Around the world, scientists and advocates call for keeping carbon in the ground as a means of staving off climate change. But in the Southwestern United States — mainly in Colorado and New Mexico — a mainstay of obtaining more oil is facilitated by doing the exact opposite: drilling pure reserves of carbon dioxide out of the ground. After it’s extracted from these natural-source underground fields, the gas then gets piped to the Permian Basin, the nation’s top-producing oil fields of West Texas and southeastern New Mexico. There, oil companies use the CO 2 to flood their wells, forcing the last dregs of crude to the surface in a process also known as enhanced oil recovery, or EOR.