Estimating the impacts of warming trends on wheat and maize in China from 1980 to 2008 based on county level data

摘要

This study estimated the past warming impacts on wheat and maize from 1980 to 2008 based on data from 2339 counties in China, providing a finer portrait of climatic effects than earlier assessments that often focused on a provincial scale. We detected an overall negative effect of the average temperature (T_(avg)) and diurnal temperature range (DTR) on wheat and maize yields on a national level, but our results also indicate notable beneficial effects of the T_(avg) in the northcentral region for wheat and the eastern parts of northeast for maize that, in most previous studies, were overlooked due to the coarseness of provincial data. Because wheat cultivation is highly intense in the north, the positive T_(avg) effect in the region has offset losses from warming in other areas, improving national production by up to 1.6% relative to the average level over the study period. For maize, unfortunately, approximately 5.8% production was lost due to increases in the T_(avg) as the dominant adverse effect. Given the reduced DTR in the major producing regions, the past trends of the DTR have boosted wheat production by up to 2.1% and maize by up to 1.4%. As a result, the combined effects of the T_(avg) and DTR have increased wheat production by up to 3.7%, but decreased maize production by 4.4%, equivalent to approximately 10% of the actual change in Chinese wheat and maize production from 1980 to 2008.