Athanasios Gioumpasis/Getty Images

The Sahara Is Expanding, and Human-Caused Climate Change Is Partially to Blame

North Africa’s vast desert grew by 10 percent in the past century, driven primarily by fluctuations in the Atlantic Ocean. But climate change has also been a factor.

This pair of images shows the change in the boundaries of the Sahara Desert during the period 1920-2013, broken down by season. Dotted lines show the boundary as it existed in 1920, while solid lines show the boundary in 2013. Both boundaries are averaged across the three months of each season. (Winter = Dec-Feb; Summer = Jun- Aug). Brown shaded regions indicate desert advance while green shaded regions indicate desert retreat. | Natalie Thomas/Sumant Nigam/University of Maryland.