Earth Greening Under Water Stress

AGU EOS 10 Sep 2026 2 min read

How the science connects

AI Insight

Satellite observations show Earth has been "greening" with increased leaf coverage due to rising CO2 levels, but a new study reveals this greening masks a widespread increase in plant water stress. Researchers used a novel index that accounts for both structural changes in vegetation and physiological responses to separate the effects of increased leaf area from declining water availability. The analysis demonstrates that despite more foliage, plants are experiencing greater water stress globally due to soil moisture depletion, atmospheric aridity, and regional climate changes, revealing fundamental water limitations on continued vegetation growth.

Why it matters

This finding challenges the assumption that CO2-driven greening will continue to enhance carbon uptake and suggests that water constraints may limit future ecosystem productivity and climate mitigation potential. The research highlights critical interdependencies between carbon and water cycles that must be considered in climate projections and land management decisions.

Confidence

8/10Peer-reviewedInterdisciplinary

Understand the Science

Remote sensing 62 articles Explore Concept → Photosynthesis 19 articles Explore Concept → Water stress Concept coming soon

Editors’ Highlights are summaries of recent papers by AGU’s journal editors.

Source: AGU Advances

Leaf area index, which measures the ratio of leaf area to ground area, is commonly used by researchers to track foliage coverage and ecosystem health. One consequence of global warming, observed by satellite remote sensing, has been a long-term increase in leaf area index. This Earth “greening” is predicated on increased terrestrial carbon uptake under increasing CO₂.

Chang et al. [2026] examine water controls on vegetation greening by isolating structural (e.g. leaf area index, LAI) and physiological (e.g., water use efficiency, WUE) impacts under increasing CO₂. Their analysis shows worldwide patterns of increased plant water stress (PWS) and ecological drought, attributed to soil moisture, atmospheric aridity, and regional climate. This study demonstrates water limits on Earth greening emerging from local interdependencies between the carbon and water cycles.

Attribution of variables, including meteorological factors (air temperature, Ta; and net radiation, Rn), soil and atmospheric aridity (VPD; surface soil moisture, SMsurf; and root-zone soil moisture, SMroot), and atmospheric CO₂ to the changes of PWS indicated by ESI_LAI over the past four decades with a Random Forest model. ESI_LAIis the evaporative stress index that accounts for dynamical changes in Leaf Arae Index (LAI). a. Spatial distribution of dominant factor; b. Area ratio for the distribution of each dominant factor in a. Credit: Chang et al. [2026], Figure 7

Citation: Chang, Q., Wang, L., Barnes, M. L., Ficklin, D. L., Benson, M. C., & Novick, K. A. (2026). Widespread increase in global plant water stress obscured by greening. AGU Advances, 7, e2025AV002243. https://doi.org/10.1029/2025AV002243

—Ana P. Barros, Editor, AGU Advances

Text © 2026. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: Earth Greening Under Water Stress

Where this fits

Emerging research journeyPlanetary Surface Dynamics29 discoveries · 3 conceptsExplore journey →

Source
AGU EOS

Editors’ Highlights are summaries of recent papers by AGU’s journal editors.

Source: AGU Advances

Text © 2026. The authors. CC BY-NC-ND 3.0Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Text © 2026. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.