Each GLAD alert ¹ indicates a 30 by 30 meter area (around the size of two basketball courts) that has experienced a disturbance in the forest canopy, which indicates that trees in that area may have been lost or removed. The primary purpose of the GLAD alert system is to alert people to potential deforestation, but GLAD alerts also pick up additional disturbances such as rotation cycles in plantations, forest degradation from fires and storms, and natural changes like landslides and windthrows.