Global warming threatens Yosemite's unique flora. Shutterstock

Where are you going on your next vacation? Putting off that trip to Joshua Tree National Park in favor of another trip to Disneyland? You might want to reconsider, before the park's namesake is no longer. Because it is dependent on winter freezes to flower and seed, rising temperatures are already killing off the Joshua tree. The western United States is warming considerably faster than the East, threatening the region's national parks and some of the West's iconic landscapes. Scientists estimate that the glaciers of Glacier National Park could be gone by 2030; hikers report snowfields melting weeks earlier than the historical average. The wildflower-filled meadows of Yosemite National Park might well be overrun by sagebrush. A new report from the Rocky Mountain Climate Organization and NRDC details the forecast for many of our western parks: increased wildfires, flooding, and erosion, and dramatically reduced snowpack. Read the report online, where you'll also find trail maps and historical photographs: www.nrdc.org/land/parks/globalwarming.