Impacts of climate change on glacial retreat during 1990–2021 in the Chinese Altay Mountains

Melting glaciers have changed the spatial–temporal distribution of water resources in inland river basins and are one of the important inducements of extreme hydrological events. Most previous studies on glacier changes in the Chinese Altay Mountains have focused on the period 1960–2011; however, there is a lack of glacier data reflecting recent changes (1990–2021) over the past decades, and the response of glaciers to regional climate change is still unclear. In this study, Landsat images and the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) were used to map glacier outlines from 1990 to 2021 for the whole region and its surrounding areas, and the impacts of temperature, precipitation, and solar radiation variation on glacier retreat were investigated. The results indicate that (1) the glacier area retreat rate of 0.55 %∙a-1 in the Chinese Altay Mountains during 1990–2021 is obviously lower than the glacier area shrinkage rate of 0.75 %∙a-1 from 1960 to 2009, and the retreat rate of glacier volume is 0.60 %∙a-1. (2) More than 80 % of the total glacier area located at elevation ranged from 2600 to 3400 m, and the greatest glacier area loss occurred within the elevation range of 2800–3000 m. Although the glacier area was retreating in all orientations, the south-facing glacier has the largest retreat rate. (3) The rate of change of glacier area was −1.26 %∙a-1, −0.71 %∙a-1 and −0.51 %∙a-1 in the Haba sub-basin, Sawir Mountains region, and Burqin sub-basin, respectively. (4) Owing to the slowdown in the warming rate since 1990, the glacier shrinkage rate was moderate during 1990–2021 compared to the 1960 s–1980 s, and contribution of the increase of solar radiation (35.72 %) and summer temperature (25.3 %) to glacier retreat from 1990 to 2021 were more prominent than other climate factors.