| Climate change has already manifested in a range of ways and posed serious threaten to all aspects of our living environment. Climate change refers to the differences in the mean state of the climate of the two points in time or for a specified period of time. There may be many factors that cause the climate change, including natural factors and human factors. And nowadays the research shows that the main factors are human activities on the atmosphere. In recent years, because of the serious impact of climate change on the social and economic operation, the extreme climate events caused by climate change have become one of the environmental problems that decision makers and managers pay attention to. Therefore, it is necessary to understand the changes and trends of climate change. Understanding the ongoing climatic changes is very important for human subsistence and sustainable development of economy and society.In this paper, using the CLIMDEX dataset and through the Mann-Kendall mutation test method, the extreme climate indices from Beijing-Tianjin-Hebei region, which contain eight stations from 1951 to 2012, will be analyzed research in response to global warming. The extreme indices contain temperature indices (including frost days, summer days, icing days, tropical nights, growing season length, cool nights and warm nights, cool days and warm days, and daily temperature range) and precipitation indices (including PRCPTOT, SDII, CDD, CWD, R20mm, R10mm, Rxlday and Rx5day). First, the causes and status of climate change will be introduced, also the serious impact of it. And it expounds the problems and significance of this study. Secondly, it describes the current climate change and its analysis method. Then there would be a detailed analysis of the original data. The specific research process is as follows:the time series of these extreme climate data is analyzed and then the trend of the data is analyzed and the mutation test is used to evaluate the changing trend of the past climate. Finally, the main research conclusions are summarized. To sum up the shortcomings of this paper and propose the prospect of future research.The results showed that there are six conclusions.1) In the region, it was reported that indices for minimum temperature showed decreasing trends while indices for maximum temperature showed increasing trends. Temperature changes in the overall upward trend. The mutation points for these temperature indices almost happened in 1980s and 1990s, and then it showed a significant historical trend.2) In the region, the precipitation indices showed a trend of slow decrease trend. Precipitation decrease amplitude was small but in the long term changes obviously. And there were no significant mutation points.3) In the east of two stations showed the opposite climate historical trend from other stations. The change trend of temperature index in Chengde was opposite. The historical trend of precipitation index in Leting was opposite.4) Through comparing of results between coastal and inland stations, it found that changes in temperature extremes in inland stations were less linear than those in costal stations.5) Through comparing of results between coastal and inland stations, it found that changes in precipitation extremes in inland stations were more linear than those in costal stations. It was just opposite from the temperature extremes.6) The results showed that the historical trends of these extreme temperature indices were nonlinear in Chengde, Tianjin and Cangzhou-Potou but almost linear in Huailai, Beijing, Leting and Shijiazhuang:The stations in Chengde, Tianjin and Cangzhou-Potou almost compose a straight line. The results showed that the historical trends of these extreme precipitation indices were nonlinear in Shijiazhuang, Cangzhou-Potou, Tianjin and Leting. These stations are in the southeast side, so they could compose a curve from the southeast side of analysis region. |
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