Miao et al. (2026) The influence of vapor pressure deficit changes on global terrestrial evapotranspiration

Identification

• Journal: Hydrology and earth system sciences
• Year: 2026
• Date: 2026-10-09
• Authors: Guofeng Zhu, Yuhao Wang, Enwei Huang, Qingyang Wang, Yani Gun, Jiangwei Yang, Wenmin Li, Ziwen Liu
• DOI: 10.5194/hess-30-6249-2026

Research Groups

• College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu, China
• Comprehensive Observatory of Ecological Environment in Shiyang River Basin, Northwest Normal University, Lanzhou, Gansu, China
• Remote Sensing Application Center of Ministry of Agriculture and Rural Affairs, Lanzhou Branch, Lanzhou, Gansu, China
• Gansu Key Laboratory of Oasis Resource Environment and Sustainable Development, Lanzhou, Gansu, China

Short Summary

This study quantifies the influence of vapor pressure deficit (VPD) changes on global terrestrial evapotranspiration (E) from 1981-2020 using multi-source remote sensing and reanalysis data. It reveals that VPD positively correlates with E across 60.7% of land, particularly in warm and humid regions, with aridity-dependent thresholds and an overall negative net effect on E through interconnected ecohydrological pathways.

Objective

• To quantitatively evaluate the role of vapor pressure deficit (VPD) in regulating global terrestrial evapotranspiration (E) variability, characterize its spatiotemporal dynamics, and elucidate its influence on land-atmosphere water and energy feedback processes under climate warming.

Study Configuration

• Spatial Scale: Global, analyzed on a 0.1° grid using a 0.5° x 0.5° (5x5 grid-cell) moving window.
• Temporal Scale: 1981–2020 (40 years).

Methodology and Data

• Models used:
  • Theil-Sen Slope and Mann-Kendall Test for trend analysis.
  • Moving window strategy for estimating apparent sensitivity of E to VPD (dE/dVPD).
  • Partial correlation analysis (residual-based method) for relationships between VPD and E components.
  • Piecewise linear regression and Generalized Additive Models (GAM) for threshold detection.
  • Structural Equation Modeling (SEM) to quantify multi-factor coupling pathways.
• Data sources:
  • Evapotranspiration (E, Et, Eb): Global Land Evaporation Amsterdam Model (GLEAM v4.2a) product, based on Penman-Monteith framework.
  • Vapor Pressure Deficit (VPD): Calculated from ERA5-Land (2 m air temperature, dew point temperature). Cross-validated with CRU TS v4.09.
  • Precipitation (Pre) and Surface Solar Radiation (SR): ERA5-Land reanalysis.
  • Root-zone soil moisture (SMrz) and Surface soil moisture (SMs): GLEAM product.
  • Land-use data: MODIS MCD12C1 version 6.1 (0.05° spatial resolution).
  • Leaf Area Index (LAI): GIMMS LAI V1.2 dataset.
  • Elevation data: WorldClim elevation dataset.
  • Aridity Index (AI): Used for global land classification into arid, semi-arid, semi-humid, and humid regions.

Main Results

• Global terrestrial VPD increased significantly at a rate of 0.002 kPa yr⁻¹ from 1981 to 2020, with strongest increases in southwestern North America, central Africa, parts of Central Asia, and eastern Australia.
• Terrestrial E showed spatially heterogeneous trends, with 68.9% of land pixels exhibiting positive trends and 31.1% negative trends. Increases were noted in East Asia, northern Europe, and high-latitude regions, while declines occurred in Africa, central South America, southwestern North America, and eastern Australia.
• Approximately 60.7% of global land area showed positive apparent sensitivity of E to VPD, with a global mean sensitivity of 293.3 ± 62.3 mm hPa⁻¹. Stronger positive responses were observed in warm and humid regions, while negative or weak sensitivity occurred in arid and cold regions.
• VPD was positively correlated with transpiration (E_t) across 65.8% of valid pixels, particularly in mid-to-high latitudes of the Northern Hemisphere, after controlling for root-zone soil moisture and precipitation.
• The relationship between VPD and bare-soil evaporation (E_b) was weaker and tended to be negative in water-limited regions (59.1% of pixels showed negative partial correlation), after controlling for surface soil moisture and precipitation.
• The VPD–E relationship exhibited a pronounced aridity-dependent threshold: 1.90 kPa in arid regions, 1.46 kPa in semi-arid regions, 0.49 kPa in semi-humid regions, and 0.47 kPa in humid regions.
• Structural Equation Modeling revealed that VPD regulates E through interconnected pathways involving atmospheric demand, soil moisture, vegetation physiology, and energy supply. The total effect of VPD on E was negative across all aridity zones, being strongest in arid and semi-arid regions (standardized total effect of -0.96 and -0.69, respectively).

Contributions

• Provides a comprehensive, global-scale quantitative evaluation of the influence of VPD on terrestrial E, addressing a gap in understanding beyond leaf/canopy scales.
• Identifies and quantifies the spatial heterogeneity and aridity-dependent thresholds in the nonlinear VPD–E relationship.
• Elucidates the dominant ecohydrological pathways (atmospheric demand, soil moisture, vegetation physiology, energy supply) through which VPD regulates E under multi-factor coupling.
• Offers quantitative constraints for improving predictions of the terrestrial water cycle's response to increasing atmospheric aridity under climate warming.

Funding

• National Natural Science Foundation of China (grant no. 42371040)
• Western Light Young Scholars Program of the Chinese Academy of Sciences (grant no. 25JR6KA001)
• Key Natural Science Foundation of Gansu Province (grant no. 23JRRA698)
• Key Research and Development Program of Gansu Province (grant no. 22YF7NA122)
• Cultivation Program of Major key projects of Northwest Normal University (grant no. NWNU-LKZD-202302)
• Oasis Scientific Research achievements Breakthrough Action Plan Project of Northwest Normal University (grant no. NWNU-LZKX-202303)

Citation

@article{Miao2026influence,
  author = {Miao, Yuxin and Zhu, Guofeng and Wang, Yuhao and Huang, Enwei and Wang, Qingyang and Gun, Yani and Zheng, Zhijie and Yang, Jiangwei and Li, Wenmin and Liu, Ziwen},
  title = {The influence of vapor pressure deficit changes on global terrestrial evapotranspiration},
  journal = {Hydrology and earth system sciences},
  year = {2026},
  doi = {10.5194/hess-30-6249-2026},
  url = {https://doi.org/10.5194/hess-30-6249-2026}
}