Looking Back in Time at Utah's Climate

A decade of collecting thousands of tree ring samples from throughout the western United States is resulting in new data and producing a new way of reconstructing Utah’s past climate change patterns.

Utah State University climatologist Simon Wang and U.S. Forest Service Rocky Mountain Research Station researcher Justin DeRose recently published the results of their study in the Journal of Hydrometeorology. In addition to his work with the Utah Climate Center, Wang is a faculty member in the Plants, Soils and Climate Department in USU’s College of Agriculture.

Wang believes the large number of samples and close spacing between sites provides a much finer resolution than any known conventional tree ring records.

“The new tree ring dataset essentially provides a telescope for us to look into Utah’s past climate with great detail,” said Wang.

This information helps climatologists and policy makers make more informed decisions regarding Utah’s changing climate.

“For example, we know that 150 years ago the phenomenon of El Niño affected the entire state of Utah, rather than the weak opposite effect divided between northern and southern Utah we see today,” said Wang.

Derose explained that tree rings give important climate signals to be discovered by scientists.

“As a tree grows, it produces a ring for each year that it ages,” said DeRose. “The thickness of each ring normally reflects fluctuations [of] climate conditions with a harsh climate resulting in narrower rings and a favorable climate producing wider rings as a tree grows faster.”

Derose believes that the information gathered from the data can aid dendrochronologists (tree ring scientists) in future site selection.

“One important finding of the current study is that forest-grown trees record the same signals that are found on highly-sensitive sites, meaning that climate signals can be found almost everywhere,” said Derose.

The team hopes that by extending the dataset to the rest of the Interior West and eventually to the West Coast, that it will be possible to map climate drivers such as El Niño over progressively larger areas and longer time scales. The data is far from finished; many thousands of samples from across the Interior West still need to processed and analyzed. Upon completion, a high-resolution climate data set will be reported and made available.