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Assessing the threat of future megadrought in Iberia

Lookup NU author(s): Dr Selma GuerreiroORCiD, Professor Chris Kilsby, Professor Hayley Fowler



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2017 Royal Meteorological Society. Water scarcity is a critical issue in Iberia but few studies have investigated future drought over the region. The few that do are continental or global studies and do not report the range of possible future projections. In this paper, historical drought and future projections of drought were examined, using observed and downscaled rainfall data from climate models, for the main Iberian international basins (Douro, Tagus and Guadiana). Two drought indices were used, the standardized precipitation index (SPI) and the drought severity index (DSI). However, problems were found in the distribution fitting required for the calculation of SPI which render this index inadequate for assessing droughts in Iberia. The skill of CMIP5 climate models in representing historical drought for the Douro, Tagus and Guadiana is very variable with some not showing enough persistence of dry conditions, and others simulating droughts that are too long and too severe. Nevertheless, the observed range of drought conditions for these basins was encompassed by the ensemble members. Furthermore, we found no relationship between performance in simulating mean large-scale circulation and model ability to reproduce the historical drought characteristics for the region. All models project an intensification of drought conditions for the three basins. However, some only project small increases, while most project extreme multi-year droughts by the end of the century. We found that climate model future projections are neither related to their performance in simulating historical drought nor to their large-scale circulation patterns. This result emphasises the need for climate change impact studies to take into account the whole range of climate model projections in order to provide the best information for robust adaptation. Choosing one or a subset of climate models based on historical performance would not lead to a credible and justified reduction in uncertainty.

Publication metadata

Author(s): Guerreiro SB, Kilsby C, Fowler HJ

Publication type: Article

Publication status: Published

Journal: International Journal of Climatology

Year: 2017

Volume: 37

Issue: 15

Pages: 5024-5034

Print publication date: 01/12/2017

Online publication date: 25/05/2017

Acceptance date: 19/04/2017

Date deposited: 19/06/2017

ISSN (print): 0899-8418

ISSN (electronic): 1097-0088

Publisher: John Wiley and Sons Ltd


DOI: 10.1002/joc.5140


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Funder referenceFunder name
NE/H003517/1Natural Environment Research Council (NERC)
WM140025Royal Society