Ecosystems on the Tibetan Plateau (TP) are particularly sensitive to climate change. Significant advances have been made towards understanding the effects of climate change on the vegetation productivity of the plateau by using satellite observations, but a comprehensive study including various satellite measurements has yet to be presented. Here, we analyze the spatiotemporal variability in Tibetan vegetation productivity using a variety of proxies, including the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Near‐Infrared Reflectance of vegetation (NIR_v) and Solar‐Induced chlorophyll Fluorescence (SIF). Firstly, in terms of productivity responses to seasonal climate variation, NIR_v and SIF‐based growing season length had better correlation with eddy‐covariance site measurements, and was ~50 days shorter than those of the other proxies. Secondly, all proxies, except the NDVI derived from Système Probatoire d'Observation de la Terre (SPOT), displayed a dipole‐like trend pattern, similar to the observed north–south dipole pattern of precipitation change. This result is explained by the finding that moisture is a dominant driver controlling the interannual variation in productivity. Thirdly, we analyzed the long‐term responses of vegetation productivity to the precipitation regime, and found four distinct productivity regimes: desert steppe; alpine steppe; meadow; and shrub/forests, indicating that Tibetan productivity varies with precipitation in a nonlinear way. The result offers insights into how Tibetan vegetation will respond to future climate change. Our results provide a multi‐satellite perspective on the impacts of climate change on spatiotemporal variation in productivity, and suggest an urgent need to improve Tibetan productivity simulation.

Introduction: Understanding the seasonality of vegetation growth is important for maintaining sustainable development of grassland livestock systems over the Tibetan Plateau (TP). Current knowledge of changes in the seasonality of TP grasslands is restricted to spring and autumn phenology, with little known about the date of peak vegetation growth, the most relevant quantity for grassland productivity.Methods: We investigate the shifts of the date of peak vegetation growth and its climatic controls for the alpine grasslands over the TP during 2001–2020 using a framework based on the law of minimum, which is based on the assumption that peak vegetation growth would be consistent with the peak timing of the most limiting climatic resource.Results: The date of peak vegetation growth over the TP advanced by 0.81 days decade-1 during 2001–2020. This spring-ward shift mainly occurs in the semi-humid eastern TP, where the peak growth date tracks the advancing peak precipitation, and shifted towards the timing of peak temperature. The advancing peak growth over the eastern TP significantly stimulated the ecosystem production by 1.99 gCm-2 year-1 day-1 during 2001–2020, while this positive effect weakened from 3.02 gCm-2 year-1 day-1 during 2000s to 1.25 gCm-2 year-1 day-1 during 2010s.Discussion: Our results highlighted the importance of water availability in vegetation growth over the TP, and indicated that the TP grassland is moving towards a tipping point of transition from thermal-constrained to water-constrained ecosystem under the rapid warming climate.