The Climatic Evolution In Southern Xi’an Area During The Holocene

The importance of modern climate environment is becoming more and moreoutstanding in the development of human society, since the industrial revolution, alarge number of greenhouse gas emissions leading to global warming had become anindisputable fact, the IPCC fourth assessment report pointed out that the climate wasgoing to keep on warming in the future. Under the background of global climate andenvironment gets deteriorating, global climate and environment variation research hasbecome the major task of all mankind, if we want to fully understand the change ofmodern environmental mechanism and to predict the future development of climatechange, more researches on ancient climate environment is indispensable.The Holocene climate research has long been the hot spot of climate changestudies, because Holocene ten thousand years ago as the last page in the history of theearth, the volatility and periodicity of climate during this period is closely related tothe evolution and development of human. Modern climate is the development andcontinuation of the Holocene climate, relevant evidence shows that temperatureshould fall in late Holocene, but the influence of human factors lead to globalwarming, which aspect the future climate and environment will change to need morescientific proof.Southern Xi ’an area is located in the edge of Qinling, Bordering on the LoessPlateau, there are many loess hills composed of loess and paleosol cycle cover in thisarea. This loess hill sequential deposition, stable horizon, obvious boundary, high ageresolution, taken down the climate and environment changing information from theHolocene completely. In order to further explore the change rule of the paleoclimateenvironment since Holocene, through the Holocene loess profile in Xi an He Jiaying,describe the stratum lithology, using magnetic susceptibility age model to determinechronostratigraphic sequence, with the Magnetic susceptibility curve drew bymagnetic susceptibility values of samples to qualitative analyze the Holocene climatechange. Then using regression equation put forward by Lv et al.to quantitativecalculate the holocene ancient temperature and precipitation in this area. Meanwhile we selected other scholars climate curves for comparison, the Holocene climate inXi’an region is divied into5stages:10~8.5kaBP, changes in temperaturetransformation stage;8.5~7kaBP, Megathemal changes in temperature fluctuationstage;7~5kaBP, Megathemal maximum;5~3.4kaBP, Megathemal warm temperaturefluctuation stage; After3.4kaBP up to now, the temperature droped first thenstabilized stage.