The Air We Breathe

The Appalachian Mountains, with dense forest cover, make western North Carolina a unique laboratory from which to monitor air quality and atmospheric conditions and their impact on ecosystems.

The Blue Ridge Mountains and the Great Smoky Mountains are unique in the world.

It’s not just because of the beauty of the mountain region. If you want easy proof of that, just look at photos. Or look at attendance figures for Great Smoky Mountains National Park. More than nine million people visit the park each year, making it the most visited national park in the system.

It’s also not just because of the region’s incredible biodiversity: more than 700 varieties of trees and plants live in the region. Scientists call the entire area a temperate rainforest.

It’s also not because of the age of the mountains, which are roughly 400 million years old. They are small compared to the Rocky Mountains of the Western U.S., but that is because the mountain chain, which stretches along the nation’s east coast, is older and erosion has taken its toll.

But in addition to all of those unique qualities, scientists have recently discovered that, at a time when the rest of the planet is getting hotter, global warming hasn’t really arrived in the Blue Ridge and the Great Smokey Mountains, yet.

“This is an unusual area because the Southern Appalachians is one of the few areas of the world that has experienced very little warming yet,” explains Dr. Howard Neufeld, Professor of Ecosystem Ecology at Appalachian State University. “If you go to Vermont or New Jersey you find the temperature has gone up one or two degrees but it hasn’t here yet.”

That’s right, the region is not getting warmer, so far. But scientists expect that to change.

While the Intergovernmental Panel on Climate Change reports the earth has warmed roughly 1.5 degrees from 1880 to 2012, the temperature of the Southern Appalachians has stayed essentially the same. Scientists believe elevation, geography, air currents and the region’s large number of trees all combine to affect the region’s climate and hold off the rise in temperature. But more data is needed to understand the phenomena.

“This provides an opportunity to get baseline data of what the normal climate is, so when the area does begin to warm, researchers can point to what the area’s climate was like in the early part of the 21st century and then follow it along,” adds Neufeld.

To gather that baseline data, researchers built a 110-foot tower atop a mountain near Appalachian State University's campus in Boone. The multiple instruments at the top of the tower record such things as temperature, wind speed, air particles, carbon dioxide and ozone. 

While some of the sensors record data, other instruments collect air samples, which are piped into a small, technology-packed building at the base of the tower. The data that's collected is used in local research. But it is also sent to NASA and the National Oceanic and Atmospheric Administration (NOAA) as part of a nationwide research project to study weather systems and climate change.

“The collective purpose of this set of instruments is to monitor the effect of aerosols, haze, dust and smoke on the solar radiation budget, which in turn affects climate,” explains Jim Sherman, professor of Physics and Astronomy at Appalachian State University. The solar radiation budget is the amount of sunlight that actually reaches the ground and is not absorbed or reflected by the atmosphere or man-made particles in the air.

Ironically, the questions scientists are trying to answer center around how the Blue Ridge Mountains got their name. Scientists want to find out if the blue haze that is so well known for enveloping the mountains is affecting the climate and helping to hold global warming at bay. It turns out much of that haze is natural.

Trees, especially conifers, emit what are called volatile organic compounds. The region’s warm temperatures increase the amount of those compounds that are released. Those compounds react with the atmosphere and form particles, which block sunlight. Scientists also want to know the effects on the climate when man-made pollution mixes with those naturally occurring compounds.

“One focus of our research is to count the particles in the atmosphere and this group of instruments does that,” explains Sherman, pointing out one of the machines. “It uses a laser to count the particles coming in through a flow stream, this measures the amount of light that gets absorbed by the aerosols, and these measure the amount of light that gets scattered by the aerosols.”

“And this device shows how dynamic the atmosphere really is,” Professor Neufeld adds. “This device gets a carbon dioxide reading from the tower outside and right now it says 390 ppm."

When asked if that number should be higher in the summer time, Neufeld agreed it would seem that way, but he then explained why it doesn’t happen.

“It’s summer, it’s all green outside and the plants are photosynthesizing, which takes CO2 out of the atmosphere which then lowers the concentration.”

He went on to explain that if we were to come back to the monitor at night, the CO2 levels are higher because the plants are not photosynthesizing and they are also respiring, which adds carbon dioxide to the atmosphere. That’s why the system monitors the levels 24 hours a day, seven days per week.

Scientists say long term data collection is the key to answering the area’s climate change questions, because it’s the only way trends can be spotted.

In addition to the long term monitoring planned at the mountain-top research station, researchers are also looking over data collected at the weather station run by the United States Forest Service (USFS) at the Bent Creek Experimental Forest near Asheville.

The facility is one of the region’s oldest weather stations. Weather data has been collected there since 1945. Climate change wasn’t a concern back then. Forest researchers collected information on rainfall, temperature, and soil moisture content to study tree growth. Now, all of that information is finding a new purpose.

“We can make correlations between what we know about the distribution of seasonal rainfall across this diverse topography in the past and see how that correlates with how trees grew in the past,” says Henry McNab, Research Forester with the USFS. “And then we can use modeling to see how they will grow in the future, because climate change will definitely have an affect on how trees grow across this landscape.”

“People need to care about this because we are not only dealing with climate change but about air quality. The quality of the air is directly related to the quality of your health. Everybody needs to breath and you want clean air,” says Neufeld, as he looks out the window and up to the top of the research tower. “But we also need to know what factors give rise to global warming and without a baseline we can’t say human activity is causing things to change.”

The bottom line is if scientists don’t know what conditions were like in the past and they only look at the present, nobody will ever know how things have changed.


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