Comparing Palmer Drought Severity Index drought assessments using the traditional offline approach with direct climate model outputs
<p>Anthropogenic warming has been projected to increase global drought for the 21st century when calculated using traditional offline drought indices. However, this contradicts observations of the overall global greening and little systematic change in runoff over the past few decades and clim...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-06-01
|
| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/24/2921/2020/hess-24-2921-2020.pdf |
| Summary: | <p>Anthropogenic warming has been projected to increase global
drought for the 21st century when calculated using traditional offline
drought indices. However, this contradicts observations of the overall
global 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 traditional offline drought indices. Here we calculate
a widely used traditional drought index (i.e., the Palmer Drought Severity Index, PDSI) using direct outputs from 16 Coupled Model Intercomparison Project Phase 5 (CMIP5) models (PDSI_CMIP5) such that the hydrologic consistency between PDSI_CMIP5 and CMIP5 models is maintained. We find that the PDSI_CMIP5-depicted drought increases (in terms of drought severity, frequency, and extent) are much smaller than that reported when PDSI is calculated
using the traditional offline approach that has been widely used in previous
drought assessments under climate change. Further analyses indicate that the
overestimation of PDSI drought increases reported previously using the
PDSI is primarily due to ignoring the vegetation response to
elevated atmospheric <span class="inline-formula">CO<sub>2</sub></span> concentration ([<span class="inline-formula">CO<sub>2</sub></span>]) in the traditional offline
calculations. Finally, we show that the overestimation of drought using the
traditional PDSI approach can be minimized by accounting for the effect of
<span class="inline-formula">CO<sub>2</sub></span> on evapotranspiration.</p> |
|---|---|
| ISSN: | 1027-5606 1607-7938 |