Long‐Term Trends in Global Natural Vegetation Greenness Rate and Its Climatic Drivers in a Warming World

Abstract The vegetation greenness rate (GR: green‐up rate, SR: senescence rate) quantifies canopy development, reflecting the acceleration and deceleration of photosynthesis during the growing season. However, long‐term changes and climatic drivers of natural vegetation greenness rates remain poorly understood globally. Here, utilizing multi‐source remote sensing and climatic data sets, we examined trends in the greenness rate of global natural vegetation over the past four decades, identified primary climatic drivers, and evaluated their sensitivities. The results reveal significant global changes in greenness rates. Notably, the GR increased significantly in 24.1% of pixels, while the SR rose in 23.9% of pixels ( P < 0.05). Conversely, GR and SR experienced significant decreases in 13.4% and 15.1% of pixels, respectively. Temperature was the primary driver of GR changes in 32.9% of pixels worldwide. A higher accumulated temperature rate during the green‐up phase generally accelerated GR, enhancing vegetation greenness at maturity onset. Similarly, temperature influenced SR in 28.6% of pixels; however, a higher accumulated temperature rate during the senescence phase typically slowed SR, delaying dormancy onset. In contrast, moisture‐related factors, solar radiation, and VPD exhibited strong regional influences, with precipitation and soil moisture exerting particularly positive effects in drylands. Additionally, advancing or delaying green‐up onset significantly decreased or increased GR, subsequently affecting greenness amplitude, the senescence rate (SR), and autumn phenology. Our study highlights that the rate of vegetation greenness is a critical transitional variable linking phenological timing and vegetation productivity, and a robust indicator in assessing the climate change impacts on Earth's terrestrial ecosystems.