrease with temperature increase(more than 3 %/°C), indicating a significant effect of temperature change on crop yields. On the contrary, in the statistical models, the temperature sensitivity mainly belongs in the range of -3~3 %/°C, indicating that temperature increase causes minor changes in the crop yields. At the regional scale, the response of wheat yield to temperature increase is found to be negative, and strong. This is observed everywhere in the country, except northwestern regions, for processed-based models. No regional differences are found for the statistical models. The results for rice show northeastern regions experience lower yield losses with increasing temperature than southeastern and southwestern parts of China for the process-based model simulations, but more yield gains for the statistics models. For the process-based models, both positive and negative responses are found in the northwestern regions. Overall, the process-based models simulate more negative yield response to temperature increase than the statistical models.