The Misunderstood Nature of Fire

Fire has inspired wonder in human beings since prehistory. Fire is used for cooking, warming and a variety of other purposes in our daily lives. It is also a key part of nature’s habitat, providing important ecological benefits that are often overlooked. Despite its importance, fire is also one of the most misunderstood natural phenomena. The way we think about and interact with fire can impact the effectiveness of its management and impose harm on ecosystems that evolved around it.

When you gaze at a blazing flame, it can seem solid and substantial, but that’s an illusion. The fire we see is actually a chemical reaction that consumes oxygen and combustible fuel to generate heat energy. Moreover, it’s a self-sustaining chain reaction. The heat produced breaks apart molecules in the fuel (wood or gasoline), which ignites a second reaction and releases even more heat energy, and so on. If the reaction stops, the fire is extinguished. This happens when the molecular structure of the fuel is consumed or when there is no more available oxygen near the combustible fuel source.

A fire’s heat is emitted through radiation, conduction and convection. The heat can travel through objects that conduct electricity, such as metals. It can also rise through the air in the form of smoke or hot gases and ignite combustible materials beneath it. The hottest parts of the flame are blue and orange, while the cooler parts glow yellow or white.

As we’ve all learned from the adage “ignition is everything,” it takes three things to start a fire: a combustible material like wood or gasoline, oxygen and an ignition source. Whether from lightning or a match, the initial heat produced by the ignition source raises the temperature of the fuel to its combustion point. That’s when the chemical reactions in its molecules begin to break down, and the resulting gases ignite.

Once the initial phase of a fire is over, it can spread to other fuels by conduction or radiation. This process can cause damage to structures like homes and businesses and create dangerous conditions for people and animals. It’s essential to monitor fire activity and follow fire restrictions when using outdoor fireplaces, campfires or barbeques.

When managed well, wildfire can reduce emissions and restore the natural balance of the ecosystems that depend on it. However, uncontrolled wildfires produce more carbon dioxide and can have negative impacts on human health. National Geographic Explorer Mercy Ndalila explains that improved wildfire management is critical for reducing these negative effects and protecting the ecosystems that evolved with fire. For example, the seeds of lodgepole pine trees are enclosed in resin that must be melted to release them. That requires fire to melt the pine cones and expose the seeds for planting. In these cases, the fire is intentionally set to accomplish a specific land management goal, and it’s known as a prescribed burn. This method of controlled fire is being implemented across the globe as a way to reduce environmental and societal risks.