Drought monitoring of sugarcane and dynamic variation characteristics under global warming: A case study of Guangxi, China

Sugarcane planting is the largest cash crop industry in Guangxi and plays an essential role in national sugar security. However, as the climate warms in recent years, agricultural drought has occurred frequently and repeatedly in Guangxi, including drought in 2009–2010. Extreme warm and dry created a shortage of water resources, resulting in a severe reduction in sugarcane production in Guangxi and a large gap in the sugar market. Our study used the standardized precipitation evapotranspiration index (SPEI) to identify and monitor sugarcane drought disasters in Guangxi, analyze the impact of long-term warming on drought in different sugarcane growth periods caused by precipitation deficits, and explore the change in sugarcane drought exposure under climate change. (1) Based on historical climate observations, warmth and precipitation deficits co-occurred, and the possibility of drought in the sugarcane growth stage was 100%. We found that although the probability of precipitation deficit did not change substantially in sugarcane, the occurrence of seeding and maturity stage drought years was greater in the past 30 years than in the preceding 28. In addition, the different growth periods of sugarcane also exhibited more warming characteristics. (2) The multi-model ensemble reveal that climate warming has increased the probability of drought years are also warmer in all sugarcane growing seasons, with the highest incidence of drought occurring during the seeding, tillering, and maturity stage. As the forced emission scenario is strengthened, the probability of precipitation deficits and warm conditions occurring simultaneously will increase, as will the probability of warming-induced drought. (3) Under the warming scenario, the sugarcane drought-affected areas are gradually expanding, which could result in the current highly suitable sugarcane planting areas reach the drought tolerance limit. From stem elongation to whole growth period, drought occurrence increases as latitude decreases, in addition, the risk of short-term drought risk of sugarcane becomes more challenging, especially the drought in the mature period, which may become the main limiting factor in achieving a high yield of sugarcane in this region.