Dürre in der Sahel Zone
→ Google Earth
Originally it was believed that the drought in the Sahel primarily was caused by humans over-using natural resources in the region through overgrazing, deforestation and poor land management.
In the late 1990s, climate model studies suggested that large scale climate changes were also triggers for the drought. In 2002, after the phenomenon of global dimming was discovered, a CSIRO study suggested that the drought was probably caused by air pollution generated in Eurasia and North America, which changed the properties of clouds over the Atlantic Ocean, disturbing the monsoons and shifting the tropical rains southwards.