Modern Glacier Changes In The Main Peak Area Of West Kunlun Mountains

In the background of global warming,most of the glaciers are faced with severe melting,but the phenomenon that the glaciers in the karakoram region were stable and glaciers moving forward,which is also known as the"karakoram anomaly",found by previous researches in recent years.There are more surge-type glaciers in the main peak area of the west Kunlun region,which is similar to the karakoram,and the anomaly of the glacier is a widespread concern.In this paper,we used the high temporal and spatial resolution remote sensing image,and extracted the information of the length/area,surface elevation and surface motion velocity of the glacier in the main peak area of the west Kunlun region.Then,according to the spatial distribution and the changing trend of the length/area,surface height and surface motion velocity of the glacier,the surge-type glacier in the main peak area of the west Kunlun region was further identified,and the basic characteristics were discussed.Finally,the influence factors of modern glacial changes and the potential trends in the future in the west Kunlun region are discussed combined with the characteristics of temperature and precipitation.The following conclusions are as follows:?1?In 1972-2018,the terminal location of 95%of the small glaciers in the main peak of west Kunlun is basically unchanged.A study of 21 large glaciers found that:the changing trend of the nine glaciers is consistent,showing a continuous forward,backward and stable state;There is a clear shift in trend at the terminal locations of the12 glaciers.The maximum variation of the glacier terminal location is about 2500m.The total area of the glacier decreased by 7.99 km²,of which,1972-1991 decreased the12.02 km²,1991-2010 had slightly change but basically maintained,and 2010-2018increased by 4.7 km² in the study area.Changes in the total area of the glacier are mainly controlled by the size of large glaciers.?2?In 1970-2016,the average ice reduction in the main peak area of the west Kunlun region was about 1.9m,including the average reduction of about 2.5 m in 1970-2000 and the ice loss was about 6.28±0.44 Gt;while the average increase was about0.6m in 2000-2016 and the ice gain was about 1.51±0.11Gt.There is a significant difference in the variation of different glacier levels,especially in the ablation area,which is that there are two periods?1970-2000 and 2000-2016?:thinning,thinning first and then thickening,thickening first and then thinning.?3?The annual movement speed of 95%of the glaciers in the main peak area of west Kunlun is less than 10 m·a^-1,which is smaller than the marine glacier and subcontinental glaciers of the same size.The high value of glacier velocity is generally distributed near the material balance line,and the terrain factors have a certain influence on the distribution of the movement.During the period from 1991 to 2018,the annual movement speed variation trends of 21 major glaciers were quite different,and the surface movement speed variation trends of some glaciers were basically consistent with each other,showing accelerating,decelerating or stable states,while some glaciers were inconsistent with each other,showing obvious acceleration and deceleration.From2017 to 2018,the surface movement speed of most glaciers in summer is higher than that in winter,but the winter movement speed of five glaciers,such as the East Branch of West Kunlun and 5y641h067,is higher than that in summer.?4?According to the length of the glacier,the variation and distribution of surface elevation and velocity,we found that among the 423 glaciers in the main peak area of west kunlun,there were 13 surge-type glaciers and 3 possible surge-type glaciers.These16 glaciers are all larger glaciers,with 12 having an area greater than 50km².For non surge-type glaciers,the length change is generally small,the glacier movement speed is small and the change is not big,and the change of ice quantity tends to be stable and presents a slight increase trend.As for the surge-type glacier and the possible surge-type glacier,the length and area of the glacier vary greatly,which controls the change of the glacier area in the whole west Kunlun region.The movement velocity of the glacier varies greatly,and the maximum movement velocity of the surge-type glacier can reach 250 m·a^-1.In addition,the amount of ice in the surge-type glacier is decreasing as a whole.?5?By comparing with meteorological data,it is found that the changes of non-surge glaciers in the study area in recent years are mainly affected by the combined action of temperature and precipitation,while the changes of surge-type glaciers are mainly affected by their own glacier surge.Since 2000,the frequency of glacier surge has increased in the main peak of the west Kunlun region,and the main reason for this result is rising temperature,increasing precipitation.In this climate pattern,glaciers accelerate,the surge cycle is shortened,and the glaciers in still time may early enter surging,and they also induce avalanche,ice collapse and other natural disasters,and even new surge-type glaciers.