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Temperature Research to Aid Climate Studies

Temperature Research to Aid Climate Studies

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Karen King cores a mountain hemlock tree in Lassen National Park in 2022.
Karen King cores a mountain hemlock tree in Lassen National Park in 2022. The assistant professor in the Department of Geography and Sustainability at the University of Tennessee, Knoxville, is expanding her earlier work in the West to create a North American Temperature Atlas. Photo by Meryl Phair

A three-year National Science Foundation (NSF) grant will allow researchers to build a North American Temperature Atlas (NATA) with more than five centuries of data to inform climate studies and guide natural resource managers. 

Assistant Professor Karen King in the UT Department of Geography and Sustainability is the principal investigator for the $230,732 NSF grant.

Karen King uses a drip torch to light a fire during prescribed fire training in 2019 with The Nature Conservancy. “Working as a wildland firefighter, as well as in prescribed fire management, was an opportunity to travel, to see a lot of really diverse and complex forest ecosystems, and to gain a better understanding of some of the impacts changing climate and land use change has on forests,” said King, now an assistant professor in the Department of Geography and Sustainability at the University of Tennessee, Knoxville. “I always tell my students that it was traveling through fire management that I started thinking like a biogeographer.” Photo by The Nature Conservancy

The University of Tennessee, Knoxville, will be collaborating on the NATA with her co-principal investigators from Columbia University, the University of Arizona, the University of Idaho, and Indiana University. The Lamont-Doherty Earth Observatory also is involved. King will have a UT graduate research assistant on the project for two years, and other graduate students will have opportunities to participate in field and lab work for the NATA.  

“This funding will allow me to expand work I’ve already started on in the western part of North America to create a gridded temperature reconstruction that provides coverage for all of North America,” King said. 

Her recently published research from the West showed that the past century has seen more frequent periods of hot drought, a combination of extreme heat and drought conditions.

Analyzing Tree Samples

Many collections already exist of the tree samples they seek. “It is important to me that my team approaches dendrochronological research from a ‘minimizing disturbance’ perspective,” King said.

The researchers will examine a measure called blue intensity, which is closely coupled with seasonal temperature variability when the tree was growing. They target temperature-sensitive species, such a spruce and hemlock in the eastern US.

“We then can use these tree-ring estimates of temperature to look at the relationship between temperature and drought in the modern period and compare it to the past,” King explained.

During field work in 2023, Karen King cuts samples of Engelmann spruce in Utah for a tree-ring record that will provide information going back more than 1000 years. The assistant professor in the Department of Geography and Sustainability at the University of Tennessee, Knoxville, is working on a North American Temperature Atlas. Photo by Grant Harley

“The full NATA dataset will extend back to 1300 CE in many places, but we are aiming for 1500 CE across all grid cells for North America,” she said.

Forest to Lab to Community

The project represents the efforts of many in the tree-ring community, King said. “My goal in leading this effort is to build a dataset from the tree-ring community for the greater community.”

Once the dataset is complete, the researchers will make it available on a digital platform, where others can analyze and interpret it. 

They plan a series of webinars about climate change impacts in North America, for the general public as well as managers of natural resources, including water and forests. 

They also expect to develop several lessons for middle and high school students on climate change through the lens of trees. “These materials will be publicly available for educators, and we hope to get involved with programming in Knox County Schools or other organizations such as Ijams Nature Center,” King said.

To apply for the NSF funding, King worked with the College of Arts and Sciences’ Office of Research and Creative Activity, which recently expanded to support faculty with proposals. “Annie Brown and Jenny Toll were excellent to work with and super helpful,” King said.

By Amy Beth Miller