USA On Monday night, thousands of people in Gatlinburg and Pigeon Forge, Tenn., were forced to evacuate as a raging wildfire exploded on nearby Chimney Tops mountain and spread into the towns. Its the most recent incident in a weeks-long string of wildfires throughout the Southeastern U.S., and perhaps a sign of whats to come in a steadily warming region.
I think its pretty clear that one of the driving factors of these fires is the pretty intense drought conditions right now in the Southeastern U.S., said Jeff Prestemon, a research forester with the U.S. Forest Service based in North Carolina.
In recent weeks, the Southeast has seen some of its driest conditions in the past decade. Across the region, some research stations went record-breaking periods without rain during the past few months, according to Charles Konrad, director of the Southeast Regional Climate Center, based at the University of North Carolina Chapel Hill.
Its been incredibly dry, and that dryness unfortunately has occurred over the period in which the leaves turn and they fall off the trees, Konrad said. So of course youve got all the leaf litter on the ground.
These conditions helped prime the region for an unusually intense fire season. So far, around 100,000 acres have burned from Alabama to states as far north as Virginia and Kentucky. Whats less clear-cut is the reason for these unusually dry conditions in the first place.
There is not a smoking gun, Konrad said.
Currently, were in the midst of a mild La Niña event, a phenomenon in which an influx of cool water in the Pacific causes global changes in weather patterns, including across the United States. But while La Niñas are often associated with higher temperatures and lower precipitation in the southern U.S., Konrad noted that these effects tend to be most pronounced in the winter, rather than the fall. Also, this years effect has been notably weak, meaning the phenomenon likely has not had a significant effect on the regions fire season.
The relentless progression of climate change, on the other hand, has likely contributed to a pattern of warming temperatures in the Southeast in recent years and this seasons conditions are absolutely no exception, according to Konrad.
In the areas experiencing the drought, the temperatures have been well above normal, he said, adding that high temperatures can also lead to more water evaporation from plants and soil, making conditions even drier.
That said, Prestemon cautioned, its difficult to attribute any isolated event like a single drought or wildfire solely to climate change. Weather events and natural disasters are generally the combination of a complex set of factors, which may include long-term patterns of climate change, but also chance and natural variability in climate and weather systems.
Even so, the ongoing events in the Southeast may provide some insight into the regions future.
Its pretty clear that over time, temperatures [are rising] in the region and are expected to continue to rise as greenhouse gases accumulate, Prestemon said. Whats less clear is how precipitation patterns will change due to climate change.
According to Konrad, many experts expect that variability in precipitation will increase in the future. The amount of total rain the region sees on an annual basis might not change much, but the dry and wet periods throughout the year may become more intense, leader to greater likelihoods of both floods and droughts at different times.
This means that dry periods when they do happen may be even more intense as temperatures continue to climb into the future. And when those conditions occur, they could come with a greater likelihood of the kinds of intense and widespread wildfires that have plagued the Southeast this fall.
Prestemon and a group of colleagues published a set of projections earlier this year, accounting for predicted changes in both the climate and human populations, suggesting that the total area burned by wildfires in the Southeastern U.S. will slightly increase by the year 2060 compared to today.
Prestemon also added that, regardless of the way wildfire patterns change in the future, human populations will almost certainly continue to increase, meaning that there will be more and more people exposed to the fires that occur.
For now, welcome downpours on Monday night and Tuesday helped break the dry streak in parts of the Southeast, including the Gatlinburg area, and helped suppress some of the fires. However, firefighters are still working to contain blazes throughout the region, and experts expect that overall drought conditions will continue to persist or even expand in the next couple of months.