Grassland Greening and Water Resource Availability May Coexist in a Warming Climate in Northern China and the Tibetan Plateau

Greening of Northern China and the Tibetan Plateau (NCTP) has been observed by increases in the remotely sensed leaf area index (LAI), driven primarily by CO2 fertilization effects, anthropogenic warming, and the implementation of ecological restoration programs. Continued growth of LAI throughout the 21st century is also projected by the Coupled Model Intercomparison Project Phase 6 (CMIP6) scenarios. However, the question of whether local water resources can sustain ongoing grassland greening has not been adequately investigated. Here we assessed the sustainability of water resources under grassland greening across NCTP under various climate scenarios using water yield (WY, defined as precipitation minus actual evapotranspiration) as the key metric. Unexpectedly, we observe the coexistence of increases in LAI and WY in most of NCTP. In a warming climate with increasing precipitation and CO2, we find that grasses maintain high water use efficiency to sustain their growth, contributing to continued local water resource availability. Thus, livestock production may also continue to increase under the simultaneous growth of LAI and WY in the future. The greening of Northern China and the Tibetan Plateau (NCTP) has been observed through increases in remotely sensed leaf area index (LAI), driven primarily by ecological restoration programs, climate change, and CO2 fertilization effects. While continued growth of LAI throughout the 21st century is projected by Coupled Model Intercomparison Project Phase 6 (CMIP6) scenarios, there is limited understanding of whether local water resources may sustain the ongoing process of grassland greening in the context of more frequent and severe drought conditions under global warming. Using three schemes considering plant physiological and hydrological feedbacks toward climate change, our study unveils changes in regional water sustainability (i.e., water yield) under grassland greening across NCTP over the past four decades and up to the end of the 21st century. Surprisingly, we observe the coexistence of future grassland greening and enhanced water resource availability in most of NCTP. Moreover, increased precipitation from atmospheric transport and evaporation recycling, coupled with a warming climate and rising CO2 levels, enables grasses to maintain high water use efficiency, sustaining their growth and contributing to the availability of local water resources. Additionally, projections suggest that the area occupied by livestock production across NCTP may continue to grow due to the simultaneous improvement in grassland and water resource availability. Grassland greening and enhanced water resource availability may coexist in most of NCTP in a warming climateEffects of plant physiological and hydrological factors along grassland greening on water yield in the future were analyzedThe positive influence of enhanced water resource availability and ongoing grassland greening on future livestock production was quantified