Preliminary Study on Signal, Impact and Foreground of Climatic Shift from Warm-Dry to Warm-Humid in Northwest China

A rapid, high amplitude global climatic warming would speed global water cycle and strengthen rainfall and evaporation. Climatic warming and drying course were dominated in past about 100 years since the end of Little Ice Age in Northwest China. The strong signals of climatic shift to warm humid pattern have been appearing in the western part of Chinese Tianshan Mountains and neighborhood regions including Northern Xinjiang since 1987. Precipitation, meltwater of glacier and runoff of rivers increase continuously , and results in lake level rising, flood damaged magnification and intensified, vegetation coverage extending and dust storm weaken in western parts of Northwest China. In the other areas of Xinjiang, and the middle and western section of Qilian Mountains, the precipitations and runoff of rivers have also an increasing tendency. How is the foreground of climatic shift to warn humid conditions, it is just restricted to decadal fluctuation, or possibility to century scale shift trend, and is just limited to western Tianshan or could extend and/or wholly Northwest China down to North China?Using the results of regional climatic model simulation from IPCC and China Assessment Report published, predicting river runoff regime and similar paleoclimate scenarios for the Northwest China are analysed and discussed, and the trend of shifting warm humid climate can be fixed in recent future. However, uncertain of projected results remain, and rating and magnitude of climatic shift extending in temporal and spatial scales can not at present be projected in detail and in being exactitude.