We know we live on a planet in flux, that human activity has radically altered the Earth, and continues to do so. Yet such changes can seem abstract; forming a clear picture of their scale and sweep can be difficult.
But there’s one technique that brings those changes into focus. Repeat photography sounds simple: Find historic photos, and return to where they were taken to photograph the sites again. It may be straightforward – but as the work of ecologist James Cornett shows, the results can be profound.
“And it was the first time I was ever glad that I was getting older,” Cornett said, “because I had these old photographs and I probably would've thrown them away. But as it turned out, they showed some big changes in a short amount of time. As I get older now, I become a historical figure, or at least my work becomes historical.”
Cornett is the former curator of the Palm Springs Desert Museum. Last year, he published “The California Deserts: Then and Now.” The book features historic and contemporary photos of 64 sites. He’s now expanding the project across the Southwest, including Big Bend National Park.
Cornett’s focus is changing vegetation. For his California book, he’d hoped to use high-quality vintage photos, but that proved difficult: artists like Ansel Adams mostly photographed cliffs and mountains – not desert plants. Cornett found an exception in Stephen Willard, an accomplished early photographer. And he made use of less artful historic images.
That included a 1906 photo of a woman horseback in what’s now Anza-Borrego State Park. She was surrounded by teddy bear chollas – cacti whose tiny thorns give them a deceptively fuzzy appearance.
When Cornett returned, he found a very different scene.
“I went back to that exact same site and instead of a thousand teddy bear chollas in that scene, it was zero, none,” he said. “I mean, nobody can look at that and not say, ‘Gee, something has happened here.’”
The pattern was repeated with two other early 20th-century photos. And, as Cornett noted, his own images proved useful. In 1979, he’d taken a picture after a snowfall in a California desert park. The snow lay gentle on a cholla thicket, which is gone today.
“And so I found four sites where the teddy bear cholla, a very robust, typical Sonoran Desert plant, had vanished,” Cornett said, “not just declining in numbers, but vanished. No indications that disease was a factor – the only reasonable explanation is climate change.”
In another sign of climate-change impacts, the photo captures the park’s last snowfall.
At site after site, Cornett found that perennial shrubs had disappeared, to be replaced by bare ground. And he found that the most dramatic changes have taken place since the 1980s. He suspects desert plants are being squeezed both by hotter and drier conditions, and by intensifying wildfires.
“And so you've got this double whammy going on,” Cornett said. “As Michael Crichton said, ‘Life finds a way.’ But not when you're getting hit from two directions at the same time.”
Big Bend is Cornett’s “next victim,” he said. He’s found abundant archival photos, taken by the park’s first rangers.
Cornett’s work is still underway. But he suspects that, for now, Big Bend desert plants are faring better than those in California.
Historic park service photos are free online. Cornett hopes others will pursue studies like his.
“These repeat photography projects in terms of natural landscapes will be our best window into the impacts of climate change,” he said. “And so these are really exciting times in terms of that technique.”
It’s a technique that reveals stark truths in black and white.
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