Each termite produces, on average, about half a microgram of methane per day, a seemingly insignificant amount. However, when this is multiplied up by the world population of termites, global methane emission from this source is estimated to be about 20 million tonnes each year.

There are more than 2000 different species of termites and the amounts of methane produced varies considerably between species, with some producing no methane at all. Methane is produced in termite guts, by symbiotic bacteria and protozoa, during food digestion.

Photo courtesy of Tim Myles.

Termite methane does not always end up going straight into the atmopshere, many species are subterranean or live in above ground earth mounds where much of the methane can be used up by soil methanotrophs before it gets out into the atmosphere.

Human Impact

The primary impact of humans on termite methane is reduction of emissions through termite habitat destruction. Many of the most important methane producing termite species are found in tropical forest areas, huge swathes of which are destroyed each year for logging, agriculture and housing developments. Additionally, in North America and elsewhere colonies of termites are regularly exterminated due to the threat they pose to wooden structures.

Potential for control

Aside from direct extermination of termite colonies and habitat removal, there exists the possibility of controlling termite methane production rates using methods originally developed for reducing methane production in ruminant livestock. Similar kinds of methanogenic bacteria and protozoa can be found in the guts of ruminant livestock and termites, so treatments which inhibit methanogens in ruminants could also work for termites. The key problem to be overcome with this methane reduction strategy would be application. The isolated nature of many termite colonies, and the fact that many are inaccessible for direct treatment by air means that applying a methane inhibitor on a large scale would be very difficult. One possible option is to spray just a handful of termites from each colony with the inhibitor and rely on these termites transferring it to the rest of the termite colony. Overall though, the long-term importance of this source of methane is likely to be determined by tropical and sub-tropical land-use practices.