Charting a century of climate change.

• Position: Eye on Ecology

"The main effect observed by ... researchers [in the west's national parks over the last 100 year] is not coming from summers getting hotter, but from the milder winters."

ALL SCIENTISTS follow in the footsteps of earlier scientists. Steve Beissinger, Jim Patton, and their colleagues at the University of California, Berkeley's Museum of Vertebrate Zoology take this more literally than most. Since 2005, they have tried to walk exactly where their predecessors walked a century ago in an attempt to understand where California's native animals are heading in a warming climate.

Joseph Grinnell, the first director of the Museum of Vertebrate Zoology, was a prodigious collector and famously detailed note taker. Between 1904-39, Grinnell and his students crisscrossed California in his Ford Model T, painstakingly surveying and collecting mammals, birds, reptiles, and amphibians from more than 700 locations from Yosemite to Mt. Lassen to the Mojave Desert, spanning the diverse habitats of the state. This work resulted in roughly 100,000 specimens, 74,000 pages of field notes, and some 10,000 photographs.

The word "biodiversity" had yet to be coined; the modern methods of ecological research were just being born; and there was no concept of DNA at the time, but Grinnell knew the work he and his students and colleagues were undertaking was important. The value, Grinnell said in 1910, will not be realized "until the lapse of many years, possibly a century, assuming that our material is safely preserved--and this is that the student of the future will have access to the original record of faunal conditions in California and the West." Notes Beissinger, "We are those students of the future."

With the U.S. National Park Service celebrating its 100th anniversary in 2016, Beissinger, Patton, and colleagues are following Grinnell's path across the iconic landscapes of Yosemite, Death Valley, and other national parks in California, repeating animal surveys in the same locations. One big-picture result from the Grinnell resurvey work tracks with multiple other studies from around the world: many species are on the move as the planet warms, a fact that Pres. Barack Obama called out in a visit in June 2016: "Here in Yosemite, meadows are drying out. Bird ranges are shifting farther northward. Alpine mammals like pikas are being forced farther upslope to escape higher temperatures."

"I was thrilled he had heard of our research," relates Beissinger. "He even knew...