Climatic Causes of Maize Production Loss under Global Warming in Northeast China

Maize (Zea mays L.) is one of the most important staple crops in Northeast China, and yield losses are mainly induced by climate anomalies, plant diseases and pests. To understand how maize yield loss is affected by global warming, daily precipitation and temperatures, together with provincial agricultural data sets, were analyzed. The results showed that the accumulated temperature, an important factor in agricultural productivity, increased by 5% in 1991-2017, compared to 1961-1990, and that the frequency of low temperatures decreased by 14.8% over the same time period. An increase in drought by 21.6% was observed from 1961-1990 to 1991-2017, caused by decreased growing-season precipitation by -4 mm/decade. In addition, days with heavy rain in August and September increased slightly in Northeast China. In general, maize growth responded positively to the increased thermal conditions; in 1961-1990, 22.7% of observed maize yield-loss cases were due to low temperatures, but only 10% in 1991-2017. However, during the same time, the number of drought-induced yield loss cases increased from 27.3% to 46.7%. Moreover, yield loss cases caused by heavy rainstorms increased from 4.5% to 13.3%, indicating that heavy rainstorms have become an increasing threat to agriculture in Northeast China over the last three decades. In total, at least 70% of cases of provincial yield losses in Northeast China over the last three decades could be attributed to climatic factors. The frequency of climate hazards has changed under global warming, resulting in new challenges for agriculture. While drought and low temperatures were the primary causes for climate-induced yield losses before the 1990s, negative impacts from extreme events, mainly drought but also heavy precipitation, have increased in the last three decades, associated with global change. Farmers, agricultural scientists, and government policy makers could use these results when planning for adaptation to climate change.