Almost every time we have a major wildfire, alarmists blame global warming and claim that such warming will increase the incidence of wildfires. They also often claim that the number of wildfires is increasing. Their argument seems logical at first, higher temperatures and less precipitation will dry out forests making them more susceptible to wildfire.

The graph below compiled by C3Headlines using data from the National Interagency Fire Center in the U.S. and the National Forestry Database in Canada shows that the number of wildfires has decreased dramatically since 1970 and has remained relatively constant since the mid 1980s. The number of acres burned, however, has slightly increased and that may have to do with wildfire fighting decisions.

These numbers suggest some possible conclusions: either global warming does not have much influence on the number of wildfires, in contrast to alarmist claims, or there has not been sufficient warming since 1970 to test the hypothesis. Fire incidence could also reflect the time and severity of cyclic drought.

I’ve also included below the UAH lower tropospheric temperature record since 1979 when satellites began measuring global temperature.

Meanwhile, NASA says “Climate Models Project Increase in U.S. Wildfire Risk” The analysis was based on current fire trends and predicted greenhouse gas emissions. Time will tell if this is just another “garbage in, garbage out” computer simulation.

See also:

Mega-fires in Southwest due to forest mismanagement

Drought in the West

Droughts in the Southwest put in perspective

USDA says carbon dioxide can reverse effects of drought

From April 3 to 5, approximately 70 people, representing various federal, state, and local agencies, researchers and practitioners, gathered at the University of Arizona’s Biosphere 2, north of Tucson for the 2012 Southwest Wildfire Hydrology and Hazards Workshop. The purpose of the workshop was to: 1) share the most recent research regarding post-fire hydrology and hazard assessments and mitigation and warning systems; and 2) discuss ideas for bridging funding gaps for research and warning system implementation.

Thirty papers presented at the workshop are available from the Arizona Geological Survey document repository here. The files consist mostly of power point presentations and PDFs. I recommend beginning with the first paper (50 pages) on the list (see here) which gives an overview of the proceedings.

A new tree-ring and fire scar study from SMU and the University of Arizona finds that today’s mega-wild fires in the Southwest are unusual.

The 1,400-year record encompassed the Little Ice Age (1600 to mid 1800s A.D.) and the Medieval Warm Period (800-1300 A.D.) and found that fire incidence was nearly the same under both cool and warm, wet and dry conditions.

Forest policy of fire suppression prevented forests being naturally thinned by relatively small ground fires. The result was a build up of brush which exacerbated fires to produce even larger, more destructive wild fires. The researchers say, “The U.S. would not be experiencing massive large-canopy-killing crown fires today if human activities had not begun to suppress the low-severity surface fires that were so common more than a century ago.”

“This new study is based on a first-of-its-kind analysis that combined fire-scar records and tree-ring data for Ponderosa Pine forests in the southwest United States.”

“Fire scientists know that in ancient forests, frequent fires swept the forest floor, often sparked by lightning. Many of the fires were small, less than a few dozen acres. Other fires may have been quite large, covering tens of thousands of acres before being extinguished naturally. Fuel for the fires included grass, small trees, brush, bark, pine needles and fallen limbs on the ground.”

“The fires cleaned up the understory, kept it very open, and made it resilient to climate changes because even if there was a really severe drought, there weren’t the big explosive fires that burn through the canopy because there were no fuels to take it up there.”  ”The trees had adapted to frequent surface fires, and adult trees didn’t die from massive fire events because the fires burned on the surface and not in the canopy.”

Read the entire press release from SMU here.

This study implies that attempts at “sustainable” forest management and endangered species issues have in fact made our forests more unsustainable.

See also:

Drought in the West
Droughts in the Southwest put in perspective