Spatiotemporal Changes in Extreme Temperature and Precipitation Events in the Three-Rivers Headwater Region, China

Extreme climate events affect sustainable development in many parts of the world. Although several studies of local extreme climate events exist, such events need more thorough investigation. Detailed studies of climatic variations that assess changes on both spatial and temporal scales are becoming increasingly necessary. In this study, 14 indices for extreme temperature and 12 indices for extreme precipitation were used to analyze the spatial distribution and temporal trends of extreme climate events in the three-rivers headwater region (TRHR), China, over the past five decades. We found that the frequency of high temperature extremes has increased, whereas the frequency of dry extremes has decreased. Statistically significant upward trends emerged for the number of warm nights (TN90p) and the number of warm days (TX90p) in the TRHR, which increased at a rate of 11.75 and 6.79 days/10 years (p < 0.05), respectively. We also found a highly significant downward trend in the number of consecutive dry days with a rate of -4.05 days/10 years across the whole region. Overall, the TRHR has become warmer and wetter over the past 50 years and the frequency of extreme events has increased. Wavelet analysis indicated that there are significant relationships between extreme climate events in the TRHR and large-scale ocean-atmosphere circulation patterns, for example, the Pacific Decadal Oscillation and the El Niño-Southern Oscillation. Our findings will help local water managers and stakeholders ensure that there are effective measures in place to adapt to and mitigate the effects of potential future climate change in the TRHR.