2016 SIGNIFICANT AREA WILDFIRES
› Chattahoochee National Forest: The Rough Ridge fire, started by lightning in mid-October, burned close to 30,000 acres in the Cohutta Wilderness area of North Georgia.
› Cherokee National Forest: Several fires combined to cover more than 1,000 acres in Polk and Monroe counties in Tennessee during November.
› Hamilton County: Three wildfires along Waldens Ridge burned more than 2,000 combined acres and contributed to a smoke blanket that enveloped Chattanooga on certain November days.
› Dade County, Ga.: The Fox Mountain, Tatum Gulf and Sulfur Springs fires combined to burn more than 4,000 acres.
› Whitfield County, Ga.: The Rocky Face fire covered roughly 600 acres.
› Other: By the middle of November, dozens of fires burned across counties in southeast Tennessee. These were the counties most-affected on Nov. 16:
Bledsoe County: Four fires, 2,047 acres
Hamilton County: Four fires, 1,847 acres
Marion County: Five fires, 1,025 acres
Sequatchie County: Five fires, 1,056 acres
Source: Tennessee Division of Forestry, newspaper archives
WASHINGTON — People have triggered five out of six wildfires in the U.S. over the last two decades, tripling the length of the wildfire season and making it start earlier in the East and last longer in the West, a new study finds.
Even as climate change worsens the nation's fire season — making it longer and easier to burn more acres — researchers said human activities play an even bigger role.
While fire experts have long blamed people more than lightning, the new work details the extent of human-caused ignitions and how they interact with global warming to make matters worse.
Scientists analyzing fire data from 1992 to 2012 found that 84 percent of all U.S. wildfires — but only 44 percent of the total acres burned — were started by people, either by accident or on purpose. And human-caused blazes have more than tripled the length of the wildfire season from 46 days to 154 days, according to a study in Monday's journal Proceedings of the National Academy of Sciences.
"People are moving more and more into natural wild areas and essentially providing ignition for wildfires," said Jennifer Balch, a fire ecologist at the University of Colorado.
Of the more than 1 million human-started fires since 1992, about 29 percent began by trash burning, another 21 percent were arson and 11 percent were from misuse of equipment, Balch said.
Last year's Soberanes fire in California was sparked by an illegal campfire and burned for nearly three months.
One out of every five wildfires occurs on the Fourth of July from fireworks, Balch said.
THE HOTTEST SPOTS
The Southeast is a hot spot for human-triggered wildfires. Kentucky, West Virginia, and Tennessee had fire seasons that lasted more than 200 days, and 99 percent of the wildfires in those states are caused by people.
The region is home to swaths of forests with trees that don't catch fire easily or naturally so people are the main culprits, said study co-author Adam Mahood of the University of Colorado.
In Gatlinburg, 14 people were killed and more than 2,400 homes and businesses destroyed when a wildfire ripped through the resort town on Nov. 28. Two teens have been charged with aggravated arson in the case.
Escaped debris fires are usually the No. 1 source of fire responded to by the Tennessee Division of Forestry. That changed in 2016, when 322 of 538 fires the agency responded to in the Cumberland district suspected to be caused by arson, according to state records.
"Honestly, we don't know why an arsonist sets a fire," Tennessee State Forester Jeter said in December. "Sometimes it's a vendetta against a neighbor."
In other cases, the arsonists start blazes because they think fire will get rid of snakes or other unwanted critters.
The Flipper Bend fire in Hamilton County that grew to more than 1,000 acres in November is suspected to have been started by an arsonist. Other arson-started fires in the area netted quick arrests during the busy wildfire season.
An Alabama man, Matthew Ryan Wallace, 27, of Tuscaloosa, was charged with setting a fire along Standifer Grant Road in Sequatchie County.
In Monroe County, Tenn., Charles Edward Martin, 50, of Madisonville, was arrested and charged with setting a fire along Gamble Road.
The state typically offers a $1,500 reward for information leading to the conviction of an arsonist. That amount was raised to $2,500 during the 2016 wildfire season.
THE CLIMATE CONNECTION
Climate change has lengthened the U.S. fire season by a few weeks, which is dwarfed by what humans do. But the study shows how both human-sparked flames and man-made climate change work together to make America burn more, especially during more frequent dry, hot weather.
"If a campfire grows out of control during a wet, cool period, then it probably isn't going to grow into a large wildfire," said University of Utah fire scientist Philip Dennison, who wasn't part of the study. "Climate change loads the dice toward warmer, drier conditions that make it more likely that a fire will develop from human-caused ignitions."