Simulation and forecast of the Tien Shan glacier's changes

Two mathematical models: glacial-covered areas/glacier numbers and glacial volume changes developed based on assessment of the glacier recession that occurred in a Tien Shan glacial massif for the last 60 years. According to estimations performed in the Akshiirak glacierized massif for the period from 1943 to 1977, change in mean altitude (Hm) of each individual glacier in the massif is a linear function of the change in the mean of Equilibrium Line Altitude (ELA). For the Aksiirak massif, the ratio between Hm and ELA is 1/4. For other Tien Shan glacier basins the ratios, determined from topographic data and NASA ESE System products vary from 1/3 to 1/5. The ELA under air temperature and precipitation changes was calculated to estimate the changes in mean ELA and area of each individual glacier. In a stepwise approximation, we took into account two new small glaciers that appeared as a result of the disintegration of a larger glacier. The simulation of the glacier-covered areas and volumes changes are based on two output/prediction models. The first model focuses on the forecast of glacier characteristics using an iteration technique and based partly on overlap domains with areas of about 1000 km2. The ELAs were subsequently increased by 1 m to calculate a new adjusted glacier surface area in each domain. For the second model, all calculations for the glaciers were completed through a differential calculus iteration technique with 1m of ELA increase. Hypothetical Tien Shan climate-change scenarios imposed as a stepwise progression predict that by the year 2100, the ELA could rise up to 407 m due to an average increase in air temperature of 3îÑ and an average increase in precipitation of 1.2 times the current level in Tien Shan. The number of glaciers, glacier covered areas and glacier volumes are predicted to be 77.6 percent from the current state. The threshold conditions of glacier distribution and disappearance (when Hm<ELA) under air temperature and precipitation changes were also estimated.