Change Of Glaciers And Their Service Value In The Three River Source Region From 2000 To 2018

Glaciers provide essential resources and services for human activities,and have produced important ecological and economic effects.The retreat of mountain glaciers caused by global warming will fundamentally change human well-being in the future.It is very important to study the spatial and temporal changes of glaciers and their service values for the sustainable development of regional social economy and ecological environment protection.In this paper,the current situation and spatiotemporal changes of the Three River Sources glacier were analyzed based on the data of three periods in 2000,2010 and 2018.Combined with meteorological station data,reanalysis data and socio-economic statistics data,guided by the theories of glaciology,geography and ecological economics,building the glacier service value evaluation system,adopts the glacier surface radiation balance model,Pearl growth curve model and service price method,value equivalent factor method and the glacier service value change index,etc.,to evaluate glacier service value and its space-time evolution characteristics.In this study,2018 was selected as the baseline period to discuss the area change of the Three River Sources glacier under the climate change scenarios of 0.7℃,1℃and 1.5℃temperature rise respectively in combination with the Paris Agreement,and then the service value and threshold of the Three River Sources glacier in the future were analyzed.The main conclusions of this research can be summarized as follows:(1)There are 1714 glaciers in the Three River Sources,covering an area of 2331.16km~2,with an ice volume of about 185.90 km~3.Glaciers with an area of less than 1.0 km~2and glaciers with an area between 1 km~2 and 50 km~2 are the main glaciers in terms of quantity and area.Among the first-level basins of the Three River Sources,the Yangtze River basin has the largest number of glaciers,glacier area and ice volume,the Yellow River basin has the least number and area of glaciers,the Lancang River basin has the smallest average area of glaciers.In terms of administrative area,Haixi Mongolian and Tibetan Autonomous Prefecture has the largest glacier area and ice volume.The second is Yushu Tibetan Autonomous Prefecture.Hainan Tibetan Autonomous Prefecture is the administrative unit of the city(autonomous prefecture)with the least glacier distribution in the Three River Sources.(2)From 2000 to 2018,the number of glaciers decreased by 69(-3.87%),the area decreased by 272.37 km~2(-10.46%),and the ice volume loss was about 18.76 km~3.The rate of glacier area retreat and the degree of ice volume loss showed an accelerated trend.The sharp shrinkage of glaciers with an area ranging from 0.1 km~2 to 50 km~2 is the main reason for the decrease in glacier area in this area.Glacier retreat mainly occurred below5,900 m,and the mean median area glacier altitude increased from 5,594.68 m to 5,616.03m.In the north direction,the glacier area decreased the most,while in the east direction,it decreased the least and changed the slowest.The glacier change rate in each basin and each autonomous prefecture is mainly related to the glacier area in the region.The larger the glacier area is,the greater the glacier change rate is.The relative rate of glacier change in each basin and autonomous prefecture is mainly related to the average area of glaciers in the region.The larger the average area of glaciers in each region,the smaller the relative rate of glacier area change.(3)In 2018,the service value of the Three River Sources glacier was 42.151 billion yuan,of which climate regulation and runoff regulation were the most important services,followed by hydropower and freshwater supply,and other types of service value was 135million yuan.Among the river systems in the Three River Sources,the glacier service value of the Yangtze River basin was the highest,the glacier service value of the Lancang River basin was lower,and the glacier service value of the Yellow River basin was the lowest.In terms of administrative division,the glacier service value of Haixi Mongolian and Tibetan Autonomous Prefecture was the largest,the second is Yushu Tibetan Autonomous Prefecture.The proportion of each glacier service value to the total regional value in different regions is mainly affected by the relative rate of glacier area change.The higher the glacier retreat rate is,the higher the proportion of the glacier freshwater supply,hydropower and runoff regulation will be,and on the contrary,the higher the proportion of the climate regulation service value to the total value will be.(4)During the period from 2000 to 2018,the glacier service value in Three River Sources decreased by 5.014 billion yuan(-10.63%).In the glacier service composition,the value of climate regulation service is reduced,while the value of other types of service is increased.From the perspective of the overall change of glacier service value in each river system and autonomous prefecture during 2000-2018,the eastern section has gains,while the central and western sections have losses.The changes of glacier service value generally show a meridional zonal differentiation law,and the loss of glacier service value shows an accelerated trend from east to west.(5)Taking 2018 as the base period,0.7℃,1℃and 1.5℃increase in temperature caused the area of the glaciers in the Three River Sources to shrink and the total value of glacier services to decrease continuously.The value of climate regulation services decreased significantly.The value of freshwater supply,hydropower and runoff regulation services increased first and then decreased,and reached the inflection point at about 0.7℃(2038 year).The value of aesthetic appreciation and recreation will reach the maximum value at about 1℃(2047 year).The service value of scientific research and environmental education is increasing gradually.