Abstract
Drought is a natural hazard that can have severe and long-lasting impacts on natural and human systems. Although increases in global greenhouse forcing are expected to change the characteristics and impacts of drought in the 21st century, there remains persistent uncertainty about how changes in temperature, precipitation and soil moisture will interact to shape the magnitude - and in some cases direction - of drought in different areas of the globe. Using data from 15 global climate models archived in the Coupled Model Intercomparison Project (CMIP5), we assess the likelihood of changes in the spatial extent, duration and number of occurrences of four drought indices: the Standardized Precipitation Index (SPI), the Standardized Runoff Index (SRI), the Standardized Precipitation-Evapotranspiration Index (SPEI) and the Supply-Demand Drought Index (SDDI). We compare these characteristics in two future periods (2010-2054 and 2055-2099) of the Representative Concentration Pathway 8.5 (RCP8.5). We find increases from the baseline period (1961-2005) in the spatial extent, duration and occurrence of "exceptional" drought in subtropical and tropical regions, with many regions showing an increase in both the occurrence and duration. There is strong agreement on the sign of these changes among the individual climate models, although some regions do exhibit substantial uncertainty in the magnitude of change. The changes in SPEI and SDDI characteristics are stronger than the changes in SPI and SRI due to the greater influence of temperature changes in the SPEI and SDDI indices. In particular, we see a robust permanent emergence of the spatial extent of SDDI from the baseline variability in West, East and Saharan Africa as early as 2020 and by 2080 in several other subtropical and tropical regions. The increasing likelihood of exceptional drought identified in our results suggests increasing risk of drought-related stresses for natural and human systems should greenhouse gas concentrations continue along their current trajectory.
| Original language | English |
|---|---|
| Pages (from-to) | 196-207 |
| Number of pages | 12 |
| Journal | Journal of Hydrology |
| Volume | 526 |
| DOIs | |
| State | Published - Jul 1 2015 |
Funding
We thank the editor, guest editor and three anonymous reviewers for their insightful and constructive comments. Support for data storage and analysis is provided by the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725 . We acknowledge the World Climate Research Program’s Working Group on Coupled Modeling responsible for CMIP, and we thank the climate modeling groups for producing and making available their CMIP5 model output. We also thank U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison for providing coordinating support and leading development of software infrastructure in partnership with the Global Organization for Earth System Science Portals for CMIP. This work at Oak Ridge National Laboratory is supported by Regional and Global Climate Modeling program of DOE Office of Science and Oak Ridge National Laboratory LDRD project 32112413 , and the work at Stanford was supported in part by NSF award # 0955283 to NSD.
| Funders | Funder number |
|---|---|
| National Science Foundation | |
| U.S. Department of Energy | |
| Directorate for Geosciences | 0955283 |
| Office of Science | |
| Oak Ridge National Laboratory | 32112413 |
Keywords
- CMIP5
- Climate change
- Drought
- Drought index
- Permanent emergence
- Uncertainty
