For graduate students, it's getting ever easier to be green, thanks to an interdisciplinary newcomer called sustainability science by some, and sustainable development by others. The challenge of figuring out how to keep the world in balance is now a boom area. Navin Ramankutty is an assistant professor at McGill, where he is helping launch a new undergraduate Earth System Science initiative. Is there a graduate program down the line? "We're talking, but one thing at a time." His students are interested, and so are others, around the country and the world.