The rainforest is being cleared and burned in Borneo. A majestic Meranti tree is close to the edge of the forest. As flames from the nearby fires rage closer to this ancient tree, water quickly evaporates from its leaves, transforming the foliage into dry fuel for the fire. When turbulent, convective winds within the canopy bring hot air to the immediate surroundings of our tree, long-chain cellulose molecules in the desiccated foliage begin to crack, producing hydrocarbon gases and solid char deposits; with a flash, the gases ignite, forming the flames of the fire.
This brief, catastrophic episode at the end of this tree’s life quickly rebalances a century of organic chemistry. Throughout its life, the tree had accumulated a great amount of potential energy in the form of carbon stripped from its preferred partner oxygen thanks to energy from the sun through photosynthesis. Once provided with a source of ignition, carbon atoms in the tree and oxygen atoms in the air gain enough energy to reunite, releasing a great amount of energy, sustaining high temperatures and producing a chain reaction that is a fire. As the great physicist Richard Feynman once put it, “the light and heat that’s coming out [of a log fire], that’s the light and heat of the sun that went in. So it’s stored sun that’s coming out when you burn a log!”
According to Feynman, one could explain that a forest fire is ‘recycled sunlight’, a natural component of the carbon exchange between the biosphere and atmosphere. After all, fire is endemic to many of our planet’s natural environments, essential for regeneration, fertilisation and germination of many plant species. But does all of this burning have any influence on our climate? Continue reading “Why wildfires fuel climate change”