This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers at the Faculty of Social Sciences at the University of Hong Kong (HKU) have discovered that fine particulate pollution (PM2.5) significantly impairs plants' ability to use water efficiently and absorb carbon dioxide. The findings reveal that PM2.5 pollution weakens the vital carbon-water coupling of vegetation, highlighting that mitigating air pollution is not only a public health priority but also a critical climate action imperative.
While rising atmospheric CO2 and climate change have generally enhanced plant water-use efficiency (WUE) globally in recent decades, the specific influence of PM2.5 on this process has remained poorly understood. Drawing on a comprehensive global database of tree-ring isotopes, eddy-covariance fluxes and satellite-derived vegetation metrics, a research team led by professor Yuyu Zhou from the Department of Geography, Faculty of Social Sciences at HKU, demonstrated that PM2.5 exerts a predominantly negative influence on WUE across various spatial scales. This pollution effectively weakens the CO2-induced WUE gains observed since the 2000s, with the magnitude of this effect varying geographically based on interactions among vegetation traits, pollution levels and local climates.
The study reveals that this decline in WUE is primarily driven by PM2.5-induced suppression of photosynthesis—the process by which plants gain carbon—rather than changes in evapotranspiration (water loss). PM2.5 pollution reduces photosynthetically active radiation and plants' carboxylation capacity, fundamentally hindering their ability to thrive and capture carbon. Furthermore, the research exposes a critical flaw in current ecosystem models, which systematically misrepresent these effects.
Because existing models omit aerosol processes and rely solely on vegetation responses to covarying climate drivers, they fail to reproduce the observed PM2.5-WUE relationship. The study is published in the journal Nature Climate Change. Jian Wang et al, Particulate air pollution undermines plant water-use efficiency by inhibiting photosynthesis, Nature Climate Change (2026).
DOI: 10.1038/s41558-026-02712-y Journal information: Nature Climate Change Swati Mestri holds a bachelor's degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space. Full profile → Bachelor's in mathematical biology, Master's in creative writing.
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