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The number and severity of wildfires in California is expected to increase if global warming is not curbed. A fire chief from San Bernardino and a scientist explain how this could affect health and safety in the video, Up in Flames.

IMPACTS Wildfires

Wildfires are a major environmental hazard that have historically cost California more than $800 million each year and contribute to "bad air days" throughout the state. As global warming accelerates, so will these wildfires, and the damage to health and property that they cause. By century's end, we may see as many as 55 percent more large wildfires if we fail to make significant cuts in global warming emissions.

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More Wildfires Expected

If average statewide temperatures rise to the medium warming range (5.5 to 8°F), the risk of large wildfires in California is expected to increase about 20 percent my mid-century and 50 percent by the end of the century. This is almost twice the wildfire increase expected if temperatures are kept within the lower warming range.

Along with temperature, wildfires are determined by a variety of factors, including precipitation. Because of this, future wildfire risk throughout the state will not be uniform. For example, a hotter, drier climate could increase the flammability of vegetation in northern California and promote up to a 90 percent increase in large wildfires by the end of the century. A hotter, wetter climate would also lead to an increase of wildfires in northern California, but to a lesser extent—about a 40 percent increase in wildfires by century's end.

More "Bad Air Days"

Wildfire smoke produces small soot particles, which can cause or aggravate cardiovascular and respiratory illness and lead to premature death. For example, the wildfires that burned nearly three-quarters of a million acres in southern California in 2003 caused particulate matter (soot) to increase four to five times above normal levels throughout the southern part of the state. Five million people were exposed to dangerous levels of air pollution for at least two days during the fires, and nearly two million were exposed for five days in a row.

Wildfire Costs Expected to Increase

If global warming emissions continue unabated and temperatures rise into the higher warming range, property damage costs from California wildfires could increase as much as 30 percent toward the end of the century. This estimate is conservative because it assumes population and land-use patterns are held constant at 2000 levels, even though the state's population is expected to grow from 36 million today to more than 55 million by 2050. Furthermore, other fire-related costs such as fire prevention and suppression, health effects of fire-related pollution, flooding, mudslides, altered recreation opportunities, and loss of timber were not included.

Because most global warming emissions remain in the atmosphere for decades or centuries, the energy choices we make today greatly influence the climate our children and grandchildren inherit. We have the technology to increase energy efficiency, significantly reduce these emissions from our energy and land use, and secure a high quality of life for future generations. We must act now to avoid dangerous consequences.



Westerling, A., and B. Bryant. 2006. Change and wildfires around California: Fire modeling and loss modeling. Sacramento, CA: California Climate Change Center. Online at www.energy.ca.gov/2005publications

Wu, J., A. Winer, and R. Delfino. 2006. Exposure Assessment of Particulate Matter Air Pollution Before, During, and After the 2003 Southern California Wildfires. Atmospheric Environment January.


See the warming projectionsTo learn more about the effects of global warming on California under different emissions scenarios, see the Impacts Overview.


charts showing increase in wildfire frequency
chart key

* Projected range highlights the dual role of precipitation and temperature.
Chart data source: Westerling and Bryant 2006


ucsusa.org: Global warming and California wildfire fact sheet. (PDF)

energy.ca.gov: "Climate change and wildfire in and around California," California Climate Change Center. (PDF)

energy.ca.gov: "The response of vegetation distribution, ecosystem productivity, and fire in California to future climate scenarios," California Climate Change Center. (PDF)

energy.ca.gov: "Fire and sustainability," California Climate Change Center. (PDF)

energy.ca.gov: "Predicting the effect of climate change on wildfire severity and outcomes in California," California Climate Change Center. (PDF)

energy.ca.gov: "Climate change-projected Santa Ana fire weather occurrence," California Cliamte Change Center. (PDF)

Union of Concerned Scientists