The Sahara Desert we know, with its rolling sand dunes and hot temperatures, used to be a verdant grassland with lakes. Scientists have traditionally attributed the dramatic change to a wobble in Earth’s orbital axis, but now archaeologist David K. Wright of Seoul National University is suggesting actually, humans may have been to blame.
A 10,000-year or so wet period called the African Humid Period brought moisture to northern and eastern Africa. But around 8,000 years ago the moisture balance began to change. Today below the sand-dominated landscape can be found signs of rivers and plants, remnants of a greener history. In an article published in the journal Frontiers in Earth Science, Wright explained humans used to be thought of as passive agents in the end of the African Humid Period. But he 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.” He 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.
As yet, Wright needs more evidence for other scientists to fully get on board with his ideas. He said, “There were lakes everywhere in the Sahara at this time, and they will have the records of the changing vegetation. 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.”
If Wright turns out to be right, his research could yield insights into how we can adapt to large scale climate change.