The eco-system in the Qinghai-Tibet Plateau (QTP) is extremely fragile, and highly vulnerable to climate change. Knowledge of the changes in the ecological conditions is vital to mitigate the impact of climate change. In this study, we investigated the trend of ecological conditions of the QTP using the remotely sensed ecological index (RSEI), which is the first PCA (principal component analysis) axis of the four indexes derived from the MODIS (Moderate resolution Imaging Spectroradiometer) images captured in the growing season of 2000–2020. The four indexes, i.e., NDVI (normalized difference vegetation index), heat (land surface temperature, LST), wetness (tasseled cap wetness index, WET) and dryness (normalized difference impervious surface index, NDBSI), were calculated on the Google Earth Engine platform. Using land use cover change (LUCC) data, long-term meteorological records and the supplementary annual livestock production, we explored the drivers of spatiotemporal changes in the RSEI. The results show the following points: (1) the ecological conditions of the QTP have remarkable spatiotemporal variations. There were two ecological degradation periods, one of them occurred in the central region during 2005–2010, mainly attributed to the rising temperatures and decreasing precipitation. The other occurred during 2015–2020, driven primarily by overgrazing in the southwest. From 2000 to 2005, it was a period of rapid ecological restoration in the ecologically fragile northeast region. (2) The contribution rate of pc1 was stable at 60%, while the contribution rate of pc2 remained below 40%, indicating that pc1 demonstrated most of the characteristics of the four indexes. The correlation coefficients between NDVI and WET with pc1 are both positive, while LST and NDBSI have negative correlation coefficients, i.e., negative effects. This is consistent with the actual situation. (3) Overgrazing caused grass degradation in the southwest area of the QTP, which might be the main reason for the poor ecological conditions (i.e., low RSEI value) during 2015–2020. (4) Temperature and precipitation showed an increasing trend during the study period. A warmer and wetter climate is expected to have profound impacts on the ecosystems in QTP and practices should be concentrated on identifying climate-sensitive ecosystem components and designating adaptative options.

Global climate change has significantly impacted waterbird communities in the warming and humidifying wetlands of the Qinghai–Tibet Plateau. However, further research is needed as these wetlands transition to warmer and drier states. This study focused on the diversity and richness of wintering birds in the alpine wetlands of the Yamzho Yumco Lake. By analyzing data collected from 17 sampling sites over seven years, we examined the abundance changes of waterbirds in the lake and surrounding land and determined the relationship between the structure of waterbird communities and climate data. The results have shown that the abundance, richness, and α-diversity index of wintering waterbirds fluctuated. Wintering waterbirds were positively correlated with monthly mean temperature and monthly mean higher temperature and negatively correlated with monthly total precipitation and water level. Principal component analysis (PCA) showed that temperature contributed the most to the wintering waterbirds. Bird abundance and diversity in the drying wetlands of Yamzho Yumco Lake showed the same results. As temperatures continue to increase and precipitation decreases, the number of wintering waterbirds may also increase. We have highlighted the indicative role of Yamzho Yumco Lake in climate change responses from warming and humidification to warming and aridification and suggest that decision makers strengthen monitoring of the Yamzho Yumco Lake Reserve, restrict human activities, improve water resource management, and actively respond to the challenges brought about by climate change.