Climate change has been a key factor in increasing the risk and extent of wildfires in the Western United States. Wildfire risk depends on a number of factors, including temperature, soil moisture, and the presence of trees, shrubs, and other potential fuel. All these factors have strong direct or indirect ties to climate variability and climate change. Climate change enhances the drying of organic matter in forests (the material that burns and spreads wildfire), and has doubled the number of large fires between 1984 and 2015 in the western United States.

Research shows that changes in climate create warmer, drier conditions. Increased drought, and a longer fire season are boosting these increases in wildfire risk. For much of the U.S. West, projections show that an average annual 1 degree C temperature increase would increase the median burned area per year as much as 600 percent in some types of forests. In the Southeastern United States modeling suggests increased fire risk and a longer fire season, with at least a 30 percent increase from 2011 in the area burned by lightning-ignited wildfire by 2060.

Once a fire starts—more than 80 percent of U.S. wildfires are caused by people—warmer temperatures and drier conditions can help fires spread and make them harder to put out. Warmer, drier conditions also contribute to the spread of the mountain pine beetle and other insects that can weaken or kill trees, building up the fuels in a forest.

Land use and forest management also affect wildfire risk. Changes in climate add to these factors and are expected to continue to increase the area affected by wildfires in the United States.

Since 2000, 15 forest fires in the United States have caused at least $1 billion in damages each, mainly from the loss of homes and infrastructure, along with firefighting costs. The 2017 wildfire season was well above average, with deadly fires in California and throughout the West, including Montana, Oregon, and Washington state. The 2018 wildfire season went on to also break records as the deadliest and most destructive season on record in California. NOAA estimates the total costs of wildfires in 2017 and 2018 to be more than $40 billion. In 2019, wildfires caused an estimated $4.5 billion in damages in California and Alaska. Alaska’s record-breaking heat and dry conditions over the summer months set the conditions for the state’s historic wildfire season. In 2020, five of the six largest fires on record burned in California and Oregon saw historic levels of wildfire spread and damage. Wildfires across the West led to weeks-long periods of unhealthy air quality levels for millions of people.

See a map of billion-dollar extreme weather disasters here.

• Wildfire can affect:
  • Federal and State Budgets: U.S. Forest Service fire suppression expenditures had increased from about 15 percent of the agency’s appropriated budget to more than 50 percent in 2017. Nationwide suppression costs in 2017 and 2018 ballooned to $2.9 billion and $3.1 billion respectively, while state wildfire expenditures have also increased substantially.
  • Public Health: The growing number of people in wild lands is increasing the risk to life, property and public health. Smoke reduces air quality and can cause eye and respiratory illness, especially among children and the elderly. Wildfires that burn in residential areas can melt plastic water pipes and cause contamination of water systems with a known carcinogen.
  • Natural Environment: Wildfires are a natural part of many ecosystems. Although wildfires produce a number of greenhouse gases and aerosols including carbon dioxide, methane, and black carbon, the plants that re-colonize burned areas remove carbon from the atmosphere, generally leading to a net neutral effect on climate. However, when fires burn more frequently and consume larger areas, as they are doing with climate change, the released greenhouse gases may not be completely removed from the atmosphere if plants can’t grow to maturity before burning, or if the plants that re-colonize are less efficient at carbon uptake.

How to Build Resilience

• Communities, builders, homeowners, and forest managers can reduce the likelihood and impacts of wildfires by:
  • Discouraging developments (especially residential) near fire-prone forests through smart zoning rules.
  • Increasing the space between structures and nearby trees and brush, and clearing space between neighboring houses.
  • Incorporating fire-resistant design features and materials in buildings.
  • Increasing resources allocated to firefighting and fire prevention.
  • Removing fuels, such as dead trees, from forests that are at risk.
  • Developing recovery plans before a fire hits, and implementing plans quickly after a fire to reduce erosion, limit flooding, and minimize habitat damage.
  • The Climate Mapping for Resilience and Adaptation portal helps communities understand and plan for their climate risks today and in the future, including a real-time map of wildfire, drought, flooding, and extreme heat across the United States.

For more details on wildfire resilience, read our report, Resilience Strategies for Wildfire.

Learn more about resilience by visiting our Climate Resilience Portal.