2.2.4. ERA5

The fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) global climate and weather reanalysis v5 (ERA5) data were used to analyze the changes in temperature and precipitation in the HMA region over the past 20 years. The reanalysis process combined model data with observations from the world into a globally complete and consistent dataset. We extracted the temperature and precipitation data for the HMA region from 2003 to 2020. The temperature data is the air temperature at 2 m height above the surface of land, ocean or inland water; the precipitation data is the accumulated liquid and frozen water that falls on the earth's surface, including rain and snow, but does not include fog, dew or moisture that evaporates in the atmosphere before reaching the earth's surface. The data were downloaded from the ECMWF (https://www.ecmwf.int/ en/forecasts/datasets/reanalysis-datasets/era5, accessed on 1 September 2021).

### 2.2.5. Auxiliary Data

This study used the Randolph Glacier Inventory (RGI 6.0) data to determine glacier boundaries. The RGI 6.0 data provide a global list of glaciers, with Landsat TM/ETM+ images as the primary data source, and interpreted with high-resolution imagery and topographic maps such as ASTER, IKONOS and Systeme Probatoire d'Observation de la Terre (SPOT) as supplementary data.

According to the regional division of HMA by Brun et al. [17], the HMA is divided into Bhutan, Nepal, Nyainqentanglha, Spiti Lahaul, Karakoram, West Kunlun, Tienshan, Inner TP (Tibetan Plateau), Pamir and Hindu Kush (Figure 1a). Additionally, using the "One Belt, One Road" boundary map of the major Asian river basins [43], the HMA is divided into 14 basins, namely Amu Darya, Brahmaputra, Ebinur and Manas river, Ili river, Shule and Heihe river, Indus river, Qiangtang Plateau, Mekong river, Qardam, Salween river, Issyk-Kul lake, Syr Darya, Tarim river and Yangtze, for analysis of changes in glacier elevation in basin scale (Figure 1b).
