Decadal trends in global grassland growth peaks and their drivers since the 1980s.

Abstract

Grasslands, Earth's most widespread terrestrial ecosystems, are vital for global carbon sequestration and food security. A key indicator of these functions is vegetation growth peak, reflecting maximum seasonal productivity. However, whether this growth peak consistently increases across global grasslands remains unknown. Here, using satellite-derived vegetation data from 1982 to 2021, we reveal a widespread increase in grassland growth peaks, with 71% (20/28) IPCC climate regions exhibiting significant trends. However, this trend reverses between 1998 and 2009 in 64% of regions, notably across the Tibetan Plateau and East Asia. The reversal is supported by a global gross primary productivity dataset generated via machine learning, trained on eddy covariance flux data. The interruption is primarily associated with a global-scale decadal drought. These findings demonstrate that persistent drought can disrupt the upward trajectory of grassland growth peaks, posing a spatially uneven but widespread threat to ecological functions of grasslands under climate change.