When Laura Boggess first visited the cliff face in Boone, North Carolina, she admired the colourful rock tripe covering the vertical surface, and the green moss mats perched on top.
The crag was part of a rolling, mountainous landscape, sheer cliffs jutting above an enormous valley filled with trees of varying shades of green. It showcased the pristine, usually inaccessible natural beauty that draws so many climbers to the sport.
But when Boggess returned to the cliff face almost a decade later, in 2022, she found it dramatically changed. Since she first visited the spot, it had spiked in popularity among climbers. The moss mats had been torn down, and the rock tripe scrubbed away.
“I’m not speaking like a scientist here, but the energy of the route felt different, like the area had changed,” says Boggess, a rock climber and assistant professor in biology at Mars Hill University, North Carolina, who is keeping the name of the crag a secret – hoping to protect it from further damage.
Cliffs, largely for accessibility reasons, are among the world’s least-disturbed ecosystems. Their walls can house rich communities of rare plants, lichens, nesting birds and bats. Increasingly, however, a new species has been taking to the cliffs: humans, in their millions. From fewer than 500,000 climbers in the US in the late 1990s, there are now more than 10 million. Worldwide, there are between 40 and 50 million climbers, and enthusiasm for the sport is continuing to grow. For many rock-climbers and boulderers, the chance to connect with nature in pristine, isolated locations is part of the attraction. But the rising popularity of rock climbing has some ecologists concerned.
In the Enciña da Lastra natural park in Spain, the Petrocoptis grandiflora flower is under threat: a subshrub with purple petals, it prefers sparsely vegetated land and a temperate biome, and is considered vulnerable on the IUCN red list.
Martí March-Salas, a postdoctoral researcher in plant evolutionary ecology at Goethe University Frankfurt, says there are only two to three populations of the species left in the area – and increasingly, they were coming into contact with climbers. “Climbers were installing climbing routes very close together that were absolutely damaging one population,” says March-Salas. That damage, he says, made the likelihood of species extinction higher.
Research suggests that cliffs hold at least 35% of native plant species, and provide refuge for a range of rock-dwelling animals. The physical act of climbing has been shown to affect animal and plant species, as has the use of chalk in the sport. Climbers use chalk to improve friction between their hands and the rock, but the magnesium content changes the pH of the surface, affecting the ability of plants to grow. In many areas, there is also little regulation of where climbing routes can be set.
“Nowadays if you’re a climber and you have the knowledge to establish a climbing route, you can go to almost any place and install one,” says March-Salas, who used to be a climber. He recently wrote a letter in Conservation Biology calling for better regulation of climbing routes to protect cliff ecosystems.
Though he wants more regulation, March-Salas isn’t trying to stop people from climbing because, he says, the sport provides physical and mental health benefits. He believes better communication would help to protect cliff ecosystems. “I think it’s really important to put some signs close to the cliffs for climbers to understand what is there and what they can admire in the place that they’re climbing,” he says.
Boggess agrees that climbers need to be part of the solution. “We’re not going to be able to discourage people from climbing – you can’t put the toothpaste back in the tube,” she says.
The Carolina Climbers Coalition bought some land in Rumbling Bald, North Carolina, to stop development on it and protect the endangered small whorled pogonia. Climbers helped gather data by doing species counts and monitoring every year. Now, the perennial orchid is stable in the area, Boggess says.
“Many of the conservation biologists and land managers are pretty overtaxed when it comes to monitoring, and climbers go to a certain area over and over again,” she says. “Climbers visit through all the seasons, through all times of year, and you can develop this really special relationship with your local crag. That’s a really deep and beautiful thing that many people don’t have the opportunity to experience.”
Rob Roy Ramey’s first job as a biologist was as a climber abseiling into peregrine falcon nests in the 1980s when the insecticide DDT threatened the birds. In the decades since, he has gained a PhD in ecology and has worked with nesting raptors across many parts of the US. Part of his expertise is in finding nesting sites and determining which are being used – knowing where birds are nesting allows parks to open and close routes at the right times, to protect them from climbers.
This year, to help safeguard a successful golden eagle nest in Boulder Canyon, Colorado, Ramey helped remove traverse ropes over the Colorado River in collaboration with the US Forest Service. “The river is too high and you’ll drown if you try to cross it,” he says. “So that eliminated the problem.”
While aware of the impact of rock climbing on cliff ecosystems, Ramey thinks the problem is overstated and says there are far bigger issues for birds – including lead poisoning from bullets they ingest from their prey, and avian influenza. “The younger cadre of sport climbers, I think, should just be more mindful of cleaning cliffs and cutting trees,” he says.
When they are armed with knowledge, climbers can be a potent self-regulating force. Ramey recalls seeing one climber violate a closure, and how the man in question was shamed on social media – which, Ramey says, helped avoid problems for many years. “Climbers have to be our own sort of police force in some ways,” he says.
Indra deCastro-Arrazola, a climber with a PhD in biology who has studied cliff ecosystems, agrees that the ecological impact of rock climbing might be exaggerated. “We’re trying to find the ants in the room when there is an elephant in the room,” he says. He recognises his involvement in the sport and his job as a mountain guide might present conflicts of interest, but says bigger threats are habitat loss and pollution.
For species that are highly endangered, however, even small interventions can push them towards the brink. March-Salas refers back to species such as the Petrocoptis grandiflora flower in Spain. “Climbers didn’t know that this plant was under protection and that it was very vulnerable to disturbance,” he says.
Because so many rock faces are essentially unregulated – with climbers able to open routes wherever they choose – other rare or endangered species could be affected too. March-Salas wants more research on cliff ecosystems, and he and DeCastro-Arrazola called for environmental impact assessments to better determine which cliffs can be climbed, and which should be left alone.
“The problem is the lack of knowledge,” he says. “As climbers, we are blind in what we are affecting.”
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