The Sahara Desert is one of the driest places on Earth. About 75 mm of precipitation falls here per year – ten times less than in Chicago, for example.

However, rising global temperatures could make the Sahara much wetter. According to researchers from University of Illinois at Chicago (UIC) which they shared in the magazine npj Climate and Atmospheric Scienceby the second half of the 21st century, rainfall in the North African desert could increase by 75% compared to historical norms. They expect similar changes in south-eastern and south-central Africa.

“Changing rainfall patterns will affect billions of people, both in Africa and beyond. We must start planning how to cope with these changes, from flood management to drought-resistant crops,” said climate scientist Thierry Ndetatsin Tagela of the UIC College of Liberal Arts and Sciences, lead author of the study.

Understanding the impact of rising temperatures on precipitation can help develop adaptation strategies, he said. The study used an ensemble of 40 climate models to project summer rainfall in Africa in the second half of the 21st century, compared with the historical period 1965–2014. Tagela analyzed the model results under two climate scenarios: one assuming moderate greenhouse gas emissions, the other very high.

Both scenarios predicted that rainfall over Africa as a whole would increase by the end of the 21st century, although with some regional variations. Specifically, rainfall is expected to increase by 75% in the Sahara, 25% in southeast Africa and 17% in south-central Africa. In the southwest of the continent, on the contrary, it will become 5% drier.

“The Sahara is projected to nearly double its historical rainfall levels, which is surprising for such a climatically dry region. But while most models agree on a general trend toward wetter conditions, there remains great uncertainty about how much rainfall they predict. Improving these models is important to increase confidence in regional forecasts,” the climatologist emphasized.

The predicted changes are mainly due to the effects of global warming, as as temperatures rise, the atmosphere retains more moisture, which in turn increases precipitation. Changes in atmospheric circulation also played a role in reducing rainfall in some areas.

“Understanding the physical mechanisms that control precipitation is critical to developing adaptation strategies that can withstand both wetter and drier futures,” the researcher concluded.