“People have used satellites to map cropland extent before. What distinguishes this effort is that we are showing change over a long period of time,” said Peter Potapov, the co-director of GLAD and the lead author of the study. “We also do it in a way that is consistent across international borders so we can compare what is happening in different regions or countries in a meaningful way.” Most previous attempts to map and compare farmland relied on the compilation of local or regional data via methods and definitions that varied significantly.