Global water use efficiency saturation due to increased vapor pressure deficit

Fei Li, Jingfeng Xiao, Jiquan Chen, Ashley Ballantyne, Ke Jin, Bing Li, Michael Abraha, Ranjeet John

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


The ratio of carbon assimilation to water evapotranspiration (ET) of an ecosystem, referred to as ecosystem water use efficiency (WUEeco), is widely expected to increase because of the rising atmospheric carbon dioxide concentration (Ca). However, little is known about the interactive effects of rising Ca and climate change on WUEeco. On the basis of upscaled estimates from machine learning methods and global FLUXNET observations, we show that global WUEeco has not risen since 2001 because of the asymmetric effects of an increased vapor pressure deficit (VPD), which depressed photosynthesis and enhanced ET. An undiminished ET trend indicates that rising temperature and VPD may play a more important role in regulating ET than declining stomatal conductance. Projected increases in VPD are predicted to affect the future coupling of the terrestrial carbon and water cycles.

Original languageEnglish
Pages (from-to)672-677
Number of pages6
Issue number6658
StatePublished - Aug 11 2023


  • Carbon Dioxide
  • Ecosystem
  • Photosynthesis
  • Vapor Pressure
  • Climate Change
  • Hot Temperature
  • Water Cycle


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