Li et al. (2026) Dryland dominance in the slowdown of global vegetation carbon uptake

Identification

• Journal: Nature Geoscience
• Year: 2026
• Date: 2026-04-01
• Authors: Fei Li, Jingfeng Xiao, Jun Chen, Ashley P. Ballantyne, Josep Peñuelas, Julia K. Green, Shichao Tian, Yingjun Zhang, Benjamin Poulter, Stephen Sitch, Jiming Jin, Xinmiao Hu, Gang Bao
• DOI: 10.1038/s41561-026-01957-8

Research Groups

• Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China
• Key Laboratory of Grassland and Agricultural Ecological Remote Sensing, Ministry of Agriculture and Rural Affairs, Hohhot, China
• Earth Systems Research Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA
• Department of Geography, Environment, and Spatial Sciences, Michigan State University, East Lansing, MI, USA
• Department of Ecosystem and Conservation Science, University of Montana, Missoula, MT, USA
• Laboratoire des Sciences du Climat et de l’Environnement, Université Paris-Saclay, Gif-sur-Yvette, France
• CSIC, Global Ecology Unit CREAF-CSIC-UAB, Barcelona, Spain
• CREAF, Cerdanyola del Vallès, Barcelona, Spain
• Department of Environmental Science, University of Arizona, Tucson, AZ, USA
• College of Grassland Science and Technology, China Agricultural University, Beijing, China
• Spark Climate Solutions, San Francisco, CA, USA
• Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
• College of Resources and Environment, Yangtze University, Wuhan, China
• College of Geographical Science, Inner Mongolia Normal University, Hohhot, China

Short Summary

This study reveals an asymmetric slowdown in global vegetation carbon uptake, dominated by drylands since 2001 due to water constraints from rising vapor pressure deficit, while humid regions maintain increased uptake. Current global vegetation and Earth system models fail to capture this divergence, indicating a potential limitation to the future land carbon sink.

Objective

• To investigate how rising atmospheric carbon dioxide (CO2) concentrations, temperature, and vapor pressure deficit (VPD) interact to alter plant photosynthesis and terrestrial carbon uptake across different climate regimes globally.

Study Configuration

• Spatial Scale: Global, with a specific focus on distinguishing between dryland and humid regions.
• Temporal Scale: Historical analysis from 1982 to 2022, with future projections for 2041–2060 and 2081–2100.

Methodology and Data

• Models used: Machine learning models for Gross Primary Production (GPP) estimates, 20 Dynamic Global Vegetation Models (DGVMs) from TRENDY v12, and 6 Earth System Models (ESMs) from CMIP6 (e.g., ACCESS-ESM1.5, CESM2, CanESM5.0.3, EC-Earth3, MIROC6, MPI-ESM1.2).
• Data sources: Globally distributed FLUXNET eddy covariance measurements, satellite-derived machine learning estimates of GPP (e.g., MF-CW datasets), satellite observations (e.g., microwave satellite observations for soil moisture), climate re-analysis products (e.g., ERA5, MERRA-2, TerraClimate), GRACE/GRACE-FO data assimilation for soil moisture, and various gridded precipitation products (e.g., GPCC, CRU TS, MSWEP).

Main Results

• An asymmetric shift in vegetation productivity was observed between drylands and humid regions during 1982–2022.
• Drylands exhibited a substantial slowdown in the rate of increase in GPP since 2001, primarily attributed to water constraints linked to rising vapor pressure deficit.
• Humid regions demonstrated a sustained increase in GPP, driven by rising temperatures and atmospheric CO2 concentrations.
• Dynamic global vegetation models and Earth system models failed to accurately capture this observed divergence in GPP trends in both historical simulations and future projections.
• The study anticipates a broad water constraint on global photosynthetic capacity, potentially limiting the land carbon sink, given increasing atmospheric aridity and the continued expansion of drylands.

Contributions

• Provides empirical evidence of an asymmetric shift in global vegetation productivity trends, highlighting dryland dominance in the slowdown of global carbon uptake.
• Identifies rising vapor pressure deficit and associated water constraints as the primary driver for the observed dryland GPP slowdown.
• Reveals a significant discrepancy between observed vegetation productivity trends and those simulated by state-of-the-art global vegetation and Earth system models.
• Emphasizes the critical need for prioritizing adaptive strategies in drylands and nature-based solutions in humid regions to enhance global climate action.

Funding

• National Natural Science Foundation of China (42471426)
• Science and Technology Program of the Inner Mongolia Autonomous Region (2025YFDZ0055)
• Science and Technology Breakthrough Project of the Inner Mongolia Autonomous Region (2025KJTW0026)
• US National Science Foundation (NSF) (Macrosystem Biology and NEON-Enabled Science program: DEB-2017870)
• Google
• NASA
• USDA
• Catalan Government (AGAUR2023 and CLIMA00118)

Citation

@article{Li2026Dryland,
  author = {Li, Fei and Xiao, Jingfeng and Chen, Jun and Ballantyne, Ashley P. and Peñuelas, Josep and Green, Julia K. and Tian, Shichao and Zhang, Yingjun and Poulter, Benjamin and Sitch, Stephen and Jin, Jiming and Hu, Xinmiao and Bao, Gang},
  title = {Dryland dominance in the slowdown of global vegetation carbon uptake},
  journal = {Nature Geoscience},
  year = {2026},
  doi = {10.1038/s41561-026-01957-8},
  url = {https://doi.org/10.1038/s41561-026-01957-8}
}