Across the National Park System, more than $100 million a year is spent in a bid to control invasive plant and animal species, though the actual cost in lost recreational opportunities is difficult to measure.

The 1988 wildfires that drew the nation's attention to the world's first national park were considered simply part of the fire regime that historically has existed in Yellowstone National Park. But in the aftermath of the fires, "climate change" entered the country's lexicon and increasingly intense wildfires have forced the National Park Service in the West to both evaluate and refine its approach to battling flames that are arriving with greater and greater ferocity.

Water is big business, bigger in the Southwest than perhaps anywhere else in the United States, and so where the Colorado River flows, economics and politics closely follow. More than 40 million people downstream depend upon its waters for agriculture, cities and businesses. At Glen Canyon National Recreation Area in southern Utah and northern Arizona, that reality rises in the 710-foot tall Glen Canyon Dam and shimmers in the lake that it has formed, Lake Powell.

A warming climate has been linked to human activity around the world, and has affected the Colorado River System as well. The impacts are substantial, from reduced water flows, threats to indigenous species and the influx of new invasive species along the river system. National Parks Traveler sent Patrick Cone to investigate the impacts on Canyonlands National Park and Glen Canyon National Recreation Area. From Moab to Green River, Utah, and Page to Flagstaff Arizona he talked to Park Service personnel, river runners, residents, business owners and other stakeholders who rely on a healthy Colorado River for their existence