Massive wildfires that have become increasingly common in recent years are a flash point for climate change, which in turn will spark additional devastating fires, research released Friday indicates.
The investigation suggests that the Earth is caught in a damaging feedback loop: Wildfires emit huge amounts of carbon dioxide, increasing the rate of global warming. That warming then increases the number and severity of wildfires.
It's a thought that should concern scientists studying climate change, as forecasting models haven't incorporated the link between fire and global warming, said Thomas Swetnam, director of the University of Arizona's Laboratory of Tree-Ring Research.
"The biggest concern I have is that it is possible that we are underestimating the positive feedback of fire to the climate system and affecting future climate," said Swetnam, a co-author on the study. "We may be underestimating how much carbon future fires will contribute to the atmosphere."
The researchers' main contention - that there's a greater link between wildfires and climate change than previously thought - might seem obvious at first, said David Bowman, a lead co-author and professor at the University of Tasmania.
But the research is important because international scientists involved in the investigation estimate that fires - whether caused by humans or by nature - release half as much carbon dioxide as comes from the burning of fossil fuels.
"We've provided a framework to think about fire in the Earth system, moving away from the thought that fire is just a disaster," Bowman said during a teleconference Thursday.
"Fires capture the attention of the media, but their effects are deeply subtle."
The article, titled "Fire in the Earth System," is set to appear in Friday's issue of the journal Science.
The findings are only a starting point, because the paper draws on preliminary data from disciplines including ecology, physics and climatology.
While the research suggests that wildfires breed more fires through climate change, it's clear that not all fires are caused by global warming, Swetnam said.
For example, fires in Southern California have other factors that impact their severity, such as seasonal wind and oceanic conditions.
Even some human-caused fires may have mitigating effects on global warming, such as increasing the amount of snow in a region after a forest has been converted to a tundra or plain, Swetnam said.
"The point is, we just don't have a good understanding of this," he said.
That's why the paper's authors are calling on the Intergovernmental Panel on Climate Change to study fire's impact, said Jennifer Balch, another lead co-author, who works at the National Center for Ecological Analysis and Synthesis in California.
"What we're calling for is inclusion of these important fire feedbacks," she said. "Fire hasn't previously been adequately and completely included in the models."
Swetnam estimates that human-caused fires account for about 20 percent of human-produced greenhouse gases, but he thinks that number could be greater.
Preventing massive fires through common practices such as controlled burns and other land-management tactics is important, though Swetnam believes the best way to prevent the cycle from growing is to reduce greenhouse gases.
"We don't want to get in a runaway situation where we lose control of it," he said. "Beyond the feedback effects from fires to the climate system, the fires cause all kinds of social and economic problems."
Arizona Daily Star reporter Tony Davis contributed to this story. E-mail Aaron Mackey at amackey(at)azstarnet.com.
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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