Bryan Oller / AP
A utilities worker walks through homes destroyed by the Waldo Canyon Fire in the Mountain Shadows neighborhood of Colorado Springs, Colo., on Monday. So far, the blaze, now 45 percent contained, has damaged or destroyed nearly 350 homes.
As firefighters continue fighting the devastating Waldo Canyon blaze in Colorado, FBI agents are investigating what could have triggered the blaze, which forced more than 30,000 people from their homes.
Elsewhere in the state, lightning was to blame. But more typically, humans start wildfires. In 2011, humans started six times more fires than did lightning, scorching 5.36 million acres, according to government statistics.
Cigarette butts tossed in the dry grass and improperly extinguished campfires have started fires. But railroads, climate change and gun ranges have also noted as causes for wildfires.
In Utah this summer, fire officials said shooters started 20 wildfires, according to the Salt Lake Tribune. The Christian Science Monitor reported that the Dump fire 40 miles south of Salt Lake City started when a bullet hit a rock, emitting a spark. Strong winds and dry vegetation allowed the fire to spread, resulting in 2,300 evacuation notices.
Firefighters came face-to-face with flames that shot 100 feet into the air as a wall of fire barreled down the hills in Colorado Springs. NBC's Miguel Almaguer reports.
“Now is not a good time to take your gun outside and start shooting in cheat grass that’s tinder dry,” Utah Gov. Gary Herbert said, according to the Christian Science Monitor.
Target shooters also triggered a fire near Saratoga Springs that burned 5,600 acres, the Monitor reported.
Railway saws have also stirred controversy. In 2008, Union Pacific Railroad paid the U.S. government $102 million to settle damage from a 2000 wildfire in Northern California that burned 52,000 acres. Union Pacific maintenance workers had allegedly not used spark shields to prevent hot pieces of metal from flying into the grass.
In 2009, NBC affiliate KING5 found that 234 fires in Washington state were attributed to railroads. Forty-two of those fires scorched two or more acres.
At the time of the report, Burlington Northern Santa Fe spokesman Gus Melonas said that railway saws keep tracks smooth and safe, adding that they’re equipped with water tankers to prevent fires.
On Tuesday, six of the air force C-130's were back in the air after being grounded following Sunday's fatal air tanker crash. NBC's Miguel Almaguer reports.
"We invest everyday through technology, through training, through equipment to make sure we aren't starting fires," Melones told KING5.
Climate change may also contribute to wildfires, according to the Christian Science Monitor.
The Monitor compared this summer’s hot, dry weather to 1910, when a unseasonably warm spring turned into a scorcher of a fire season. In that summer, known now as the Big Burn, fires destroyed three million acres of forest in Montana, Idaho and eastern Washington.
Climate change may explain the modern fires that burn tens of thousands of acres; after all, warmer summers dry up vegetation, creating fuel for spreading fires.
Researchers examined tree rings and 34 years of western U.S. wildfire history and found a marked increase in large fires in the 1980s, Science Magazine reported in 2006. Wildfire seasons are longer than they were before; the researchers attribute that to increased spring and summer temperatures and an earlier spring snowmelt.
Additionally, wildfires contribute billows of carbon themselves.
“If the average length and intensity of summer drought increases in the Northern Rockies and mountains elsewhere in the western United States, an increased frequency of large wildfires will lead to changes in forest composition and reduced tree densities, thus affecting carbon pools,” the Science Magazine report said.
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