Droughts occurring at the same time across different regions of the planet could place an unprecedented strain on the global agricultural system and threaten the water security of millions of people, according to a new study in Nature Climate Change.

A Washington State University-led research team analyzed climate, agricultural and population growth data to show continuing fossil fuel dependence will increase the probability of co-occurring droughts 40% by the mid-21st century and 60% by the late 21st century, relative to the late-20th century. That comes out to an approximately ninefold increase in agricultural and human population exposure to severe co-occurring droughts unless steps are taken to lower carbon emissions.

“There could be around 120 million people across the globe simultaneously exposed to severe compound droughts each year by the end of the century,” said lead author Jitendra Singh, a former postdoctoral researcher at the WSU School of the Environment now at ETH Zurich, Switzerland. “Many of the regions our analysis shows will be most affected are already vulnerable and so the potential for droughts to become disasters is high.”

The elevated risk of compound droughts estimated by Singh and colleagues is a result of a warming climate coupled with a projected 22% increase in the frequency of El Niño and La Niña events, the two opposite phases of the El Niño Southern Oscillation (ENSO).

The researchers’ projections show that nearly 75% of compound droughts in the future will coincide with these irregular but recurring periods of climatic variation in the world’s oceans, which have played a large role in some of the greatest environmental disasters in world history.

Read the full article about droughts and global food security at Environmental News Network.