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Increasing impact of compound agricultural drought and hot events on maize yield in China

Xinying Wu*, Dabang Jiang, Fan Zhang

*Corresponding author:

ABSTRACT: Drought episodes with hot events usually trigger dramatic impacts on crop yield. However, most previous studies on climate stress only focus on individual droughts or hot conditions, leading to a neglect of compound information. Based on various combinations of soil moisture and temperature, the impact of six modes of events, namely, compound drought and cold events, compound wet and hot events, compound agricultural drought and hot events (CADHEs), compound wet and cold events, droughts, and hot events, on maize yield in China is investigated in this study. We present evidence from country-level, province-level and grid-cell yield data that CADHEs have emerged as a major threat to maize yield, with higher yield reduction than the five other soil moisture and temperature related events, including agricultural droughts defined by soil moisture only. Among the 6 modes, the highest probability of yield reduction is prevalent under CADHEs. The negative maize yield anomalies due to CADHEs have increased during the past decades at both national and regional scales. The increase in the frequency, spatial extent, and severity of compound events can partly account for this enhanced negative impact on maize yield. Also, the concurrent intensification in the positive soil moisture-yield relationship and negative temperature-yield relationship is likely responsible for this change. The negative response of maize yield suggests that if the increase in CADHEs persists, more adaptation and mitigation strategies are needed to ensure sustainable food security.