全球变化知识资源中心

Extreme climate events have become more severe and frequent with global change in recent years. The Chinese temperate steppes are an important component of the Eurasian steppes and highly sensitive and vulnerable to climatic change. As a result, the occurrence of extreme climate events must have strong impacts on the temperate steppes. Therefore, understanding the spatio-temporal trends in extreme climate is important for us to assess the sensitivity and vulnerability of Chinese temperate steppes to climatic changes. This research had two specific objects to (i) specify the temporal changes in extreme climate events across the whole steppe and (ii) compare the trend differences for extreme climate events in different types of steppesumeadow steppe, typical steppe and desert steppe.

To investigate extreme climate trends in the temperate steppes of China, 82 meteorological stations with daily temperature and precipitation data (19612013) were used. Meanwhile, eight core extreme climate indices (extreme high-temperature threshold, extreme low-temperature threshold, frost days, heatwave duration, heavy rainfall threshold, percentage of heavy rainfall, heavy rainfall days and consecutive dry days) from the Statistical and Regional Dynamical Downscaling of Extremes for European Regions (STARDEX) project were selected to analyse the trends in extreme climate across the whole temperate steppe and the three main types (meadow steppe, typical steppe and desert steppe) through time and space.

The results showed that (i) the changes in extreme climatic temperature events across the whole temperate steppe were obvious during 19612013. The frost days (3.40 days/10 year [yr]) decreased significantly, while the extreme high-temperature threshold (0.24C/10 yr), extreme low-temperature threshold (0.52C/10 yr), and heatwave duration (0.58 days/10 yr) increased notably. The annual changes in extreme precipitation were small and not significant. (ii) Differences appeared in the extreme climatic trends in different types of steppes. The desert steppe showed strong climate extremes and underwent the most significant asymmetric warming compared with the meadow steppe and typical steppe. At the same time, the heatwave duration (0.62 days/10 yr) increased. In terms of the extreme precipitation, there was no significant trend among the three types of steppes. However, the fluctuations in extreme precipitation were the largest in the desert steppe compared to those in the typical steppe and meadow steppe.