Compound high-temperature and drought events is one of the complex extreme climate events with high incidence in the Shiyang River Basin, which has more serious impact on industrial and agricultural production and ecological environment than a single extreme climate event. Based on the average temperature, maximum temperature and precipitation data of five meteorological stations in the Shiyang River Basin from 1961 to 2023, the compound high-temperature and drought events were identified and determined using percentile threshold method and Ped meteorological drought index, and spatial and temporal evolution characteristics of compound high-temperature and drought events were analyzed with linear trend method. The results show that the spatial difference of annual average frequency of compound high-temperature and drought events was small in the Shiyang River Basin, however, the spatial difference of compound high-temperature and drought events frequency was obvious in each decade and increased decade by decade. Annual frequency of compound high-temperature and drought events decreased first and then increased in the Shiyang River Basin, it decreased before 1996 and then increased in the whole basin. Compound high-temperature and drought events mainly occurred from June to August, and the most occurred in July. The frequency of compound high-temperature and drought events with different grades changed greatly, with the increase of drought grade, the frequency of drought increased first and then decreased, the frequency of medium drought was the highest, and the frequency of extreme drought was the least.

The 2023 heat and drought event in Wuwei, Gansu, the worst in 60 years, caused significant economic losses. In order to enhance the forecast accuracy of extreme weather events and mitigate their impact, using precipitation, temperature and drought data from 1959 to 2023 from the national basic meteorological stations in Wuwei, along with the ENSO （El Niño and Southern Oscillation） event records from the National Climate Center, the influence of El Niño event on the arid climate of the region was analyzed by using climate statistics methods. The results showed that in the El Niño event occurring year, the region tends to experience higher temperatures of the whole year and reduced precipitation in summer and autumn, but increased precipitation in winter. Abnormal climate phenomenon may occur in all four seasons. Moreover, the probability of moderate to severe droughts increased significantly during these years. In the El Niño event ending year, the regional climate is characterized by higher temperature across all seasons, increased spring precipitation and decreased winter precipitation, alongside a heightened probability of extreme weather events. In the year following the end of El Niño event, approximately 25% of the time occurs a La Nina, while 50% of the time, another El Niño event may commence, with climate change primarily influenced by the current climatic event. The study also finds that the year immediately following the end of a La Niña event transitioning into an El Niño phase exhibits particularly pronounced climate anomalies and an increased likelihood of extreme weather.

Drought disaster is one of the most frequent meteorological disasters in the Gannan Plateau, which seriously affects agricultural and animal husbandry production and ecological environment security in this region. Monthly precipitation and air temperature data from 31 meteorological stations in the Gannan Plateau and its surrounding areas from 1973 to 2022 are used to characterize meteorological drought employing the Standardized Precipitation Evapotranspiration Index (SPEI), and the temporal and spatial distribution of drought and its variations on annual and seasonal scales in the Gannan Plateau are analyzed by using Mann-Kendall test and Sen’s slope estimation methods. Results show that the annual SPEI in the Gannan Plateau presented significant downward trend with an obvious turning point in 1986, and the whole Gannan Plateau tended to be dry in the past 50 years. There were seasonal differences in the variation trend of drought, and the trend of drought intensified in summer and autumn, but in spring and winter it mitigated. In addition, there were spatial differences in the trend of annual and seasonal SPEI. In summer, it presented drought intensification trend in the middle and eastern regions of the Gannan Plateau, and in spring it showed similar to that in summer, but the area and degree of drought intensification were obviously smaller than that in summer. While in winter, it showed drought decreasing trend in the whole region. There were obvious spatial differences in the frequency of drought with different levels in the Gannan Plateau at the annual and seasonal scales. Light drought occurred frequently in the central and eastern parts of the Gannan Plateau, while medium and severe drought occurred frequently in the southern part of the Gannan Plateau, and the frequency of serious drought was less across the whole regions. Overall, the frequency of drought in the western was less than that in the central and eastern parts of the Gannan Plateau.

The temperature and precipitation in the Tibetan Plateau (hereinafter referred to as the ‘TP’) increase as a whole, and the vegetation of the plateau has changed significantly under the influence of climate change. This paper summarizes the research progress on plateau climate change and its impact on plateau vegetation coverage and normalized difference vegetation index (NDVI), phenology, net primary productivity (NPP), biomass carbon pool, plant diversity and so on, and the future directions of research are discussed and expected. The main conclusions are as follows: (1) In recent 60 years, the annual average temperature increased significantly with an average increase of 0.37 ℃ per 10 years, and the annual precipitation increased with an average increase of 10.40 mm per 10 years in the TP. The warm and dry trend of climate in the southeast of the TP and the warm and humid trend of climate in the northwest of the TP were obvious. (2) Under the background of overall improvement, the vegetation coverage and NDVI degraded in local regions of the TP. The improved area accounted for 67.7%-75.0% of the plateau total area, and they mainly distributed in the central and eastern regions. (3) Under of the influence of climate change, the green returning period of vegetation in the plateau advanced, the dry and yellow period postponed, and the growth period prolonged on the whole. However, there is a great debate on the green returning period of plateau vegetation in advance after 2000. (4) NPP of plateau vegetation increased significantly as a whole, while the increasing rate of NPP slowed down after 2000. NPP of vegetation increased significantly in southern Qilian Mountains and alpine meadows of northern Nianqing Tanggula Mountains, while it decreased in northern Tibetan Plateau, ‘one river, two rivers’ and the central and western regions of Tibet three river sources. (5) The biomass carbon pool of the plateau vegetation showed an increasing trend, which was carbon sink in general, and the spatial heterogeneity was obvious. The biomass carbon of alpine meadow and steppe increased significantly, while that of other grassland increased slightly, and even decreased in some areas. (6) The plant diversity in the plateau has changed significantly. Although the research results were different, there is no doubt that the climate change has affected significantly on species composition and plant diversity of alpine grassland community. It is suggested to strengthen data networking observation comparison and multi-scale effect research, deepen internal mechanism research and multi-factor comprehensive and quantitative analysis, strengthen sharing mechanism and improve the coping ability to climate change in the future, so as to promote ecological protection and high-quality development of the plateau.