Wildfire is a fire that burns in wildland or rural areas and can also impact communities with structures and infrastructure. It is a complex natural disaster that impacts the environment, society, and economics. Its adverse effects include property loss and direct human health impacts from smoke inhalation.
Wildland fires are a natural part of the ecosystem and occur when weather conditions allow them to ignite and spread. Droughts create dry, flammable fuels; heat and wind speed flames; and topography influences where fires start and spread. In some places, ecological factors such as vegetation type and management practices influence the likelihood of wildfire. Mowing, thinning, and prescribed fires decrease fuel availability.
Climate change can increase the amount of dry fuels in a given area, and the frequency of drought-like conditions and hotter summer temperatures can make it easier for wildfire to ignite and spread. Additionally, warmer nighttime temperatures enable fire activity to continue into the night. As a result, over the past 21 years extreme fire behavior has more than doubled worldwide, especially in temperate conifer forests of the Western United States and boreal forests of Northern North America and Russia.
The majority of wildfires are caused by humans, including unattended camp and debris fires, discarded cigarettes, and arson. In addition, human activities can increase the number and severity of wildfires by encroaching on or starting in wildlands that were previously undeveloped. While the number of wildfires varies widely, national trends may be difficult to discern because of inconsistencies in reporting, and a lack of long-term records that could be used to compare current wildfire activity to previous periods.