The challenge of estimating global termite methane emissions

• Published in: Global change biology Vol. 30; no. 6; pp. e17390 - n/a
• Main Authors: Law, Stephanie J., Allison, Steven D., Davies, Andrew B., Flores‐Moreno, Habacuc, Wijas, Baptiste J., Yatsko, Abbey R., Zhou, Yong, Zanne, Amy E., Eggleton, Paul
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-06-2024
• Subjects: Animals; Budgets; Carbon dioxide; Carbon sources; Climate Change; Data collection; Dead wood; deadwood; Ecology; Emissions; Estimates; Global temperatures; Global warming; Greenhouse effect; Greenhouse gases; Greenhouse Gases - analysis; Isoptera - metabolism; Isoptera - physiology; Land use; Methane; Methane - analysis; Methane - metabolism; methane budget; methane emissions; methane oxidation; methanotrophs; Mounds; Nests; Permafrost; termite mesocosm; Termites; tree stems; Wetlands; methane emissions; termites; methane budget; methanotrophs; termite mesocosm; deadwood; tree stems; methane oxidation
• ISSN: 1354-1013; 1365-2486; 1365-2486
• DOI: 10.1111/gcb.17390

Methane is a powerful greenhouse gas, more potent than carbon dioxide, and emitted from a variety of natural sources including wetlands, permafrost, mammalian guts and termites. As increases in global temperatures continue to break records, quantifying the magnitudes of key methane sources has never been more pertinent. Over the last 40 years, the contribution of termites to the global methane budget has been subject to much debate. The most recent estimates of termite emissions range between 9 and 15 Tg CH4 year−1, approximately 4% of emissions from natural sources (excluding wetlands). However, we argue that the current approach for estimating termite contributions to the global methane budget is flawed. Key parameters, namely termite methane emissions from soil, deadwood, living tree stems, epigeal mounds and arboreal nests, are largely ignored in global estimates. This omission occurs because data are lacking and research objectives, crucially, neglect variation in termite ecology. Furthermore, inconsistencies in data collection methods prohibit the pooling of data required to compute global estimates. Here, we summarise the advances made over the last 40 years and illustrate how different aspects of termite ecology can influence the termite contribution to global methane emissions. Additionally, we highlight technological advances that may help researchers investigate termite methane emissions on a larger scale. Finally, we consider dynamic feedback mechanisms of climate warming and land‐use change on termite methane emissions. We conclude that ultimately the global contribution of termites to atmospheric methane remains unknown and thus present an alternative framework for estimating their emissions. To significantly improve estimates, we outline outstanding questions to guide future research efforts.
Methane is the second most important greenhouse gas. Like ruminants, termites produce methane as a by‐product of microbial digestion in their gut and have a comparable global biomass. Therefore, various studies have quantified global termite methane emissions. However, we conclude that global termite methane emissions remain unclear due to inadequate data and insufficient consideration of termite ecology or accountability of methanotrophs, which remove any methane produced before it reaches the atmosphere. To reach a better estimate, new technology must be utilised to consider all termite sources, including soil, deadwood, tree stems and termite mounds.