Fine-particle pollution may undermine plants' ability to absorb carbon and conserve water

Researchers at Hong Kong University's Faculty of Social Sciences have uncovered that fine particulate pollution (PM2.5) significantly diminishes plants' capacity to efficiently utilize water and sequester carbon. The study underscores that combating air pollution is crucial not only for public health but also for climate action.

Although increased atmospheric CO2 and climate change have generally augmented plant water-use efficiency (WUE) over the past decades, the precise impact of PM2.5 on this process has been understudied. Utilizing a vast global database encompassing tree-ring isotopes, eddy-covariance fluxes, and satellite-derived vegetation metrics, Professor Yuyu Zhou's team revealed that PM2.5 predominantly exerts a negative effect on WUE across diverse spatial scales.

This pollution effectively counteracts the CO2-driven WUE improvements since the 2000s, with the severity of this impact varying across regions depending on vegetation traits, pollution levels, and local climates. The decline in WUE is primarily attributed to PM2.5-induced photosynthesis reduction—critical for carbon acquisition—rather than alterations in evapotranspiration.

This pollution diminishes photosynthetically active radiation and plants' carboxylation capacity, impeding their growth and carbon capture. Moreover, the research highlights a significant oversight in existing ecosystem models, which underrepresent these effects due to the omission of aerosol processes and reliance on vegetation responses to climate drivers.

Published in Nature Climate Change, the study emphasizes the necessity of incorporating aerosol impacts in climate models.