Recently, the Sahara Desert, the world’s largest desert, has been experiencing frequent heavy rainfall. In northern Morocco, an extraordinary scene of “lakes emerging in the desert” has occurred due to torrential downpours, leading to floods unseen in decades. Meanwhile, countries along the southern edge of the Sahara have been hit with rainfall several times higher than usual. What is the culprit behind this unusual phenomenon?
Abnormal Rainfall in the Sahara Desert
The Sahara Desert is typically controlled by a subtropical high-pressure system, where hot, dry descending air inhibits the formation of precipitation. Additionally, its proximity to the Eurasian landmass and the prevailing northeast trade winds blowing from the land further reduce the moisture in the air, exacerbating the dryness. These factors have made the Sahara one of the driest regions in the world.
However, since September this year, the southeastern provinces of Morocco, such as Tata and Errachidia, have been hit by multiple thunderstorms, causing flooding. In addition to claiming the lives of dozens, the heavy rains disrupted roads, destroyed infrastructure, and severely impacted daily life. Media reports indicate that some regions in southeastern Morocco, which usually receive less than 250 mm of annual rainfall, experienced more rain in just two consecutive days in September than they usually do in an entire year.
The southern edge of the Sahara has also experienced unusual rainfall this year. Satellite images show that long-dry regions along the southern Sahara have recently been hit by storms, leading to the growth of green vegetation in the usually barren desert. According to the Climate Prediction Center of the U.S. National Oceanic and Atmospheric Administration, parts of Niger, Chad, and Sudan have seen rainfall exceeding four times the normal amount since mid-July.
In fact, many desert regions globally have experienced similar extreme weather this year. In April, the Middle East experienced intense convective weather, caused by a powerful low-pressure system that transitioned into a cyclone after moving across the Arabian Sea and Gulf from the Indian Ocean. In less than 24 hours, the Al Ain region of the UAE, which usually receives less than 100 mm of rain annually, recorded 254.8 mm of rainfall. In Oman, continuous downpours triggered flash floods, killing at least 19 people. Bahrain and Qatar were also affected by heavy rains.
What Is Causing the Desert Floods?
Deserts are typically associated with heat and drought, so why have such large-scale rainstorms occurred this year?
Meteorologists explain that the heavy rainfall in Morocco was caused by a strong, slightly cooler low-pressure system pushing into the subtropical high-pressure zone. The collision of warm and cold air created an upward convective flow. At the same time, the cyclonic system, which rotates counterclockwise, transported moisture from the Atlantic Ocean and the Mediterranean Sea. Solid particles floating in the desert air acted as condensation nuclei, facilitating the formation of heavy rainfall.
There is also a link between the Sahara’s rainfall and global warming. As global temperatures rise, the atmosphere holds more moisture, and changes in temperature can affect atmospheric circulation, such as altering the paths of low-pressure systems.
According to meteorologists, the unusual weather in the Sahara is also related to changes in the position of the Intertropical Convergence Zone (ITCZ). When humid tropical air near the equator meets the hot, dry air from northern Africa, storms increase. The ITCZ, where trade winds from the northern and southern hemispheres converge to form stormy weather, usually shifts northward during the northern hemisphere summer and southward during the warmer months of the southern hemisphere.
The latest data from the U.S. National Oceanic and Atmospheric Administration indicate that since at least mid-July, the ITCZ has moved farther north than usual, bringing storms to areas south of the Sahara, including parts of Niger, Chad, and Sudan, even reaching as far north as Libya.
Carsten Hauesthein, a meteorologist at Leipzig University in Germany, points out that global warming is a major reason for these changes. He explains that most models suggest that as the world gets warmer, the ITCZ moves further north.
Impact of Extreme Weather on Deserts
Desert ecosystems help regulate global climate by facilitating the movement of moisture and balancing temperature differences due to the large daily temperature variations in deserts. If extreme weather events like heavy rainfall become frequent in deserts, it could alter the desert ecosystem, with potential ripple effects on the global ecosystem.
The climate in the Sahara Desert has already been changing subtly. Before the recent floods, Morocco had experienced years of drought. In 2023, the country’s second-largest dam, the Massira Dam, held less than 6% of its capacity. 2023 was also Morocco’s hottest year on record, with temperatures exceeding 50°C for the first time. According to a report published by the World Meteorological Organization in September 2024, climate change has led to recurring droughts in many African countries. While extreme heat waves hit some countries in northwest Africa in 2023, parts of East Africa were struck by floods, causing significant losses across the continent.
A study published in Nature in June 2023 shows that as carbon dioxide levels in the atmosphere increase and global warming continues, the ITCZ may shift further north more frequently in the coming decades. Although extreme weather may green some long-arid desert regions, it also disrupts the hurricane season in the Atlantic and causes droughts in areas that usually receive rainfall, while bringing floods to long-dry regions.
Hauesthein notes that as global warming continues, the atmosphere will hold more moisture, potentially leading to wetter monsoons and more severe floods. While it’s difficult to attribute any single flood directly to climate change, climate change makes such floods more likely to occur.
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