Wildfires on the Rise with Global Warming

People's homes and America's natural resources at risk

Posted: 11-Jul-2007; Updated: 20-Jul-2007

As the climate warms, hot, dry summers are creating tinderbox conditions ideal for wildfires.

For a time, many scientists believed that the alarming increase in U.S. wildfires was caused by poor forest management practices. But now the groundbreaking research by Dr. Westerling and colleagues at the Scripps Institution of Oceanography at the University of California, San Diego, points to global warming as the principle driver.

Several factors, exacerbated by global warming, add to fires

Extended warm seasons and milder winters also fuel the fire literally. Not only does this combination translate into longer fire seasons; it also promotes outbreaks of tree-eating beetles. These insects add large amounts of dead, dry wood that help fuel forest fires. The confluence of heat, drought and pests has made wildfires increasingly destructive in recent decades.

Because milder winters have allowed beetles to survive in regions where they could not previously, northern regions are among the places hit particularly hard by wildfires. Alaska, northern Canada, Scandinavia, and Siberia are susceptible to fires in the summertime — especially during warm, dry years. Huge tracts of Arctic spruce and pine forest in these areas have gone up in smoke.

"Since 1986," Steven W. Running reported in Science magazine in August 2006, "longer, warmer summers have resulted in a fourfold increase of major [U.S.] wildfires and a sixfold increase in the area of forest burned, compared to the period from 1970 to 1986."  He noted a similar increase in wildfires in Canada for the seven decades since 1920.

What's at risk

Here are just a few staggering statistics associated with recent wildfires.*

• Lives - In October 2003, the Cedar wildfire caused 15 deaths in California. In March 2006, 11 Texans lost their lives to the East Amarillo Complex wildfires.
• Property – In June 2002, the Rodeo-Chediski wildfire destroyed 426 structures in Arizona; the same month, Colorado’s Hayman fire took out 600 structures. California’s Cedar fire burned down 2,400 structures. The East Amarillo Complex wildfire destroyed 907,245 acres and 80 structures in Texas.
• Natural resources - In June 2002, the Hayman wildfire burned 136,000 acres of land; the Rodeo-Chediski fire charred 462,000 acres.

The increase in major fires is taking its toll on the United States. In addition to the loss of life and property destruction, wildfires:

• destroy one of our nation’s most treasured resource -- our forests,
• put public health at risk through worsening air quality. Fires produce smoke, noxious gases, and tiny soot particles. The smoke can be transported hundreds or even thousands of miles to urban centers, exposing millions of people to wildfire fumes.

* Statistics from NIFC

Recent wildfire stats

• 2006. The wildland fire season set new records for the number of reported fires (96,385) and acres burned (9,873,429). This season was 125 percent above the 10-year average and stressed firefighting resources. (More details)
• 2005. Despite an overall moderate season, Alaska bore the brunt of fires (accounting for about 51 percent of total acres burned), and a record number of acres burned. (More details)
• 2004. Alaska experienced its most severe fire season on record. The fire season started early with a lot of fire activity in January and February in Oklahoma, Maryland, Arizona, New Mexico, Texas and Mississippi. The year 2004 saw the warmest spring on record across the contiguous United States, including Alaska. (More details)
• 2003. Though at the season’s end, the 4.9 million acres burned was just slightly above the 10-year average, the number of structures destroyed by wildland fires was quite devastating. Of the 5,781 structures that were burned, 4,090 were primary residences, 51 were commercial buildings and 1,640 were miscellaneous outbuildings. (More details)

Sources

James Wang and Michael Oppenheimer. Global Warming’s Increasingly Visible Impacts. Environmental Defense. 2005.

Historically significant wildland fires, National Interagency Fire Center (NIFC).

"Is Global Warming Causing More, Larger Wildfires?" [PDF] Science magazine, Vol. 313, August 18, 2006.

Westerling, et al. 2006. Warming and Earlier Spring Increases Western U.S. Forest Wildfire Activity. Science.