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.

Based on the hourly precipitation from automatic weather stations, radar data at Xifeng station and radiosonde data at Pingliang station from 2008 to 2018, the temporal and spatial distribution, physical quantities and radar echo characteristics of short-term heavy rainfall in the Loess Plateau of Qingyang were analyzed statistically. The results are as follows: (1) The short-term heavy rainfall was easily to occur in the north and southeast of the Loess Plateau of Qingyang, and the business forecast should focus in Huan county and Zhengning county. (2) The earliest and latest short-term heavy rainfall occurred in mid-April and mid-October in the Loess Plateau of Qingyang from 2008 to 2018, respectively, and it occurred mostly in July and August, the peaks were in mid-July and mid-August. The diurnal variation of short-term heavy rainfall appeared typical double peaks pattern, the major and minor peaks occurred at about 17:00 BST and 09:00 BST, respectively, and the frequency of short-term heavy rainfall with different levels was higher from 16:00 BST to 18:00 BST. (3) The early warning indicators of water vapor condition of short-term heavy rainfall were 700 hPa specific humidity equal to or more than 7 g·kg-1 and temperature dew-point difference equal to or less than 4 ℃ in the Loess Plateau of Qingyang, as to energy condition, CAPE was equal to or more than 100 J·kg-1 and CIN was equal to or less than 120 J·kg-1, and for instability condition, △T7-5 was equal to or more than 15 ℃ and SI was equal to or less than 1 ℃. In addition, the early warning indicators of -20 ℃ and 0 ℃ layers height averaged 8.6 km and 5.1 km, and the thickness of frozen layer averaged 3.4 km. (4) The radar echo intensity of short-term heavy rainfall exceeded 38 dBZ, the height of echo top and the strongest echo center were more than 7.0 km and 3.6 km, respectively, and the VIL was more than 20 kg·m-2, which could be used for early warning indicators of short-term heavy rainfall. Upon inspection, these early warning indicators could provide some useful references for potential forecast and nowcasting of short-term heavy rainfall in the Loess Plateau of Qingyang.