Impacts of climate change on historical locust outbreaks in China

To probe if greenhouse‐effected climate warming strengthens severe locust outbreaks that would cause continental‐scale crop failures in China, we studied their statistical relationships in history and examined the impacts of climate change on the long‐term locust outbreaks. According to analysis for interannual time series during the past 100 years, the most severe locust outbreak years were in the warm‐dry years with warm‐dry summers and warm‐wet winters in the Yellow River–Haihe River region, northern China, and warm‐wet years with warm‐wet springs in the Yangtze River–Huihe River region, southern China. Checking wavelet‐analyzed variance series, these interannual time scale synchronous changes with 2–10 periodicity years were 58–60% among the total locust outbreak years of the past 1000 years. Locust outbreak correlation analysis with decadal time scale temperature proxy and general circulation model–simulated climate during the past 1000 years showed significant correlations in warm‐winter‐half years and in warm‐dry May–June and annual means in the northern region (p < 0.05), where p is probability, and in warm years and warm‐dry August–September years in the southern region (p < 0.10), while these decadal time scale synchronous changes with 20–110 periodicity years were 56–65% of the total locust outbreak years of the past 1000 years. Historical records on “drought locust” were true, as we found that the drought of spring‐summer season in the northern region caused the highest regional locust outbreaks, but it is not a sensitive factor for locust outbreaks in the wet‐humid Yangtze River region. Although warm winter condition is a key factor for locust egg survival and preservation, it works well when winter temperatures reach to −10° to −30°C in the northern region but is not a limiting factor for locust survival in the warm southern region. We found that both interannual and decadal variability of higher temperature changes have led to the highest locust outbreaks in the past 1000 years, so as to suggest that greenhouse‐effected climate warming would increase the severe locust outbreaks in the area.