A bachelor's degree is the absolute minimum, but that’s for an environmental scientist who only wants to figure out the best way to clap your hands over your face when the air is a little smoggy. Pretty bush league stuff. If you’re serious, you will need to complete a graduate program. You will have to become knowledgeable in a wide range of areas, everything from biology to physics to statistics to 20th century women’s feminist literature. (All right, that was an elective.) If your goal is to get legislation passed that will change the world for the better, you may also want to get a background in law. Think of your brain as a giant sponge that, once full of information, can be used to go out there and scrub up the planet.