So it can be easy to feel lost at sea. A group of scientistsat the University of California at Berkeley, for instance, claimed that a previously unknown, petroleum-munching microbe accounted for the surprise disappearance of a 22-mile-long oil plume after the Deepwater Horizon disaster in the Gulf of Mexico last year. But others argued that the plume hadn't disappeared at all, or that we simply didn't know enough to know if it had. "The true unknown is the interdependencies, the absolutely complex linkages," says Larry Mayer, the chairman of a National Academy of Sciences committee studying the gulf's ecosystems after the spill. "When you start asking questions about the impact of midwater oil on deepwater biota, or how that cascades into the atmosphere, or how that affects clams and mussels—things like that, nobody really knows."