The Sahara Desert, often referred to simply as "the Sahara," is the largest hot desert in the world and the third largest desert overall, trailing only Antarctica and the Arctic, which are cold deserts. Stretching approximately 9,200,000 square kilometers, it covers much of North Africa, sprawling across 11 countries including Morocco, Algeria, Tunisia, Libya, Egypt, Mauritania, Mali, Niger, Chad, Sudan, and Western Sahara. Its landscape is not just the stereotypical sea of endless sand dunes (known as ergs); it also features mountain ranges, rocky plateaus, and even areas of sparse vegetation, which receive a bit more rainfall than the hyper-arid regions.
One of the most fascinating aspects of the Sahara is its climate history. The desert has gone through shifts between desert and savanna grassland during various ice ages and interglacial periods. Approximately 5,000 to 10,000 years ago, during the African Humid Period, the Sahara was significantly greener and more hospitable than it is today. Paleoclimatology studies suggest that this greening was due to a shift in the Earth's axis and changes in orbital patterns, which increased monsoon activity in the region. Today, however, the climate is predominantly arid, with some of the highest temperatures recorded on earth — temperatures that can exceed 50 degrees Celsius (122 degrees Fahrenheit).
The Sahara also plays a crucial role in the environment through its aerosol particles, which are swept up by winds and transported across vast distances. These sand and dust particles can affect weather patterns far beyond the desert’s borders, influencing the formation of hurricanes in the Atlantic or fertilizing the Amazon rainforest with essential nutrients. This massive "dust transport" can have both beneficial and detrimental effects on the global climate, making the Sahara a significant point of interest for climatologists and environmental scientists.
Culturally and historically, the Sahara has been a cradle of various nomadic tribes like the Tuareg, often called the "blue people" because of their indigo-dye colored clothing. These communities have adapted impressively to the harsh desert conditions. Their routes and interactions facilitated the trans-Saharan trade, which connected the empires of sub-Saharan West Africa with the Mediterranean and Middle East. Salt, gold, ivory, and slaves were commonly traded commodities. Despite the harsh environment, archaeological findings such as the cave paintings at Tassili n'Ajjer, which date back thousands of years, provide a window into past lifestyles and the environmental conditions of the Sahara over the millennia, illustrating a time when the region supported a much more abundant and varied life.