With contributions from the University of Wyoming, a new study suggests the world has entered a new age of wildfires – larger, stronger, and more frequent.
Bryan Shuman, a professor in the Department of Geology and Geophysics at the University of Wyoming, is a primary co-author of a recently published paper titled “Rocky Mountain Subalpine Forests Now Burning More Than Any Time in Recent Millennia.” The report was published in Proceedings of the National Academy of Sciences, a prestigious multidisciplinary journal.
Facts and patterns for wildfires are studied in one area: the Rocky Mountain region of southern Wyoming and northern Colorado. The research concludes with a dire prediction for future wildfires in this region and elsewhere.
Philip Higuera, a professor at W.A. Franke College of Forestry and Conservation at the University of Montana, and Ph.D. candidate in paleoecology and forest ecology Kyra Wolf are the paper’s lead authors. Higuera and Wolf analyzed a unique network of fire-history records to understand how current fire activity compared to wildfires of the past.
The paper concludes that the 2020 fire season burning rates in high elevation forests were so high, they are in contention for the highest recorded in the past two thousand years.
By November 2020, wildfires in southern Wyoming and northern Colorado were responsible for 72 percent of the total area burned in high-elevation, subalpine forests since 1984. During 2020, Colorado had experienced three of its largest fires on record.
Between 1984 and 2019, 840,000 acres burned in the Rocky Mountains of northern Colorado and southern Wyoming. According to the study, 660,000 acres burned in 2020 alone.
Approximately 1.1 million acres burned in the past decade in the Colorado-Wyoming study area, even though only 400,000 acres — less than half as much — burned in the previous 25 years.
But it’s not just the severity of these massive Wyoming fires – it’s their frequency.
Over 2,000 years, fires in high-elevation, subalpine forests historically burned, on average, once every 230 years. In the 21st century, those fires now occur, on average, every 117 years.
This is a 22% increase over the historic maximum rate recorded over the last 2,000 years. During what is called the Medieval Climate Anomaly (770-870), Northern Hemisphere temperatures were 0.3 degrees Celsius above the average in the 20th century.
U.W.’s professor Shuman helped develop the scope of the study. In his view, the implications of this research and dire for the forests of Wyoming and Colorado.
“The results indicate that, if fires continue to burn as often as they do now, every forest in the region could be burned by the beginning of the next century,” Shuman explains. “In the past, it would have taken 200 to 300 years, if not longer, for fires to affect that much area.”
Shuman says that trees are turning into dry fuel with drier winters and hotter summers, ready to burn without much spark. This means when the fires start, they burn bigger and longer.
“Then, after the fires, big areas with few live trees mean few seeds to help forests regrow and, even when seeds are plentiful, seedlings can often die from drought and heat,” he continues. “Some forests may never grow back.”
The good news is this research will provide information for fire management crews who will be battling future fires. But the key, according to lead author Philip Higuera, is taking action to reduce human-caused climate change.
“It may sound dire, but it’s critical to remember that we have ample opportunities to limit or reverse climate warming while still working to adapt to the increasing fire activity expected in upcoming decades,” Higuera says.
