Climate Extremes Threaten the Smokies

Knoxville, Tenn.-- The Great Smoky Mountains are looking at a warmer and wetter future. People see the Smokies as an untouched piece of land, but the mountains are seeing negative effects from climate change. The changing climate is affecting soil, trees, and wildlife from the bottom of the mountains to the top.  As temperatures continue to rise the Smokies will continue to be affected, and the park as we know it will continue to change and transform.

“I look back over the different years and I see we are having wetter records, looking at the climate trends going back into the 1800s we are warmer and wetter,” says Jim Renfro, air resource specialist for the Great Smoky Mountains National Park. “Overall when you look year to year, we are warmer, and we are projected to keep getting warmer. But the models are unsure of if we are going to get wetter or if we are going to get drier in the future.”

Although the models are unable to predict such outcomes, Renfro is able to analyze the past. “Overall the park has been wetter over the past 30 years. I think this year, the extremes are starting to happen more.”

The park is coming out of a three-month long period of moderate drought spanning August through October, however the second half of October the park saw a large rainfall, causing October to be one of the wettest months on record. “The prediction is that we will have these longer periods of drought, and then when it rains it really rains so we have these extremes in both ways,” Renfro says.

Ed Perfect, professor in the department of Earth and Planetary Science at the University of Tennessee, agrees that extremes will play a large role in the environment of the Smokies. “On average we will have more rainfall and higher temperatures, the extremes mean we will also get more droughts.”

“We can expect more [droughts] because climate change predictions for the next 50 to 75 years are all indicating an increase in temperature in this area potentially up to 6 degrees in temperature,” Perfect explains.

“The predictions are that we will get a slight increase in rainfall, because our climate is going to move from what it is now to what it is in Mississippi,” Perfect says. “It will be warmer and wetter, but there will be increased extreme events meaning increased rainfall events and increased droughts as well.”

When looking at extremes in the environment, it is important to take into account that averages can be misleading. “Well we had 80 inches of rain again, but we had some months that were wettest, some months that were driest.” Renfro gives as an example. “It’s just averages over a couple of months, those are two totally different things, but the average number is the same.”

These averages are important because they can give misleading statistics of the rainfall the mountains get. The Smokies don’t need small periods of a lot of rainfall, instead they need rainfall that will come to the mountains year-round. It is important that the mountains get a steady amount of rainfall, because moisture is the key for the Smokies.  “So clouds, the namesake of the park, the smoky mountains, the mist like clouds that come up after a rain, that’s moisture, that’s humidity coming from the plants, evaporating from the leaves,” Renfro says.

“The predictions made in the national assessment report that was released last year says that there will be massive changes to ecosystems.” Perfect says.

Perfect is interested in how the mountains might manifest drought. “With regard to the Smokies,” he said, “droughts are even more accentuated due to the topography. We have fairly steep slopes and shallow soils. You will get a more pronounced drought in these conditions as opposed to places with deep soils.”

Warming affects not only the soils but the skies, and the wildlife that resides in higher elevations. “If climate change warms in the future, and if we lose our clouds and have more heat, we could lose ecosystems in the higher elevations like our spruce fir ecosystem,” Renfro says. 

“If we are warmer and drier due to drought, and the clouds are less and it heats up the higher elevation, then we know the lower elevations are seeing nonnative animals and vegetation coming in because it’s warming,” Renfro says. “If we warm, plants will have to shift up in elevation to survive. If we have drought and lose moisture and clouds, the shading the cooling, even the cloud water drips almost as much rainfall in a year from just cloud water dripping to the leaves, then we will see a complete shift.”

 “As certain trees die out because of drought stress, certain vegetation dies out then more species, like invasive species come and replace those species that are not able to adapt to the changing conditions.” Perfect says.

The wetness and dryness also affect the acorns in the park, a food source for much of the parks wildlife. “If it’s a wet year it tends to be a better acorn crop the next year, so in those drought periods the food supply, and it is cyclical, some years are better than others and it has to do with weather and moisture,”  Renfro says. When the mountains see a wet year there are acorns everywhere, so the bears and turkeys are on the roadsides eating their natural food, the acorns. When years are dry these animals will come out of the park looking for food. This is what leads black bears to dig through people's garbage and what puts them in danger of being poached or killed.

Rivers and streams can also see the effects of extreme droughts as they occur. “In the national park when things get really dry the streams get low,” Renfro says. “The lower it gets the lower the oxygen levels go, and more fish compete for habitats and the habitats get smaller. And you can have a die back of the fish species you are trying to protect like Brooke trout or bass.”

 Of course, extreme droughts can also have broader effects. “I think about our soils too how dry the soils can get and the trees,” Renfro says. “They are stressed, I think of fire hazard. That's what happened in 2016 with the Sevier County Gatlinburg fires.”

With droughts in mind Perfect also sees fire as a looming threat. “There will be increase wildfire possibilities in the area.”

Renfro’s best advice for how people can help avoid these extremes is to stay informed. “If people really care about what's going on, they should consider being an advocate, it’s always good to share what you have done. Let people know that you care, and that it matters.” Understanding the issue can then perhaps change behaviors such as a reduction in use of water and other resources.

But we can only do so much as individuals. “It’s not something that is easily controlled by humans,” says Perfect. The best movement to fewer extreme environmental events, he says, is for a global push in legislation to support worldwide global changes.