As one of the most important reservoirs of water in arid regions, lakes experience a series of complicated changes. However, the natural driving mechanisms behind such changes remain unclear. In this study, we collected data from 1333 lakes in the arid region of Central East Asia (CEA) to investigate the underlying natural causes of lake changes over the past five decades. The lakes were located within three different geomorphological zones: (I) Tibetan Plateau zone; (II) high mountain—basin zone; and (III) low mountain zone. Our results show that lakes as a whole in CEA exhibit a unique change trend, with an overall lake area increase of 7099 km² (41%) and with heterogeneous spatial variations over the past five decades. The lake area increase was 6236 km² (47%), 935 km² (31%) and decrease was 72 km² (~1%) in zones I, II, and III, respectively. The different geomorphological zones have influencing factors. In zones I and II, increased precipitation (including cloud water) and temperature rise (causing glacier, frozen soil, and snow melt) contributed to approximately 66% of the change in lake area; in zone III, changes in precipitation contributed to approximately 87% of the lake changes. Increased atmospheric circulation of water vapor caused by warming of the ocean surface appears to be the main driving factor of these changes; this is supported by future projection scenarios. From 2006 to 2098, temperature and precipitation will increase by 4.0–7.8 °C and 1.07 to 1.29 mm per day, respectively, under both the RCP4.5 and RCP8.5 scenarios. Notably, although the climate appears to have become more optimum for lakes in CEA at the interdecadal timescale, short timescale climatic events such as lake expansion will bring more extreme climate events, such as extreme high-temperature heat waves, which should be considered as a potential threat to lake ecology in the future.

The average thickness of Paleogene sandstones reaches about 3000–4000 m at the northern margin of the Qaidam Basin. However, the provenance and sedimentary environment of these sandstones are uncertain; thus, more comprehensive research is needed. Integrated research is conducted on the provenance and weathering process based on petrographic characteristics, clay minerals, and geochemical compositions of sandstones in the center of the northern Qaidam Basin. The results of lithofacies analysis show that the Paleogene sandstones were mainly derived from an active continental magmatic arc, subduction accretion, or a fold-thrust belt. The average illite content in the Paleogene clay minerals is more than 50%, followed by chlorite and smectite, which reflect climatic and environmental characteristics that were arid to semi-arid, whereas the characteristics of carbon–oxygen isotopes reveal a mainly freshwater sedimentary environment. The corrected chemical index of alteration (CIA_corr) is between 56.3 and 75.7, with an average value of 66.5. These results indicate that the provenance of the Paleogene sandstones in the center of the northern Qaidam Basin mainly formed under cold and dry climatic conditions and experienced limited chemical weathering with a small amount that underwent intermediate chemical weathering under warm and humid conditions.