Climate: With climate change ‘glacial drought’ is increasing

With human-induced climate change, the frequency of ‘flash droughts’ has accelerated – droughts that are harder to predict and more difficult to adapt to, warns a new study published on Thursday.

If we generally think of drought as a long-term phenomenon, some appear suddenly, in a matter of weeks, when conditions meet. However, global warming favors some of these conditions: lack of precipitation in some areas and increased evaporation, associated with higher temperatures, can dry the soil more quickly.

For their work published in the journal Science, the researchers analyzed more than sixty years (1951-2014). They relied on data combining satellite and ground observations of soil moisture.

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“Sudden droughts are increasing, especially in Europe, North and East Asia, the Sahel and the west coast of South America,” author Jing Yuan told AFP and Tech.

They are “dangerous because they start quickly and don’t allow enough time to prepare,” for example through measures to allocate water resources, he stressed. Flash droughts also put ecosystems to the test: “Plants also don’t have enough time to adapt”, he added.

The study also shows that the frequency of classic droughts has increased in most regions and that they are occurring more quickly. Despite this, according to Jing Yuan, there is a “change from slow to flash drought”.

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In the future, using climate models, the researchers calculated the impact of different greenhouse gas emission scenarios on flash droughts. If emissions moderate, the trend toward more flash droughts will continue to strengthen in almost all regions of the world.

As emissions levels rise, this trend will increase in most regions. “We think reducing emissions will slow this transition” and flash droughts, Xing Yuan said.

The concept of flash drought emerged at the beginning of the 21st century, but gained more attention after the 2012 summer drought in the United States, which caught on particularly quickly and caused more than $30 billion in economic losses.

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David Walker, a researcher at Wageningen University in the Netherlands who was not involved in the work, said the study’s authors’ “caution” should be “taken seriously.” Areas particularly affected by sudden droughts are many in low-income countries, where people’s resources do not cope with these extreme climate events, he points out in a commentary published in Science.

The intensity of the impact on crops often depends on when the drought occurs, especially when it is during the flowering or pollination period or later in the year. The proliferation of flash droughts is finally posing a challenge to their prediction.

For now, drought maps are released more often than once a month, David Walker said. “There is a need for drought detection methods that work on shorter time scales,” he argued.

(AFP)Show comments