Drought and climate change: an uncertain future?

A press release from the Centre for Ecology and Hydrology (UK): 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...

Entering Arizona on I-10 from New Mexico, shot by Wing-Chi Poon, Wikimedia Commons,  under the Creative Commons Attribution-Share Alike 2.5 Generic license