Climate change has already altered the timing of plants blooming, insects hatching, and birds migrating and breeding. Now, researchers have found that it may be altering human vacation plans as well. A team analyzed attendance data at U.S. national parks from 1979 through 2008. Of the 27 national parks that had seasonal variations in attendance, at least 100,000 visitors in 1979, and for which long-term attendance data were available, nine parks showed increases in average temperatures in spring, according to weather data collected there or nearby. And at seven of those nine parks, peak attendance moved forward an average of 4 days over the 30-year period , the researchers report in an upcoming issue of International Journal of Biometeorology. At Grand Canyon National Park (shown), for example, peak attendance shifted from 4 July in 1979 to 24 June in 2008. At the 18 parks analyzed that didn't experience climate change, only three showed shifts in peak attendance. The researchers blame climate change for the shifts: A warmer and longer spring allows tourists to visit parks earlier, which nudges peak attendance earlier in the year, they contend. Other major factors likely to influence park visitations—including population growth, economic trends, and travel costs—would tend to affect the total number of park visits but not their timing within the year, the researchers say.
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