What Causes Wildfires (and How to Protect Yourself Against Them)
Wildfires have been occurring longer than there have been humans on the planet Earth. They are unavoidable—scientists believe they began around 420 million years ago, as soon as plants began to grow. Many of the same conditions that make Earth hospitable to life also make it inherently flammable: its high amount of atmospheric oxygen, and its covering of vegetation rich in carbon both contribute to inevitable wildfire conditions, as does its instances of lightning and volcanic eruption. Seasonally dry climates add to a perfect storm of ingredients that make the occurrence of wildfires a question of when, not if.
Different areas of the Earth have different primary reasons for wildfires in those regions. In Canada and northwestern China, lightning is a major cause for wildfires. In Central America, Africa, New Zealand, South America, and Mexico wildfires are more often attributed to human activities. These activities include agriculture and animal husbandry, and land-conversion burning. Human carelessness is considered a major cause of wildfires in the Mediterranean Basin and in China. In North America and Australia sparks from machinery, cigarette butts, and arson are all thought to be significant causes of wildfires, as is lightning.
The spread of fire is then determined by the availability of what is commonly referred to as the “fire triangle”; that is, the components necessary for burning to occur. These components are heat, fuel, and oxygen. If the fuel for a wildfire is subterranean roots and the duff covering a forest floor, the wildfire is known as a “ground fire”. In the case of a wildfire using as fuel grass, debris, shrubbery, and leaves on the forest floor, the fire is known as a “crawling fire” or a “surface fire”. “Ladder fires” are wildfires where the fuel for the flames comes from mid-level vegetation in between the forest floor and the canopy, such as vines, small trees, and downed logs. “Crown fire,” “canopy fire,” and “aerial fire” are all different names for the same thing: a wildfire that uses for fuel the suspended material at the canopy level. These different types of wildfire all have different properties, such as the rate at which they spread and their susceptibility to specific causes, due to the varying “fire points” (the temperature required to burn them) of their respective fuel sources. Moisture content, weather conditions, and the verticality of the topography all affect the intensity of a wildfire and how fast it is able to spread.
Regions with dry seasons have always been more susceptible to wildfire than moister regions, such as the Amazon rainforest, or deserts where there is a lack of fuel. The cycle of moist seasons and dry seasons is ideal for the creation of wildfires: the moist season creates fuel in the form of vegetation, which is then susceptible to burn during the dry season. Lowered humidity and increased temperatures both strengthen the intensity of wildfires and the speed at which they spread.
For millennia humans have intentionally started fires as part of crop-growing techniques, and these fires sometimes spread beyond their intended scope. Slash-and-burn farming is the technique of burning an area used for farming once its soil has been depleted; the fire returns important nutrients back to the depleted soil, and the area is later able to be reused. It is believed that many areas of the Earth once had much more woodland than they do currently, but that widespread practices of slash and burning have destroyed much of them—this is true of the Mediterranean basin, which classical authors such as Homer described as being more heavily wooded. The forests of Central Europe were more resilient than their Mediterranean counterparts, and thus lasted longer, but many of these too were largely destroyed by the Viking Age. While slash-and-burn farming practices have been abandoned by most modern industrial countries such as the United States, they still survive in other parts of the world and can unintentionally begin wildfires.
Several regions of the United States are particularly susceptible to wildfire. California, Colorado, and Texas are the states with the highest amount of homes at risk from wildfires, and northern California specifically has been victim in recent times to the most devastating wildfires in its recorded history. The recent Camp Fire which swept the town of Paradise has taken more lives than any other. The droughts and increased temperatures of the region, along with low humidity, have created the perfect storm for wildfire destruction.
If you or a loved one lives in California or another area at risk for wildfires, you may be concerned about what precautions can be taken for protection. Fortunately there are several available measures to fire-protect a home. The first is to install a fire and ember resistant vent. Sparks from wildfires can travel for miles through the air until they land on a flammable material, such as your home. Even if the roof and exterior of your home is made of a fire-resistant material, sparks may easily enter through the home’s ventilation system and ignite the incredibly flammable materials of an attic or crawlspace. The only way to prevent this from happening is with a fire and ember resistant vent (we recommend the Vulcan Vent, which in addition to being able to resist intense heat is coated with a non-toxic material that will actually expand when exposed to flames, closing up its ¼ inch holes to prevent heat from passing through). Such a measure is incredibly important and can save your home and possibly your life. Use rocks, mulch, sand, and fire-resistant (high moisture) plants in your landscaping to create a defensive barrier against the spread of flames. Make sure your smoke detectors are working, and be careful if there are any smokers in the home that cigarette butts are properly disposed of. It’s always important to prepare for the worst, so have an evacuation plan.