More than a century ago, naturalist John Muir urged urban dwellers in bustling Eastern cities to look up from their labors and head west to a national park for a fresh perspective.
"Nature's peace will flow into you as sunshine flows into trees," wrote Muir in 1901. "The winds will blow their own freshness into you and the storms their energy, while cares will drop off like autumn leaves."
Beginning this Sunday America's premier documentary filmmaker, Ken Burns, issues that same clarion call. This time it's in high-definition video in a six-part, 12-hour series on PBS called "The National Parks: America's Best Idea."
But behind Mr. Burns's armchair tour of the fascinating history and scenic splendor of the parks is the hope that the series will inspire Americans to visit these treasures and experience their transformative powers firsthand. Those visits should also inspire Americans to take the urgent steps needed to preserve their parks.
In this year of recession and lower gas prices, millions have already headed to the 391 US national parks and monuments. In fact, this may turn out to be a record year for visits.
The parks have always represented a bargain getaway for the ordinary American. Free weekends at the parks have sweetened the deal. In August, President Obama and his family visited Yellowstone and the Grand Canyon, providing even more visibility for two of the world's special places.
This Saturday, National Public Lands Day, represents the other side of the equation: what Americans owe these parks. Thousands of volunteers will head to these treasures (on yet another free-admission day) to pick up trash, remove invasive plants, restore trails, fix bridges, and plant trees.
That's welcome help. But the parks are in dire need of some $8 billion worth of major maintenance overhauls – repairs to water-treatment plants, dams, roads, and so on that weekend volunteers can't provide.
Yet the biggest long-term threat comes not from neglect but from climate change.
As winters warm, for example, tiny mountain pine beetles move farther north and into higher elevations, boring into the bark of whitebark and lodgepole pines and killing them. Large swaths of forest will likely be lost. The collateral damage may include harm to one of America's most charismatic mammals, the grizzly bear, which relies on whitebark pine nuts as a key food source.
Glacier National Park is expected to lose all its glaciers in the next two decades. Ellis Island, the landmark historic site in New York Harbor, could disappear underwater later this century due to rising sea levels.
Warmer water temperatures and ocean acidification caused by higher CO2 levels are contributing to major "bleaching" and die-offs of staghorn and elkhorn coral reefs in the Virgin Islands National Park and elsewhere. The list of climate threats to parks goes on and on.
The solutions begin with the worldwide effort now under way to limit emissions of greenhouse gases. Beyond that, the animal and plant life in the parks can be helped to adapt to a changing climate.
Eliminating or reducing other stresses, such as air and water pollution, will help. Creating "escape corridors" between parks for animals and plants to move north as the climate shifts may save some species.
"National parks are the best idea we ever had," Wallace Stegner wrote. "Absolutely American, absolutely democratic, they reflect us at our best rather than our worst."
Living up to that idea is now the job of early 21st-century Americans. They are charged with protecting these treasures, entrusted to them by their predecessors to be preserved for all generations to come.