Hydrological droughts in the 21st century, hotspots and uncertainties from a global multimodel ensemble experiment
journal contributionposted on 27.07.2016 by Christel Prudhomme, Ignazio Giuntoli, Emma L. Robinson, Douglas B. Clark, Nigel W. Arnell, Rutger Dankers, Balazs M. Fekete, Wietse Franssen, Dieter Gerten, Simon N. Gosling, Stefan Hagemann, David M. Hannah, Hyungjun Kim, Yoshimitsu Masaki, Yusuke Satoh, Tobias Stacke, Yoshihide Wada, Dominik Wisser
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Increasing concentrations of greenhouse gases in the atmosphere are expected to modify the global water cycle with significant consequences for terrestrial hydrology. We assess the impact of climate change on hydrological droughts in a multimodel experiment including seven global impact models (GIMs) driven by biascorrected climate from five global climate models under four representative concentration pathways (RCPs). Drought severity is defined as the fraction of land under drought conditions. Results show a likely increase in the global severity of hydrological drought at the end of the 21st century, with systematically greater increases for RCPs describing stronger radiative forcings. Under RCP8.5, droughts exceeding 40% of analyzed land area are projected by nearly half of the simulations. This increase in drought severity has a strong signal-to-noise ratio at the global scale, and Southern Europe, the Middle East, the Southeast United States, Chile, and South West Australia are identified as possible hotspots for future water security issues. The uncertainty due to GIMs is greater than that from global climate models, particularly if including a GIM that accounts for the dynamic response of plants to CO2 and climate, as this model simulates little or no increase in drought frequency. Our study demonstrates that different representations of terrestrial water-cycle processes in GIMs are responsible for a much larger uncertainty in the response of hydrological drought to climate change than previously thought. When assessing the impact of climate change on hydrology, it is therefore critical to consider a diverse range of GIMs to better capture the uncertainty.
This work has been conducted under the framework of the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP). The ISIMIP Fast Track project was funded by the German Federal Ministry of Education and Research, with project funding reference number 01LS1201A. The work has been in part funded by the Centre for Ecology and Hydrology- Natural Environment Research Council water program. I.G. was funded by a PhD scholarship from the United Kingdom Natural Environment Research Council (NE/YXS1270382). R.D. was supported by the Joint Department of Energy and Climate Change/Department for Environment and Rural Affairs Met Office Hadley Centre Climate Programme (GA01101). Y.M. was supported by the Environment Research and Technology Development Fund (S-10) of the Ministry of the Environment, Japan.
- Social Sciences
- Geography and Environment