## 3 Results
### Climate Change in the SAM
#### 3.2.4 Ongoing Shrinkage and Disappearance of Mountain Glaciers  
The mountain glaciers in the SAM have undergone rapid mass loss over recent decades, and this continues today. The number of mountain glaciers in the SAM decreased from 403 to 271 between the First and Second Chinese Glacier Inventories in the 1960s and 2000s, respectively, with 32.75% of the SAM mountain glaciers disappearing. The regional glacier area also decreased from 289.29 to 185.77 km\({}^{2}\), which equates to a loss in the glacial area of 35.78%. The simulation results from a mass-balance model that was forced by the outputs of a regional climate model indicated that the mean specific mass balance for the entire Altai Mountain Range was about \(-\)0.69 m water equivalent (w.e.) yr\({}^{-1}\) during the period 1990-2011, with about 81.3% of these glaciers experiencing a negative net mass balance [47]. The mass balance rates in the SAM, which were based on topographic maps (1959), the SRTM DEM (2000), and ASTER stereo images (2008), were \(-\)0.43 \(\pm\) 0.02 and \(-\)0.54 \(\pm\) 0.13 m w.e. yr\({}^{-1}\) during the periods 1959-1999 and 1999-2008, respectively, which indicated that the mountain glaciers experienced continued and accelerating shrinkage over this 50-year timeframe, with 7.06 \(\pm\) 0.03 km\({}^{3}\) of total ice loss [48]. Increased mass accumulation due to additional snowfall has not slowed this rapid glacial loss, with the rise in air temperature being the dominant factor controlling glacial retreat in the SAM.  
The cryosphere in the SAM has generally been shrinking, and this trend is expected to continue. The Representative Concentration Pathway (RCP) 4.5 climate scenario suggests that the glacial area in the Altai Mountains region will shrink by 26 \(\pm\) 10% by 2100, whereas the RCP 8.5 scenario suggests that it will shrink by 60 \(\pm\) 15% [49]. The globally averaged river ice duration for the period 2080-2100 declines by 16.7 days relative to the period 2009-2029 under the RCP 8.5 scenario, whereas it declines by 7.3 days under the RCP 4.5 scenario; the river ice duration in the SAM is predicted to shorten by more than 50 days [46]. An assessment of the COP21 climate change targets indicated that the global permafrost area would eventually experience a >40% reduction if the climate stabilized at 2 \({}^{\circ}\)C above pre-industrial levels, whereas stabilizing the climate at 1.5 \({}^{\circ}\)C would save approximately 2 million km\({}^{2}\) of permafrost relative to the 2 \({}^{\circ}\)C threshold [50]. The permafrost in the SAM is already on the verge of disappearance. Global snow cover (depth or mass) is projected to decline by another 25% (10% to 40%) in the near future (2031-2050), regardless of which RCP climate scenario is applied [51]. Reductions of up to 80% (50% to 90%) are expected under RCP 8.5, 50% (30% to 70%) under RCP 4.5, and 30%(10% to 40%) under RCP 2.6 by the end of the century (2081-2100). Snow cover will also shrink across the SAM for different increases in the global mean temperature in the future. All of the climate scenarios point to a reduction of the cryosphere in the Altai Mountains in the future.