To what extent is the methane produced by termites contributing to climate change?
Termites produce methane and methane is a potent greenhouse gas. So, are termites contributing towards climate change? There are certain challenges in calculating their impact, but researchers in Japan have recently updated the estimate of the global impact of termite-produced methane using the latest data sets and a biogeochemical model.
In digesting wood, termites break down lignocellulose with the aid of their symbiotic gut microbes. One of which, Methanogens archaea, produces methane. As a result, termite nests are methane-producing hotspots. Previous estimates of methane production by termites have used estimates of termite biomass and known rates of methane emission to generate a global figure for termite methane emissions. However, the rate of emissions in the different environments around the world are highly variable, depending on temperature, vegetation, land use and termite population, making accurate estimates difficult. Also, little consideration was given to how emission levels may change over time due to global and local environmental changes.
This new study attempted to produce a more accurate estimate of global termite emissions using a detailed range of factors in the analysis plus the latest modelling techniques. It also investigated the factors that could be impacting the changing levels of termite methane emissions by carrying out simulations for historical and future periods. The study took into account factors such as climate, land use and vegetation productivity (using a biogeochemical model). The land area estimates of potential termite habitat were based on a temperature model, restricted by taking into account land area used for agriculture. This allowed a total termite biomass to be estimated.
The estimated global termite biomass was 122.3 Tg dry weight. A Tg = 1 billion (109) kg! This is comparable to previous estimates and implies the global termite biomass is larger than ants and similar to humans (100 Tg dry weight).
Based on these biomass estimates, the total termite methane emission in 2020 was estimated at 14.8 Tg methane per year.
Although this sounds like a lot, how much is this compared to total global methane emissions? The researchers estimate that termite emissions “are a substantial component of the global methane budget – about 2% of the total emissions (natural and human generated) and 4% of the natural emissions”. Or put another way, the total termite methane emission is more than the human-generated methane emissions released from most countries (on an individual basis), except for the six largest countries.
Whilst termites have been emitting methane for millions of years, certainly before the arrival of humans, it’s important to understand their contribution to methane production and importantly to understand how human activity is actually changing the level of methane produced by termites due to human-mediated climate change and changing land use.
The researchers estimated that the amount of termite methane emissions had increased from 13.1 Tg methane per year in 1900 as a result of increasing termite biomass due to higher climate temperature and increased vegetation productivity (due to increasing carbon dioxide in the atmosphere).
Estimated future termite methane emissions are very much impacted by the climate change model use – are humans going to take the necessary steps to reduce global warming or not?! Best case scenario estimated that termite methane emissions will increase by 0.5 Tg/year and worse case scenario by 5.9 Tg/year. The Global Methane Pledge calls for country-level methane reductions of 30% by 2030.
The study points out that the forecasted increase in termite methane emissions from this latest modelling would seriously undermine efforts to reduce methane emissions, more so for countries with a higher termite biomass.
More information on termites and latest termite research.
Further reading: Ito, A (2023). Global termite methane emissions have been affected by climate and land-use changes. Scientific Reports: 13
