The Sahara desert is the largest hot desert in the world and the third largest desert after the South Pole and the North Pole, both of which are cold deserts. The Sahara desert is one of the worst environments on earth, covering 3.6 million square miles ( 9.4 million square kilometers ), almost one third of the continent of Africa, equivalent to the land area of the United States ( including Alaska and Hawaii ). The name of desert comes from Arabic arā, which means ” desert”.
The Sahara Desert is bounded by the Atlantic Ocean in the west, the Red Sea in the east, the Mediterranean Sea in the north, and the Sahel steppe in the south. This vast desert spans 11 countries: Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Western Sahara, Sudan and Tunisia.
In fact, the Sahara desert is not only a desert in the traditional sense, it has various landforms, but the most famous is the sand dunes that often appear in movies. These dunes can reach nearly 600 feet ( 183 meters ) high, but they cover only 15% of the entire desert. Other topographical features include mountains, plateaus, gravel-covered plains, salt flats, basins and depressions. An extinct volcano in Chad, the Kuxi volcano, is the highest point in the Sahara desert with an altitude of 11,204 feet ( 3,415 meters ). Egypt’s Qattara depression is the lowest point in salaha, 436 feet ( 133 meters ) above sea level.
Although water is very scarce in the whole region, the Sahara has two permanent rivers ( Nile and Niger ), at least 20 seasonal lakes and huge aquifers, which are the main water sources for more than 90 major desert oases. The water resources management department had feared that the Sahara desert aquifer would soon be exhausted due to overuse, but a study published in 2013 in Geophysical Research Express found that ” fossil” ( non – renewable ) aquifers were still supplying water through rainwater and runoff.
Animals and plants
Despite harsh desert conditions and drought, some plants and animals still take this as their home.
According to WWF data, there are about 500 plants, 70 known mammals, 90 birds and 100 reptiles in the Sahara desert, as well as several spiders, scorpions and other small arthropods.
Camels are one of the most representative animals in the Sahara desert. According to a 2015 study by the Journal of Agricultural and Environmental Management Research, these large mammals originated in North America and eventually crossed the Bering Isthmus 3 to 5 million years ago. About 3,000 years ago, camels in the southeast of the Arabian Peninsula were domesticated for transportation in the desert.
Camels, also known as ” boats of the desert”, can adapt well to hot and dry environments. The hump on the hump stores fat, which can be used to supplement energy and water between meals. Camels store energy so efficiently that they can not drink water for more than a week and eat for months.
Other residents of the Sahara Desert include various gazelles, Adax ( an antelope ), cheetahs, wild cats, desert foxes and wild dogs. Many reptiles can thrive in desert environments, including some kinds of snakes, lizards, and even crocodiles. Some arthropods also take the Sahara desert as their home, such as dung beetles, scarabs, ” death tracker” scorpions and many kinds of ants.
Plant species in the Sahara desert have adapted to the arid environment. Their roots go deep underground to find buried water sources, and their leaves are shaped like thorns to minimize water loss. The driest part of the desert is completely devoid of plants, but oasis areas, such as the Nile valley, are home to a variety of plants, including olive trees, date palms and various shrubs and grasses.
According to a study published in the journal Science Progress in 2019, the Sahara will change from a dry, uninhabitable desert to a lush oasis every 20,000 years or so.
The authors of the study studied marine sediments containing dust sediments from the Sahara desert over the past 240,000 years. The team found that the circulation between the dry Sahara and the green Sahara corresponds to a slight change in the tilt of the earth’s axis, which is also the driving factor for monsoon activity.
When the local axis tilted the northern hemisphere toward the sun for one degree ( about 24.5 degrees instead of 23.5 degrees today ), it received more sunlight and increased monsoon rainfall, thus supporting the lush green landscape of the Sahara desert.
Archaeologists have discovered prehistoric caves, rock paintings and other archaeological remains, providing clues to the living conditions of the once green Sahara desert. Pottery fragments show that about 7,000 years ago, ancient herdsmen raised livestock and harvested plants in what is now a dry desert.
In the past 2,000 years or so, the climate in the Sahara has been quite stable. Northeastern winds dry the air over the desert and blow hot air to the equator. These winds can reach abnormal speeds and cause severe sandstorms, reducing visibility to zero. Dust from the Sahara Desert travels all the way to the other side of the earth through trade winds.
Precipitation in the Sahara Desert ranges from 0 to 3 inches per year, and in some places it hasn’t rained for several years. Occasionally, it snows at high altitudes. In summer, daytime temperatures usually exceed 100 degrees Fahrenheit ( 38 degrees Celsius ) and fall to temperatures near freezing at night.
Impact of climate change
According to a study published in the ” Climate Journal” in 2018, the area of the Sahara Desert has increased by nearly 10% since 1920.
Although all deserts, including the Sahara desert, will increase in dry season and decrease in rainy season, human-induced climate change, together with natural climate cycles, will make the Sahara desert grow more and shrink less. The authors of this study estimate that about one third of the desert expansion is caused by man-made climate change.
One suggestion to mitigate the effects of climate change is to install large-scale wind and solar power plants in the Sahara region.
A study published in the journal Science in 2018 shows that these farms will provide clean energy, reduce the amount of greenhouse gases entering the atmosphere, and may also promote an increase in precipitation in nearby areas.
Computer simulations show that in areas with wind farms, because wind turbines bring warm air from the higher atmosphere to the ground, there will be higher temperatures, especially at night. Researchers also estimated that the average rainfall in the wind farm would double, thus increasing vegetation by about 20%.
The simulation of the solar power plant produced similar results.
The research authors predict that a large-scale Saharan wind farm will generate about 3 terawatts of electricity, while a large-scale Saharan solar power plant will generate about 79 terawatts of electricity, which is much more than the 18 terawatts consumed in 2017. Additional energy can be used for larger-scale projects, including increased agriculture and seawater desalination.