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As world warms, droughts coming on faster

A new study published in a recent issue of scientific journal Science says that droughts are coming on faster and higher global temperatures are increasing the frequency of flash droughts.

Droughts are generally considered a long and slow developing climate hazard. A persistent lack of rainfall dries out soil and vegetation, followed by declining water levels in rivers and lakes. Droughts may build and endure for years over large areas, with snowballing consequences for people and the environment.

Conversely, droughts can arise rapidly, changing conditions from ‘normal’ problematically to dry in a matter of weeks. These so-called ‘flash droughts’ are akin to flash floods in that they appear suddenly with little warning.

Consequently, impacts can be severe because there is little time to prepare for or deal with such a drought before it is too late. These abrupt dry spells could have grave consequences for people in humid regions whose livelihoods depend on rain-fed agriculture. The study found that flash droughts occurred more often than slower ones in tropical places like India, Southeast Asia, sub-Saharan Africa and the Amazon basin.

Nanjing University of Information Science and Technology hydrologist and lead author of the study Xing Yuan said, “Even for slow droughts, the onset speed has been increasing.”

The world has probably always experienced rapid-onset droughts, but only in the past decade or two have they become a significant focus of scientific research. New data sources and advances in computer modelling have allowed scientists to home in on the complex physical processes behind them. The study said human-caused climate change is a major reason.



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