Wildfires also getting the blame for spewing global warming gas

WASHINGTON — In one week, Southern California’s wildfires spewed the same amount of carbon dioxide — the primary global warming gas — as the state’s power plants and vehicles did, scientists figure.

A new study by two Colorado researchers shows that U.S. wildfires pump a significant amount of the greenhouse gas into the air each year, more than the state of Pennsylvania does. It raises questions about how useful it is to plant trees to offset rising carbon dioxide emissions and soothe environmental consciences.

Because the California wildfires occurred just as the study was about to be published, the researchers calculated how much carbon dioxide was likely to come from the devastating blazes Oct. 19-26. It’s a lot: 8.7 million tons.

That’s more than the state of Vermont produces in a year. And it’s also more than the 6 million tons estimated by California’s air control agency, which used a different calculation method.

On average, wildfires in the United States each year churn out 322 million tons of carbon dioxide. That’s about 5 percent of what the country emits by burning fossil fuels, such as gasoline and coal, according to the new research published online Thursday in the peer-reviewed journal Carbon Balance and Management.

“It is quite a big chunk,” said study co-author Jason Neff of the University of Colorado at Boulder. But he adds: “It’s nothing compared to our fossil fuels burning.”

Mostly when scientists look at carbon dioxide emissions, they spend their time on the stuff that man adds to power industrial life. But Neff and Christine Wiedinmyer at the National Center for Atmospheric Research in Boulder, Colo., looked at forests, which act as a sponge and absorb some of the carbon dioxide, but which also burn and produce it.

“The problem is that what goes in, comes out,” Neff said.

The Western continental United States is responsible for more than one-third of the country’s carbon dioxide from fires. But Alaska is king. Alaskan fires produce twice as much of the greenhouse gas than burning fossil fuels in that state. Alaskan fires make up 27 percent of the nation’s yearly fire-related carbon dioxide emissions.

In the Lower 48, Washington, ­Oregon, Idaho, California, Montana, Louisiana, Georgia, Alabama, Florida and Texas are top 10 emitters of carbon dioxide through forest fires.