Along the Appalachian horizon, a burning sun illuminates distant hills. As it slowly descends out of sight, dazzling layers of red, orange, and yellow drift across cloudy skies. Blankets of mist gather and disperse as the mountains draw one last breath of sunlight. Shades of blue, violet, and deep indigo close in from behind like a cosmic eyelid.
From atop Clingmans Dome, sunset is an event that truly rivals the greatest of natural phenomena. Indeed, the sweeping views offered at the summit are the epitome of ancient Appalachia. But the future of these vistas is uncertain.
At one time, deep within our past, the native Americans considered this a sacred place. Referred to by the Cherokee as "Shaconage," meaning "land of the blue smoke," the Great Smoky Mountains once served as a mystic refuge from European settlement for these native peoples. Today, these mountains act as a critical haven of biodiversity. Indeed, since 1998, over 900 species new to science have been discovered in the park. However, in recent decades, air quality issues have plagued the park's vitality, creating both aesthetic and ecosystem concerns.
As early as the 1940s, air pollution in the Smokies gained momentum as numerous power plants and factories introduced excessive pollutants into the atmosphere. So, the pollution is predominantly human-induced, or anthropogenic, originating from industries outside the park's borders. Prevailing winds transport these harmful pollutants—such as nitrogen, sulfur, and other fine particles—toward the Smokies from larger urban areas. Ultimately, large portions of these pollutants become trapped in the mountainous terrain of the Smokies, with high elevations acting as barriers to their passage.
Joshua Fu, an associate professor of civil and environmental engineering at the University of Tennessee, has studied these dynamics in depth. "The pollutants are transported from numerous places, which can vary based on season," he explains. It's not uncommon for these particles to travel from nearby urban areas, such as Atlanta, or as far away as Ohio.
Moreover, development in Knoxville and in Sevier County has lurched outward in all directions, creating a massive scene of urban sprawl right in the Smokies' backyard. Fu stresses the importance of recognizing this, and the fact that no meteorology or atmospheric studies program exists in the area to study these growing problems. No doubt, as populations in areas surrounding the park grow, pollutants such as automobile exhaust will continue to increase. And that's not counting automobiles inside the park. The annual number of auto-tourists visiting the Smokies often tops 9 million, inviting an influx of harmful vehicle emissions in for the proverbial cup of tea.
Taken together, this mixture of pollutants has drastically lowered visibility over the years, making air-quality issues hard to ignore. Vistas such as Clingmans Dome once provided views of up to 100 miles. In recent decades, average views have been reduced to as little as 14 miles, at times reaching lows of nine or 10.
Additionally, the excess nitrogen oxides and sulfur dioxides mix with water in the atmosphere to create acid deposition, otherwise known as acid rain. High elevations in the Smokies receive copious amounts of this dangerous precipitation, jeopardizing mountain streams and soils by increasing acid levels. Numerous species of plants, trees, fish, and amphibians have exhibited extreme sensitivities to even the slightest changes in acidity.
Making matters worse for life in the park are ground-level ozone issues. Similar in origin to acid deposition, ground-level ozone originates from factories, power plants, and vehicle emissions in the form of nitrogen oxides. Upon entering the atmosphere, these chemicals react with organic compounds with the aid of sunlight and are the preeminent building blocks of smog. Research within the park has demonstrated significant ozone damage to numerous species of plants and trees, especially at higher elevations. Moreover, excessive ozone exposure can lead to lung and respiratory issues for humans.
The good news? Since the 1970s, the Tennessee Valley Authority has spent over $5 billion in reducing air pollutants and curbing emissions at its 11 coal-fired power plants. On average, visibility has increased to roughly 25 miles, and was even reported at 40 miles earlier this year at Look Rock observation tower. Levels of nitrogen oxide and sulfur dioxide have been reduced drastically; in some areas, up to 90 percent reduction has been achieved. Moreover, as part of their agreement with the Environmental Protection Agency, TVA will continue their efforts to reduce emissions with over $2 billion set aside in additional funding for the next several years.
Steve Mueller, an air quality and atmospheric scientist with TVA, emphasizes the complexity of these plans. Not only do regulations put forth by the EPA have to be considered, state regulations, budgeting, projected future electricity demands, and also "special haze rules" for national parks all must be kept in mind when forming these long-term objectives. Not to mention the engineering feats that must be accomplished in modifying existing facilities to remove harmful pollutants such as nitrogen oxides.
Nonetheless, growing public concern and regulations to improve air conditions are forcing large utilities like TVA to remediate these environmental damages. "By 2064, these areas must achieve air quality conditions that are naturally occurring, without pollution," Mueller says. While this may seem improbable, Fu believes it's in the realm of possibility. "Data speaks, and the conditions continue to improve," he says.
Fortunately, there's another reason for hope on the horizon: moving away from coal.
"The worst-case scenario is business as usual and continuing to use coal as our primary fuel," Fu warns. But renewable energy resources have the potential to turn the pollution problem on its head. "You use wind and solar power to replace coal, and your emissions are minimized."
Even more encouraging, Fu believes this transition could be a swift process. "Coal isn't cheap. And the switch to sources such as natural gas has already begun taking place in various power plants," Fu says.
In theory, this does sound encouraging. But natural gas is only considered "clean" because it emits half the carbon dioxide as coal. Indeed, it is still a fossil fuel and certainly not as clean as wind or solar power. Yet a natural gas revolution is well underway, and hydraulic fracturing, or "fracking," is the front-runner.
A method of extracting natural gas from deep beneath the Earth's surface, fracking has been shown to release significant amounts of methane into the atmosphere. While methane's lifespan in the atmosphere is brief compared to that of carbon dioxide, it reigns superior at trapping solar radiation. In fact, estimates generated by the EPA suggest it could trap up to 20 times the amount of radiation trapped by carbon dioxide in a 100-year time span. This source of energy—although shrouded with controversy—has secured momentous support in the energy industry.
Meanwhile, back in the Smokies, there is much work to be done. Despite efforts to reduce emissions, ground-level ozone pollution continues to persist in the park, which is still in ozone non-attainment by EPA standards, meaning it still exceeds maximum levels. Furthermore, simulations by Fu and his research team predict higher levels of methane in the area's near future—hence the concerns surrounding increased reliance on fracking and natural gas. From a broader perspective, the International Energy Agency predicts only minor increases in global renewable energy use over the next several decades—a mere 1-2 percent increase by 2035.
Another uncertainty is how isoprenes—hydrocarbon compounds released naturally by plants—interact with other human-induced emissions. According to Mueller, these natural reactions could potentially be to blame for some of the remaining visibility issues. Describing a recent visit to Look Rock observation tower, he recalled the persistence of the haze across the western portion of the park. Scanning the horizon, its cloud-like presence stood in contrast to the research monitors at the station, which showed the sulfates had all but disappeared.
"So, we're trying to find out how biogenic plant emissions interact with other particles to form the haze aerosols that really are a hallmark in that part of the country. And whether or not there's anything else we can realistically do," Mueller says.
Often overlooked are the resilient inhabitants that have called the Smokies home for millennia, American Indians. "We have to take ownership of what's happening now to our land. Everything around us," says Amy Walker, tribal elder of the Eastern Band of Cherokee Indians. "It's a part of who we are, and we can't get along without it. All native peoples that are still connected to the Earth—that's their understanding, that everything is connected—and that every little detail affects all other beings."