Shifts in the Upper Limit of Alpine Grasslands Lag Behind Climate Warming Across the Tibetan Plateau

ABSTRACT Alpine grasslands are vital for biodiversity and ecosystem service delivery, yet their responses to climate change remain a focus of intense scientific interest. While studies have examined separate ecological processes such as biodiversity changes or treeline shifts, broader ecosystem changes are not as well understood. Here, leveraging time series of high‐resolution images from the Landsat satellite, we developed an automated method to track the shifts in the upper limits of alpine grasslands on the high and expansive Tibetan Plateau, a region of high ecological and climatic significance. Our analysis revealed modest upward boundary shifts of −0.55 to 0.99 m year −1 (2nd–98th percentile; mean = 0.12 m year −1 ) across the plateau over nearly four decades, from 1986 to 2023, with faster rates in wetter areas, yet drastically slower than the rapid climate‐driven isotherm shifts of 3.35 to 12.04 m year −1 . This substantial lag, further confirmed by ≤ 3 m resolution satellite images, is potentially attributed to water scarcity, poor soil quality, and a lack of stable substrates beyond the current boundaries and geomorphological features. Consequently, the upward expansion of alpine grasslands on the Tibetan Plateau—attributed to the shift of the upper grassland boundary—was limited to approximately 6100 km 2 . Notably, two high‐spatial‐resolution CMIP6 models simulated more rapid upward expansion of alpine grasslands and greater carbon sequestration than observed. These findings underscore the need to integrate local environmental nuances into future predictions. Our study elucidates the resilient yet vulnerable nature of alpine ecosystems, sparking new conversations regarding effective strategies to safeguard these extraordinary landscapes under changing climate.