Humans could have led In desertification of the Sahara

Posted on March 20, 2017 12:00 am

Dr David Wright, an archaeologist at Seoul National University has published a study that claims humans may have played a very active role in the desertification of the Sahara, the world’s largest desert. He wrote his research in the journal frontiers in Earth Science saying it was Neolithic people who inhabited the green landscape of the Sahara back then who were primarily responsible for the speedy desertification. Wright explained humans used to be thought of as passive agents in the end of the African Humid Period. But Wright thinks humans might actually have been active agents in the change.Wright said, “In East Asia there are long established theories of how Neolithic populations changed the landscape so profoundly that monsoons sopped penetrating so far inland.” Wright thinks a similar phenomenon could have happened in the Sahara. People growing crops and raising livestock could have changed the environment, exposing soil, and sunlight bouncing from the soil could have warmed the air, influencing atmospheric conditions enough so there wasn’t as much rainfall, which only added to the desertification of the Sahara.After surveying the available archaeological evidence, he found that pastoral communities started arriving at the lands around the river Nile from some 8,000 years ago. From there, they spread westward, following the spread of scrub vegetation.However this human migration would have a devastating effect on the local environment. As people’s livestock grazed on vegetation, the domesticated animals denuded the landscape of its greenery. That created a brighter land surface and changed the amount of sunlight that could reflect off it in what is known as the albedo effect, thereby triggering changes in atmospheric conditions.

Those changes in turn led to a slowdown and finally stop in hitherto regular monsoon rainfalls, which then led to increased desertification and further losses in vegetation cover. Within a relatively short period of time, what resulted is today’s Sahara with scarcely any vegetation save for hardy desert plants and a mere tenth of its former amount of rainfall. “There were lakes everywhere in the Sahara at this time, and they will have the records of the changing vegetation,” Wright explains. “We need to drill down into these former lake beds to get the vegetation records, look at the archaeology, and see what people were doing there.” Despite taking place several thousands of years ago, the implications of humans being responsible for environmental and climatic degradation are easy to see. With approximately 15% of the world’s population living in desert regions, Wright stresses the importance of his findings: “the implications for how we change ecological systems have a direct impact on whether humans will be able to survive indefinitely in arid environments.” After reading Dr Wright findings, it became clear that while concerns about food insecurity in Nigeria, Ethiopia and Somalia grab headlines, one of the key drivers of the problem is overlooked and that is few seems to notice that good farm land is being lost to the desert winds in Africa.Africa’s fight against desertification is a fight to save land productivity and soil fertility in the arid, semi-arid and dry-sub humid areas or drylands, as they are simply called. It is a fight to prevent the creation of man-made deserts in areas that have served us so well in the past. As Dr Wright found out, one of the environmental movement’s best kept secrets is that drylands supply Africa’s breadbasket. They account for 60 per cent of all cultivated systems and 70 per cent of the livestock. In Africa, one in every three plants that we cultivate is from the drylands.Only a third of Africa’s land can be farmed without irrigation. Yet, agriculture takes up 70 per cent of the total land area, with livestock grazing as the most extensive use.

To be sure, combatting desertification is not only fighting to ensure future generations can enjoy a bag of potato chips and a salad laced with olives. It is about ensuring there is food on the table, access to clean and safe water and energy to use today, and everyday.In my view it cannot be done without ending land and soil degradation.But every year, million hectares of land are lost through desertification and drought alone in Africa and 6 billion tonnes of fertile soil is lost forever each year. Overall, about 600 million Africans live off degrading land, of whom 90 per cent are the poor.More significantly, land degradation exceeds its restoration. Continuing with business as usual means that Africa’s food production could fall by 24 per cent due to land degradation alone. This would increase Africa food prices by up to 55 per cent. Otherwise, about 30 million hectares of new land must be cleared to meet the expected increase in food demand. Currently, 90 per cent of deforestation in Africa is due to cropland expansion.The biggest challenge is that political will in Africa is lacking because drylands and other degraded areas are viewed as marginal land that central governments can afford to abandon. So, there is little interest to develop in these areas.There is also a very weak link between science and policy at all levels. Since the issue is sophisticated, diagnosis must be site specific.In addition, lack of African institutions to monitor these trends at all levels and across all land ecosystems is a serious policy gap that need to be addressed. Time has come for Africans to challenge misperceptions and offer solutions to speed up the change otherwise despite being home to the world’s largest desert, Sahara, the next big desert perhaps bigger than Sahara could be on the way. Dr Wright study can’t be said to be conclusive but it reminds that healthy soil sustains lives and therefore Africans and rest of the world need to address desertification.

Contador Harrison