Changes Of Global Climate Landscape Pattern And Its Impact On Surface Water Resource In Qinghai-Tibet Plateau

A large number of anthropogenic greenhouse gases dominate the global climate change and have an important impact on nature and human system.Under the background of global warming,except for the polar climate types,the spatial scope of other climate types has basically become a more pronounced expansion trend.However,at present,most of the relevant researches are based on the area-based indicators,and lack of understanding of the spatial heterogeneity of the climate itself,including the unique alpine climate in China.Based on the observation,reanalysis and climate model data of long time series,this research,from the perspective of spatial morphology,organically combines the global climate spatial change with landscape ecological indicators to construct the global climate landscape pattern,and makes in-depth exploration on its structure and function.At the same time,based on the background of the rapid evolution of alpine climate in the Qinghai Tibet Plateau,this paper focuses on exploring the change of surface water resources,understanding its spatial and temporal distribution characteristics and laws,and analyzing the response between the plateau climate and surface water resources.The results of this research mainly include the following 7 aspects:(1)based on the area change of major climate types,SD index was used to characterize the dispersion changes of the major climate types on the global land,and the evaluation system of global climate landscape pattern was constructed,which revealed that there was a clear climatic patch aggregation process at a global scale;At the same time,the climate diversity decreased obviously during 1950 to 2010.(2)The possible structural changes of global climate landscape pattern under high emission scenarios RCP8.5 were explored.The results showed that during 1901-2095,the patch aggregation effect of landscape pattern in global major climate types increased significantly.The patch aggregation effect appeared in tropical,arid,temperate and continental climates,while fragmentation occurred in polar climate zones;At the same time,the structure of global climate landscape pattern is changed with a clear latitudinal trend and the spatial distribution of different periods based on standard deviation ellipse tends to aggregate.(3)We use the Shannon(SHDI)and Simpson(SIDI)diversity index to explore the heterogeneity of global climate itself.From 1901 to 2095,the global climate diversity tends to decline.With the intensification of radiation forcing from RCP2.6 to RCP8.5,the decrease and trend of SHDI diversity index and SIDI diversity index increased.The sensitivity experiment resulkts indicate that the influence of temperature on climate heterogeneity is greater than that of precipitation.Climate heterogeneity change has important potential ecological significance.With the decline of climate heterogeneity,the corresponding eco geographical space regions may also disappear,and species may face an increasing risk of extinction.(4)The exploration of climate change in different time and space scales is helpful for us to understand climate change itself.From 1961 to 2014,the climate change of Qinghai Tibet Plateau also tended to accelerate,and the accumulation of main climate types increased significantly at the rate of 0.086(MK).The change rates of arid climate,temperate climate and continental climate were 0.021,0.007 and 0.177 respectively,while the decline rate of alpine polar climate was significantly-0.206.Temperature is also the main driving force for the evolution of alpine climate types in the Tibetan Plateau.(5)The wetland of Qinghai Tibet Plateau occupies a small area of the whole plateau,which is relatively scattered in space and has strong spatial heterogeneity.Based on the concept of climatic water balance,the results show that the surface of Qinghai Tibet Plateau tends to be humid,especially since 1995,especially in the central and western regions of the plateau.The glaciers in the Yarlung Zangbo River Basin in the southern part of the plateau,the Yellow River source area and the Indo River Basin in High Asia have the most obvious decline.The glacier retreat in the inland source area of the plateau is also obvious,about 9.5%.After 1995,the number and area of lakes on the Qinghai Tibet Plateau showed a continuous increasing trend,and concentrated in the inland areas of the Qinghai Tibet Plateau.There is a clear response between the significant increase of inland lake area and the decrease of snow depth,mainly concentrated in the north of Tanggula Mountain,following the trend of southeast and northwest of the mountain,indicating that the rapid decline of snow depth may be an effective supplement to the plateau lakes.From the perspective of atmospheric circulation,there great differences in atmospheric humidity,wind speed and wind direction in dry(DJF)and wet(JJA)seasons over the Qinghai Tibet Plateau,which may be an important reason for the changes of surface moisture and dryness.