How can a beetle kill a grizzly bear? By wiping out one of its most important food sources. In the northern Rockies, warming temperatures and an infestation of pine beetles are combining to destroy entire forests of whitebark pine. Feasting on the tree's large, nutritious seeds helps grizzly bears survive hibernation.

But as global warming brings milder temperatures, beetles are spreading to high peaks that were once hostile to them. Many of those peaks are too remote for regular visits, and satellite data has not provided sufficiently accurate information, so scientists studying the beetle infestation have come up with another solution: aerial surveys that help map the whitebark pine's destruction throughout the entire 20 million-acre Greater Yellowstone ecosystem.

I took a seat on one of those recent flights. Here's what I saw: