Following a pair of recent studies that exposed man-made and climate-caused deterioration at those two iconic American attractions, environmentalists are raising new concerns about the future health of all 58 U.S. national parks in a time marked by barren budgets, rising energy cravings and warming skies.

By Bill Briggs -- Contributor

Environmental Sustainability
population growth

Updated: Tue, Aug 31st 2010 @ 10:00am EDT