Ecosystem changes like droughts and desertification are often thought of as a gradual processes, slowly taking place over hundreds of years. In fact, scientists have found that drastic changes in ecosystems can happen quickly and often unpredictably. A small nudge can be enough to shift an ecosystem from a grassland into a desert. “We don’t know where the thresholds are,” ecologist Marten Scheffer told Momentum magazine. “But we know they’re there and that we cross them.” Scientists are now trying to figure out how to predict these drastic changes in the climate, how to handle them once they happen.