Spring has sprung--way too early.

• Position: National Parks

National parks across the country are seeing earlier springs driven by climate change, according to research conducted by a team of scientists from the University of Arizona, Tucson; U.S. Geological Survey; and National Park Service. Compared with historical average conditions, the change is occurring earlier in three out of every four parks examined, and more than half of the parks included in the analysis are experiencing extreme early onsets of spring.

Published in Ecosphere, the study examines patterns of historical temperatures for 276 of the 413 national parks, including sites from Alaska to Florida. The study analysis spans 1901-2012, a period that provides the best historical temperature data and overlaps the history of the National Park System.

The study leverages a set of climate-change indicators, models based on nationwide field observations of first leaf-out and first bloom dates in two common and widely distributed flowering plants: lilac and honeysuckle. Using the indices, the authors calculated annual dates for the onset of spring in each park and analyzed those trends over the 112year period.

At the iconic Grand Canyon National Park, the study found that recent springs are occurring earlier than 90% of historic springs. Educators and managers at the park already have taken note, and have engaged visitors in observing the phenology of key species, including the Gambel oak and Fremont cottonwood, since 2013.

"These results provide a key longterm perspective on change across the National Park Service," says study coauthor Katharine Gerst, research scientist at the UA School of Natural Resources and the Environment. "In addition to this study, we are working with 25 parks across the country to collect and analyze observational...