Coffee crops around the world are under serious threat from rising temperatures, shifts in rainfall, insects and disease. In the October Scientific American writer Hillary Rosner reports on the coffee crisis and what scientists are doing about it. The central challenge is that cultivated coffee is highly homogeneous, making it particularly vulnerable to environmental change. Researchers are thus studying the vast genetic diversity in wild coffee plants, searching for helpful genes that could be introduced into cultivated crops via cross-breeding. Scientists have described around 125 coffee species and no doubt more await discovery.