As we celebrate the Fourth of July, it’s fitting that we also recognize the centennial of the National Park Service. Today on Sea Change Radio we speak with author and environmentalist Jason Mark about the challenges that the national parks face moving forward. Mark is the editor of Sierra Magazine and author of a new book, Satellites in The High Country, which focuses on the state of wilderness in the U.S. We talk about the hidden wild gems that Mark encountered while researching the book, and discuss how environmental groups like the Sierra Club are approaching the issue of climate change which looms over the entire conservation landscape.