"Humans have become a geologic agent comparable to erosion and [volcanic] eruptions ..." Paul J. Crutzen, a Nobel Prize-winning atmospheric chemist. Using Landsat imagery, scholars create a grid showing land use type, such as urban, rural, river, etc. Then, they draw another land use grid for the same area using data from a decade later. The comparison of the two grids shows how humans have altered the environment. Lesson focuses on the impact humans have on the climate in the seventh lesson plan in a series of 21.