Fire is a natural part of the ecology of forest and wilderness areas. It can also impact human communities and the health of people living in wildlands, but how a hazard develops into a disaster depends on the decisions people make about where they live and their behavior. Wildfire can cause a wide range of damage, from displacing families to destroying homes, and it can release greenhouse gases into the atmosphere and contribute to climate change.
There are three key elements that can fuel wildfires: conducive weather, dry fuel and an ignition source. As the world gets warmer and drier, the conditions for fires have become increasingly extreme. Warmer temperatures cause normally green vegetation to turn bone-dry, making it more flammable; droughts shrink available water resources; and high winds speed up the spread of fire. These factors are all driving a dramatic increase in the size and severity of wildfires.
Wildfires can be started by lightning or by human activity, such as a downed power line, unattended campfire or discarded cigarette. While most wildfires are naturally-occurring, about 85 to 90 percent of them in the United States are caused by humans.
Fire can be dangerous and destructive, but when it is managed well it helps restore forests and landscapes. At low intensity, fires consume and destroy invasive species, clean up debris and undergrowth, and provide space for healthier grasses, herbs and trees to grow. This can help reduce erosion and flooding and improve soil nutrient cycling.