Environmental change, economic development, and the constant demand for energy are profoundly affecting natural systems the world over. There are places where this is a good thing. New jobs, electricity, and new water sources can be great news for local populations. Unfortunately, they can also spell curtains for the singular landscapes and ecosystems that suddenly find themselves besieged. These are some of the beautiful places that may not be around for the next generation — places to visit before it's too late.