Drought and Climate Change: An Uncertain Future?
Published on by Ashantha Goonetilleke, Professor, Water/Environmental Engineering at Queensland University of Technology in Academic
Drought frequency may increase by more than 20% in some regions of the globe by the end of the 21st century, but it is difficult to be more precise as we don’t know yet how changes in climate will impact on the world’s rivers
The results come from a study, published this week in Proceedings of the National Academy of Sciences (PNAS), which examined computer simulations from an ensemble of state of the art global hydrological models driven by the latest projections from five global climate models used for the fifth assessment report of the Intergovernmental Panel on Climate Change.
The research was led by Dr Christel Prudhomme from the UK’s Centre for Ecology & Hydrology working with colleagues from the UK, USA, the Netherlands, Germany and Japan.
Increasing concentrations of greenhouse gases in the atmosphere are widely expected to influence global climate over the coming century. The impact on drought is uncertain because of the complexity of the processes but can be estimated using outputs from an ensemble of global hydrological and climate models.
The new study concluded that an increase in global severity of hydrological drought - essentially the proportion of land under drought conditions - is likely by the end of the 21st century, with systematically greater increases if no climate change mitigation policy is implemented.
Under the ‘business as usual’ scenario (an energy-intensive world due to high population growth and slower rate of technological development), droughts exceeding 40% of analysed land area were projected by nearly half of the simulations carried out. This increase in drought severity has a strong signal to noise ratio at the global scale; this means we are relatively confident that an increase in drought will happen, but we don’t know exactly by how much.
Dr Prudhomme said, “Our study shows that the different representations of terrestrial water cycle processes in global hydrological models are responsible for a much larger uncertainty in the response of hydrological drought to climate change than previously thought. We don’t know how much-changed climate patterns will affect the frequency of low flows in rivers.”
Source: Environmental Research
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