Monitoring the variations in terrestrial water storage (TWS) is crucial for understanding the regional hydrological processes, which helps to allocate and manage basin-scale water resources efficiently. In this study, the impacts of climate change, glacier mass loss, and human activities on the variations in TWS of the Qaidam Basin over the period of 2002-2020 were investigated by using Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) data, and other hydrological and meteorological data. The results indicate that TWS anomalies (TWSA) derived from five GRACE solutions experienced significant increasing trends over the study period, with the change rates ranging from 4.85 to 6.90 mm/year (1.37 to 1.95 km(3)/year). The GRACE TWSA averaged from different GRACE solutions exhibited an increase at a rate of 5.83 +/- 0.12 mm/year (1.65 +/- 0.03 km(3)/year). Trends in individual components of TWS indicate that the increase in soil moisture (7.65 mm/year) contributed the most to the variations in TWS. Through comprehensive analysis, it was found that the temporal variations in TWS of the Qaidam Basin were dominated by the variations in precipitation, and the spatial variations in TWS of the Qaidam Basin were mostly driven by the increase in glacier meltwater due to climate warming, particularly in the Narin Gol Basin. In addition, the water consumption associated with human activities had relatively fewer impacts.

Tibetan Plateau (TP) lakes are important water resources, which are experiencing quick expansion in recent decades. Previous researches mainly focus on analyzing the relationship between terrestrial water storage (TWS) change and lake water storage (LWS) change in the total inner TP, it is still lack of researches about the spatial difference and the characteristic of sub-region in the inner TP. In this study, we estimated the area change of 34 lakes by using Landsat images in the northeastern TP during 1976-2013, and LWS change by using the Shuttle Radar Topography Mission (SRTM). The results suggested that LWS had shrunk from 1976 to 1994, and then expanded quickly until 2013. LWS had a serious decrease by 13.6 Gt during 1976-1994, and then it increased quickly by 35.4 Gt during 1994-2013. We estimated TWS change, soil moisture change, and permafrost degradation based on the satellite data and related models during 2003-2013. The results indicated that their changing rates were 1.86 Gt/y, 0.22 Gt/y, and -0.19 Gt/y, respectively. We also calculated the change of groundwater based on the mass balance with a decreasing trend of -0.054 Gt/y. The results suggested that the cause of TWS change was the increase of LWS. We analyzed the cause of lake change according to water balance, and found that the primary cause of lake expansion was the increasing precipitation (80.7%), followed by glacier meltwater (10.3%) and permafrost degradation (9%). The spatial difference between LWS change and TWS change should be studied further, which is important to understand the driving mechanism of water resources change.

The exploration of the spatiotemporal distribution of greenhouse gas (GHG) exchange in the cryosphere (including ice sheet, glaciers, and permafrost) is important for understanding its future feedback to the atmosphere. Mountain glaciers and ice sheets may be potential sources of GHG emissions, but the magnitude and distribution of GHG emissions from glaciers and ice sheets remain unclear because observation data are lacking. In this study, in situ CH 4 and CO 2 and the mixing ratios of their carbon isotope signatures in the air inside an ice cave were measured, and CH 4 and CO 2 exchange in the meltwater of Laohugou glacier No. 12, a high-mountain glacier in an arid region of western China, was also analyzed and compared with the exchange in downstream rivers and a reservoir. The results indicated elevated CH 4 mixing ratios (up to 5.7 ppm) and depleted CO 2 (down to 168 ppm) in the ice cave, compared to ambient levels during field observations. The CH 4 and CO 2 fluxes in surface meltwater of the glacier were extremely low compared with their fluxes in rivers from the Tibetan Plateau (TP). CH 4 and CO 2 mixing ratios in the air inside the ice cave were mainly controlled by local meteorological conditions (air temperature, wind speed and direction) and meltwater runoff. The carbon isotopic compositions of CH 4 and CO 2 in the ice cave and terminus meltwater indicated 6 13 C-CH 4 depletion compared to ambient air, suggesting an acetate fermentation pathway. The abundances of key genes for methanogenic archaea/genes encoding methyl coenzyme M reductase further indicated the production of CH 4 by methanogenic archaea from the subglacial meltwater of high -mountain glaciers. The discovery of CH 4 emissions from even small high -mountain glaciers indicates a more prevalent characteristic of glaciers to produce and release CH 4 from the subglacial environment than previously believed. Nevertheless, further research is required to understand the relationship between this phenomenon and glacial dynamics in the third pole.