Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 4.936 IF 4.936
  • IF 5-year value: 5.615 IF 5-year
  • CiteScore value: 4.94 CiteScore
  • SNIP value: 1.612 SNIP 1.612
  • IPP value: 4.70 IPP 4.70
  • SJR value: 2.134 SJR 2.134
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 107 Scimago H
    index 107
  • h5-index value: 63 h5-index 63
Discussion papers
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 03 Feb 2020

Submitted as: research article | 03 Feb 2020

Review status
This preprint is currently under review for the journal HESS.

Little change in Palmer Drought Severity Index across global land under warming in climate projections

Yuting Yang1,*, Shulei Zhang1,2,*, Michael L. Roderick3,4, Tim R. McVicar4,5, Dawen Yang1, Wenbin Liu6, and Xiaoyan Li2 Yuting Yang et al.
  • 1State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, China
  • 2State Key Laboratory of Earth Surface Process and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, Beijing, China
  • 3Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia
  • 4Australian Research Council Centre of Excellence for Climate Extremes, Canberra, ACT, Australia
  • 5CSIRO Land and Water, Canberra, ACT, Australia
  • 6Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
  • *Equal contribution.

Abstract. Anthropogenic warming is reported to increase global drought for the 21st century when calculated using offline drought indices. However, this contradicts observations of greening and little systematic change in runoff over the past few decades and climate projections of future greening with slight increases in global runoff for the coming century. This calls into question the drought projections based on offline drought indices. To resolve this paradox, here we calculate a widely-used conventional drought index (i.e., the Palmer Drought Severity Index, PDSI) using direct outputs from 16 CMIP5 models (PDSI_CMIP5) such that the hydrologic consistency between PDSI_CMIP5 and CMIP5 models is maintained. Results show that the global PDSI_CMIP5 remains generally unchanged as climate warms, demonstrating that CMIP5 models do not actually project a general increase in PDSI drought (more reflecting soil moisture/agricultural drought) under future warming. Further analyses indicate that the projected increase in PDSI drought reported previously is primarily due to ignoring the vegetation response to elevated atmospheric CO2 concentration ([CO2]) in the offline calculations. On one hand, elevated [CO2] directly reduces stomatal opening; on the other hand, elevated [CO2] increases air temperature and thus vapor pressure deficit, which also causes partial stomatal closure. Finally, we show that the overestimation of PDSI drought can be avoided by directly using the relevant climate model outputs or by accounting for the effect of CO2 on evapotranspiration. Our findings refute the common warming leads to drying perception and highlight the importance of elevated CO2 in controlling future terrestrial hydrologic changes through vegetation responses.

Yuting Yang et al.

Interactive discussion

Status: open (until 30 Mar 2020)
Status: open (until 30 Mar 2020)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Yuting Yang et al.

Yuting Yang et al.


Total article views: 290 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
223 65 2 290 16 3 1
  • HTML: 223
  • PDF: 65
  • XML: 2
  • Total: 290
  • Supplement: 16
  • BibTeX: 3
  • EndNote: 1
Views and downloads (calculated since 03 Feb 2020)
Cumulative views and downloads (calculated since 03 Feb 2020)

Viewed (geographical distribution)

Total article views: 245 (including HTML, PDF, and XML) Thereof 245 with geography defined and 0 with unknown origin.
Country # Views %
  • 1



No saved metrics found.


No discussed metrics found.
Latest update: 18 Feb 2020
Publications Copernicus
Short summary
Many previous studies using offline drought indices report that future warming will increase world-wide drought. However, this contradicts observations/projections of vegetation greening and increased runoff. We resolved this paradox by re-calculating the same drought indices using direct climate model outputs and find no increase in future drought as the climate warms. We also find that accounting for the impact of CO2 on plant transpiration avoids the previous overestimation of drought.
Many previous studies using offline drought indices report that future warming will increase...