Cli­mate change still a fac­tor but hu­mans lengthen fire sea­son

USA TODAY US Edition - - NEWS - Doyle Rice @us­ato­day­weather USA TO­DAY

The hor­rific wild­fire that scorched Gatlin­burg, Tenn., in Novem­ber, killing 14 peo­ple, was hu­man-caused — and that’s not un­usual: Whether de­lib­er­ate or ac­ci­den­tal, a whop­ping 84% of all wildfires in the U.S. are started by peo­ple, says a new study.

The re­main­ing 16% are started nat­u­rally, by light­ning, ac­cord­ing to the report, one of the most com­pre­hen­sive to date.

The study also found that hu­mans have added al­most three months to the na­tional fire sea­son on av­er­age. “Thanks to peo­ple, the wild­fire sea­son is al­most year-round,” said study lead au­thor Jen­nifer Balch of the Univer­sity of Colorado. Hu­mans also ac­count for nearly half the acreage burned each year.

Balch and her study co-au­thors looked at 1.5 mil­lion wildfires from 1992 to 2012 and found that the hu­man-ig­nited fire sea­son was three times longer than the light­ning-ig­nited fire sea­son and also added an av­er­age of 40,000 wildfires per year.

“Fires are burn­ing ear­lier in the spring in the South­east and later in the fall in the West,” Balch said. Fight­ing wildfires in the U.S. has ex­ceeded $2 bil­lion in re­cent years, the study said.

“Although con­sid­er­able fire re­search in the United States has rightly fo­cused on in­creased fire ac­tiv­ity (larger fires and more area burned) be­cause of cli­mate change, we demon­strate that the ex­panded fire niche as a re­sult of hu­man-re­lated ig­ni­tions is equally pro­found,” the study said.

Catas­trophic fires have scorched the Western U.S. over the past decade. Sev­eral states, such as Wash­ing­ton and Cal­i­for­nia, have seen some of their largest wildfires ever recorded.

“We have known for a long time that fires set by peo­ple are an ex­tremely im­por­tant fac­tor in wild­fire prob­lems, but this study shows in de­tail how im­por­tant peo­ple are in length­en­ing the fire sea­son and con­tribut­ing to in­creas­ing num­bers of large wildfires,” said Thomas Swet­nam of the Univer­sity of Ari­zona, who was not in­volved in this re­search.

It’s not that peo­ple are be­com­ing more care­less or more ar­son is oc­cur­ring, he said. He said light­ning-caused fires are in­creas­ing in the West be­cause of warm­ing tem­per­a­tures, ear­lier springs and droughts, which mean “that cli­mate change is still a pri­mary driver of the trends.”

The study ap­peared in the jour­nal Pro­ceed­ings of the Na­tional Academy of Sciences.


A build­ing at the West­gate Smoky Moun­tain Re­sort goes up in flames dur­ing the spate of wildfires that hit Gatlin­burg, Tenn.

SOURCE Pro­ceed­ings of the Na­tional Academy of Sciences JANET LOEHRKE, USA TO­DAY

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