Increased Nashville temperatures and rainfall in August are signs of climate change, experts say


Nashville skyline. (Photo by Aubrey Salm)

Story by Maddy Williams | Contributing Writer

Nashville Augusts are gradually getting warmer, causing an increase of 2.3 degrees since 1970 and the average temperature sitting at 80, which is 0.3 degrees above average, according to the Applied Climate Information System.

The temperatures aren’t the only thing changing, with precipitation reaching 3.99 inches, which was 105% of the normal amount of precipitation from 1991-2020, according to the Applied Climate Information System.

“This is a long-term trend in Tennessee and across the U.S,” Peter Girard, Director of Communications for Climate Central said. “Nashville’s average summer temperatures have warmed almost three degrees since the 1970s, with 26 more above-normal days than fifty years ago.”

The likelihood of temperatures hitting new highs will increase as the planet keeps warming, Girard said.

“Communities around the U.S. are facing more intense rain as the climate warms, even in relatively dry areas, which means higher risks of flooding,” Girard said. 

Nashville is not alone in these changes. Temperatures across the U.S. are rising, creating more rain, Girard said. Girard also said that the atmosphere can hold 4% more moisture for every degree of warming, and since temperatures keep rising, rain is increasing.

“As our temperatures in the southeast continue to increase, we can say that increased rainfall has the fingerprint of climate change,” said Alisa Hass, a geosciences professor at Middle Tennessee State University.

Excessive rainfall each year can be an outlier of climate change, Hass said. With warmer air holding more water, more rain is produced as a result.

“Nashville is one of the areas where thunderstorm potential in the summer has increased in the past forty years, and where rainfall intensity has increased by more than 10% since the 1970s,” Girard said. “Downfalls are becoming more common, and they’re delivering more water, which means more drainage is needed to protect residents from flooding.”

Low-income neighborhoods are put at risk under these conditions, Girard said.

Hass also mentioned that “cooling centers, free air conditioning rental programs, and ensuring there is enough power in these neighborhoods so there aren’t blackouts or rolling brownouts” can give low-income areas the help they need.

Nashville is an urban heat island, meaning there’s excessive concrete and little vegetation, Hass said.

These areas “are often 10-20 degrees warmer than nearby rural areas,” Hass said. “The closer you are to the inner core, where buildings are more packed together and there is very little green space, the warmer it will be.”

Hass recommended that in order to solve this issue, planting more trees, using permeable pavers and installing green roofs can help mitigate this issue. 

“City residents, especially in neighborhoods with less green space and more paved surfaces, experience even higher summer temperatures than their neighbors,” Girard said. “Nashville’s urban heat island effect raises temperatures by nearly six degrees above what would be expected without the influence of city development.”

Cities are hit much harder by these increased temperatures, but rural areas are also affected due to the hotter temperatures putting stress on trees.

“Warmer temperatures contribute to stress on trees, which can make fall foliage even more unpredictable,” Girard said. “Over time some species of trees may shift toward cooler climates, so their fall colors will shift with them, away from warmer places.”

Leaf-peeping is when people travel to see fall foliage. Leaf-peeping is a money-making industry for the Smokies and the Cumberland Plateau. Hotter temperatures can alter Tennessee forests and leaf colors.

“And when summer heat continues into the fall, leaves may turn later, potentially shortening the season and squeezing local economies that rely on leaf-peeping tourists,” Girard said.

Girard said that leaves turning later in the season and less vibrant colors can affect tourism and Tennessee economies.

“Interestingly, there is a possibility that the color palate of leaves will change.  Warmer weather leads to more orange and yellow leaves, rather than red,” Hass said.

Cool nighttime temperatures ensure that the sugars that leaves produce in photosynthesis help create more vibrant colors in the fall. With warmer nights, leaves can become less vibrant, Hass said.

MTSU, other universities, non-profits and the Nashville mayor’s office were given funding from the National Oceanic and Atmospheric Administration in August to heat map Nashville to track which areas are most exposed to high temperatures in Nashville, Hass said. 

Hass said they collected GPS, temperature and humidity data by providing sensors to local residents and having them drive through Nashville on a warm summer day. They helped them discover where the urban heat index and resident vulnerability are highest. 

Heat maps can help protect neighborhoods from exposure to extreme heat. By collecting this data, neighborhoods most impacted by these changing temperatures can get the aid they need.

To contact News Editor Matthew Giffin and Assistant News Editor Kailee Shores, email newseditor@mtsusidelines.com.

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