Researchers from the University of Maryland have revealed that the Earth's largest hot desert, the Sahara, has expanded by about 10 percent since 1920.
World's Deserts Are Expanding
In a new study, which was published in the Journal of Climate on March 29, Sumant Nigam and colleagues revealed that the desert is advancing south into the more tropical areas in Chad and Sudan. Soil that was once used for farming are drying up and have become barren.
The study did not only show changes to the boundaries of the Sahara desert. The findings also suggest that other desserts in the world are also getting bigger.
"Our results are specific to the Sahara, but they likely have implications for the world's other deserts," Nigam said.
Man-Made Climate Change And Natural Climate Cycles
The study further indicates that climate change and natural climate cycles contribute to the expansion of the desert.
Climate cycles such as the Atlantic Multidecadal Oscillation or AMO, which affect sea surface temperatures can influence surface temperatures, and precipitation on land and these effects can last for decades.
While man-made climate change and natural climate cycles both contribute to the expansion of the desert, the researchers found that climate change is responsible for about a third of the increase.
By using statistical methods that remove the effects of natural climate cycles on rainfall variability, the researchers were able to identify climate change as a significant factor to the phenomenon.
Expansion Of Sahara Desert Varies Depending On The Season
The researchers also found that there are seasonal variations in the geographical pattern of expansion and that the most notable differences occur along the northern and southern boundaries of the desert.
"The Sahara Desert has expanded significantly over the twentieth century, by 11%-18% depending on the season, and by 10% when defined using annual rainfall," Nigam and colleagues wrote in their study.
"The desert expanded southward in summer, reflecting retreat of the northern edge of the Sahel rainfall belt, and to the north in winter, indicating potential impact of the widening of the tropics."
African People Vulnerable To The Impacts Of Expanding Desert
The researchers said that the observed trends could have a devastating impact on the lives of African people who are reliant on agriculture-based economies. Some areas become vulnerable to drought as the places where people grow crops become drier. This could affect food supply and raise the possibility of famine.