The Sahara is now the largest desert on the planet. Billions of square kilometers occupy the upper quarter of the African continent, huge in its proportions, and have separated for millennia the sub-Saharan cultures of the Fertile Crescent and European civilizations. So imposing, so unfathomable, that it seems to have been there since the beginning of time.
A logical thought. But incorrect
Green Sahara. It’s widely known to the scientific community that the Sahara wasn’t always a desert. From the end of the Holocene to around 10,000 years ago, North Africa contained vast grasslands, scattered forests and abundant water sources. That episode is known as the African Humid Period (AHP), and its transition to a drier and warmer one is the subject of much discussions.
Human role. A recent study by David K. Wright, a researcher at Seoul University, offers a suggestive theory: humans played a fundamental role in the creation of the desert. The presence of extensive cattle ranching has depleted the grasslands, disrupted the environmental balance of the region and precipitated an increase in aridity, favoring the emergence of drier and warmer terrain.
Albedo. Wright argues that the presence of very voracious goats and other animals caused an albedo effect. The whitish earth replaced the green grasses, and the sun’s rays began to reflect off the surface, increasing the temperature of the atmosphere and reducing the volume of clouds. And therefore of precipitation. In the long term, livestock farming contributed to the drying up and deforesting of the Sahara.
Doubts. It is not a theory shared by all specialists in the field. Traditionally, the scientific community had explained the end of the AHP by slight changes in the Earth’s rotation. North Africa was less exposed to rainfall. Plant species regressed. Their disappearance reduced environmental humidity. A vicious circle was formed that fed the drought, generating a desert.
Future. It is a theory that, as its own author admits, requires more evidence on the ground. But it makes sense if we think in similar processes experienced by deserts today in North America or Asia. We know that human activity and livestock farming can lead to conditions that favour (or reduce) drought. Some argue that the Amazon is suffering that fate.
Did humans cause the drying up of North Africa? No. The causes are multiple. But it could have put its grain of sand in a process that has left us, thousands of years later, facing an endless desert.