Scientists call for drought to be redefined for the climate change age

Citing low-to-no precipitation in the American West, an area constantly suffering from a lack of rainfall, experts believe we need to rethink what constitutes ‘drought’. 

With researchers from six universities involved, a team headed up by UC Santa Barbara Assistant Professor Samantha Stevenson of the Bren School of Environmental Science & Management has found a number of global regions will enter permanent dry or wet states this decade, rendering modern climate definitions irrelevant. 

brown sand near brown mountain during daytime

Findings were published in the Proceedings of the National Academy of Sciences, and emphasise the importance of changing established classifications, along with responses to catalyst events. Using ‘drought’ as an example – meaning conditions are drier than expected in a certain area – scientists now believe this can no longer be used for regions entering or approaching eras of ‘perpetual dryness’.

‘Essentially, we need to stop thinking about returning to normal as a thing that is possible,’ said Stevenson, whose colleagues used a new collection of climate models from different institutions to predict future precipitation and soil moisture. Each of these was run numerous times to build ensembles that take into account natural unpredictability of the planet’s climate. 

The Western United States has been cited as one area that has already exceeded the benchmark for a megadrought, and therefore need new terminology. Parts of Australia, southern Africa, and western Europe are now heading in the same direction. Those involved in the work are therefore now proposing a move away from fixed terms towards nuanced labels. 

‘When we talk about being in a drought, the presumption is that eventually the drought will end, and conditions will return to normal,’ Stevenson said. ‘But if we’re never returning to normal, then we need to adapt all of the ways that we manage water with the expectation that normal will continually be drier and drier every year.’

In related news, last year a study was published showing that the Amazon rainforest may be at significantly higher risk of drought than previously hoped. Meanwhile, recent research into streams in North America confirms human activity greatly increases the risk of both flooding and drought. 

Image credit: Oz Seyrek


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