By the end of the century, possibly sooner, a hotter climate likely will wipe out Joshua trees from 90 percent of their current range, which includes Joshua Tree National Park, according to U.S. Geological Survey researchers.

Across the National Park System many changes are expected from climate change, from more wildfires and vanishing glaciers to invasions of non-native species and flight of long-term residents. Writer/photographer Michael Lanza, concerned that today's park landscapes will change significantly by the time his young kids are his age, has been touring the park system with his family to show his children what they might miss later in life.

They collar moose at Voyageurs National Park. And by doing this, biologists and ecologists can learn not only how the animals are coping with warming weather related to climate change, but how different land-management techniques affect them.

What are the top issues confronting the National Park System? A slew of answers could be tacked onto that question, ranging from sprawl outside park boundaries and habitat fragmentation to pollution.