Abstract:  The climate change in the source area and the upper reach of the Yellow River and its impact on the Yellow River runoff are reviewed. The impacts of climate change on the ecosystem and frozen soil in its source area are discussed further. It is shown that the annual runoff amount of the source area and the upper reach of the Yellow River significantly decreased from the early 1990s, which seriously affected the annual runoff amount of the middle and lower reaches of the Yellow River and caused the increase of dryingup days of the lower reach of the Yellow River during the 1990s. Moreover, the decrease of the precipitation amount in the source area and the upper reach of the Yellow River from the early 1990s to the early 21th century may be a main reason led to the significant decrease of the runoff in the sources area and the upper reach of the Yellow River, and the weakening of the rainfall intensity in these areas during this period has an important impact on the significant decrease of the runoff in these areas. The obvious warming in the source area of this river from the 1980s to the early 21th century did not lead to a large change of the evaporation in this area. Thus, it maybe explain that the increase of air-temperature in the source area of the Yellow River slightly affect the runoff in this area. Besides, this obvious warming has an important impact on the degeneration of vegetation and frozen soil in the source area of the Yellow River.  

Key words:  climate change, Yellow River, runoff, ecosystem, frozen soil