Environmental woes imperil America’s national parks

Disappearing glaciers, decreasing air quality and foundation species pushed to the brink of survival. America’s national parks are facing environmental threats that range from tiny invasive species to the planet-spanning impacts of climate change. In some cases, the situation is dire; in others, progress is being made. In aggregate, the issues point to how important — and how fragile — these special places are.

“Each unit in the system has its own unique challenges,” said Al Nash, spokesman for Yellowstone National Park, “but they all reflect a component of who we are and where we’re going. They’re about our shared experience as Americans.”