2nd Annual Threatened And Endangered Parks: Natural Darkness And Sounds

Across the Intermountain West, light pollution is significantly altering the dynamics of predator-prey interactions, according to a 2020 study conducted by the University of Michigan. The study --which focused specifically on cougars and their primary prey, mule deer, which are two of the most ecologically important large mammal species in the West -- noted that at certain times and locations, there was “simply too much artificial light and/or human activity for cougars, creating a protective shield for deer.”

As one of the first research studies to examine the ecological impacts of light pollution on a large scale, the results underscore what natural darkness advocates have been saying for years. 

“The Intermountain West is the fastest-growing region of the U.S., and we anticipate that night light levels will dramatically increase in magnitude,” said Neil Carter, a senior author of the study, in a prepared statement. “These elevated levels of night light are likely to fundamentally alter a predator-prey system of ecological and management significance—both species are hunted extensively in this region and are economically and culturally important.” Supporters of the research included the National Park Service and Grand Canyon, Zion, and Capitol Reef national parks in particular, among others.

As the human population grows and development along with it, Earth is growing brighter at a rate of more than 2 percent each year, according to recent research. Although many national parks remain sanctuaries for natural darkness and sound, the encroachment of light and noise pollution threatens to disrupt both the visitor experience and ecological conditions for people and wildlife that rely on natural light-dark cycles, as well as natural quiet.

According to the 2016 World Atlas of Artificial Night Sky Brightness, 80 percent of the world’s population and 99 percent of residents of United States and Europe live under light-polluted night skies. Artificial light is disorienting to nocturnal and crepuscular wildlife and can disrupt circadian rhythms for both humans and other animals. It inhibits the ability of both amateur and professional astronomers and astrophotographers to do their work and the sense of awe that park visitors often feel when seeing a truly dark sky.

Although it’s hard to imagine the night sky at, say, Yellowstone becoming overly light-polluted anytime soon, light pollution is a noticeable factor at many national parks, especially those near popular gateway towns or urban areas, such as Great Smoky Mountains National Park, Muir Woods National Monument, and Acadia National Park. Even remote Theodore Roosevelt National Park in western North Dakota has suffered from light pollution from nearby oil and gas fields, whose nighttime glow is as visible on satellite maps as major cities like Chicago or Atlanta.

“About four years ago I was fortunate enough to go to Glacier National Park,” says Chris Kagy, an astronomer, astrophotographer, and president of the Northern Virginia Astronomy Club, which regularly holds astronomy nights and festivals in Shenandoah National Park and elsewhere. “I remember waking up on one of the first nights there and looking out the window, and the stars were just everywhere. They were like huge light bulbs, instead of these little pin-pricks in a gray piece of paper [like in urban areas].

"A real piece of the human experience is recognizing your place in the universe and recognizing that things are bigger than you. It’s hard to develop an appreciation and awareness of that in a heavily light-polluted area.”

Noise pollution is also a growing problem worldwide, with similarly disruptive and stress-inducing impacts on humans and animals. In addition to the expected cacophony related to human development, even melting glacial ice due to climate change is raising decibels in the ocean in ways that can impact marine animals. According to a 2010 study, U.S. road traffic has outpaced population growth since 1970 by a factor of ten, and the number of domestic flights more than tripled in the prior three decades. Not surprisingly, the national parks have long been plagued by human-caused noise, whether from car traffic, air tours over places like the Grand Canyon and Great Smokies, military training flights, and other sources.

“At Shenandoah, from our perspective it’s still a pretty dark sky,” Kagy says, “but even there, people are commenting that the light dome is approaching [primarily from the Washington, D.C., metro area] and it’s not as dark as it used to be.”

Potential solutions to the chronic problems of light and noise pollution, scientists and park advocates say, include more research, policy changes that recognize natural darkness and quiet as important natural resources, increased interpretation, night-sky-friendly lighting (such as fixtures that point light downward), and third-party recognition of dark places. The National Park Service has long maintained a Natural Sounds and Night Skies Division, which funds research and conducts outreach, and the International Dark-Sky Association recognizes dark parks, communities, and other places as part of its International Dark Sky Places program. In December, Voyageurs National Park became the latest national park unit to be designated as a Dark Sky Park, joining more than two dozen other U.S. national park units on the IDA’s list.

Still, the world isn’t getting demonstrably darker or quieter anytime soon, and more needs to be done to protect the national parks from these chronic and growing problems. Kevin Poe, a park ranger at Bryce Canyon and a longtime natural-darkness advocate, wants to see more widespread outreach within the National Park System, including more interpretive materials about natural darkness and light pollution and more dynamic speakers to engage the public on these issues. 

“It’s great to have these designations, but if you don’t have a means for your visiting public to support them, if you don’t make them part of the experience, it’s not intrinsic,” Poe says. “You wouldn’t have people go to the Grand Canyon and not have an interpretive wayside there. We interpret everything else under the sun. How about the entire universe when the sun is on the other side of the planet?”

Poe does see an increase in the number of people asking for night-sky programming.

“Park visitors have come to expect it, ask for it, embrace it,” he says. “The most common question we get is still ‘where is the bathroom?’ But the second most common question now is ‘Do you do astronomy?’”