African Vegetation: Comparing September 1984 and September 1994

For many years, scientists have believed that the southern expansion of the Sahara has been due to human activity. However, results from the AVHRR instrument and its measurements of vegetation suggest a different explanation: rainfall patterns. In drier years (1984 was one of the driest summers in recorded history in Northern Africa), the Sahara expands south, but in wetter years (such as 1994), vegetation moves back and there is no net expansion of the Sahara as had been previously suggested. Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional