Global warming and decades of outmoded fire prevention strategies are merging to set the stage for massive "mega-fires" that scar communities' homes and pocketbooks, according to a new assessment.

Preliminary findings from the United Nations' Food and Agriculture Organization (FAO) released this week trace the circumstances around eight mega-fires across the world in a quest to uncover clues on how best to ward them off and minimize their damage. Such fires are defined more by their impact on people and the environment than by their specific size.

"Mega-fire is more of a concept than a construct," said Robert Keane, a research ecologist at the U.S. Forest Service's Missoula Fire Sciences Laboratory who was not involved with the report. "What I interpret [mega-fire] to mean is not only is it large, but it affects a lot of people," he said.

Collectively, that type of definition might include the wildfires that are currently tearing through Texas or the Fourmile Canyon Fire in Colorado, which left an estimated $217 million of property damage in its wake last year (ClimateWire, April 26); ClimateWire, Oct. 26, 2010). Mega-fires manage to thwart all efforts to control them until firefighters get a favorable change in weather or until they burn all available fuel.

In the United States, only 1 or 2 percent of all wildfires become large incidents, but they engulf about 85 percent of total suppression-related costs and amount to more than 95 percent of the total acres burned, the report notes, citing earlier work. "Among all wildfires, mega-fires are the most costly, the most destructive and the most damaging. Against the backdrop of global warming, their onset may be signaling that many conventional wildfire protection strategies are 'running out of road,'" the authors write.

Droughts set a larger stage for human error

These large fires can have significant regional or global repercussions, including interrupting or altering water cycles and releasing vast amounts of carbon into the air. Scorched hillsides left in the aftermath of far-reaching flames can also leave lands more vulnerable to mudslides and prone to future burns.

"The growing number of large wildfires and the increasing incidence of mega-fires -- along with climate change projections for hotter and drier fire seasons -- lend urgency to this issue," the report states.

Mega-fire examples cited in the report include the 1997-1998 Kalimantan Complex burn in Indonesia, which scorched 9.7 million acres and released 700 million tons of greenhouse gases into the atmosphere, and another fire that wreaked havoc in Botswana in 2008 -- burning 3.6 million acres and costing about $240,000 to suppress. The work also looks at recent fires in Australia, Brazil, Israel, Greece, the Russian Federation and the United States.

For comparison, the report also examines two areas that have been plagued with drought but have managed to reduce the incidence of mega-fires -- Florida and Western Australia. Their secret: consistently conducting prescribed burns to minimize those areas' fire risk, the authors wrote. Spearheading the report is Jerry Williams, the former national director of fire and aviation management for the U.S. Forest Service.

"Drought sets the stage and human negligence may provide the spark, but vulnerable vegetative conditions are fueling the mega-fire threat," his team writes.

While the jury may still be out on the exact science behind mega-fire threat, it seems likely that risk of mega-fire is heightened as "droughts deepen, fuels accumulate, and landscapes become more homogeneous," the report says. Another ingredient fueling these fires may be government policies that impede effective wildfire protection capabilities, it notes.

In its recommendations, FAO calls for more comprehensive fire management and improved monitoring of wildfire emissions, underscoring that greenhouse gas emissions can perpetuate a dangerous feedback loop.

Focusing on mega-fires and demonizing large burns comes with its own set of risks, warned Keane. Large fires can sometimes be a good thing for the landscape -- as long as they don't endanger lives.

Click here to read the report.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500