Climate change impacts on glaciers and water resources in the headwaters of the Tarim River, NW China/Kyrgyzstan

Abstract

Glacierised river catchments have been shown to be highly sensitive to climate change, while large populations may depend on their water resources. The irrigation agriculture and the communities around the Tarim River, NW China, are strongly dependent on the discharge from the highly glacierised catchments surrounding the Taklamakan Desert. While recent increasing headwater discharge has been beneficial for the expanding agricultural sector, future runoff under climate change is uncertain. We assess three climate change scenarios (Representative Concentration Pathways (RCP) 2.6, 4.5, 8.5) by forcing two glacio-hydrological models with output of eight General Circulation Models. The models have different glaciological modelling approaches but were both calibrated to discharge and glacier mass balance observations. Projected changes of temperature, precipitation, glacier cover and river discharge are examined over the 21st century and generally point to a warmer and wetter climate in the ensemble median. The climate model ensemble projects median temperature and precipitation increases of +1.9–5.3°C and +9–24%, respectively, until the end of the century compared to 1971–2000. Glacier area is projected to shrink by 15–73% (model medians, range over scenarios), strongly depending on catchment and scenario. River discharge is projected to first increase by about 20% in the Aksu River catchments with subsequent decreases of up to 20% until 2100 compared to 1971–2000. In contrast, discharge in the drier Hotan and Yarkant catchments is projected to increase by 15–60% towards the end of the century. The large uncertainties mainly relate to climate model ensemble and the limited observations to constrain the glacio-hydrological models.