Termites and Methane: The Underestimated Climate Force
When we talk about animals and climate change, cattle usually come to mind. But there is another group of animals that, in total, is at least as significant for global methane emissions — and they are tiny, nearly invisible, and present almost everywhere in the world: termites. Estimates suggest that the roughly 50 trillion termites on Earth together produce several million tonnes of methane per year.
How Termites Digest Cellulose
Termites feed almost exclusively on wood, grass, leaves, and other cellulose-rich plant materials — substances that are largely indigestible for most other animals. Their success rests on a highly specialised digestive community in the hindgut: a complex ecosystem of bacteria, protozoa (in lower termites), and methane-producing archaea. These microorganisms break down cellulose anaerobically — that is, without oxygen. Anaerobic fermentation produces hydrogen, CO₂, and methane as by-products. The archaea use hydrogen and CO₂ to synthesise methane — a process called methanogenesis. The resulting methane is largely released into the environment through the termite's cuticle, excreted through the gut canal, or trapped inside the termite mound and later released by diffusion.
The Numbers: How Much Methane Is That?
Estimates of global termite methane production vary considerably — depending on the model and measurement method, they range from 2 to 22 million tonnes of CH₄ per year. The most commonly cited figure is around 11 million tonnes annually — approximately 4 percent of total natural methane emissions worldwide. For comparison: global cattle farming produces around 115 million tonnes of methane per year — about ten times more. Termites are therefore significant, but not the largest animal methane source. What makes them special: they are a natural component of many ecosystems, their emissions are not caused by human intervention — and they simultaneously play a crucial role in nutrient cycling in tropical forests.
Where Termites Are Most Active
Termite methane production is very unevenly distributed geographically. Tropical and subtropical regions — particularly the forests of Central Africa, Southeast Asia, and South America, as well as the African savannas — host the highest termite densities and therefore the largest emission sources. A single termite colony can consist of several million individuals. A large termite mound can function as a methane 'chimney': the porous structure of the mound allows gas to slowly diffuse outward. Measurements at termite mounds in Brazil and Australia found methane concentrations inside more than a thousand times higher than in outside air.
Climate Change Alters the Equation
A little-noticed consequence of climate change: termites benefit from rising temperatures. Their activity and population density increase with rising ambient temperature. Models predict that termite biomass in tropical regions could increase by up to 40 percent by 2100 — which would correspondingly increase methane emissions. At the same time, termites are advancing into regions previously unsuitable for them due to warming. This is an example of a positive feedback loop in the climate system: warming → more termites → more methane → further warming.
Did you know?
- There are an estimated 50 trillion termites on Earth — that's approximately 6,250 termites per human.
- A single termite colony can consist of several million individuals.
- Termites are responsible for about 4% of natural methane emissions worldwide.
- Climate change favours termites: rising temperatures increase their population density and thus their methane production.
Fun Fact
Termite mounds are remarkable air conditioners: they regulate temperature and humidity inside almost independently of outside temperature. A mound in the African savanna can maintain a constant 30°C inside at an outside temperature of 40°C. Architects study these structures as models for energy-efficient buildings — a concept known as 'biomimicry'.
Sources
- Sanderson, M.G. (1996). Biomass of termites and their emissions of methane and carbon dioxide. Global Biogeochemical Cycles, 10(4), 543–557.
- Brune, A. (2018). Methanogenesis in the digestive tracts of insects. Advances in Microbial Physiology, 74.
- Zimmermann, P.R. et al. (1982). Termites: a potentially large source of atmospheric methane, carbon dioxide, and molecular hydrogen. Science, 218(4572), 563–565.
- Eggleton, P. et al. (2020). The state of the world's insects. Annual Review of Environment and Resources, 45.