The Sahara was once a forest. Its desertification was not caused by human activity. On the other hand for the Fertile Crescent: the overuse of irrigation and w

The Sahara was once a forest. Its desertification was not caused by human activity. On the other hand for the Fertile Crescent: the overuse of irrigation and water steering with shorter term agricultural goals with only direct affects in mind. The area was largely marshlands in the past. And also mismanagement of forests lead to desertification of formerly fertile areas on the timescale before the current large scale climate change era began. This was before humanity could have as big possible part in the forming of climate as currently.