MIT Study Explains Why Climate Change Will Make Some Mediterranean Countries Drier

The human body can go about 3 minutes without oxygen and about 30 days without food, but it can only go about 3 days without water. People without access to clean water either move or die. If enough of them move, they risk becoming stateless refugees, unwelcome in other areas (particularly the United States), which leads to political unrest.

Image credit: MIT

Researchers at MIT, in conjunction with colleagues at Université Mohamed VI Polytechnique in Morocco, have been working lately on understanding the connection between a warming climate and reduced rainfall in northwest Africa and in the Middle East. Drier climates in those areas have already been noted and many analysts believe drought is a major reason why millions of Syrian people are fleeing their homeland. (A bloody war that has gone on for over a decade hasn’t helped, either.)

The findings have been published by the Journal of Climate. According to MIT News, the research was conducted by MIT graduate student Alexandre Tuel and professor of civil and environmental engineering Elfatih Eltahir. A hotter climate tends to have more water vapor in the atmosphere, which leads to more precipitation. So why so virtually all climate models predict parts of Africa and the Middle East will get drier?

The answer is two fold. One, the jet stream that steers weather patterns across North America, Europe, and Asia gets disturbed by mountain ranges like the Rockies, the Alps, and the Himalayas. As hotter temperatures make the jet stream more powerful, one result will be the creation of a high pressure zone with low humidity parked directly over the Mediterranean the MIT study suggests. That’s ideal for sun-seeking tourists on Ibiza, but devastating for farmers in Morocco and the Levant.

“It just happened that the geography of where the Mediterranean is, and where the mountains are, impacts the pattern of air flow high in the atmosphere in a way that creates a high pressure area over the Mediterranean,” Tuel explains. “What’s really different about the Mediterranean compared to other regions is the geography. Basically, you have a big sea enclosed by continents, which doesn’t really occur anywhere else in the world.”

The second factor, the researchers say, is that the land abutting the Mediterranean will warm faster than the sea. That temperature differential will lead to a clockwise wind pattern around the Mediterranean basin. Local topography will interact with that wind flow to amplify the effect of the high pressure area to reduce rainfall in northwest Africa, including Morocco, and the eastern Mediterranean region, including Turkey and the Levant.

“We document from the observed record of precipitation that this eastern part has already experienced a significant decline of precipitation,” Eltahir says. The fact that the underlying physical processes are now understood will help to ensure that these projections will be taken seriously by planners in the region and will enabling them “to understand the exact mechanisms by which that change is going to happen.”

The overall result of the research is that significant parts of the land that borders the Mediterranean will face critical shortages of water in the near future, shortages that will lead to lower crop yields and a lack of drinking water. Those challenges could drive investment in desalinization systems powered by electricity from renewables like the one installed in Kenya recently by GivePower.